How-To: Diagnose Motorcycle Vacuum Leaks

[@tamaraharrah9674]

Thanks I’m in the middle of a poker run. On an old machine. Loosing power. Engine idle change with steering Watched your video and hopefully be back in game soon!!

[@hazimreitz]

After watching your video, and I was making sure nothing was leaking. My bike still struggle to stay idle until it warms up. Low and behold, i got a cracked exhaust valve 🤣🤣🤣 I was spraying stuff and see if anything changes, and as I spray it died. Long story short i was chasing my own tail for 2 hours before I realize my boot and all that is good which is a plus, but a cracked valve was not what I was expecting. Anyway awesome guide and explaination!!!

[@murphytoadster9864]

Hate when you go crazy trying to clean your carbs all day and then you finally realize it was the bad boots

[@Mediapickle]

You did a good job explaining how to find vacuum leaks. I'm going to try this when I get my carbs back on. I have a 2002 Yamaha Vstar 1100 custom. When in the throttle, it runs great and you had better hold on. When you let off it bucks a bit and runs rough. You have to stay in the throttle for it to run smooth. I am putting in new jets and a K&N air filter. It has cobra slash cut slip ons already. I am also adjusting the pilot mix screw to 2-1/2 to 3 turns. Then Im going to sync carbs.

[@rjbizz198787]

Chris Dill I have the same bike same exhaust and cold air Intake mine is back firing badly throttle hangs runs like shit gets hot real quick can't figure it out do you have any suggestions

[@qamihai2585]

​@@rjbizz198787Air cut-off valve?

[@HTMR]

Check for leaks and correct pilot screw adjustment.

[@sjp4ut]

You are awesome man! Thanks for what you do, including answering peoples questions in the comments.

[@HTMR]

No problem!

[@NYCMTB-SITR]

This is the only video that I have found that claims intake leaks for decel popping. Glad I did this video. Going to auto parts for another can of carb clean to check my Harley. I have been chasing this problem in this new to me Harley.. Good news is I did a stage 1 upgrade but tired of popping especially on a long down hill

[@HTMR]

Jose, stage 1 is what? A high flow air cleaner? Is this carbed or FI? Did you rejet or get a fuel programmer?

[@NYCMTB-SITR]

A stage 1 is a high flow exhaust and intake, larger keys for more fuel delivery and an upgraded ignition system

[@HTMR]

Larger keys? Carb or FI?

[@ToAnEnd]

I have a Shadow 600 that bogs down and sometimes will even die at half throttle but only when I’m in gear and moving, I can rev all the way up to redline in neutral though. I’ve taken the carbs off multiple times and cleaned the heck out of them and everything looks really good. I haven’t tested for vacuum leaks yet but I plan to tomorrow. Do those symptoms sound like they could be caused by worn out boots?

[@HTMR]

Sounds lean for some reason. Stock bike? Including air cleaner assembly?

[@BLASTERGIFT]

These old boots are awful!!!! And i thought mine had a problem! Anyway I did a quick repair and covered them with a good coat of the black RTV all the way around but yours are damaged beyond any repair . RTV is for small cracks to prevent farther damage.Now all i have to do is the test with the carb cleaner.Thank you ! Im glad you fixed these old boots

[@HTMR]

Possibly. Check out my CB750 vacuum leak video where I take it for a spin. If you have the same symptoms, then yes you have leaks.

[@HTMR]

Boots run anywhere from 10-30 each, depends on the model.

[@jamesa6272]

Careful with those intake boots on these old bikes. I needed a set for my 86 rebel 450. No one had them in the world except ebay(crazy crazy prices) or one man in the Netherlands. Luckily I got a set from him!

[@HTMR]

Does it stumble and die? What do the plugs look like? It probably is not getting fuel due to a plugged passage in carb or massive vacuum leak.

[@HTMR]

Have you checked timing, compression, valve adj? What does the plug look like?

[@alexgrein9882]

Hey quick question- my cb 450 engine revs like crazy without the choke on it. I did your test with the carb cleaner and found that the rubber boots on the intake manifold absorb ALL of the carb cleaner I spray on it. That means the boots have an air leak and are no good right?

[@baydude1701]

Alex Grein Yes

[@harvinjoy9895]

Yup .. Change . change them all . and pray for good luck

[@B3nAn]

What kind of symptoms were you having? My idle is supposed to be set at 1500 rpm and it stays at 2100 and if I try to lower them with the idle screw when the rpms go lower than 2100 bike dies.

[@rodofsteel6662]

Cb900c I sprayed all over and the only spot that made the bike rev was the 2 crank case breather tubes, they meet at a t that goes to the air box. I am lost and not sure if that makes sense but also after a ride it revs 5000rpm when I hold the clutch in, once I shift and take off again everything is fine.

[@joegardiner4220]

Now I tried this on my bike and it started revving higher, so I cleaned the manifold, installed new boots exactly how it stated in the manual and it still notice high revs if I spray brake cleaner. I don’t have the air box installed could and I’m not spraying the cleaner through a straw. Could the carbs be sucking in mist from spraying the boots ?

[@HTMR]

Revving up is a vacuum leak. Get a straw on it and try to pinpoint the exact area. Boot clamps not tight enough? Throttle shaft vacuum leak?

[@joegardiner4220]

MatthewMCRepair yeah I will have another go at the weekend, only thing I can think is I did re use the gaskets ( gsxf 750 ). Anywho I’ll install the air box and try it with a straw. So frustrating when you think you’ve got it all figured out then boom, back to square one ! Thanks very much for the fast reply

[@HTMR]

So you had to remove the cams? I would double check cam timing.

[@CanadianMapleleaf]

Spraying carb cleaner on your rubber intake ports while diagnosing will dry out the rubber and cause it to crack.

[@eastcoastmostwanted710]

not if you spray a few sprays my boiii

[@HTMR]

I would check compression, put in new plugs, check timing if applicable, clean carbs, check for vacuum leaks, synch carbs, and tune pilot fuel screws.

[@jerryrodriguez1630]

Hello I have an 03 Yamaha R6 and I'm having a light rattling noise when I accelerate around 3 to 4 thousand rpms I had the valves,coils,plugs,cam chain checked and according to the yamaha dealer they are all in spec however the noise is still there and I am noticing that the exhaust is way louder than before and when I accelerate it feels rough kinda like a muffled sound. Any help would be greatly appreciated Thanks

[@ivandepasquale2717]

I will also be replacing the intake manifold as I have noticed a few small air bubbles when spraying petroleum jelly while the bike is running. One question: In addition to its "paper" seal, should a high-temperature sealing paste also be applied?

[@HTMR]

Use carb spray. If there is an idle change then there is a leak. Otherwise don't worry about it. Any sealant would be specified in your service manual. Depends on make and model.

[@NomadicDreamcatcher]

I have a Johnny Pag Spder with twin carb and having trouble with it when riding. No trouble in starting but when in low revs and then open up at 1/4 tern of throttle, the bike will stutter. I have cleaned the twin carbs so that they look new now. Also cleaned the spark plugs...that had normal colour...air filter. The problem still the same and that is, when crawling in trafic and then open up the throttle, 1/4 turn the bike will stutter, in all gears. I have no idea now what to do. Love your video man.

[@HTMR]

Have you checked for vacuum leaks and/or adjusted the fuel screws?

[@NomadicDreamcatcher]

No leaks as for the fuel screws mine are on the air side of the carb, I have not touched them. Thinking no need as the bike was working fine one second then the next second the problem. The strange this is the next day after doing nothing to the bike, the bike was behaving as normal but after about twenty back the problem again.

[@HTMR]

NomadicDreamcatcher Can you post a video? Also, if you did not touch them, how did you clean the carb?

[@NomadicDreamcatcher]

When I said I did not touch them I was meaning I did not change the settings of them. They were three terns out and when putting them back I counted three turns. So they were put in the same amount of turns as they were taken out. The strangest thing is sometimes the bike runs perfectly then back to the same problem after about 1/2 hour. I'm beginning to think that it's a electrical problem!

[@HTMR]

NomadicDreamcatcher If they are indeed air screws (if they have a blunt tip), then 3 turns out is really lean. Does the problem appear once engine is hot? Try adjusting the air screws, you can always go back to 3 turns out. A video would help tremendously.

[@jamesdavey453]

Your probably not still on here but I’m having a problem with my 125cc moped it idles nicely but when I throttle it bogs out when I get to about half throttle, I’m going to try clean the carb but I thought it could of been the filter too.

[@jimmydavis5055]

I really hope you still check this. I think I have a vacuum problem, but I just can't seem to find where it's at. The original boots looked fine. I swapped them out just in case. The thing is, my motorcycle won't run at all unless we add suction on the vent valve on top of the carburetor. Then it runs normally. That's why we think it's a vacuum issue. We've gutted out this carb and cleaned everything. None of the diaphragms look bad at all. We changed the petcock. Do you have any idea what it might be? I've blown in the gas tank and the overflow hose blows out (not sure of that might be an issue, but it was just to check). I'm about to break down and have a mechanic work on the bike, but I've spent so much on parts

[@HTMR]

Email me some pics

[@scroogehowsshehandle]

Do this same problem effect 2 strokes?

[@archygrey9093]

I got a used bike recently and it ran alright, but when i serviced it and replaced the very dirty airfilter (could not see any light through it at all) it ran like shit afterwards. Found the big vaccum leak soon after and figured the clogged air filter was creating enough of a rich mixture to actually counter the vacuum leaks leaning effects.

[@HTMR]

Ken, I never tried WD-40. I found that really flammable fluid works best. Send me an email and we can talk about your Silverado.

[@norcal8718]

How could spraying something flammable in the intake make the idle go down? And what are the odds of all four boots leaking, I'm just saying I never heard the idle change at all when you were spraying.

[@HTMR]

It goes really rich and kills the cylinder.

[@plantagenant]

Thanks for the reply...will check those things. I've noticed bike over-revs when starting from cold but doesn't do it if I start the bike when the engine is warm......ah! the joys of motorcycle maintenance!

[@Thegoodteamthatone]

I got a Baja 125 all the problems of a vacuums leak I have and I know I have one and my manafold I was told when I bought it was bad and I know it is by looking at it just wondering would this also cause a full throttle change and not being able to floor it without it bugging out and bogging down and decelerating

[@HTMR]

+PLAN Fazz Yes, vacuum leaks will cause it to BOG.

[@Thegoodteamthatone]

ight what i thought cuz it wouldnt be getting enough air thx man for the reply

[@steve5912]

MatthewMCRepair Hey man i have a 1978 Honda xr75 and it runs and drives but it revs up really high 75%-80% throttle at all times it is rideable do u think this might be the problem

[@namelesssnitchy]

Is partscleaner also usable? Or does it eat rhe rubbers too much?

[@travis00017]

Thanks for this video. A question about the carb cleaner, though. I've read in forums when cleaning carbs to make sure carb cleaner only gets on the metal parts because it can eat away at some of the rubber diaphragms, etc. I also remember the first time I put jets in a plastic cup to soak in carb cleaner and how it instantly melted the bottom of the cup. Couldn't this do damage to the boots you are spraying and potentially anything else nearby? Maybe you are using a less caustic type of carb cleaner?

[@HTMR]

travis00017 As long as you wipe up the carb clean you will be OK. I usually take a blow gun immediately after dry all the solvent up. The issue is when it is left to "soak", like you already found out.

[@johnconnersmithllc6095]

How do you know the difference between a vac leak or a fuel shortage? My GSXR 1000 sucked some s*** in the injectors. I clean the fuel pump and all that crap out put it all together is a b**** to start and ran like s***.. I put some fuel additive and s*** in there it started to smooth out pretty good but now it's backfiring like crazy and sounds like my f****** Ninja 650 or something. The airbox was loose but I tightened it all up now so I'm trying to figure out if the injectors are jammed or if it's a damn vacuum leak

[@HTMR]

A vacuum leak is air introduced OUTSIDE the air tract to engine. So if you spray carb clean and idle goes up or down, you have a vacuum leak.

[@fipl1205]

I want to get into riding. Decided to buy a motorcycle. A cheap one to learn how to ride. I bought a 125cc venom x22. The revv during idle is too high. varies from 3,000 to 4,000. I just got the bike two days ago. I checked the idle screw on the carburetor and turned it counter clockwise as told by many articles I have read about this issue but the issue isn't fixed. Do you have an idea what else it could be and how to do it myself?

[@HTMR]

Make sure there is proper slack in throttle cable

[@barcusful]

Thanks Matt. I wonder if you could advise me?;;;;;; My XJ600 1989 pre-diversion is running like a distempered rats bottom! Just bought her, only to discover she idles (just about) with intermittent 3 cylinder firing and then all 4. At low revs, under power, she splutters upto 2k rpm and then takes off. When she reaches 6k rpm she simply does not want to go any further in the revs and chokes. I have changed the fuel pet cock, but no change. Any advice? Thanks.

[@dg2thetop351]

My carburetor makes a whistling sound after give it a lot of gas is that an air vacuum leak?

[@HTMR]

Sounds like a good plan. Let me know how it works out.

[@KaibaCorp57]

Hey man! My motorcycle dies after a hard acceleration run. Engine dies after I let go of the throttle after twisting it fully for some seconds. Is it torn diaphragm? I didn't understand the diaphragm valve you were talking about.

[@HTMR]

Watch this video: kzbin.info/www/bejne/ioebeH-voc9oma8

[@reyland8439]

The sound from the enging after you fix the vacuum leak, is it normal sound? Please reply, i need answer

[@ISN1P3RxK3LLY]

hi matt i have a 250 recon atv when i start it up i have to keep my thumb on the throttle to keep it running or it will just die out it does this even when its been running a while, ive tried adjusting the throttle cable but to keep it running it has to idle very high which isnt right.the quad is burning some oil too but im getting the cylinder bored soon and ill use a larger piston but i dont think these problems are related. any help would be appreciated.

[@HTMR]

I would recommend not using RTV at all, boots are cheap. If they are not available, then that is a different story:)

[@Mini-uq6px]

Carb clean cracks rubber no?

[@bradycervetti7492]

This could be a dumb question, but I was told that you should avoid getting carb cleaner on gaskets and o rings and stuff because it would ruin the rubber somehow. Is this just false or is it a different case with the rubber boots? Thanks!

[@HTMR]

Brady, yes you want to wipe up or blow with compressed air to dry the carb clean as soon as posible to prevent damage. I have found that a quick spray does not do any damage. Soaking them overnight is a different story. Sorry if I missed that in the video.

[@johncavenaugh9453]

I have a buell blast 500, it sounds like i have a vaccum leak. When i pull the throttle it sounds like it is sucking air in and maybe a little bogging down also.

[@HTMR]

Did you check for vacuum leaks? Could be a dirty carb as well.

[@darktimefreak1678]

I have a fuel injected bike and when i rev it at idle it sticks to 4k rpm and struggles to go down to 1.8k... it happened to me last night when i was about to go to work .. glad i got second bike .. any tips .. you think its vaccum leak if idle rev stays high rpm and dont go back to normal idle ?

[@SupremeDuckLord]

That most definitely is a vacuum leak. Have you fixed it by now?

[@angrypanda6942]

My carbs is balance at idle but not when I revs. The left have more vacuum than the right

[@rasmushaun1773]

Hey MatthewMCRepair, I have replaced my intake boots on my cbr 600 f2. If I do a vaccum leak test with starting fluid, and spray a lot at the same spot, I can still make the engine rev a little bit. Is that an issue? How tight should those boots clamps be?

[@HTMR]

Clamps should be tight.

[@basstradamus1]

Matt any chance you can publish some tips how to test exhaust leaks, especially where the head pipes meet heads?

[@cfraser650]

A BBQ lighter and watch the flame when you hold it near the flanges or suspected leaks. You will see the flame move and wave.

[@kevinsmith9317]

hello, I recently purchased a project bike that was reported to have been running fine, then during a ride the bike cut out and has sat since. I checked the bike, it cranks and shifts fine, but will not fire. I just cleaned the card, but think it is a vacuum leak. I noticed there is a T connection on one of the lines on top of the carb and the cap is torn up real bad. will the "cali emissions" T connector on this hose, cause vacuum issues that stop fuel from flowing to the carb?

[@HTMR]

Email me here so you can share some pics: www.howtomotorcyclerepair.com/contact/

[@jessicagalvan3427]

MatthewMCRepair

[@rideout_ryan]

someone told me my dirt bike has an air leak because it doesn't return to idle very well

[@rc2634]

Exactly. It is a sign of air leak

[@rjwgardensandmachinery]

I have just found a similar problem with my bike and on inspection straight away I found a load of splits in the intake boot

[@RCNFLOriginal]

What do I do if it Redlines when it starts?

[@CamTheNomad]

I just bought a 81 cb650. That looks like what you are working on here. I am having a cylinder misfiring type of issue. Could the vacuum leak be what is causing that? Also it doesnt want to run higher then 5k when under load. Any advice would be much appreciated. Thanks!

[@HTMR]

I responded to your message.

[@TylerCook]

How much should replacement boots run? I saw some new on EBay for 165$. And i feel thats way too much . Where can I get some for the front and rear.?

[@HTMR]

+Tyler Cook Tyler, based on your comment on my blog, I believe you got quotes from the dealer?

[@TylerCook]

No, I have not.

[@HTMR]

+Tyler Cook PN 16214-438-000, 16213-438-000, 16212-438-000, & 16211-438-000. Qty 1 ea and about 20ea from partzilla.

[@TylerCook]

Wow! thank you so much. This really helps out a lot!

[@HTMR]

+Tyler Cook No problem :)

[@HarryVanderBerg]

Hi,ive replaced carb,cables,cam,spark plug,on a 4year old 200cc chinese bike,set the valves but not replaced the boots,but i think there is a leak or a clogged up pipe as this bike start difficult and does not want to idle,it goes great but at stop streets if you dont rev it it will die

[@rishikeshkumaran3437]

will leak causes missings,when throttle closed.im getting back fire,and after fire.too when the card are tuned.no way out.with sometimes missing from high rpm to low ones.is it vaccum leaks causes back fires and missing?

[@HTMR]

Rishikesh Kumaran It can, why not just check for them?

[@tybi12]

i replaced valve shims on my bmw f650st,also cleaned carb.now bike wont start and i can hear a sucking sound from the carburator.what could be the problem?thx

[@mattdonovan8517]

Thanks for showing how to Matt!

[@xxstocktown209]

i have a 95 rm125 that i rebuild, it starts up and does not idle high but when i was riding it would red line when i was not giving it gas and bouge out when i gave it gas and now it wont start could this be a vacuum leak if not could u give me any advise o what i should do

[@aaronlee8845]

Can you help me identify the problem I'm facing with my motor? There's a strange noise emanating from my engine. And it's driving me crazy. The video's title 'noise - suzuki gs550' The video's a bit dark, red bike. Thanks by Aaron Lee

[@sesaenosorez7161]

Do vacuum leaks have to do with an engine not sucking gas to a carburetor ?

[@HTMR]

It will suck less gas and more air through leaks, so it will run lean.

[@sesaenosorez7161]

MatthewMCRepair thank you just wanted to know because my quadrunner bike is not sucking gas to the carburetor and I did detect these vacuum leaks

[@sesaenosorez7161]

MatthewMCRepair thank you just wanted to know because my quadrunner bike is not sucking gas to the carburetor and I did detect these vacuum leaks

[@handyman7297]

have you think about this= that the carb cleaner that you are using might eat some of the rubbers of your carbs? as far as i know you should not be using carb cleaner upon any rubber part...it is just for metal parts correct me if im wrong please.......including your motorcycle intake manyfolds

[@HTMR]

Been doing it for years and never had an issue. The cleaner is on for a short period of time and then I blow it off with compressed air. If you soak them for a long time then yes you will have issues.

[@handyman7297]

Ok thanks for the reply

[@Chrischristopherson1313]

can the leaks be from other side of carb to air filter

[@HTMR]

Yes, but that is not a vacuum leak. That is simply unfiltered air entering engine.

[@alexbates6732]

I have 2015 versys 650 when I rev the engine the revs drop slowly and sit around 2000rpm. Cables are fine throttle snaps back instantaneously but revs still sit high for a few seconds or until I move again. Not always 2000rpm sometimes a little less or little more

[@HTMR]

Alex Bates sounds lean

[@DarylJaimes88]

My old honda xl500r hardly idles with choke and dies when choke comes off, i still can keep it running if i keep the throttle open. After it dies it takes about 10 minutes of leaving the bike sit until i can start it again (carb has been fully cleaned) i tested for vacuum leaks and it seems to leak by the cylinder head in the inlet manifold, the inlet manifold itself is in good shape (its metal so doesnt seem to have any crack), could the o-rings of the inlet manifold cause a leak? they seem to be in good shape.

[@HTMR]

+Daryl Jaimes Yes, if there is an o-ring between head and manifold, they tend to get hard and brittle, and no longer seal.

[@DarylJaimes88]

+MatthewMCRepair Great! I'll get some new ones then, there's actually 2 of them. Also, im missing 2 seals from the exhaust manifold (where it connects to the engine) can that also affect the idle like a leak? First day i started the bike it run great and idled perfectly, all these problems started the second day i started it (no changes where made to the bike) why do you think this happened? Run smoothly first day, next day seemed to leak a lot.

[@HTMR]

+Daryl Jaimes Exhaust leak shouldn't affect idle, however can cause decel pop etc...

[@DarylJaimes88]

+MatthewMCRepair awesome, thanks for the answers, sub'd!

[@DarylJaimes88]

+MatthewMCRepair awesome, thanks for the answers, sub'd!

[@ComandanteJ]

A friend of mine got a '91 Virago 535 a week ago, runs ok but it needs a lot of choke to start (ambient temp in the 20 ºC range), and a little help from the throttle. And even with full choke, it sometimes would die randomly while idling. So we gave the throttle adjusting screw tat's between the two carbs a couple of turns, it idled a little highe but i was a lot smoother, too, and didnt die. But today, my friend started it, went to grab his gear while the engine warmed up, and the bike died in a minute or so, and now he cant get it to start. He tried to re-start it with a little gas, and i think he might have flooded it. He tried cranking the bike with the choke off and full throttle, but after like 15 secs of cranking he got nothing. He has taken the plugs out and covered the holes with a rag, and will wait a couple of hours, but, my question is, what could be wrong with it? The bike has around 30k KM and looks very well maintained.

[@HTMR]

+ComandanteJ Older bikes like that usually develop vacuum leaks. Have you checked? Also, there is a good chance that the carbs need to be cleaned, followed by a carb synch and fuel mix adjustment.

[@ComandanteJ]

MatthewMCRepair Thanks for taking the time to answer. We've checked for cracks in tubes and boots, they look fine, but we havent got any carb cleaner to check thoroughly (it's kinda rare were i live, you rarely see carburated vehicles anymore). We do have a butane containter with a valve and a tube, could we use it safely to check for leaks? if we do, the RPM's should go higer or lower?

[@HTMR]

+ComandanteJ Any auto parts store should have carb clean or starter fluid. The RPM can go up or down. You need to spray it, visual is not enough.

[@MgOrt231]

Did you ever figure this out? Im having the same issues for a few months now....so frustrating Ive tried so many things

[@briholt100]

Pick-up coil may have finally died Mine did on a 91 bandit. Starts, runs fine, but once it warmed up, it dies.

[@whinycleric]

I think you just solved the problem on my bike, my gsxr either has the vacuum leak on that valve cuz the padcock or what you call it shows leakage of fuel? could that also cause my bike to idle horribly or not?

[@HTMR]

Carlo Pelser Are you referring to the petcock? The vacuum port should hold vacuum and NOT leak fuel, otherwise it will suck fuel into motor and cause that cylinder to run rich.

[@daltoncastro5012]

hi i have that exact enduro 80 and it has spark and fule but only backfires when I try to start it. do you know what i can mabye check?

[@HTMR]

+Dalton Castro You have fuel all the way to a wet looking spark plug? How much compression? Is timing set properly if applicable?

[@bobsanders-up4vs]

I rebuilt my carbs and replaced o rings in fuel feeder tubes on my 2000 valkyrie. bike starts runs and idles fine but while synchronizing the carbs with vacuum gauges I have one that fluctuates. also if I hold throttle at a steady speed there is popping in the exhaust. anybody have an idea what I did wrong ?

[@HTMR]

Did you check for vacuum leaks? What brand of gauges do you have? Did you remove pilot jets and fuel screws and clean all passages really well?

[@bobsanders-up4vs]

MatthewMCRepair I did a d-smog so vacuum is not an issue. I did not remove fuel mixture screws but cleaned everything else and blew it dry .

[@HTMR]

Bob you have to remove the fuel screws to clean carbs properly. I would also recommend a fuel adjustment procedure per this video: kzbin.info/www/bejne/sJ6YnnVph52Imdk

[@bobsanders-up4vs]

MatthewMCRepair this is a honda valkyrie. Not easy to remove carbs .Can I remove idle screws while on bike and spray carb cleaner in hole and blow out without taking them apart again ? initially bike ran excellent when I bought it ,after 1500 miles carbs began to leak . dicovered rust residue in fuel filter and float needles weren't seating . Again bike ran fine before cleaning just leaked gas .

[@HTMR]

You have to remove carbs. If you just take the fuel screws out, you will just blow the gunk elsewhere in to the carb. You have to take it all apart and clean it well, there are no shortcuts. If you found rust in your carbs, then you will need to seal the tank otherwise you will have issues. Adding a fuel filter will not solve the problem. I recommend Caswell tank sealer, here is a video: kzbin.info/www/bejne/b4i5ZIF5nL6qr7M

[@kennethwong8009]

Hi Matt, I was wondering if I can check using WD40? I own a 2007 Yamaha Silverado 1100 and recently checked the starter one way clutch and now I am having a difficult time getting my timing back to normal. Any suggestions?

[@battlestef7274]

yes you caj

[@HTMR]

Yeah, tell me about it!

[@olliejacksonsr9334]

I cant find the vacuum concection for the petcock to the engine for a vf700 honda magna can you help me

[@HTMR]

Should be located on one of the carb boots IIRC.

[@adamsicotte1151]

How am I supposed to do this when my bike wont idle from the get go? It just revs super high. Plz answer me!!! Thnx

[@rc2634]

It revs high when you start it? Cant you adjust the idle? And then do this test?

[@crustymarine86]

Do you do any work on xs650's? If so can I send an email to you of a video to see what might wrong with my bike?

[@HTMR]

+Will Fullen Yes, send me an email here: www.howtomotorcyclerepair.com/contact/

[@plantagenant]

Interesting. Stumbled across your video trying to find solution to my bike problem. Honda xl 250. Been sitting a few years. Starts fine but revs like crazy even when I haven't touched throttle. Dies down to normal idle speed after about 20 - 30 secs. Blows black smoke if you give it big throttle. Seems to burn a lot of fuel only doing 30mpg max as opposed to 60-70mpg others get. Have cleaned carb twice. Any ideas would be greatly appreciated!

[@handsome-soup3294]

Did you fix it yet

[@plantagenant]

@@handsome-soup3294 Got a new Carb!

[@johnk815]

I wonder if carb cleaner will dry out the rubber boots?

[@HTMR]

Never had an issue. Make sure to dry the solvent off ASAP.

[@DarylJaimes88]

Hey man, i got another question, my bike seems to be running fine, starts first kick, idles okay and all, but i cant get rid of the hanging revs problem, i checked around for a vacuum leak and cant find none. Could the hanging revs be caused by something else than a vacuum leak?

[@HTMR]

Yes, a lean fuel screw setting and/or lean pilot jet. What year make model?

[@DarylJaimes88]

+MatthewMCRepair Its a 1982 Honda xl500r, the spec setting for the fuel screw is 2 and a half turns out, tried that and also tried it further out, hanging revs still there. Also im pretty sure im not running lean, the bike starts first kick when cold without choke..

[@HTMR]

Does the idle speed increase as you turn the fuel screw out? You can also try raising the needle.

[@DarylJaimes88]

+MatthewMCRepair if i get it fully in, the bikes stalls. as i start to turn the screw out the rpm increases until a certain point, although the bike never stalls when unscrewing it

[@HTMR]

That happens sometimes. How many turns out when it hits highest RPM? Anyway you can post a video?

[@HTMR]

Sounds like a clogged pilot jet. Take the carb apart and make sure it's clean.

[@ctcape708]

Hi mathew, love your vids and wonder is ther anychance i can chat with you? Really need some advice on my bike

[@HTMR]

Yes, email me here: www.howtomotorcyclerepair.com/contact/

[@ctcape708]

MatthewMCRepair thank you, will do that, apriciate you are willing to try and help

[@VaansWorld]

Thanks for the video! My question is how the heck you're going to order that part lol

[@romanaskovzonas7987]

hey, can I do with any spray ?

[@HTMR]

You can use water however not as noticeable.

[@HTMR]

Thanks!

[@craigzilla100]

Question for anyone on here. Could this cause a bike to run full throttle once started? Just put a brand new carb on my four-wheeler. I have to have the choke completely pulled out to start it. Once it starts (takes a while) it runs almost full throttle for a few seconds, then slowly comes down and dies. Any ideas? A intake vacuum leak wouldn't cause this would it?

[@HTMR]

What year make model? Did you buy a cheap chinese replacement carb?

[@craigzilla100]

Its a 2002 Yamaha 350 warrior ATV. I believe it's a zoom zoom parts item, but I could be wrong. I had a highly recommend carb mechanic try to fix my stock carb and he could NOT get the float valve or the pilot jets out. Totally seized up inside- partly my fault for trying to get the jet out myself and stripping it. He ordered me a new one from a distributor in California, where he gets all his stuff. It's got a 1 year warranty at least. Mechanically, it seemed great before I put it on my bike. The slide didn't appear to be sticking.

[@HTMR]

Did you tune the fuel screw and idle speed once warm?

[@craigzilla100]

No, I haven't touched it yet. Could that cause it to run almost wide open? Didn't know it allowed that much fuel in. I think it's on the underside of the carb, so I'm going to have to take it off to adjust it. Which really sucks.

[@HTMR]

It's getting too much fuel and air. Remove air cleaner and pay attention to slide. Is the slide installed backwards?

[@williamb15010]

Are the boots expensive to replace?

[@Jerkwaad]

Hey. I keep having a spontaneous backfire on my cb900 with a twin exhaust. I have had the carbs off and didnt change the boots. However I did this test and there are no leaks. Fuel is new , jets are clean. Plugs have been swapped around, but the problem is staying at the right side. I have also synced the carbs.

[@HTMR]

Aaron, I commented on your vid.

[@gazcee1]

Hi can anyone help me I have a mini dirt bike 50cc when I start it it has very high revs can anyone tell me why this is happening is it a vacuum seal or air geting in somewhere I don’t have a clue about bikes and fixing them

[@HTMR]

Could be an air leak, watch this video: kzbin.info/www/bejne/inW4Y36Fpb6qfMk

[@barcusful]

Great, informative video. Thank you.

[@sagking3667]

Thanks man this helped me a lot with my 80cc bike kit I just wrapped the intake manifold with electrical tape

[@HTMR]

Come on, electrical tape? Go buy new parts...LOL.

[@jayfrost9237]

I have a ktm duke 125 starts fine, the idle bounces and takes a while to warm up runs fine when warm but dies while riding when hot

[@novicetheaf]

Ive been having issues trying to start my bike recently, at the moment It wont start from cold unless I have the throttle open and the choke on full or near to full, I took it into the mechanic and he cleaned the carbs, and made sure the idle speed was at factory settings, when i got the bike the idle speed was about twice what it was supposed to be, but this caused idle speeds of up to 5,500 RPM Lol. So I am not sure what is is exactly, not even the mechanic does, But It im thinking maybe its a air leak not sure really, its a Honda CBF 250 2004, once its warmed up after about 3 mins it doesnt any issues at all, but i am worried that this may be a big problem down the road :/

[@HTMR]

Take it back to him and tell him it's not fixed. You paid him and he should honor making it right.

[@novicetheaf]

MatthewMCRepair I could try bringing it back to the shop I bought it off, but they've no replacement bikes for it at the moment, I like this bike, but I'm sick of having carb issues with all my bikes :/. I was looking at getting a MT03, or a Suzuki GW 250 maybe. but first I'll try see if there's an air leak and I'll replace the spark plugs and air filter maybe

[@kieroncallum08]

novicetheaf

[@rjbizz198787]

Your videos are very informative so I have a 2001 Yamaha vstar 1100 I've gone through it with a fine tooth comb I know I'm running lean my throttle hangs it back fires like a son of a bitch it must be a vacuum leak but I can't for the life of me find it any suggestions

[@HTMR]

Could also be dirty carbs.

[@revjunkie7728]

okay so the second i get my bike started its revving super high, theres a bunch of backfires and it i put the choke on at all the bike revs out to all hell, give it throttle it bogs out.. someone help lmao

[@blueskyblackthunder]

nice and easy. well done

[@BLASTERGIFT]

My story.Like i said RTV its a quick and temporary fix till i replace them with new ones.Thanks again :)

[@gromkour5341]

My ninja 300 has a whine while accelerating between 25 and 45kph

[@novaguy383]

Excellent video, very informative!

[@sdqsdq6274]

can u spray wd40 instead ?

[@HTMR]

I never tried that. Cleaning it up will be a nightmare.

[@GuruProductionsUSA]

Thank you