Scooter How-To : GY6 Valve Adjustment (Also For Buggy + Kart)

How to adjust the valves on a GY6 engine, common in scooters and go-karts.
At the time of the video, I was using 0.004"/0.005" regularly. Now I tend to use 0.002" intake and 0.003" exhaust. The loose settings will work, but may cause more noise (clatter).
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[@treypeters]

Thanks for the clear and concise info! I'm the most non-mechanically inclined person I know and I was able to adjust my valves from this video. We don't have many scooter mechanics in Baton Rouge and even less who want to work on a G6Y?

[@49ccscoot]

Nice! Glad you got it working well. Check those vales a little more regularly. Maybe every 2500 miles or so. Keep the oil changed every 500-1000 miles IMO. If you haven't done it in the 4500 miles, it's time to change gear oil and check the CVT out as well. Good luck with it. Check out my other vids and the forum if you need more help.

[@OverlandOne]

Thanks Brent. I watch this video every time right before I adjust my valves to refresh my memory and, I am setting them again tomorrow so, thanks.

[@grant2053]

Best vid for GY6 Valve job out there! Thanks man!!!!

[@electronicelaborare]

Just wanted to say thanks for replying back and using your video I adjusted my valves on my 2012 Taotao 150cc to .03 intake and .04 exhaust (because that one was super tight) and I went from going 30 slowly up a hill for no reason all the way to 50. It didn't even run like this great when I first bought the bike used 4500 miles ago!

[@bugdrvr]

Thanks for the video! I'm the keeper of a friends GY6 equipped scoot so have been learning how these things work as I go and/or as parts fall off of it. One thing that might help, you can use a square drive wallboard screw with the head bent to 90 degrees as an adjuster holder so you don't have to use pliers or whatever to hold it steady. My Honda had 8 and my Suzuki has 16 of the same adjusters so I'd go nuts trying to shove my hands in there without something to turn or hold them. I noticed a wallboard screw driver was the same size so I invented my own tool. I even put a little tube on to the end for a handle.

[@49ccscoot]

Thanks for the tip.

[@tellmesomething2go]

awesome tip, with drywall screw. beautiful.

[@tellmesomething2go]

NOW THAT WAS A GOOD ONE!

[@RaymondIlano]

Thank you so much for the informative vid. I'm about to do my first ever valve adjustment. You explained things perfectly.

[@kevinstearns4198]

best person to learn from hes awesome on everthing on fixing ur scooter. ie valve adj, top-ends, electrical etc.

[@burt1758]

That was 4 years ago I didn't know shit asking everyone now I can do everything in my sleep. Use 4 thousands on the intake and 5 thousands on the exhaust.

[@donaldmarcrum]

thank you this video helped me out on my 2014 taotao 50

[@aliihsanaksoz8072]

Video için teşekkür ederim.Scooter motorumu yeni revizyon yaptım.Gömlek,piston,segman değişiminden sonra subap ayarlarını yaptım .şu an saat gibi çalışıyor.Bütün yaptığım işlemlerde video görüntüleri beni çok aydınlattı

[@dean3434]

Thanks again for the great tutorial. Needed to review your video just to be refreshed on my latest valve adjustments. Dean Seattle, WA

[@thomasdsmith7678]

For years, I took a small piece of scrap steel, and cut a slot in it to use to hold the adjuster screw while adjusting. Putting in a "s" bend helps clearance. Thin grinder wheel cuts a good slot like in the end of an old, damaged screwdriver or small broken wrench. Grind back the broken end and make a slot. I have also used a tiny cresent wrench.

[@GreatPug]

Thanks for this. Best video regarding this on KZbin.

[@pcdubya]

Nice detailed video. If I do this, What are the chances I can I get the valve cover off with gasket intact, ( probably never been off before ) of should I get a gasket and expect to replace it.

[@MarcusBooij]

Nice video... Helped me alot.... got my gy6 runnin like it was new... Superb!

[@counteractman9380]

Very nice description 90gtvert. Thank you for creating the video...

[@EstebanGonSal]

Thank you very much, it was all I need to know. You was very clear, and I will clear uo my valves. Great video, thanks a lot..!

[@luapynneb3069]

Good Video, good sound, and easy to follow. Thx Pb

[@Talusmade]

YES!! More to the procedure, not this video(although it was good.) I couldn't figure out what was wrong with my 50cc scooter. I guess it wasn't letting enough out on the exhaust stroke and it was building pressure and dying. My exhaust valve was at about .002, put it at.004 and it's running good. Loosened the intake from .003 to .004 as well.

[@vatcheohanian2565]

Thank you for your video. Very helpful! The valve adjustment measures 50cc versus 150cc are they the same? Thanks!

[@granitigraniti83]

Hello, Why my gy6 engine is throwing to much white smoke and stalling when accelerating after replacing cylinder,piston and rings . Do I need to adjust valves or to replace valve rings or what ? Thanks

[@dannytroy]

Great video. Good explanation and nice camera work. I don't think my scoot needs an adjustment right now, but I'll be ready for when it does. The hard part will be accessing the head, since they didn't make it easy to disassemble my retro Tao Tao CY50b.

[@dean3434]

I agree. Perfect camera work.

[@Hypertenzion]

Wonderful video! Thank you!

[@Hooverdarnit]

@90gtvert I finally replaced my broken valve springs. It starts instantly and runs fairly good. But at higher speeds it will occasionally misfire. I've gone and reset the valve gaps several times, yet it still does it. Question: Is it possible to have the two smaller hols on the cam chain sprocket, and one larger hole on the sprocket, in the postion you showed, and still not be in the roght place?

[@49ccscoot]

+diga digadiga It can alter performance, but it's primarily a maintenance procedure. If the gaps get tight it will cause a lack of compression and starting difficulties. If the gaps are too loose it will cause excessive noise and wear on valvetrain components.

[@411tylere]

Great video

[@ascobil]

thx man i'll try it tomorow and give you a feedback.thx again

[@Hypertenzion]

Btw. what kind of oil do you use to lubricate the feeler gauge and the engine when adjusting the valves? Thank you!

[@galimirnund6543]

Hi, I need advice I have a speedy 50 tao tao scooter. It will turn over but won't start... I replaced the spark plug today same thing. It is getting a little spark though. It's like the gas isn't getting there. Cool videos.. :)

[@Hooverdarnit]

Do you know if a special tool is needed to change a broken valve spring on a GY6?

[@anouardj5751]

hay why do i have to adjust the valve for ? does that makes my scooter goes faster ?

[@pater429]

my valves did not even fit 0.05 both of them lol. but smoke is still there so i have to replace the valve seals and piston.

[@electronicelaborare]

What about engine temperature? Right now it's around 50ºF outside. Would that effect the measurements I take with the feeler gauge while adjusting the valves?

[@proteusmacapagal1453]

sir its that okay to use stock camshaft without camshaft stopper plate?

[@arevalogarcia9232]

Usted es un mago ,para mecanico le falta mucho ; no saca la bujía (en carrera de compresión ) manual y ser técnico ,...

[@mauricetamata7567]

THANKS FOR THE VIDEO.

[@49ccscoot]

Thanks for watching!

[@Hooverdarnit]

I need to replace some broken valve springs on my GY6 scooter. My questions are.... Do the valve stem keepers have a up or down position? Do the keepers need to be flush with the valve stem on the top? Also, is there a trick to taking the rocker arms off to get to the springs, or does the whole unit come off with the rocker arms? HELP please.

[@notsohandytim5090]

Good video! Thank you.

[@milanozilina]

Hello, van you write how much mm or inch i must use for adjustment? Thx.

[@49ccscoot]

+Vatché Ohanian Yes, you can use these for 50-150.

[@49ccscoot]

I can't say I've ever put a lot of thought into it. Like the book, if the tensioner isn't maxed out and it doesn't feel really tight or really sloppy I leave it be. 8mm sounds reasonable to me, but I've never measured the slack before.

[@yowhatsupmark]

hey Mr. do i need to turn the fly wheel again after im done adjusting the valve. will i turn the fan clockwise or leave as it is.?

[@bryanmacaraeg6768]

sir what is the valve clearance of kymco scooter 100cc?

[@gst69man]

I have a 150 cc gy6. Someone told me that there is a compression release lever that releases compression for easier starts. Is this true, and if so, do you need to rotate engine so compression lever is off the rocker? Ferd

[@PIchillin456]

I have a 2013 Kymco Agility 50 and I've been trying to find out what engine it's equipped with. Some people are saying that it's equipped with a GY6 clone. Do you know if this is correct?

[@atelhaddad]

I got myself a 150CC scooter and I was wondering whats the best clearance for the valves ... I read that it should be 0.02 to 0.03 ... but in the GY6 engine manual it says 0.08 to 0.12 ... and that's a pretty wide range for a rookie like me ... Advice please

[@SoloSolid1]

I have had my Schwinn 50cc Campus in storage for about 4 years. Last time i rode it it ran ok kinda weak.. Now I cant get it to run worth a crap. Runs for about 30seconds- 2 minutes with the tire off the ground. Do you think this is the problem? Ive checked fuel and I've taken the carb out cleaned it really good checked the float. Not sure what else to check.

[@NucIearChrist]

what do you mean by 'stick with the high end'? i adjusted them last night, without a 9mm wrench (dont have one)and hear a lil tapping.. is this ok?

[@NucIearChrist]

my owners manual says the valve gap is 0.03~0.05(cold state. what measurement is this? is that the same as .003~.005 mm?

[@joefiss23]

i have a 150cc gy6 and the marks on the fly wheel look like T F I I, how ever when i line up any of the lines or the T with the mark on the case, the holes on my cam shaft dont line up exactly right but when i line the cam shaft up properly the fly wheels markings are almost an inch to far ahead where they should be, is this an insignificant issue or should i undo the nut holding the fly wheel and adjust it until everything is lined up exactly right ?

[@martijntjuh1000]

thanks for the great video i can now do it without going to a garage

[@ArthurZdrinc]

I just got my 150cc scooter. MC_D150T, it has the GY6 engine i assume since it's chinese. But i am very concerned. Everyone on the internet says to put 80W-90 gear oil in the transmission. My "operation instruction" manual says to use 10W-40 for the engine, and 10W-40 for the transmission?¿¿¿ What should i do?

[@Benjamin-xv2hg]

Thank you so much

[@nikkahilabtanun7006]

yes thanks i am now familiar with the ticking noise... now there are other noises coming out of the engine. i'll just cjeck one of your vids if you you have something pertaining to other engine noise. is it also good to change the springs? better springs? or valves? or whatever...

[@robinhelder1471]

Wow this is just what i needed!! Thanks!! I also want to change the vario bushing to a faster one, do you have any tips in holding the vario so i can loosen the nut?

[@moekakke]

Wiht a cilinder replacing, how can you know the position of the T is the upper piston position with the spark and not the rest upper position ??

[@dedeabsrn8044]

How many mm inlet and exhaust, for gy6 80cc

[@dustinmetz9543]

ok i have a 150cc i did this after rebalding the engen but when i dive it now and give it gas it cuts back and pops wut should i do?

[@SoloSolid1]

ok last question lol. What size will fit my cvt? 16x13?

[@brandonw33zfy1184]

This video was very helpful because this is the third cylinder I've been thru in less than four months. For a gy6 150 with the 155cc kit, what should the best adjustment for intake and exhaust?

[@49ccscoot]

0.003"-0.005"

[@FwankenStein301]

hey 90gtvert! i have a 4 stroke engine that worked fine one day but today it cranked for 5 seconds and makes 1 loud knock! do you know what this might be?

[@motley679]

THANK YOU!

[@SoloSolid1]

It only runs when I spray gas in the air filter. Ive changed gas twice, changed all the lines, checked for all vacuum lines that I know of. Have checked the gas tank fuel valve. The diaphragm seems to let gas out when the engine is turning allowing gas to flow. I don't know what else to do. Runs fine for about 15 seconds while i have sprayed gas into the breather. I ordered a new GY6 Carb. Do you have any more suggestions?

[@Hooverdarnit]

Anybody know how many AC volts a 150cc gy6 with a 8 pole stator should put out from the charging coil? Plaese?

[@MrBoldmike]

thx nicely done

[@nikkahilabtanun7006]

nice video. i have a question. there will be like valve noises when you don't adjust the valves right? i just dunno or am not familiar with valve noises as my bike's engine emits other squeaky metallic noise.

[@fashionstreet1]

Hi 90gtvert great video tutorial i am trying to adjust my valves but a have a slight problem,where is the cooling fan on a 250cc roketa and where is the stator on a roketa it should be on the right side of the bike side but dont see it its a little different then on a say 150cc scooter?

[@49ccscoot]

Some of the 250s are a bit different than the smaller engines in their layout. You would be better off finding a video specifically for a 250cc scooter or checking a service manual.

[@roberthuffman4354]

DID YOU DO A BIG BORE KIT ON THIS 50CC????

[@vawndavis7535]

buddy keep up the great vids ive learned a lot from you how ever i got a problem i recently had a problem i knew it was my valve adjustment so when i went to check it and the intake lock nut is gone down in the motor is it possible to fish it out from the oil filter area with a magnet or am i looking at a complete tear down? its a gy6 50cc with a 100cc big bore kit in it thanks

[@49ccscoot]

+vawn davis You could try a thin extendable magnet in either drain plug and try checking where the cam chain goes through the engine. Good luck.

[@miguelrosmundo]

what is the length of the valves? thanks..

[@thedaydreamer7972]

Once again a great video, I have a few 50cc and 150cc chinese scooters, I notice on all of the inserts under the seat they say adjust to .006 and .007,,,,I see many people online say .004 and .005 and you like .003 and .004,,,are the manufacturer specs just not geared towards performance should I ignore that and just try what you guys recommend and see where I get the best performance? DO you really think proper valve adjust ment can really effect speed? TY for all your hard work!

[@49ccscoot]

I actually use 0.002"/0.003" most of the time these days. I don't recall seeing a manufacturer spec on any of the Chinese 50-150s as high as 0.006". I'm thinking you have have confused the specs with metric specs. It is common to see 0.06-0.07mm, which is roughly 0.0024-0.0028".

[@user-eb6kp2cx7w]

Thanks man

[@Zoomsterful]

What is the valve clearance on a 180cc? Do you know?

[@rafaeldiaz6628]

Y en que punto dejo el pistón. No importa la posición de este?

[@ejs6097]

Hello again ; P I heard your tip about excessive tapping after adjustment, and what to do. Just a question to confirm that is what i need to do. Upon opening my valve cover to to do the first adjustment i have ever been able to do, i discovered that the tappets were seated tight against the valve, i mean tight! How the heck this thing was running as good as it did, i can't understand.. Now i have excessive tapping @.004 gap. Still running great! Do you think something could be worn out from the tappets being that tight for i don't even know how long/ how many hours of running.... It did not tick at all when tight, so should i just close the gap a bit, and call it a day, or should i investigate anything else while inside? Thanks in advance.

[@49ccscoot]

You can try moving to something like 0.002" intake and 0.0025-0.003" exhaust.

[@ejs6097]

I will give that a shot. Just wanted to get your thoughts about how tight they were, and if thought that would cause any unnecessary damage resulting in my ticking.. Thank you once again good sir : )

[@ascobil]

very nice video but i just have a question to ask,i have a buggy carter sym 250 gtr but my engine valves are doing some noise (clak clak clak clak ... very fast) and im in africa so every thing here is in mm so could you plz tell me what mm should i use to adjust them.thx you and good work

[@49ccscoot]

They're saying .002" for both the intake and exhaust. Should work. I'd trust Honda specs. I set scoots to .002-.003" regularly too. You could try a little more play like .003" and set them as spec'd to .002" if you hear valve tap.

[@mattuchiha]

hey i have a 2016 taotao 50cc with 100cc big boar kit installed. after installation it ran great for 10mins. the stock carburetor and manifold were kept in during this test drive. but after this test drive i guess what is called, bogged out, happened when i pulled on the throttle. so what i did first was install a bigger carburetor and manifold. the issue didnt leave. so i upgraded the cdi,sparkplug cover, cold intake, and flywheel fan, but no nothing! whats next??

[@49ccscoot]

My first thought is to try tuning the carburetor. Checking connections is a good idea when an issue pops up, but you should have been over the connections while replacing things. A simple way to get an idea of if too much or too little fuel is an issue may be to try revving with the air inlet covered or partially covered. If it improves, it probably needs more fuel. You can also remove the airbox and see if if improves. If that helps, it may need less fuel. kzbin.info/www/bejne/gWbNaZp-nJqeg8U www.49ccscoot.com/faq/carbtune.html

[@The12Nurse]

@warezvz what was the jet size you used?

[@juanga251]

Question if adjust the valves in my scooter 0.005mm i heard tapping all the time if i turn it down to 0.003mm it will losses the tapping and gain more torque?? both sides??

[@49ccscoot]

Those numbers should be inches, not mm. Thousandths of a mm are incredibly tiny. Some tapping is normal. These days I use 0.002-0.003" on my 139QMB usually.

[@The12Nurse]

@warezvz yeah I already tried but without upjetting it..but still worked great!!

[@dantmanish]

Hi, I have a new 150 cc Chinese scooter, I had this scooter shipped to me direct, since I've had it, it has been running poorly, after watching videos and searching for blogs on the Internet I have replaced the carburetor, coil, vacuum operated fuel shutoff valve, and CDI module,at first it was very hard to start and would not idle, now it starts and idles just fine,but when it warms up and I accelerate it bogs down and sometimes won't stay running, so after a minute or two on the side of the road it starts up again and will only run at very low rpm's if I try to give it any gas it'll die,do you have any idea what would cause this, vacuum leak? Or do you think my valves need adjusting,any ideas? Thank you for your videos , Dan

[@49ccscoot]

Doesn't hurt to check the valves. See if the jet size is different in both carbs and if so see if the jet from the previous carb makes it run any better.

[@dadabg8747]

what is that knife looking tool called?

[@NucIearChrist]

what do you mean by 'stick with the high end'?

[@Wil20w]

will these work with a big bore kit

[@cptnchristMyth]

90gtvert very clear and with a good camera! 8~)> one thing i would like to say is why 7 individuals had felt the need to dislike the video??? we are animals, and as such we learn through only a few ways & for me visually is the best. Just chalk it up to people with negative energy is a huge fail imho. You are only doing this to share\educate\and help which is awesome. to dislike this or perhaps any of your vids is a fail-minus in my book So thanks again, I will subscribe(already liked) hehe

[@DGSantaFe]

Great great video! I have a CF Moto E-Charm 150 that looses power after a few minutes of riding it. Sometimes I'm doing 50mph then something goes wrong in the engine that the speed goes down to 35mph. I keep the acceleration going but it won't go past 25 then when I finally reach a safe place to stop it dies. 10m later it will start but roughly. I was wondering if you have a slight idea of what could be going on? This is water cooled fuel injected not carburetor. Thank you boss!

[@49ccscoot]

+DG MAMBO Does it have a water temp gauge? Wondering if it's getting hot.

[@DGSantaFe]

It does have one but from what I c when I ride it it never gets past below half on the temp gage

[@machos580]

i change cylinder and piston.....now it is 72cc.....how to adjust the valves..?i put IN:0.08 EX:.O.10...it is true this..?

[@iskate4myself]

If your valves aren't set right could it possibly take away 15mph top end?? I use to pull almost 50mph then after my belt broke and was replaced it can hardly go past 30mph and I can't figure it out:/I also hear a really loud ticking coming from the valve cover when I idle..

[@49ccscoot]

+Christopher Spohr You'd most likely notice other symptoms if the valves were the cause of such a loss in speed. If the belt broke and performance changed I'd go over the whole CVT and be sure I had the right belt as well.

[@sergiocontreras8930]

Hello I recently I adjusted my valves because it wasn't starting unless I use starting fluid but now the motor won't turn over like it got too much compression and my fly wheel doesn't have a t mark

[@49ccscoot]

I wonder if you may have adjusted the valves too tight and it's opening them enough to make contact with the piston. Don't force it to turn, because you could bend a valve. Back the adjusters off to create plenty of play and then see if it turns over by hand. You may need to find true TDC and make your own markings. You really don't have to know totally precisely where TDC is for a valve adjustment, but it is important that the valves are totally closed when it's done, so the engine should be at TDC between the compression and power strokes.

[@SoloSolid1]

Hey 90gtvert I got my new carb in runs pretty good now! I have a question. I didnt know how to message you. I know ita junky scooter but its a Schwinn 49cc Graduate. only has 500 miles on it. Its top speed is only 35mph. Is that normal? What are some things I can do to get some more speed? Im a pretty decent mechanic. From 30-35mph it takes awhile. Thanks if you can comment back!

[@1nathan420]

I got a GY6 139qmb with a 50mm piston, A9 Camshaft and a big valve head should I adjust the valves differently than the stock setting?

[@49ccscoot]

0.002" in / 0.003" ex should be fine. Sorry for the late reply; somehow your comment was flagged as spam and I just now saw it.

[@1nathan420]

thanks for the information I don't know why this got marked as spam. and what is your thoughts on an oil breather tube? I was thinking about getting one for my 139qmb.

[@user-eb6kp2cx7w]

How you change gear oil

[@3R1C79]

my atv was working good and one day i had dificulty to start . after it was start it was ok . after that a week after i try to start my atv and nothing . engine turn like in butter ( like a car that have a broken timing belt) can soneone help me . i set the valve and its not starting my atv . can timing make my atv 150 cc (157qmj gy6 ) not start ? event if its only jump 1 teeth on timing because it is like theres no pressure and you can hear a small pet from time to time but not enough to say its gonna start (i will try to post a video soon)

[@49ccscoot]

Double check that your cam marks are aligned with TDC and you'll know if it's moved. Check compression.

[@nerfiasjust4461]

Thank you from Ukraine)

[@jeffstake2570]

I have a new GY6 150cc that has very similar problem to dantmanish listed below. I have not adjusted the valves. Somebody suggested I put the stock air box on but I really dont want to do that. I replaced the 24mm carb with a new one that had bowl screws and idle idle mixture screw available. I cant get more than 44 mph out of it nor can i get it to run higher than 6000 rpm. I have a 108 jet in it and it seemed to help but still just not getting the performance i expected. It also idles poorly. I disconnected the choke and ordered a manual choke. The usual perf stuff - exhaust/muffler, orange cdi and coil, cold air kit, new iridium plug, Any thoughts on this one ?

[@49ccscoot]

You need to work on tuning the carb. If you've only tried one main jet, try others. This may be of some use... it's a 50cc, but same idea as far as simple tuning methods. kzbin.info/www/bejne/gWbNaZp-nJqeg8U

[@jeffstake2570]

Well I reset my focus to the carb and it turns out that there was an issue with the new carb I bought. Put the stock one on and made three runs at 53,54 and 55mph via GPS. Elavation 4450 with 225lb rider and 260 lb bike. I re jet the carb tomorrow. Starting point will be a 108 main Thanks again for your help.Always right on target.

[@49ccscoot]

Glad you're making progress. Good luck with the tuning.

[@49ccscoot]

These specs are OK on a cold engine. The outside temp prob doesn't sway enough in most places to make a huge difference. Hot isn't saying a 90 degree day, it means when the engine is at operating temp which means the head is likely 200F or more.

[@jimsox881]

it was brand new. Did not think I needed to check it. And tightened the head as much as it would go.

[@49ccscoot]

+jim crabtrey I bought a $100+ dollar brand new big valve head once and had it leak out of the box. It's even more common with Chinese replacement heads. The head should not be tightened as much as it will go. That's not good. It should be torqued to spec. 49ccscoot.proboards.com/thread/14211/139qmb-bearings-seals-bushings-torque

[@user-gb6yy9ll5q]

My gy6 50cc bo-up kit 72cc also adjusted intake to 0.05mm and exhaust to 0.07mm. Is the exhaust 0.07mm okay?

[@49ccscoot]

That's okay. I would not use any less than those.

[@DoeBoy904]

I just purchased a used 50cc taotao scooter not running replaced the carb battery an ignitions getting spark will turn over but won't crank could this be my problem?

[@49ccscoot]

It may be. It would be a good idea to check the clearances.