Carburetor jetting 101: how to adjust jets on a Honda XR400R carb

[@yoteoboth8449]

One of the most helpful videos on the XR400 starting / carburetor I have ever seen. Thanks!

[@TomsTinkeringandAdventures]

Thank you, hopefully it helped you!

[@russellbizzell2516]

@@TomsTinkeringandAdventures when would you go to a 162 at what elevation

[@TomsTinkeringandAdventures]

@@russellbizzell2516 that sounds pretty rich, maybe sea level? Or a modified engine?

[@christopherfleming5409]

Dude! Your video was fantastic. I ripped my XR400R Carb apart last week but had no prior experience. I got the slide back in yesterday and was just goofing around and found your video. Best one out there. Now I wanna change out the Pilot and Main. Wouldn’t have know this if it hadn’t been for your help. Thank you.

[@TomsTinkeringandAdventures]

Thank you, I hope you get your bike running perfectly. Come on back and let me know how it goes.

[@CBRRR-eh3ky]

First, I want to congratulate and Thank you for creating this very informative channel... the main reason for this ever since you created this video, you took some time to reply to those who value it and want to share your knowledge. There is a ton of youtubers out there and I have litterally never seen tbat. Usually they reply if the question can help them make money in some ways. Thanks again for keeping up with your channel and audience. I have been watching videos today for 4hours, all about jetting. This seem to be the cherry on top of the cake for me because the carburetor used in this case study looks identical to the one in my 2000 XR600R. A little more about it is: 1-The choke flap was removed due to the tragedy it could cause to the engine (does this cause a leaner condition? ) 2- it has a KNN air filter 3- Cobra exhaust 4- air screw 2.0 turn out 5- main jet at 168 Main jet needle position unknown 6- Dallas TX 430 feet above sea level 7- air cut off valve, intact. 8- float needle valve is 1mm off stock requirement Issues: 1- bogs/hesitates at 3/4 to wide open throttle 2- Terribly hard to start when cold (65 degrees or less). Note: issue #1 is my main concern at this time but id be the happiest man if I could fix both. History: It all started after the bike sat for a winter without draining the carb. What I have done: Disassembled and cleaned the best I could with carb cleaner (not safe for rubber part) so i was very conservative. Note: I did not mess with the main jet needle as it seemed involved but i can do it if i need to. My problem is; Not sure if fine tuning requires modifying the main jet needle position or size? I have extra oem main jet needle and several main and pilot jets bought on ebay. I need a direction to start fine tuning after I clean the carb again with an ultrasonic cleaner that I just purchased to make sure cleaning is not the culprit. Sorry for my book lol. I hope it was fairly easy to keep up with it and not confusing for you to advise me on how you would go about diagnosing my problems till i determine the cause of the bogs and the hard cold start. Thanks in advance and have a nice weekend

[@TomsTinkeringandAdventures]

Thanks for the kind words, I enjoy helping people so hopefully we can get you going again. Was the bike running well before it sat? If so, I would highly suspect that the carburetor isn't clean. It really doesn't take much to make them run bad. Ultrasonic cleaning is a good way to go. Without a choke plate, it is going to make it more difficult to start of course. I think I have heard of the issue you mentioned about the choke plate getting ingested by the engine. Try installing the new jets you have purchased, that would be the first thing I would do. Good luck, let me know how it turns out.

[@CBRRR-eh3ky]

@@TomsTinkeringandAdventures thanks for your prompt respomse Tom. Yes rbe bike was running perfectly before it sat. I opened the thorttle all the way on the freeway and never had the bogging before so ill take your advice and clean it again first then switch jets. Ill let you know

[@TomsTinkeringandAdventures]

07 CBR1000RR looking forward to hearing from you, have a great weekend.

[@runcivil]

Didn't see this mentioned in the comments. @ 11:55 ; That is a slosh baffle. It's purpose is to prevent air from getting sucked into the main jet when the carb is shook from riding thru rough terrain, hard impacts, etc.

[@TomsTinkeringandAdventures]

RUNCIVIL thank you! I don’t always get the terms correct.

[@trevorjameson3213]

Excellent video, great tutorial! I have my XR400 jetted with the 60 pilot and 160 main, with the needle in the 3rd position (middle), and I'm at 600' altitude here. Also the snorkel is removed and I'm running an fmf slip on pipe. Compared to how it ran stock, this bike is awesome now. Easy to start and tons more power at all rpms. These really are the mods you have to do if you want an XR400 to run as it should.

[@TomsTinkeringandAdventures]

Trevor Jameson they are really good bikes, not amazingly fast but plenty.

[@estebangranados4232]

Well done, good explanation

[@TomsTinkeringandAdventures]

Thank you.

[@pedrogonzalezm.2609]

vids looking good! nice explanation and thanks for the time to show it detail

[@TomsTinkeringandAdventures]

Pedro Gonzalez M. Thanks for watching!

[@Paul-hb9lx]

Thanks mate for the video. Just about to strip my carb down in the UK

[@TomsTinkeringandAdventures]

It’s always nice to hear about people watching these videos all over the world, best of luck.

[@chiliboom6140]

I appreciate you going slow and explaining each part as you go. I don’t know carbs well at all so this is a very helpful video. I have a couple questions: 1. Does the pumper carb have all the same parts as a non-pumper. So if someone wanted to re-jet but had a non-pumper, would this video still work? 2. Would jetting to larger holes decrease mpg? 3. How do you adjust the idle air control on the bike once the float bowl is back on? Or would you have to take off the float bowl again, just on the bike? 4. Where would you get the specs for which jets and needles? Sorry for all the questions but you made a great video and I want to learn.

[@TomsTinkeringandAdventures]

I believe that I misspoke about this carburetor, it's not really a pumper carb. It's the standard XR400 carburetor so if that's what you're working on everything is the same. Larger jets could reduce mpg, but going to smaller jets to increase fuel mileage could cause lean conditions which can cook the engine. There are special screwdrivers that work well to adjust the screw on the bike, I should make a video showing that. If you do some internet searching, you can find what jetting people are running at their elevation. That's usually a good place to start, if you ride in Denver you would need different jet specs than someone at sea level. Good luck and thanks for watching.

[@chiliboom6140]

@@TomsTinkeringandAdventures Thank you for the quick reply! And very informative. You have a new sub my friend!

[@jspreparednessandself-reli4856]

Hello Tom , Thanks for this video, I just bought that same bike and have same issues, Iam going to check jetting . Mine has a stumble from quarter throttle to half , but runs great everywhere else. I live at 5000 ‘ from what I hear they think it is probably jetting.

[@TomsTinkeringandAdventures]

These bikes run way better once they are set up correctly. I think for altitude like that you may need to run a bit smaller jetting? Good luck!

[@almostoemgarage8143]

Sweeeeet! Thanks for the video! Bought an 01 xr400r and already took it on its first out of state trip for some trails, yep, needs this and the other Gordon's Mods! Mostly because I hate the off idle quick throttle bog but also because it is costing $20 to wake this baby up, I don't need an air quality or fuel efficiency tune, I need a bike tuned to rip trails!

[@TomsTinkeringandAdventures]

It has seemed to be pretty good, my bike starts easily and runs great. Depending on location it might need a bit of tweaking but should be close.

[@mattyphillips8350]

Great vid mate, been a while since I’ve had a tinker and it’s helped me out heaps. Looking forward to the next one, bloody awesome

[@TomsTinkeringandAdventures]

Glad to help.

[@RideWithTheWolf]

I've learned that the trick a lot of the time is to turn up the idle one or two turns. It's a humbling experience when your bike has been running perfect and you go to show someone ... and it doesn't start for 7 kicks haha. Sometimes, I'll prime it with with several kicks of compression release, too.

[@TomsTinkeringandAdventures]

I had to laugh...bragged more than once that I can start in one kick only to be denied!

[@RideWithTheWolf]

@@TomsTinkeringandAdventures Reporting back: When my stock carb was cutting out, I moved the needle down (from the third notch to the second notch). That made it run great, but as soon as I tried to put the snorkel back in, it started cutting out at mid throttle again. So, I'm assuming I'm air starved. Now, I've ordered the 160 and the 60 and put them in. It's cutting out at 1/3 - mid-throttle again. So, should I bring the needle down more? (This would put clip on the first notch on the top), or should I go back to the 52 pilot and leave the 160 main jet? It's my understanding that the 60 and the 160 are the recommended jets. Do I need to do the rest of Gordon's mods to make the new jets work right?

[@TomsTinkeringandAdventures]

@@RideWithTheWolf so maybe run it without the snorkel? A lot of people run the air box without it. If you want to keep it, yes...will need to continue experimenting to find the combination that works for your bike and location

[@RideWithTheWolf]

@@TomsTinkeringandAdventures the snorkel is still out. What would give it too much gas at 1/3 - 1/2 throttle, the main jet? The 60 pilot jet is more for starting, right? So, I'm thinking I need a smaller main jet?

[@TomsTinkeringandAdventures]

@@RideWithTheWolf likely, remember the main jet and needle work together so you might need to readjust. It’s a bit of work but I am sure you will get it and the bike will be better!

[@EricFujidabossStanley]

Hey bro I need some help , I live in kentucky , i jus buit a 2007 honda trx 400ex to the 440 big bore with a stage 2 cam , now I'm ready to jet it , What Jets Should I use ?

[@TomsTinkeringandAdventures]

Lots of factors go into jetting including the exhaust you use, if you have opened up the airbox, altitude, cam, etc. I couldn't tell you for sure what jets to use but if you do some searching online you should be able to find someone with a similar setup and you can start from there. It will likely need fine tuning, so get a few jets bigger/smaller from your start point and just work through it. Best of luck.

[@EricFujidabossStanley]

@@TomsTinkeringandAdventures believe it or not I've looked everywhere for a answer , it has no header but slip on , airbox lid off , I'm not sure altitude but I'm in pikeville kentucky , stage 2 cam , 440 big bore kit . I think that's it lol it had 38 n 148 jets in it from stock

[@matthewturowski8281]

Great videos, I'm in the middle of fixing up an 03 XR. A fair amount of neglect by the prior owner that I've been chipping away at. Just finished a top end rebuild and it runs great.

[@TomsTinkeringandAdventures]

Matthew Turowski nice! I am editing a video of a top end rebuild on a 400EX quad, same engine.

[@matthewturowski8281]

@@TomsTinkeringandAdventures Same engine as the XR, just electric start. The top end rebuilds on those aren't bad and they go together quickly. The Clymer manual was helpful. Stock bore with a new Wiseco piston and rings, new valves, Hotcams stage 1 cam, springs, seals and cam chain on mine. Put in a new clutch for good measure while it was torn down.

[@TomsTinkeringandAdventures]

Matthew Turowski yes, easy to work on. Did a 416 kit and FCR carburetor.

[@OEF_Vet_0331]

Great video man!

[@TomsTinkeringandAdventures]

Thank you, appreciate the support.

[@JakeMadz]

Brilliant video!!!! Thankyou!!!

[@TomsTinkeringandAdventures]

You’re welcome, thanks for watching.

[@osalcedoucmsae]

At 5:41, I think that’s a fuel mixture screw, if it’s on the side closest to the engine. Similar function but opposite way to adjust it Thanks for going step by step, I’m also doing a ton of research to fix my 85 XL600R

[@TomsTinkeringandAdventures]

Omar S yes, it’s old/bad habits calling it air mixture screw.

[@osalcedoucmsae]

Tom's Tinkering and Adventures with the jetting you bought, did you individually purchase the jets or a kit? I ordered a rebuild kit for my carbs and the jets were smaller than what I had even though I believe mine are stock I have a supertrap exhaust so I’m sure I gotta change those out eventually

[@TomsTinkeringandAdventures]

Omar S I got individual jets. Part of the problem is that some companies number them different. Stock Mikuni 140 jet could be different than a DynoJet 140 jet, for example. Confusing. There are some comparison charts online that may help.

[@osalcedoucmsae]

Tom's Tinkering and Adventures yea I heard about that and it’s confusing hah Unfortunately my bike has dual carbs so more jets and harder to pull the all the pieces apart hah Thanks for responding!

[@TomsTinkeringandAdventures]

Omar S oh yeah, I forgot about those mid 80’s dual carb setups. A little extra fun! Good luck and I hope you get it dialed in.

[@ricardocarvalhomonteiro]

First of all, congrats on the awesome video. It inspire me to tune my carb. I have a 2000 xr400r scrambler that i change the entire exhaust system with a supertrapp out and a brand new dna 75mm air filter. The bike starts well cold and hot but i lack power with a quick throttle and after 3000rpm. Im thinking in change the main jet to a 160, not really sure whats the one there right now but i belive its the 140. I live by the sea and not sure if i should tune anything else or where to search those specs. Thanks in advance

[@TomsTinkeringandAdventures]

Thank you. If the bike is starting easily and idling well, you likely have the pilot jet set up right. Switching to a less restrictive exhaust and filter will require some changes. Main jet is easy to change, worth a shot. I would also suggest looking at the needle. You may have to raise it (move the clip down). Let me know how it goes.

[@christopherfleming5409]

I guess after reading this I am led to ask a question. This 400 I bought back in November has a White Brothers eSeries exhaust. I ventured to tearing down my carb and cleaning it and going through the manual where I happened to see where the Needle Jet clip suggested to be set on the “3rd drove from top”. Mine was set to the 4th. I’m thinking after reading this, I should go back and drop it on notch after what I’ve learned from your freakin’ awesome ass video, and this conversation.

[@TomsTinkeringandAdventures]

@@christopherfleming5409 you can give it a try. Every situation is a bit different, but if you have an understanding of how it all works together you should be able to get it dialed in.

[@christopherfleming5409]

@@TomsTinkeringandAdventures yep, like you said, it a little Black Magic. Just gotta play with it I suppose. Thank you again!

[@sulacoblack6288]

Cheers mate, that's gonna help out a fair bit I reckon. I've got a Chinese import road bike that uses an XR400 motor of all things. An XR was always a dream as a kid for me, never had the resources to achieve. The road bike is running rough, but just needs a tune I reckon, so thanks again.

[@TomsTinkeringandAdventures]

sulaco black interesting, what’s the brand of that bike? I have worked on some Chinese bikes, usually the carburetor is a bit odd.

[@sulacoblack6288]

@@TomsTinkeringandAdventures I bought it from a mob called Sol Invictus (Aussie mob). The bike origionated as an elstar warbird I think they call em. Mine is branded by Sol as a Scrambler Nemesis. Not too bad as a cheap road bike to learn on....or get your license.

[@TomsTinkeringandAdventures]

sulaco black I just looked it up, neat looking bike. Where in Aus are you? I have been to Perth and Sydney several times on port visits.

[@sulacoblack6288]

@@TomsTinkeringandAdventures In victoria but country. Lived in Melbourne for a bit but decided a change was best. Sounds like you get around mate.

[@TomsTinkeringandAdventures]

sulaco black US Navy for 26 years, saw a lot of the Pacific and Indian Ocean areas. I would like to do some riding in Australia....someday.

[@ernestkuczek6496]

Great video👍

[@TomsTinkeringandAdventures]

Thank you!

[@rotorhawg8052]

Thanks brother for the awesome video. Could you tell me where you got the 60/160 jets from. My 2000 Xr400R has a 52 slow jet and a 142 Main. Everywhere I've looked has a 160 Main but only a 58 Slow jet?

[@TomsTinkeringandAdventures]

When I need specific jets, I go to the website www.jetsrus.com

[@russellbizzell2516]

Hello I have just put the 60 and 160 jetting in my 2004 honda xr400r and I put the mix screw 2 and 1/4 out but if I got passed 3/4 throttle it'll bogg/popp it'll start right up

[@TomsTinkeringandAdventures]

Sounds like you have some more adjustments required. Might want to get a couple smaller/bigger main jets and experiment until you find what works best in your area.

[@russellbizzell2516]

@@TomsTinkeringandAdventures in currently at 5,500 ft what size would you recommend 👌

[@TomsTinkeringandAdventures]

@@russellbizzell2516 higher altitudes require lower jetting numbers. Try a 150 or 145 to start.

[@nathankulp3009]

please note that changing to a larger main jet will directly effect the fuel consumption. With the larger main jet you won't make the 107 mile trail loop on the stock tank any more.

[@TomsTinkeringandAdventures]

Nathan Kulp great point, thanks for watching.

[@kellygoertzen849]

I always wondered how to do this and just what it all looked like. Thanks Tom!

[@TomsTinkeringandAdventures]

Kelly Goertzen just keep buying fuel injected vehicles !

[@kellygoertzen849]

Like my leaf blower and weed whacker?!

[@TomsTinkeringandAdventures]

Kelly Goertzen those aren’t vehicles!

[@hibobb123456]

It is not a Pumper Carb (2:26)

[@TomsTinkeringandAdventures]

hibobb123456 thanks, I did mess that up. I wish I could edit stuff like that after the video is posted.

[@UncleBoratagain]

This is youtube at its best, someone uploads and remains open minded. More information is offered by subscribers and is graciously accepted. Makes a very pleasant change to observe such civility!

[@motorcycleridingadventures2023]

well explained bro

[@TomsTinkeringandAdventures]

motorcycle riding adventures thank you.

[@DrewStark-o5b]

great video! learned a lot thank you. I am running at an altitude from 6-12k ft. do I need to keep it leaner or should I go with what you're doing in the vid with the pilot and main jet sizes?

[@DrewStark-o5b]

1998 XR 400r

[@TomsTinkeringandAdventures]

@@DrewStark-o5b I’m at pretty much sea level, ride in the local mountains at around 4000 ft with no real problems. At your altitude it might be best to go leaner, yes. I don’t know exactly how much, it takes some experimenting. Good luck!

[@dtsouza2519]

Great job on the carb clean. Could you do a short video showing the procedure on how to remove the carb from the bike? I think you have to remove some screws so the tail (sub-frame under the seat) can pivot up??

[@TomsTinkeringandAdventures]

tireguy the XR400R is easy to remove the carburetor. Just loosen the clamps and it can be wiggled out.

[@patricklonnee4929]

Carb is a pain to get out its like a puzzle. has to be in just the right position. There must be easier method. What side do you remove carb from?

[@warner6495]

Just watched all three XR400 vids. New Sub here.Thanks for the info. Just got my XR400 a few weeks ago. Father in law and I cleaned up the carb, cleaned the gas tank, new petcock, fuel filter, changed the spark plug, pulled out a hornets nest from the exhaust and she fired up and ran great. Took it home, rode it around for a week, no problem. Let it sit for like 5 days while I changed the tires, added a brake light and license plate bracket. When I went to start it up again it would not start for the life of me. tried for 3 days. I did realize that when I first went to start it for the first few minutes, I didn't have the choke on. Could I have leaned out the plug by trying to start it with no choke cold? Just got a socket in today for the spark plug, I'm gonna pull it out and take a look. If not, it's on to valve adjustment and maybe new jets. But it was running great before. What are your thoughts? Thanks again.

[@TomsTinkeringandAdventures]

Jamal Warner I’ve heard a lot of people have trouble starting these bikes. Go for the plug and then keep picking away at the maintenance items. Good luck, thanks for watching .

[@matthewturowski8281]

Once you get the starting sequence down, they are not bad to start, but for someone who is not used to a kickstart bike, they can be a handful. There are a number of videos on the internet that show starting techniques that work for people. For me, cold, I put the choke on full, pull in the decompression lever and kick it through a couple of revolutions on the starter. Then I let go of the comp lever and find TDC and go just beyond that and kick it with the throttle partially on to give a high idle. Cold, it will usually start within 3-4 good kicks when you cycle it past TDC. Warm, first kick. I let it warm up with the choke on full for maybe 30 seconds and then switch it to half choke. IF it sounds like its going to die, I flip it back to full choke to get more fuel. Hondas are cold blooded and take some time to warm up. I just rebuilt the top end on mine-new piston, cam, valves, valve seals, valve springs. These air cooled Honda engines run forever if you take care of them.

[@tcb0404]

Hey man can you maybe do a xr400 engine disassemble vid and one to put it back together

[@TomsTinkeringandAdventures]

Chochy Chiefin I did a top end replacement video on a 400 EX quad which is basically the same engine.

[@Paul-hb9lx]

Just a note, if you want to change just the main jet. This can be done just by going up through the float bowl bolt so it can be done in situ

[@TomsTinkeringandAdventures]

Nice tip. This carburetor is pretty easy to remove but some are more difficult so that can be really helpful.

[@BrandonBigB956]

52 jet for example is a .52mm hole. 160 main jet would be a 1.60mm hole. This is the same for all jets across all brands just FYI.

[@TomsTinkeringandAdventures]

@@BrandonBigB956 not really the case.

[@MrBajabug65]

This will be helpful for when I buy the other XR400 in your garage

[@TomsTinkeringandAdventures]

Aaron it’s not necessary, that Honda runs perfectly already

[@peteratmore3015]

Nice vids !!!many thx

[@TomsTinkeringandAdventures]

Peter Atmore thank you for watching, have a great day.

[@Nezerkad]

Question for you.. just cleaned my aftermarket carb on a 1999 XR 400. It sat for a few years so it was gunked up bad. Once I cleaned it and put it back together, both jets were clear, it starts and idles fine, a little hard to start (always has been). The issue is if you crack the throttle quickly it sputters and the exhaust pops. If you slowly open the throttle it goes up in RPM fine. Any suggestions? I didn’t replace the jets, I didn’t even look what size they are, it’s an aftermarket carb that was on the bike when I got it and it ran fine then with tons of power.

[@TomsTinkeringandAdventures]

Does this aftermarket carburetor have an accelerator pump? If so, you need to check the diaphragm. Otherwise, the carburetor may still be dirty internally. Soak the entire carburetor body once you have removed everything that you can, ultrasonic cleaning is best.

[@Nezerkad]

@@TomsTinkeringandAdventures I’m not sure, I will check! Thanks for the reply.

[@carlosellatigo9378]

Just playing around with this atm. Does anybody know the air screw washer sequence if you were loading it up before your screw it in goes: the spring then washer then o ring, or is it reverse an the washer sits "on top of the spring" and the o ring nearest the screw driver end? Cheers.

[@TomsTinkeringandAdventures]

Install the spring onto the screw, then the washer, then the O-ring.

[@ronmower3694]

Hey brother wat jets would u put in a bike at my home orangeville Utah 5,700 roughly! Thank ya

[@TomsTinkeringandAdventures]

Usually altitude uses leaner jetting. Try a couple sizes down on the main. Maybe one lower on the pilot? My 400 is currently in Utah too, north of SLC with my son.

[@UncleBoratagain]

Great tutorial Tom. My jets have just arrived for my US import bike (I am in GB). Made a boob as we say and ordered #60 and #162 instead of #160 but I will give the jets a trial in my bike. Thanks for uploading my friend!

[@TomsTinkeringandAdventures]

Max Plankton 162 will likely be okay, a bit richer is better than a bit lean usually. Cheers!

[@UncleBoratagain]

Tom's Tinkering and Adventures Agree Tom, very close to sea level here (Nottingham) so worth an attempt. The downside is...bugger all countryside to enjoy dirtbikes compared to America :( .

[@TomsTinkeringandAdventures]

Max Plankton I wouldn’t mind exploring GB, might have to set up an adventure there. Let me know how the bike runs.

[@UncleBoratagain]

Tom's Tinkering and Adventures Tom yes please do but be aware, opportunities to explore wilderness are very limited on a bike in comparison to the US, Canada or indeed parts of Europe. That said, our landscape and history are particularly interesting to our U.S and Australian/NZ cousins! combined with even just a three day tour of Normandy, involving all of the timeline and emotion of D-Day and ensuing battles the learning curve is steep. When in GB take a two night stay in Portsmouth? There is so much to study and to understand our Naval traditions there. Stay at the Queens Hotel! Churchill has been a guest. Presumably they (very sadly) do not advertise that any more.

[@TomsTinkeringandAdventures]

Max Plankton thanks for the info, gonna make it when the world gets a bit more normal.

[@simonmears1726]

Jetted lean from factory open air box install free flowing air filter go bigger pilot jet will start easier and install Bigger main jet cheap mod for more performance better to be rich then lean the 400s run hot best of Times and if U Go high above sea level U can compensate by winding fuel screw in less fuel the higher U go the the richer U go

[@TomsTinkeringandAdventures]

Yep, just a bit of tuning gets these things running sweet.

[@williamoren3508]

I have the same carb on my 250 xr the throttle is hard to turn when started but when the bike is off it’s easy I have rebuilt everything on any suggestions would help love all the xr

[@TomsTinkeringandAdventures]

William Oren that seems odd. Have you checked the throttle cables and how they are routed?

[@patricklonnee4929]

Same problem, feels like throttle is sticking just off idle

[@johnl1739]

What needle did you end up using stock or the after market one, and what setting was the clip on

[@TomsTinkeringandAdventures]

It’s the stock needle. I can’t remember which groove, sorry!

[@johnl1739]

Just bought a 2001 its was in the original shipping crate for 10 yrs then sold to a 1owner 68 year old man . Who never got to ride it only on the lawn around his farm. Going thru everything right now.

[@TomsTinkeringandAdventures]

@@johnl1739 what a find! I hope you have years of fun in it.

[@johncook1585]

Thanks, Tom. Great info. I'm rehabbing my 2004 XR400R and went with 60/160 on the jets. I have other sizes if a change needed. My airbox and muffler are stock. Few miles on bike so no need to change. That being said, should air/fuel screw be at ~1.5 turns as a beginning and can the needle jet be at 2nd or 3rd position? I operate at sea level to 5000'. I'm an older rider who just cruises the Nevada desert looking for old mines and ghost towns. Also, do you know of an extended air/fuel screw for the stock Keihin PD carburetor so adjusting is easier on the bike? Thanks, again. John.

[@TomsTinkeringandAdventures]

Well every situation is going to be a bit different. I know it’s a pain, but you might have to mess with the clip positions and the screw a few times to find what works best for you. I have not looked into an extended screw but I’m sure there’s one on the market. Best of luck and thanks for watching.

[@Itsjake908]

What’s your opinion on the stock choke plates of these bikes? Some people say they’re prone to break what ya think

[@TomsTinkeringandAdventures]

I suppose it does happen but I don’t know that it’s common.

[@Itsjake908]

@@TomsTinkeringandAdventures ok ye I’ll just leave it I guess. Thanks for replying

[@neurozero]

i did upgrade on jets. now bike barely runs. there are lot of Hiccups and it stops running after 1/4 mile. spark plugs are pure black. also exhaust is super super loud.

[@TomsTinkeringandAdventures]

Karam Singh well that seems odd. Might want to double check it?

[@neurozero]

@@TomsTinkeringandAdventures Thank You for the reply. It might be getting flooded from float being stuck. I might put stock jets back in and see if this helps. Also being in california I am not able to order different jet sizes due to restrictions. (sucks).

[@TomsTinkeringandAdventures]

Karam Singh yes, float could definitely cause those problems. I hope you can find a solution.

[@lucasbaez8951]

I just bought a xr 400 (first bike ever) and was told it has a big bore to 440 but they never rejected the carb so it started when I got it now its really hard to start . What jet size would you recommend I rejet to .

[@lucasbaez8951]

2000 xr400

[@TomsTinkeringandAdventures]

I really don’t know, would suggest doing some research on motorcycle forums and see if people have ran your particular engine and exhaust, see what has worked for them. Good luck.

[@MrThiefHater]

Thanks for the awesome video. My bike has been sitting for a few years and now it wont start. The last time it started, after sitting for 2 years or so, it would barely idle and would run poorly at any kind of speed. I was thinking about replacing the jets in hopes that this will fix the problem. Sound reasonable? I think it has stock jets now so I would order the 60 pilot and and 160 main.

[@TomsTinkeringandAdventures]

Jason C it’s not a bad idea to just order some new ones. Might want to soak the carburetor overnight as well. Good luck and let me know how it goes.

[@therenaldrich748]

Thanks, One question... How do you adjust the idle air adjust needle once the carb is installed. Do you have to remove the float bowl to do this?

[@TomsTinkeringandAdventures]

Theren Aldrich there is a idle mixture screw which can be adjusted without removing anything.

[@RideWithTheWolf]

Nice video. My XR400 starts, runs, and idles great, but it cuts out at around 1/3 to 1/2 throttle. Once I'm past that point, it runs good at 3/4 to wide open. I'm pretty sure the jets are stock. It seems to me its having an issue with the transition from low throttle to mid throttle. So, what could that be? Should I simply upgrade the jets like you did? Maybe the float bowl is running out of fuel? It seems like a lot of XRs have this problem. I wish Honda would come out and explain this notorious issue.

[@TomsTinkeringandAdventures]

Try raising the needle.

[@RideWithTheWolf]

@@TomsTinkeringandAdventures I've ridden this bike when it's running right and it is really smooth and powerful. But it would intermittently run good and then not so good. Almost like the spark goes weak. I'm gonna order a new plug wire /voltage regulator and a carb kit. Or just a new carb.

[@TomsTinkeringandAdventures]

@@RideWithTheWolf come on back and let me know how it goes.

[@RideWithTheWolf]

@@TomsTinkeringandAdventures I've learned that I have a rich condition, so I'm going to move the needle down. What I don't understand is if the machine was running fine before, why would the needle need to be adjusted? Maybe because the carburetor is cleaner, now? LOL, sorry if you're busy. Just having a conversation.

[@RideWithTheWolf]

@@TomsTinkeringandAdventures hey, that totally worked like a charm! I moved the needle from stock which is the 3rd ring, to the the 2nd ring down. This creates a leaner mixture. Acceleration is smooth and there's better power. Thanks to you and some other videos for pointing me in the right direction! Why mess with the jets when you can mess with the needle? Ride safe!

[@kyecowen4583]

was there an O-ring for the pilot jet? Rebuilding my carb now and seem to have an extra o ring

[@TomsTinkeringandAdventures]

Kye Cowen I don’t think so. Sometimes those carb kits come with crazy stuff. There is a small o-ring on the idle/air adjust screw along with a tiny washer

[@kyecowen4583]

@@TomsTinkeringandAdventures thanks for the reply! Got'r back together and started on 3rd kick! Nice compared to the 12 it used to take!

[@TomsTinkeringandAdventures]

Kye Cowen that’s great to hear. Was it good at starting hot? Some of these bikes are tricky to restart after stalling out when they are hot.

[@kyecowen4583]

@@TomsTinkeringandAdventures this one has never had problems once it's hot. Still have more work to do before going out, I'll have to get back to you on that.

[@D0nie11]

Hi.. I'm using the same jetting but I wanna ask you, how many turns I have to give to the fuel jet? 2 1/4 2 1/2? Thanks!

[@TomsTinkeringandAdventures]

A lot of times I start at about 2. You should adjust it once you have the bike warmed up.

[@D0nie11]

@@TomsTinkeringandAdventures Hi..! Thanks so much 🙏🏻 Take care!!👍🏻

[@TomsTinkeringandAdventures]

@@D0nie11 good luck and ride safe!

[@danielarbelaezg3451]

very good video, is the spark plug working fine after these changes? i feel my xr400 kind of sleepy and was told to change the main jet to be 150, some people told me this will affect the functionality of the spark plug because will be too much gasoline, would like to know your experience on this after the changes, thanks in advance

[@danielarbelaezg3451]

by the way im going to install the DPR9Z spark plug on it

[@TomsTinkeringandAdventures]

Daniel Arbelaez G I haven’t seen any spark plug issues, I think your friends are saying it will run too rich? It’s easy enough to see, if you’re plug is getting dark then it’s probably rich.

[@danielarbelaezg3451]

@@TomsTinkeringandAdventures thanks for responding, i will try that 150 and see if it can run better, is yours getting dark? cheers from costa rica

[@TomsTinkeringandAdventures]

Daniel Arbelaez G so far, so good. I want to ride to Costa Rica sometime!

[@danielarbelaezg3451]

@@TomsTinkeringandAdventures for sure, you will have a long way to come, but its worth it

[@nolanlittle6904]

I have a xr250r and my overflow leaks really bad and I can’t get it to stop where can I get a new carb because I can’t find one anywhere

[@TomsTinkeringandAdventures]

nolan little you likely need to replace the float needle. Lots of them available on Amazon or eBay.

[@marshallburgess7360]

Where can I get the jets

[@TomsTinkeringandAdventures]

Marshall Burgess the place I like to get most of my carburetor parts from is a site called www.jetsrus.com but you can also order from eBay or amazon. Plenty of other places. Thanks for watching.

[@marshallburgess7360]

Awesome I’ll be searching around for some jets for sure. I just got my xr400r with all the original papers pretty great condition no rust bunch of extra parts. just idling pretty rough.great video man would it be possible to ask you info on getting my bike running great for this summer

[@TomsTinkeringandAdventures]

Marshall Burgess for sure, I am willing to help. It doesn’t take much to get the XR400R running great.

[@marshallburgess7360]

That’s why I got one. Did a lot of research they are bomb proof. Nothing but power

[@chrisbylhouwer9124]

I fell asleep.

[@TomsTinkeringandAdventures]

CHRIS BYLHOUWER glad I could help with your insomnia.