I owned one of these back when it was new. I never needed to work on it other than routine maintenance. I spent a lot of time waxing and polishing it. I just discovered that these bikes have Hitachi carburetors. I've worked on hundreds of Mikuni and Kehein carbs, but don't think I've ever touched a Hitachi before. I was surprised by all those extra jets all over the place. To clean tanks I first wash them out by filling them fill of Superclean, and letting it soak for at least 24 hours. be careful with it, it will take the skin right off your hands, and I mean like right now. That should get all the old gas residue out. Rinse it thoroughly with water, and if there is a lot of rust in it, remove the petcock, plug the hole, then fill the tank with full strength muriatic acid and let it soak for several hours. pour it out, flush it good with water, then pour in about a quart of WD-40 and slosh it around to prevent flash rusting. You will need a new O ring for the petcock. I use Allen screws to replace all of the float bowl screws and top cover screws. No more problems getting them out.

Great Series! Thanks for documenting your rebuild!

@kevinon4wheels

2 жыл бұрын

You’re welcome! I got more to go but have been unable to do anything with it. There’s more on the way!

Pink Floyd in the back

@kevinon4wheels

3 жыл бұрын

Only the best!

What does the jets set on

Hi Kevin, I have rebuild completly my carbs in a xj750 Seca RH, I have changed also the rubber boots, jets, needles, v-rings from the throttle shaft, o-rings from the fuel pipes (all replacements quality made, not chinese). I have done the valve clearence and syncronize the carbs using the YICS tool and an original yamaha clock syncronizer. I checked again the syncronization with a liquid gauge to see rising the levels of the four carbs at the same time. Everything is done as it should. I have finaly used the colortune to adjust the pilot screw, setting to 2,75 turns out. Now the problem.... which is driving me crazy.... I start the engine cold, choke on and the engine start fine. After seversl minutes the engine warms up I switch off the choke. The engine keeps on 1000 rpm... everything seems to be fine but once I turn the right hand throttle, the rpm rise to 3000 and they keep on 3000 or they drop slowly. Then I turn the idle screw out just a bit to keep the rpm on 1000 but they drop an the engine dies. If I screw the idle back in again just a bit, the rpm rise up again to 3000. If I let the rpm that way they drop sometimes to 1.500 but very slow which is not the right way to be driven. If I unscrew the idle screw so that the idle dies and I keep acelerating using the hand throtle, the rpm work great going up and down fast as it should. The problem is that when I stop, I have to turn the hand thortle just a bit so that the engine keeps runing otherwise it dies. This means that either I have bad idling speed and rpm keep on 3000 or I have good idle speed letting the bike to be driven nice but dying when I stop and don't use the hand throtle to avoid it. I have been told about air leaks but everything is fine no leaks found even spraynig carb cleaner over the carbs. The question is, screwing the idle screw does not work properly, using the hand throtle just 1 mm keeps the bike from dying. Both, idle screw and throtle cable push or pull the throtle shaft.... why when I pull the cable the rpm stay on 1000 and if I screw the idle screw in it mess everything up? I have also tryed to play with the throtle cable but does not make any diference. Any idea what could be happening? I would really aprecaite any help, I am lost and here in Spain I don't fine any workshop from the old school to take the bike to be repaired. Many thanks! 😉

@kevinon4wheels

2 жыл бұрын

Just off the top of my head maybe your float isn’t adjusted properly. Perhaps the fuel isn’t sufficient to keep up with the RPMs. Then needs to refill. I’ll do some more thinking on it and get back to you. It sounds like you really covered all your bases

@bestione761

2 жыл бұрын

@@kevinon4wheels Thanks kevin, tomorrow I will spray all over the carbs with carb cleaner instead of brake cleaner and if I have the chance I will use propane as I have read in the xj4ever forum hoping to find if there is an air leak. The floats are set at its level 17,5 mm. THANKS AGAIN KEVIN!!!

@kevinon4wheels

2 жыл бұрын

@@bestione761 any luck yet?

@bestione761

2 жыл бұрын

@@kevinon4wheels I gave up... although the motorbike runs fine while driving it, it keeps dying when I stop... no matter if I sync the carbs (using the YICS tool) and turning out the pilot screws out from 0,25 to 0,25 up to 4 turns. Also checked with colortune. I have been told that sometimes is not just a matter of sync the carbs, it is also by ear, listening the sound of the engine. I have also done compresion test wich is 10- 09- 10- 09, seems to be right. I took the bike to a workshop and now I have to wait. Let's see if the guy from the shop finds the issue. I guess this is going to take him a lo of time, I will be lucky if he finds the problem because after all that I have tried I don't think there will be more to be done. I will let you know. Thanks for your interest. Merry Christmas from Spain!

@jerrybigrig9475

2 жыл бұрын

@@bestione761 any luck..??

Hi Kevin you have been a huge help on my seca build just took off the carbs and need to clean them but am kinda nervous I have never built a motorcycle this is a first for me, that being said I do have a question for you, what tool did you use to measure the floats and how do I figure out the height of mine ?

@kevinon4wheels

3 жыл бұрын

Hello. I apologize for the delay AGAIN!!. I did not see a notification. I used a pair of calipers to measure them. I looked up xjbikes.com/forums/ it is a WEALTH of information!

Found a xj 750 cheap struggling with firing it up. Gas through the spark holes it promises and then takes a couple of high rpm and dies. It have been standing for 10y I cleaned the tank and now waiting for a replacement fuel cock coz I twisted it too hard while it was full of rust. And it started to leak. After starting a while got the old gasoline smell to go get out of the bike. Would love to change thoughts and vids via mail or something. Thumbs up

@kevinon4wheels

3 жыл бұрын

Hello. I apologize for the delay. I did not see a notification. Sounds like you're on your way to success! How has the last month been?

@teijokarva8545

3 жыл бұрын

@@kevinon4wheels between postal service circling around the petcock for 30days just for me to find out it's the wrong one nothing much is happening 44mm from middle to middle(mounting holes) should the petcock be and 35mm was the one what came... any other model what has the same(ish) petcock coz here in finland Yamaha's sparepart book don't even recognize the 750 maxim or other maxims

Say Kevin if you put those pod air cleaners on your carbs how did you get the air box out????

@kevinon4wheels

3 жыл бұрын

Hello. I apologize for the delay. I did not see a notification. It was easy to remove. Just a few simple screws!

@everettconrad4685

3 жыл бұрын

@@kevinon4wheels Apology not necessary, I understand completely. A XJ650 must be very different from a XJ750 because I have struggled with taken the air box off my 750 and can find no way to do it without destroying it, and I don't want to do that. I have had other people look at it and say the say thing, destroy it is the only way. So in the mean time I will keep searching for answers on how to remove it without destroying it..

Where did you get your carb from I just opened mine and the previous owner broke the same thing but I am having trouble finding just that one carb, i would appreciate any help thank you

@kevinon4wheels

3 жыл бұрын

Hello. I apologize for the delay. I did not see a notification. I got it on eBay. There is a large selection of used XJ650 parts!

How did you measure the float height?

@kevinon4wheels

2 жыл бұрын

Hello. I used calipers. Locked the calipers in the appropriate height and went down the line

Where did U get the intake boots?

@kevinon4wheels

3 жыл бұрын

www.ebay.com/itm/154311152333

Hey! at 1:47 you were putting in the big screw. This screw stripped on me and I had to drill it out completely and tap in. Where can I find a replacement or what jet # was it. Any help would really help

@isaig.9222

2 жыл бұрын

I believe the small Jet was #50, what jet number did you use to replace? Was it the same or a bit bigger

the big weird jets on the air box side of the carb are air compression jets

@kevinon4wheels

3 жыл бұрын

Thanks!

@theghostofsaturdaynite6493

3 жыл бұрын

@@kevinon4wheels no problem thank you for your videos. Just did my rebuild with kits on my 82 xj750 two days ago

@kevinon4wheels

3 жыл бұрын

@@theghostofsaturdaynite6493 Glad I could help! I like to return the favor since I'm a proud graduate of KZread University. Ha ha

Where did you order the rebuild kit and all the new jets from?

@kevinon4wheels

3 жыл бұрын

www.ebay.com/itm/401953101443

@kevinon4wheels

3 жыл бұрын

Less than $30 and all the parts were quality and fit perfecty

Hi Kevin. I have a XJ750 that needs a carb rebuild like you did so I took the bike to my local Yamaha dealer and he told me that parts were not available any more. So if you would be so kind as to help me out and tell me where you got the rebuild carb kit for your XJ650 I would be forever grateful. I don't know where you live but I live in Idaho so if you ordered it on line then I could do the same. Thanks again for your help and great video...Everett

@mmtedw

4 жыл бұрын

Hey Everett, I don't know if you ever got your answer, but I've got a 1983 XJ750 Midnight Maxim and I've been able to order some parts on XJ4Ever.com. I was able to get it sent to Canada so you shouldn't have any problems getting it to Idaho! I haven't gotten around to ordering the carb kit, but hopefully soon I'll get one and give it a shot!

@everettconrad4685

4 жыл бұрын

@@mmtedw No I never did get an answer so I just went and ordered a kit from China. Still waiting for that. Thanks for the info about Canada. I only live a few miles from Canada so maybe it is close by, Thanks again.

@mmtedw

4 жыл бұрын

@@everettconrad4685 Hopefully it'll work for ya! Let me know how it goes, because I might have to order one as well in case I can't solve my issue! I mostly need a new seal, but it wouldn't hurt to replace everything just to be safe. I'm currently in the middle of tearing it apart and cleaning the jets and hopefully that'll solve a lot of problems with running too lean.

@kevinon4wheels

3 жыл бұрын

Hello. I apologize for the delay. I did not see a notification. I am sorry. I got my carb rebuild kit on eBay. It was less than $30 and worked perfectly. www.ebay.com/itm/401953101443

I'm going to look at an 82 xj650 tomorrow. I've seen two different heads on these bikes Yamaha, and YICS. What is the difference?

Hey I’m having trouble with my bike.sometimes when I start it up and drive a bit and come to a stop,the bike starts to pop and smoke out the exhaust.it smells like it’s burning gas.will buying a carb rebuild help me out with this issue?

@kevinon4wheels

3 жыл бұрын

I think it sounds like the float may be sticking. Then when the demand for fuel stops the flows still continues, causing the rich mixture. I think giving it a good cleaning will be a good start!

@jerrybigrig9475

2 жыл бұрын

Did you get it figured out ..??

@javieradorno6342

2 жыл бұрын

@@jerrybigrig9475 yes.one of four fuel jets inside the carb,that feed it fuel,unscrewed it self,feeding the bike more fuel then needed,I think this flooded the engine causing the gas to mix with the oil,making it smoke out the exhaust.

@javieradorno6342

2 жыл бұрын

@@kevinon4wheels that’s what I thought it was.turned out it was it was a simple fix.the bike starts and I can ride it but the battery won’t charge,so I’m gonna tackle the stator when the weather gets better.thanks for the advice,I appreciate it

@kevinon4wheels

2 жыл бұрын

@@javieradorno6342 you’re welcome! Glad you got it figured out. Trace the wires back to make sure nothing is broken. Also check the rectifier. Maybe the stator just needs a deep cleaning!

you didnt the fuel mixture screw beside the choke they are dirty cant even see them lol

@kevinon4wheels

3 жыл бұрын

Ha ha. That’s probably how I missed them! I gotta do some research on them and get them cleaned out. Thanks for pointing them out!!

@simonthiboutot6701

3 жыл бұрын

@@kevinon4wheels ya mine after thoughts its a air screw there arent fuel mix screw fuel control only by the jet on those but ya mine is a 81 and the air screw is right beside the choke on the carb look for it maybe the 82 is different ..