xj 650 hard cold start?

ok so ive been though the threads an read up on what I could. I have a set of carbs that I got rebuilt/ cleaned all 9 yards completely torn apart soaked etc. well while the guy was in there I had him put the 750 jets in (why not) well the bike would start right up on the old set of carbs (still factory an dirty as hell) yet the carbs I got rebuilt with the bigger jets in it on a cold start will some times start up but than die I can't give it gas an I've played with the choke it won't fire up unless I throw some Esther in it than I can run all day long kill it an sit an than it fire back up no problem just that sitting over night is what killing me lol. Any tips tricks advice for me? It's an82 650.

 

o an if I'm sitting at a stop light some times the bike idle runs up to 3k I have to twist the grip a few times to get the idle to go down.

 

You have jets for a 750 in carbs that are on a 650cc engine!?

You answered your own question.

Swap the jets back, and make sure that you get the air jets in the correct place. Both the Haynes and the Yamaha shop manual have the same misprint.





Did the rebuilder put in new throttle shaft seals? Were the carbs dipped in carb cleaner without removing all of the rubber parts?

OH....one more thing. What are the pilot screws set at? 2 to 2 1/2 turns out is a good baseline.

 

It's set at 2 1/2 turns, all rubbers were removed an yes new throttle shaft seals. Tank bath 6 or 7 times. Adjusted according to spec In the manual. Everything is brand new in this carb lol an there not really 750 jets they were from a kit I got off eBay that had the factory jet sizes, a mid range jet an one for like heavy modifications. if I can find a picture of the kit I'll post it. it just strikes me as odd that the bike runs an starts fine if you let it sit but just that initial cold start after you let it sit over night it dosent want to run well. It start but it just Boggs down almost like my sparks weak an die than it just crank an crank an sometimes it catch. I replaced the spark plugs an it seemed to help it but is there any thing else I can adjust or would I have to remove the jets I don't want to unless I have to the bikes got a lot more snap to it now lol

 

Have the carbs been synched?

 

Are you letting it warm up on the choke before trying to pull away? It takes a minute for the combustion chambers to warm enough to support revving the engine up without flooding it. Does the air temperature happen to be around 40ºF or lower?

 

I'm having the same issue with a 650 first start up won't hit with out ether. After that just bump starter. I'm going through some stuff today. I'll let know if I get corrected. I'll be watching for what you find too

 

No the carbs haven't been synchronized yet do you think that could be the problem? the only reason I say that is because like I said I threw a old dirty set on an it fire right up. I'll get it synchronized possibly this weekend. An pax I had 2 82 650s check your boots on the fount side of the carb closer to you front wheel if these bikes have the slightestggap or dryrot your gonna have that issue.

 

Yes, definitely.