Xj 650 carbs need help!

[DRedel]

Sorry everyone I know a xj650 question doesn't belong here but I have to ask. I convinced my buddy to buy a motorcycle and I went with him and did the test ride and everything seemed fine. he bought it and after about 10 15 min of ridding the bike starts to rev out of control. He's never been able to ride it for more than 15 min it always does the same thing. We have another buddy who has the same bike xj 650 same year 82 and we always steal his carbs and put it on the other bike and we can ride no problem never revs out of control. If we put the bad carbs on the other bike it rises for 15 min then it will rev out of control. Every mechanic we take the carbs too clean them and do this or that and give a bill but it still does the same thing. He bought some new carbs salvage and thy did the same thing. Any ideas on what the problem is or how to fix it. Or of anyone has carbs that would work and they would be willing to sell them. Thanks Dustin

[crazy steve]

They need to be synced to the bike....

[DRedel]

Hey sorry I put this is the wrong place. How come taking carbs off a different bike works. People have been saying there's a leak but we tried spraying starter spray and it dident rev up more. I'm talking unrideable revving almost redlining at idle

[cywelchjr]

Hey sorry I put this is the wrong place. How come taking carbs off a different bike works. People have been saying there's a leak but we tried spraying starter spray and it dident rev up more. I'm talking unrideable revving almost redlining at idle

Those carbs are not setup properly. They need to be properly setup and adjusted and then the problem will go away. The ones from the other bike are pretty close so they work. The carbs can only be adjusted ON a bike, NO mechanic can adjust the carbs without having them on the exact same model and year bike, and to get them exact they need to be on the exact bike.

[DRedel]

So just ask of the carbs to be synced or what do you mean setup. We have taken the bike to the local shops already so jut need to know what to ask for. Thanks for the help

[tcoop]

Sync the carbs, set the float height (Clear tube method), and set the air-mixture properly. The valve clearance needs to be in spec. (not necessarily in that order)

[DRedel]

Alright thank you I will hopefully have that done tomorrow and the problems will be over.

[Geezer]

It wouldn't hurt to check the throttle cable for fraying or binding but this problem sounds like an air leak or something sticking somewhere. You won't know until you get into it. Bench syncing would be a good start when you have them apart...

Geezer

[DRedel]

We tried to check for an air leak and the throttle cable is new. It's just after ridding for 10 or 15 min the bike will start reving out of control. If we turn the idel down all the way it doesn't make a difference.

[petejw]

jat,
have u got free play in the throttle cable?

[Schming]

Like the previous posts state, look for an air leak on the engine side of the carbs. That and a good synch of the proper carbs for the bike should get ya goin'.

Also heres a link that may help ya out:

http://xjbikes.com/Forums/viewtopic/t=14692.html

[DRedel]

There is free play in the throttle cable

[CaptonZap]

We tried to check for an air leak and the throttle cable is new. It's just after ridding for 10 or 15 min the bike will start reving out of control. If we turn the idel down all the way it doesn't make a difference.

I had a similar effect on the first XS11 that I owned.
I finally decided to take the carbs off, and while I was that far, I would take the rubber manifolds off to clean them up and check for cracks. When I got to the bottom inside bolt of number three, there wasn't one. The inside of the threaded hole was packed with accumalated crud, so it had been that way for a long time. From the factory? Don't know. Ran a tap down the hole to clean it out, put it all back together, and it has been perfect since then.
When you get the carbs off, take the manifolds off, and check the gaskets. And check the torque of the bolts, to see if one is looser than the others. You have a heat expansion type leak somewhere, in all probability. CZ

[Geezer]

There is free play in the throttle cable

That leaves either an air leak or the carbs are seriously out of sync. My money is on an air leak but it's easy to make them way out of sync when trying to adjust out an air leak... I wouldn't hurt to check that the slides are going up and down smoothly but the butterfly valves should negate that.

Tony

[DRedel]

I was thinking some kind of heat leak because they work unroll they get warmed up and then it jut revs out of control. The problem I have is that he bought another set of carbs from a salvage yard and when we put them on it had the same problem. It's weird that two carbs would have the same weird leak. And once it would rev up we would spray starter spray to see if it would get sucked into the leak and the spray dident make any difference.