Motorcycle Help?

[Clarkbug]

Hey All.

So yep, you read the title right. But actually, the help isnt for me, its for my buddy who is pulling his hair out over a problem he cant tame.

He recently bought a '91 (I think) Yamaha FJ1200 bike off of a guy he is stationed with over at Andrews Air Force Base. The bike had been shipped all over, was in Germany, and back in the states for a few years. It was run for a year after being overseas, and then got damaged in a move, and sat for three years.

As of now, the bike will start up if choke is on, but thats it. You cant give it any throttle, you cant take the choke off, or it dies out.

I can get into more detail about what he has already done, but I didnt know if anyone on the boards was proficient in tuning multiple carbs or has motorcycle experience.

If no one here can help, do you guys know of any boards that might be helpful?

Thanks in advance!

~S

 

[JAmazan]

well if it will start when he chokes it, it should stay start unless his idle cable is turned all the way off.maybe he should try finding the cable, usually on the same side as the gas tanks on off switch and turn it clockwise. thats the only thing i can think of that would kill the bike when the choke is off, lemme know if this help.

 

[Clarkbug]

Thanks for the quick reply.

There isnt an "idle cable" on this bike. The problem I think lies in something dealing with the fuel/air delivery setup on things. They are the constant volume carbs, that have diaphragms and slides that move based on the vacuum created by the engine. The more you open the throttle, the more vacuum, the more the slides move, and the more gas enters the carb.

At first we thought there wasnt enough fuel getting into the bike, and that the choke was just making up for it.

There is an idle screw that controls all 4 carbs, and that can be adjusted plenty, and that doesnt seem to help at all. We worked all the way through the range, and nothing helped there. Also, even if it was idle, by using the hand throttle, you should be able to keep the bike idling without the choke, right? (assuming its just idle speed that is the problem)

We did use a synchronizer, but thats not really helpful with the choke on since the bike cant draw the way it needs to with the choke on....

If he doesnt get this bike running soon, his wife might have to hurt him...

Thanks again for the input, any other thoughts?

~S

 

[~JoJo~]

a carb built up ?

 

[xelderx]

it needs the carbs cleaned out for sure. it doesn't take more than a few months of sitting for coagulated gas to clog the idle jets...the openings in the idle jets are very small. I just got done rebuilding the carbs on a GPZ550 that has been sitting for 2 years. It's not a hard job, but there are a lot of small parts in the carbs that have to be perfectly clean for the bike to run properly. There should be carb rebuild kits available for the FJ1200, but they usually run about $20-$30 each so rebuilding 4 carbs can get expensive.

 

[JAmazan]

speaking of carbs, its time to sync all my carbs...anyone has one to let me borrow? i'll put a deposit down

back to topic: yea i guess u can clean out the carbs, but on monday i will check at the shop where i get my supplies if they have any other suggestions.

 

[chiefmg]

I am almost certain that xelderx has it right. My vehicles sit for long periods, and despite putting StaBil in the tank and running it to get it throughout the fuel system, I have to clean the carbs on at least one bike a year. If you take your time you shouldn't need a rebuild kit. Pull the carbs off the bike and one at a time, remove the float bowl (this can be a b****, take your time so you don't strip out the Phillips screws holding it). Remove all the jets you see (should be at least two), spray them with carb cleaner and then run a soft (ie brass) wire through to clean out any deposits out of the holes. I also usually pull the float and inspect the valve and seat, as well as the strainer that is on it. Put it all back together and let 'er rip! If it has been sitting for that long then you should also check the sync.

The FJ was a great bike back in the day. They are pretty much bullet proof IIRC. I almost bought one when I got my '87 1000 Hurricane, decided to go with a liquid cooled engine instead. Hope your friend likes it.

 

[Clarkbug]

Thanks for all the input guys!

He had figured the same thing, so he has already pulled all four carbs, stripped them all down, and let them soak in carb cleaner. He blew them all out with air, reassembled them, and put them back on. Still no love from the bike.

He thought it was just the sync, and has the gages for it, but cant do it until the choke can be turned off.

And actually, he really liked that bike, but two months ago his wife said "Why are you wasting your time with that one? Why dont you just go get a new bike and then we will have more time to spend with each other?" So, being the smart man that he is, he went and just bought a new suzuki something or other. (Katana or ninja maybe? Im not a big motorcycle buff myself..)

So now he needs to fix this one because he has a guy that is willing to buy it if its running. Until then its a really big paperweight....

Thanks again for the input...keep the ideas coming!

~S

 

[Sir Nuke]

the best thing he can do is to take it to a REAL shop have them make it right.

 

[Clarkbug]

Yeah, I think that he might have to do it that way....

He didnt want to, because for the most part he is pretty handy, and its gonna kill him to have to pay someone to work on it. (I mean, he lapped the valves and whatnot on his own, same guy who changed the auto tranny in his car on his own...in the parking lot....)

But at this point, the frustration, plus his wife getting angry makes it much easier to just pay up...

I was just hoping that someone here might have a good easy fix for things...

Thanks everyone for all the input.

~S

 

[insider]

He can not just soak the carbs. The pilot jets are plugged and also the passage in the float bowls. They need to be pulled out and cleaned. And if he submerged that carbs in cleaner he probable damaged all the o-ring. He needs a good dealer or repair shop.