Yamaha xj550

Hi guys
Hope you can help. I doing up a yamaha maxim that my dad had stored away (and left fuel in) . I've had the carbs cleaned change the spark plugs changed the filter and revealed the tank and got s new fuel tap. My problem is when she starts she really struddling to come off choke and the refs are all over the place . Also can't get her to idle at 1000 rpm. And ideas or tricks please feel free to comment . Regards Craig (new biker)

 

Did you break the rack when you "cleaned" the carbs?

 

The clue here is 'I've had the carbs cleaned' implying the OP didn't do them himself..

So you have two jobs to do. 1) Check valve clearances 2) Clean the carbs yourself paying particular attention to the idle circuit.

 

One item that causes idle issues is a vacuum leak even a small one can cause problems , check the condition of the intake boots if they are weather cracked a smear of RTV helps , make sure your carbs are fully seated in the boots and clamps are tight.

 

Cheers guys . I have now adjusted the pilot screw and can now get her to idLe nicely without choke, however now when I first start her up revs fly up and slowly come back down same when I rev the bike in neutral. Any ideas .

 

A hanging idle is either synch is off, or a vacuum leak most of the times the butterfly seals , you stated carbs cleaned which if you soaked in cleaner , without a full tear down the seals are toast . Spray cleaner will NOT get into the small passages of the carb. What is your idle set at ? 1050 to 1200 rpm is where you want it .

 

She idles at just over 1000rmp and ticks over nicely like I sah it's just when she first fires up it rev upto 8000 and comes down to 4/3000 then slowly comes down

 

You have a vacuum leak

 

Ok well least I know or hopefully know what's up . The boots are quite won tbh with slight cracking but not all the way through . I'll try replacing them and see how I get on

 

Think I'm gonna try and put some silicone tape on the boots first to see if that's the problem if so then I'll order new ones...... I'm impatient and wanna know if that's the problem lol

 

Clean them up and smear the outside with black RTV. Works well and much cheaper than new ones. I’ve done a few that way and still working after a few years.

 

I think someone mentioned using an inner tube too to cover up cracked carb intake stubs.

 

Well I'm still having the same problem reving very high and slowly coming so and stinks very rich . I've checked the boot and yes from the outside there's cracks but they are spot on from the inside

 

I have just found a crack in the exhaust pipe, well the pit where all 4 pipes meet together. I've put my hand under the bike and felt it. Could this be my problem . If so why would the exhaust cause this

 

Doubtful. Leaking exhaust might make it pop on the overrun though. Have you at least done a bench sync on the carb butterflies to check they're opening togther?

 

Yeah I've done that mate . I'm gonna strip the carb down again and see if there is something I've missed . My brother took it to be cleaned however I don't know if he did the needle gets and if he had did he do them properly so I'm gonna strip it right down again and see .

 

Good plan.

 

had the same problem on my xj 750 air leak was the bolts on the side of the engine , the carb sync bolt . i sanded down the copper washer on both sides then tightened them. problem fixed. this worked for me john