squeeking choke

[blacklav]

Hi all , I have a 74 xs 650 on standard carbs. Its been off the road for 3 months but now its back its making a squeeking noise from the carbs. I have traced it to the choke as when I apply it the noise stops ( mind you so does the motor if its hot).

Not being familiar with anything other than amals I don't know how to take them apart. Do I have to remove them completely or can the choke part be accessed on the bike.

Any info much appreciated.

chris r

 

[angus67]

Don't be too sure that's it your choke, the symptom of squeaking going away points to butterfly seals, I haven't replaced any, but heard it's a bitch to get the out/in, plus you have linked carbs?

 

[XSLeo]

The 74 didn't from the factory. It should have two cables coming from the throttle housing.
The "choke" is not really a choke. A choke cuts off the air to richen the mixture. These carbs have an enrichener circuit. These add fuel to richen the mix.
The enrichener is on just one carb body. It has a rubber crossover tube so some of this enrichened mixture get to the other carb.
As angus said the enrichener is seldom the issue. It could be. Check the rubber boot on the rod. If cracked it may let air in. The gasket where it seals to the carb may be leaking.
One way to test this is use a spray, like WD40 or carb cleaner. With bike at idle. Slow the idle down as low as you can. spray around where you suspect leaks. If the idle changes or the squeak stops you have found the place.
The seals angus mentioned are the throttle shaft seals. each carb has two, one on each side of the carb where these shafts pass through the carbs. checking the two outside ones is easy, getting to the two inside can be a bit tougher.
There is a thread on here about changing them.
Leo

 

[blacklav]

Thanks for the replies guys.
Mine has a single cable going to the left hand carb which connects to a spindle that opens both carbs. Likewise the choke is just a lever on the left and is connected to the right via a solid round bar which raises a needle on each carb. There is a rubber seal on top of each of these.
I have sprayed carb cleaner everywhere but it has no effect on the engine revs. The noise only comes from the right hand carb, so i`ll start with that one after ive found some more info on this site.#thanks
chris r

 

[XSLeo]

Your carbs are not 74 carbs. The 74 carbs were unlinked, No steel parts hooking the two together. They used two cables.
Yamaha changed the carbs every two years. Some changes were minor, some major. You need to ID the carbs you have before you can go very far with them.
www.xs650.fi/pohja_files/fi/XS650carbs.htm will help id the carbs. It was translated from Dutch or German so some of the words sound different but with the pic's it's not hard to figure them out.
www.amckayltd.com/carbguide.pdf will help you work on your carbs.
Leo

 

[DogBunny]

Squeaking carb might be a seal as mentioned, but in my experience it is nine times out of ten the "choke" (actually enrichener as already mentioned) body, the housing that is held on with 3 Phillips head screws and holds the plunger. You are lucky that the noise is coming from the right carb, because the right side carb enrichener is easily accessible even with the carbs on the bike. Just tighten those 3 screws and see if the squeak doesn't go away.

 

[blacklav]

XS Leo.... I must have had a moment there, My Norton is a 74 but the yam is a 77. Good to see knowledgeable members on the ball.
Dogbunny...Took the cover off the choke ( no loose screws) and sprayed all the holes with carb cleaner, put back together and no squeak, wonderfull.
I will invest in some new seals.
Thanks again to all who helped
Chris R

 

[DogBunny]

Glad you got it fixed.
I'll throw this out there for you to consider: If you aren't having trouble with your current seals, i.e. no intake leaks and carbs run good, then DON'T mess with them. It can do more harm than good to replace throttle shaft seals that don't need replacing.

 

[blacklav]

You're right, if it ain't broke don't fix it.