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throttle body adjuster screws are tight


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Need some advice please,

Was trying to sync throttle bodies, but didn't touch the left painted screw, middle was kind of fine turning easily around 180-270 degrees easily, and stiff after, but was in sync with the left one in this range. But the right one was very stiff, I thought maybe corrosion, ordered a new screw set and got the old one out (the screw head got really damaged by doing that as the screw was very tight). tried the new one and it is also very stiff going in. Am I doing something wrong? Why screws are so tight? 

Edited by ksim
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  • ksim changed the title to throttle body adjuster screws are tight

Not certain but I think one of the screws is fixed and not to be turned while the others are adjusted to match.  Someone correct me if this is wrong.

There is nothing like spending a day riding with friends in the grip of a shared obsession.

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They shouldn't be hard to turn, but sometimes brass and aluminum can develop bi-metal corrosion...... however, once moving, one can hope they turn easier.  What I recommend is to remove the throttle bodies for better access, and with a better screwdriver, note position and number of turns to remove.  If you remove the painted one, be sure to count and put it back to where it was.  I'm not sure whether on this bike Yamaha sets the reference screw fully in or not (as is on the FJR with throttle by wire)......

In any event, remove the screws and put a light coating of grease on the threads, that should fix you up.  It may be possible the extra hard one was fully seated.  IF your throttle sync was still a bit off (wishing you could turn it in more), then leave that one seated (your new reference) and back off the others to get a match, even if the painted one must be moved out somewhat (likely not much, maybe 1/8-1/4 turn).  It just means your new reference screw is the one that's fully seated (again, if that was the intent for one to be seated as reference).  The whole idea is to have them sync'ed evenly.

Edited by RaYzerman
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thank you, applied silicone grease and slowly turned the screw in, middle one got out using a good screwdriver which fits the slot perfectly, applied silicone grease also and got it back, adjected the bodies, seems fine now, will see how it works on road. didn't need to touch the left painted screw.

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IIRC, these screws have some sort of gooey thread locking compound to sort of gum up the works so they'll stay put.

IOW, I think they're supposed to be somewhat hard to turn due to sticky schmutz in the threads that keeps them from turning when they're not supposed to.

You never need to turn them very far, if at all, so there's no reason to worry if they're not easy to turn.

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There is no thread locking compound, the screw assembly consists of a tiny brass washer and o-ring, a spring, and the screw.  The screw is held in place by spring pressure........ same concept on every bike.

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