'88 Exciter runs OK, then bogs down

missed a important part of syncronizing the carbs at full throttle and at idle this is very important and could be another cause to your problems ..............these sleds have a long list of bulletins and updates that need to be done i will see if i can make a copy of them for you and the syncronizing process

Nutz
 

i would definetly agree with that,if its out of sync it will run just as your describing,i think your on the right track and almost got it,might as well learn how to sync them carbs, i check mine and adj every time its not revin right,there very sensitive to this,sounds like you bent a needle,hes right about all the updates but for now pull the top of the air box off and reach in and feel the slides,push the throttle and see if they both start to move at the same time,adj the cable on the one thats slow to react,
 
Not the airbox again. That's a pain to get out. How do you get just the top of it off? I had to take the entire thing out to get to the fuel pump - what a pain. I had the handlebars loose before, but it looks like I have to take them completely off, wiring and all, to get that top piece of plastic under the headlight off....just to get to the top of the airbox.
 
did you remove that tab on the left side of the cowl just forward of the fuel cap that has the 10mm headed bolt hidden underneath?
its about an inch wide and twice that long with a noticable slot to pry up with a screwdriver. makes a lot simpler task of airbox removal with this bolt removed.
 
Also looks like the factory power jet feed tube (hose) is still on the carb. That should be removed and pluged at both ends (bottom of float bowl, bell mouth of carb).
 
Yes, I did take the 10mm bolts out of the tab under the cowl. I guess for me the hard part about taking out the airbox is all the cables being in the way, and then getting the rubber boots back on the outsides on both sides of the carbs.

I'll look for that hose between the carbs and plug the carbs. Is there a good place to buy rubber plugs for this? Or, just the dealer? Maybe a hardware store would have something like that?

As an alternate to taking the airbox to adjust/sync the carbs, how feasible would it be to do something like described in THIS LINK?. Would that accomplish the same thing as removing the top of the airbox and manually feeling the slide position? May it even be a more accurate way to sync the carbs?
 
oops,i forgot i actually cut that plastic louver off.i have a cold air scoop attached to the hood that covers that gap,then i cut the cover in half so i can just take out three screws and remove the carb side top.that airbox setup pissed me off a long time ago,i can reach in air box to get carb boots on way easier to,the hose from the bottom of carb to top should have a ball bearing put in it,look for it at the bottom end,i thought u could pull slides and chokes out and move cables enough to get top off but maybe not,i never done it any other way so i dont know
 
would using that homemade manometer be the best way to sync the carbs? It seems to me that it may be more accurate than 'eyeballing it'

What exactly do I adjust to 'sync' the carbs?
 
need to adj the idle screws so that both slides are down equal and resting on them with 1/8 gap at lever,when you push the throttle and it pivots then moves both slides need to begin to move at the same time,ive heard of people putting drill bits under the slides and watching which one moves first,adj the cables under the rubber boot on top of the carbs till there the same,warm sled up and check idle speed,if you have to adj it higher youre putting more slack in the cables and need to check,adj again.make sure you keep gap at throttle lever or it will race engine when you turn,also will activate tors if you still have it,manometer is for rack style carbs with one cable,you got one into two system,sync carbs is a mechanical adj of slides and needle,the needle goes down threw the main jet and is tapered,when it is moving up out of jet it begins to let gas threw being metered by the taper until it is all the way out,the slides obviously let air in,the little screws on the side compensate for sudden opening of the throttle and are for fine tuning depending on weather changes,turn em allthe way in and back em out 3/4 to 7/8 for now.
 
I got to working on the yamaha again. It's idling pretty good now. It turns out that one of the long pins at the bottom of the slide was bent and I think making the slide not go down all the way. I straightened it the best I could and it ran much better. It's idling about 1500rpm or a little lower.

I did end up making that homemade manometer and it's just a little off when idling...maybe about 1/2 to 3/4 inches difference using 30W oil in the tube. When revving it up, it changes a little the other way and then back when idling. Then, I read above where the manometer is for carbs that have a separate throttle cable going to each. But, why would that matter? since the single cable from the throttle comes down and splits right before the carbs to be adjusted there. Doesn't the manometer measure vacuum at each cylinder and if it's even, the slides must be equal? Does this mean my carbs are synced?

I made a low quality video, but it probably won't tell much.
http://youtu.be/-7n4iBxrfvc
 
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