Afternoon all and appreciate all the help getting this far. Finished the full fuel system replacement, oil exchange and prime as well as Mikuni carb rebuild kit. Popoff pressure test was good at 28 and 29 respectively as was the vacuum test outlined in the carb rebuild thread so buttoned those up and put everything back together. Fired her up and she was revving what seemed super high and when you blip the gas or rev it is has a slight note change and may elevate just a touch in RPM if at all. Not looking to burn it up so checking here first. Carbs are set to factory settings for low and high. Backed off the idle screw to the point where it wasn't touching any more and reset to just touching.... same result. Should the lower butterfly be snug to the walls at idle or should it have a little bit of a gap (1/8th to 1/16th" maybe is the closed position from where its currently set working off the way it was). Was about to head out to the river for an inaugural test but looking like that may not happen. Have to head out by morning either way so any suggestions? RV and oil pump bracket seem super snug as do the carbs so while air leak could be a culprit not certain. Thanks
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finished 1994 gtx 657 rebuild, super high idle hitting the gas doesn't hardly rev higher
- Thread starter ezgoin92
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I have no experience with a 657 engine but you should have a little slack in the throttle cable so that the only thing holding the throttle plate open is the idle adjustment screw.
You need to check your oil pump cable as well I don't know what the adjustment should be but I would have a look at it for good measure.
You need to check your oil pump cable as well I don't know what the adjustment should be but I would have a look at it for good measure.
AKnarrowback
Well-Known Member
Carb butterflies should be pretty much closed.
How long did you let it run for? Have you tried running in the water yet? There are a couple of different things that might be going on. If everything is freshly rebuilt in the carbs I would suggest leaving it on the trailer at the boat launch and see how things react there.
Remember there are "delays" in how things react on the older carbed machines. I have a 94 xp and 94 gtx. Both rev pretty high when started out of the water. On the trailer both still rev up a bit for the first 15-25 seconds until the coolant passages and exhaust all start to fill and come up to pressure then my idle drops down to 1500ish. I never set my idle unless the machine is in the water and a little warmed up. Sitting in the garage without water isn't a good way to judge how well the machine will run.
There are delays in your fuel pressure and exhaust water that are inherent in the older machines and both effect performance. I like to ride my xp on the tail balancing the machine straight up. Most of the challenge in doing that is keeping the throttle high enough to keep the fuel and exhaust pressures up so the motor reacts. I don't fall over because of balance, I fall over because the motor drops off and won't react to the throttle.
How long did you let it run for? Have you tried running in the water yet? There are a couple of different things that might be going on. If everything is freshly rebuilt in the carbs I would suggest leaving it on the trailer at the boat launch and see how things react there.
Remember there are "delays" in how things react on the older carbed machines. I have a 94 xp and 94 gtx. Both rev pretty high when started out of the water. On the trailer both still rev up a bit for the first 15-25 seconds until the coolant passages and exhaust all start to fill and come up to pressure then my idle drops down to 1500ish. I never set my idle unless the machine is in the water and a little warmed up. Sitting in the garage without water isn't a good way to judge how well the machine will run.
There are delays in your fuel pressure and exhaust water that are inherent in the older machines and both effect performance. I like to ride my xp on the tail balancing the machine straight up. Most of the challenge in doing that is keeping the throttle high enough to keep the fuel and exhaust pressures up so the motor reacts. I don't fall over because of balance, I fall over because the motor drops off and won't react to the throttle.
AKnarrowback
Well-Known Member
Your throttle cable looks like it is set loose enough where it should not be holding the carbs open.
The oil pump alignment marks should be lined up just as all the throttle slack goes away and the carbs start opening. If you adjust the throttle cable you need to recheck the pump setting. The two interact.
The oil pump alignment marks should be lined up just as all the throttle slack goes away and the carbs start opening. If you adjust the throttle cable you need to recheck the pump setting. The two interact.
Thanks all, loosened up the throttle cable which closed the lower butterflies more, readjusted the oil pump witness lines and she seems to be idling better. Put the air cleaner and everything back on and will head to the water tomorrow. Can't thank you all enough for the assistance. For a few minutes I was ready to rip out my hair when it wouldn't fire up. Turned out to be a kink in the line between the fuel selector pep-cock and the fuel filter. Re-routed the fuel line and she shows signs of life. Again thanks for the assist.
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