viper 700 won't idle

sideshowBob said:
Have you done a compression test on this engine?
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compression is 140psi on all 3. ives cleaned the carbs for a third time now very thoroughly with compressed air and ran wire through every jet and checked all 3 reeds. now it will idle when its cold, as soon as I drive it for 30 seconds all the issues come back. it will idle very choppy and low then die. if I stay on the throttle it runs great. and on initial start it will idle at 2000 no problem, then idle drops when I touch the throttle and it misfires and dies.idle adjustment dosent help either, just leans out when I try to raise it. starting to run out of ideas lol. any more suggestions? thanks everyone
 
ok, it might be time to check the wiring harness under the engine for rub through as it seems to only go bad when you ride it witch causes the harness to move around a bit.
 
Another issue that was not uncommon on the tripple Yamahas was the resisters in the sparkplug caps burning out. Something worth checking but usually created hard starting issues as well. Maybe check the coils, and flywheel for rust as well.
Maybe it has always been ignition related.
 
sideshowBob said:
Another issue that was not uncommon on the tripple Yamahas was the resisters in the sparkplug caps burning out. Something worth checking but usually created hard starting issues as well. Maybe check the coils, and flywheel for rust as well.
Maybe it has always been ignition related.
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do you know what the resistance is supposed to be if I test them?
 
Evan700 said:
I cleaned all choke plungers and adjusted the cable, engines also running lean so I don't think it would be that. might worth checking again though
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You said in a previous post that the engine idles 'choppy' when it warms up. That is not lean, that sounds like rich.
 
update for tonight, installed new BR9ECS plugs and new 5000ohm plug caps. engine finally idles! still seems lean to me as it randomly shoots flames out exhaust while idling but I'm getting somewhere. rpm still hangs when I rev it but ives heard that's a viper quirk. haven't go it super hot yet but it idled for over 15 minutes and made a few laps around the yard. think I'm going to pull carbs one more time and richen the screws. set to 1 7/8 right now, how much further should I go? I live around Belwood Ontario 74nitro. again, can't thank you guys enough.
 
Trouble shooting is always a fun challenge but difficult to do when you don't have the item in front of you. Lots of great minds on these forums.
Before you posted some success I also had an idea that you could have a restricted exhaust system created from some critters moving into the silencer and plugging it up...you may still want to check that. Flames out the exhaust sounds rich rather then lean but maybe there is residual fuel still in the exhaust system??
 
alright, another update and a few questions for you guys. just took the viper out for a 20 minute ride. It went ok, when I'm on the throttle it runs great, lots of power but as soon as I come to a stop it dies. fires right back up first pull and idles good but when I engage the clutch for even a second It won't idle again. also if I let it idle with the brake off it creeps forward, is that normal? starting to think fuel pump or clutches maybe?? I'm running out of ideas lol. any more suggestions would be great. I'm tempted to just run it as is at this point
 
Sounds like your primary clutch is staying engaged.
The clutch issue could be a few things or a combination of things:
-incorrect belt
-clutch center to center distance to long
-broken primary clutch spring
-worn sticking clutch bushings
-stuck primary weights because of corrosion or worn bushings

Start by removing the belt then take the clutch cover off, check the spring and see if you can effortlessly slide the clutch outer sheave in and out.
 
sideshowBob said:
Sounds like your primary clutch is staying engaged.
The clutch issue could be a few things or a combination of things:
-incorrect belt
-clutch center to center distance to long
-broken primary clutch spring
-worn sticking clutch bushings
-stuck primary weights because of corrosion or worn bushings

Start by removing the belt then take the clutch cover off, check the spring and see if you can effortlessly slide the clutch outer sheave in and out.
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alright I think I found the issue. I pulled the belt off the machine and found that the entire secondary has about 1/4 inch of in-out play on the shaft. seems like shims are missing, going to dig into that More tonight. also while I was looking into that I found a couple small cracks on the exhaust manifold, could they be causing issues? it dosent leak from what I can see but is it worth fixing? thanks
 
I would definitely get the exhaust manifold welded or replaced and it is normal for the secondary clutch to be able to move in and out on jack shaft...the idea is that the clutch will self align with the primary clutch and belt. If the secondary clutch is jammed to one side and out of alignment then it could be a problem. The secondary clutch should freely move in and out on the shaft and not jam.
 
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