Losing top speed on the viper.

hereismylife

hereismylife

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All stock. 136 track.

Used to see 120 ish now top maybe 100 ish.

Runs great except hangs at idle.

Checked things out over a course of time and read many things.

After a lot of thinking and looking I was thinking maybe the springs are week. I just can't see springs changing that much.

Thanks Joe
 
Yes need peak rpm. Check your compression. Idle hang means your pilots are lean or fuel screws need turned out. Check fuel screw setting. If its stock it needs needles raised.

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There's alot of things to check. I'm worried your motor is going down. You've lost some serious mph there. Easiest thing to do right now is a compression test. Does the motor feel as strong as before? Track tension can hold you up. I've found on my 136 vipe that it likes the track TIGHT. I gained some top end running it real tight like 5mph. Also yes your clutches. Check cam buttons and you might as well replace the springs, rollers etc...could be a combination of things. Make sure your parking brake isn't on...I've done this before we all have.

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When you did see 120, were the clutches nice and clean. And mabey now they're not?
Just to rule out a lack of fuel issue at that speed,try and flip it to 1/2 choke and see if problem persists.
Start diggin.
 
Just went for test run to show belt ride height. Motor runs strong. Yes track is loose same as it was before losing speed. Power valves cleaned and checked. Nothing was changed from end of season to next. Just lost speed.

Choke is a good idea. Will have to try that is you think the belt is riding correctly
 
I am going to ask some questions that may seem simple minded. Did you adjust the power valves? Are they in upside down? did you confirm they are opening when sled is reved up?

If you were lean enough to lose 20mph at 8400rpm, your motor would be in a box by now.
 
BETHEVIPER said:
I am going to ask some questions that may seem simple minded. Did you adjust the power valves? Are they in upside down? did you confirm they are opening when sled is reved up?

If you were lean enough to lose 20mph at 8400rpm, your motor would be in a box by now.
Click to expand...
I'm just thinking it wouldnt make that rpm with the valves upside down or pulled through. This is a bit of an enigma haha. You need to feel the sled out and listen for new sounds and feel for vibrations. Is there anything at all new that it's doing that it didn't do before? Is the idle hang a new thing? New belts can make it act funny. Something must be broken in the clutches

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