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Acceleration Studder

bigal1951

Veteran
Joined
Oct 17, 2008
Messages
40
Age
72
Location
St. Andrews, MB
Country
Canada
Snowmobile
2014 SR Viper XTX
2004 RX Warrior
After a full carb rebuild, except removal of pilot screws, change of plugs, sync of carbs and oil change; not that an oil change should do anything, and I still have a shudder on acceleration. It will reach 9,500 rpm; but, it is not crisp up to 9,500 rpm. Does anyone know what I am missing? The sled starts and idles fine. Just when you hit it, it won't rev up smooth. It's not a real miss and it does not backfire when you let up on the throttle. On a stand you can get it to studder as well. Could it be electrical or the coil packs? I am lost at this stage.
 

I'm thinking when you say shudder on acceleration, the sled is vibrating to the point you feel it in your butt, kind of like something getting stuck in the tunnel (had an ice chunk go there when first out in the morning). If its this kind of shudder I'd be looking at the drive train not the engine.

If you have a mechanics stethoscope, you can listen with the probe on various hard points when idling and reving. If you hear a noise you can't explain, that might be an area to look at.

Shuddering....

Primary and Secondary out of alignment.
(engine) I heard there is a balance shaft in this engine, maybe something worn, but IMO unlikely.
Jack shaft/Drive shaft gearing/ bearing wear, causing shake or vibration.
(engine) bad ignition misfire or not firing as needed...would run rough...but wouldn't call that a shudder. To check coils, run in the dark with caps off. its suppose to look like a light show, if its shorting to the wall.
I heard if TORS gets flaky it can run hesitating up to 3000 but won't go over don't think this is what you have.
Mine shudders with Choke On so check thats working right, when its off its fully off.
Track isn't broken, imbalanced? Track aligned? All idlers are good.
Oil in chain case is good, oil in engine is good.

some ideas
 
Maybe make sure the clutches are clean and the belt is in good condition too. A worn belt and dirty clutches can really hurt performance and it might feel like its the engine.
 
By pass tors alsdo check coils for tracking on boots easy to find out start sled in dark place usually can see coils arcing when running j
 
Pilot screws are always the problem with the carbs on the rx 1's why did you not remove them?
 
Sounds like coils to me. I had the same issue and kept cleaning carbs with no improvement. Also my top end was not what it should be, couldnt break 90mph. Replaced coils and runs like a brand new sled. Wish I would have done that two years ago!
 


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