Snoscoot Compression ?

summitboy · Jan 1, 2010

I just bought two Snoscoots for my boys. I have been through them and both are more or less the exact same. One is a 88 and the other a 89. The 89 flat out rips. The 88 seems to start out strong but then it seems like the power all of a sudden flattens out not like the 89 which pulls to top end. I checked the carbs to see if the mains were different but both carbs are identical and set the exact same.

The 88 has a B8HS plug and the 89 has a BR8HS plug which i don't think should make a difference.

I noticed the 88 had a intake leak around the read cage where a little oil/gas was slowly seaping out. I fixed that but it did not make a difference. I did a compression test on both. The 89 was 120 hot and 125 cold. The 88 was 90 hot and 112 cold. I cannot seem to find a compression spec anywhere.

If i lift the back end and WOT it seems to stay strong all the way through and it seems to get past this flat spot.

Any other ideas ? Thoughts ?

Thistledoo · Jan 1, 2010

can you get a over size piston and ring for it?? I would say 90 is pushing it....never have checked mine but yours starts good right? even hot does it?

summitboy · Jan 1, 2010

It runs just fine even at 6000 ft it ran good. I just changed the fuel pumps around to see if that was it and no change. New plugs gapped properly no change. The funny thing is when i lift the back end off the floor and pin it it seems to almost clear out and the flat spot dissapears, until i put some weight on it the flat spot is there. It has to be either low compression or maybe a clutch issue. I have new clutches coming for both of them so that will take care of the primarys. Strange. Cold compression is up at 112 psi. I'll get her LOL

summitboy · Jan 1, 2010

I just got back from riding with my boys on the lake. I noticed if i rode down a boat launch ramp it had full power and if held to the bar it would actually accelerate to top speed and stay there until i let off the throttle and then it would have the flat spot again. Would compression do this ? Seems strange.

I really wonder if this is a compression problem or some weird fuel/oil problem. I'll have to measure the oil pump to and see if it putting out the appropriate amount. Clutching needs investigation as well, LOL

Scoots are so much fun !

M5- · Jan 1, 2010

The only solution is a turbo Nytro motor , course then you'll need 2.

M5

summitboy · Jan 1, 2010

LOL just what i need is a 6 and 8 year old with 300HP.

M5- · Jan 1, 2010

Just turn it down to 280. They'll be fine.

M5

pcp911 · Jan 1, 2010

i would try to get a hold of bullheadmoto on here

summitboy · Jan 1, 2010

Yeah i have been talking to Tony about parts etc. He told me to give him a call in the am, so i will see what he thinks. I'm sure its a weak top end. Can't see the clutches really causing this but stranger things have happened. I think Snowest needs a Scoot section to compete with the 120 section. There is a lot of good info out there, although very scattered.

TRIPLESWILLNEVERDIE! · Jan 1, 2010

Yamaha should have never quit making the sno-scoot. It was in a leauge of its own. If you are looking for parts PM triplemax.

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Snoscoot Compression ?

summitboy

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Thistledoo

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summitboy

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summitboy

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M5-

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summitboy

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M5-

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pcp911

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summitboy

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TRIPLESWILLNEVERDIE!

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