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Discussion Starter #1
1996 STX 583. 5000km's
Has low-end grunt but wont hit higher than 6500rpm if full throttle, if you play with throttle it will hit 7200rpm. Top speed is like 60mph on hardpack right now.

Plugs are wet and brown/black, pretty oily
Oil injection is pretty close to 50:1 i'd say
sled does not smoke
sled starts fairly well, its warm out so the throttle needs to be cracked open a little when first ripped but from what i've read this is normal
sled idles beautifully, needs only 2-3 primers while running to get its idle maintainable
good compression
checked the primer lines, fuel lines, breather lines, plug wires etc. for any 'simple' causes.
STX goes through a 1/4 tank in the same time a ZRT600 goes through a 1/4 tank, is this normal?
Apparently just had the carbs in... according to previous owner
Has some cheapo 2stroke oil in it. Probably a couple different brands of oil to be honest...
Floods and dies if plugs are gapped to .016, runs great with plugs at .030, just won't hit higher than 6500rpm.
Cleaned the rave valves tonight, but have not ran sled since, may have been the valves.

I figured it might be the rave valves so i took them apart and cleaned them... there was a good 4mm of carbon build up on the front of the guilotines, soaked in paint thinner, and scrubbed off, cleaned housings etc. When i pushed them in by hand they would stick a little before, belt side seems to move a little less freely, but it might be my imagination. Both seem to move much better now. Is it possible the RAVE valves were sticking enough to not open???

Is there anyway i can test this without taking the sled out... like can i lift the track and rev it up or will that be a completely useless exercise, i know on the older sled's you'd blow up the motor if you went wot with the track up... If need be i can rip down my street and hope i have the sled back in the garage before the police get to my house. (my neighbours are far too 'rich' and way too 'superior' to have sleds ripping down THEIR streets, plus i just moved here last month haha)

I dont want to start messing with other stuff until i know whethor or not it was the RAVE valves.
And im guessing those red threaded bolt type dealies on the outside adjust when the valves open right.. .. .. the one was broken before i got to it and the black piece that goes over it so that it clicks into positions is gone so the red thing spins freely when not on, when its all togethor it seems like the pressure holds it in place... the how-to i read said to snug it up, so i did... After i did the other valve that seemed wrong and i guessed that was what adjusted the spring pressure keeping the valves closed... so i loosened it 3 'theoretical' clicks from snug. I think thats where the other one is at too.

What else should i try next if it wasn't the RAVE valves and please supply me with a how-to or a basic idea at least.

I've only done mild things on sled's before, and the only one i've worked on was a 1979 440tx.
I do have a mechanical background however, and feel that only a major job would be out of my league, and even then i'd at least give it a looking over.

EDIT: Read over a better how-to, i will be adjusting the red adjustment screws tommorrow now :withstupid: ... anyone know stock specs??? The how-to i read said snug and then one full turn out.
 

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If cleaning the rave valves didnt work, i would check to make sure ur rotary valve is good.
 

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Most likely the RAVEs not functioning, Loose 500 rpm in the top when their not opening. The red caps should be fully seated unless your operating above 6000'. Do NOT spin the track up on a stand unless you desire leg amputation or worse. Mark the primary clutch sheave with a black marker pen and try the sled. Then check how far the mark is removed from the clutch to verify "full Shift". If not cleaning more than 75% of sheave, clutch maintenance is required.
 

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Discussion Starter #5
Did you pull the clutchs apart and inspect them?[/b]
no, any how-to's or a quick write up or anything out there. I've never touched a clutch before.

With the track lifted i didn't want to rev it too high but it seemed to die at 6000rpm, it sounded like it was hitting a rev limiter, i didn't go wot though, but i was giving it quick rev's to try and get it higher, but wouldn't hit higher than 6000....

Could i be running too rich? Fiance's dad took it out for about 5 minutes and said it needed a carb job... but what does he know he drives a cat.

Also how do i check the rotary valve, and where do i find it. Had one massive backfire on one of the first days this season that blew the airfilter 15 feet into the air.

EDIT: Finally found some information in my forum searching, a Formula 600 was having the same problems. Wasn't clutches, valves, carbs, or the crank seal (which are apparently the usual causes) on this guy's it turns out the Stator was broken. I'll check that on mine, might explain the plugs needing to be gapped to .030 instead of .018 as well. Anyone know what the stator should be sending out?
 

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clean the clutches after you check out your stator
 

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Hi,
The spring in the drive clutch may have become weak over time. If the spring looses pressure the engine will loose top rpm.

Just a thought and good luck.
 
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