1997 Yamaha VMAX 600 PLEASE HELP!!! - Snowmobile Forum: Your #1 Snowmobile Forum

gskellogg · 01-05-2013, 08:39 PM

Hello All,

First off, thank you for taking the time to read my post here. I recently purchased a 1997 Yamaha Vmax 600, it has around 2,000 miles. Last year I rode the sled and noticed that it was a gas hog compared to my friends sled (the exact same sled, same year and all). I burned almost an entire tank while he only used less than 1/4 of a tank. We rode approximately 15 miles. We only had a chance to ride once last year due to the lack of snow.

About a month and a half ago, before the snow started to fly- I called my local small engine repair shop to get it in for service. I advised that I was having a fuel consumption issue last season. He cleaned the carbs, new plugs, ect.

I finally got to ride about 2 weeks ago when we got dumped on with a snow-storm. I was having the same fuel consumption issue. I called another shop, because my mechanic was out of town. I took the carbs off my sled and he took them in to fix them. (He did the following to my carbs: Cleaned them, the sync was off, floats were set at 21mm and should be set at 24 mm, fuel screws should be at 1 1/4 turn, carbs were very dirty, soaked jets.)

I had the carbs put back on my sled and took it back out- again, I was still having the same issue. I go about 10 miles and burn 9-10 gallons of fuel. I say its burning it because the engine makes a sound like its bogged down, almost like a popping noise- but not a backfire). The sleds is very slugglish at low speeds but takes off and runs excellent at speeds over 50.

I took it back to my mechanic when he got back from vacation. Since then he had done the following:

New Clutch
New Plug Wires
New Coil
Several New Plugs as they appear to be fouled out (very dark, almost black, sometimes one much darker than the other).
Compression Test (75 at warm)
Check the exhaust for leaks
Something in the carbs? pins or something?
Adjusted Floats
New Fuel Pump
Something to do with the part that mixes the fuel and oil
checked the choke cable

What should I do we are all stumped....... I am to the point where I just want to ditch it but not its just the point that I can figure out what the problem is....

IRONDOG · 01-05-2013, 09:33 PM

75 pounds of compression is WAY to low. If it's actually 75, it needs to be fixed. Should be 120-130 lbs.

gskellogg · 01-05-2013, 09:46 PM

Would low compression cause poor fuel consumption?

**RJ Gleason** · 01-06-2013, 05:20 AM

Yes it would.

**kccats** · 01-06-2013, 07:31 AM

Did you do the test at wide open throtle?

gskellogg · 01-06-2013, 11:19 AM

Im not sure how they ran the compression test, I was just there when they did it... are you supposed to push the throttle when doing the test?

gskellogg · 01-06-2013, 11:22 AM

Also, I assume the only way to fix the low compression (if it is really only 75) would be to rebuild the engine?

**RJ Gleason** · 01-06-2013, 11:55 AM

New top end at least.
Pistons and rings and gasket set.

And yes. you get a true reading with both plugs out and throttle side open and pull until the gauge stops rising.

joshkidner · 01-06-2013, 12:01 PM

throttle doesnt matter. like said, hopefully your cylinder walls are fine and you can get away with just pistons/rings/gaskets. they should of told you that, if they (mechanic) knew compression was that bad.... good thing its top end rather than bottom, thats where the real cash is. good luck!

joshkidner · 01-06-2013, 12:05 PM

i dont know where throttle is supposed to be, i would guess no throttle? like said, hopefully your cylinder walls are fine and you can get away with just pistons/rings/gaskets. they should of told you that, if they (mechanic) knew compression was that bad.... good thing its top end rather than bottom, thats where the real cash is. good luck!