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Discussion Starter · #1 ·
I bought my daughter a 1995 touring sle 500 f/c. I took it out for the first ride last night and noticed that it was very underpowered so I did a compression test on it and got 105/110 psi. I have always had liquid cooled sleds so I am not real sure if the f/c sleds should have the same amount of compression. I know on a liquid cooled sled, the numbers are very poor. Do these numbers look like worn out rings or does this look like deeper trouble. The sled odometer reads 7200 miles and the sled is really clean. I only gave $550.00 for the sled so I can afford to put a little money in it but I just find it strange that the motor would need a rebuild after only 7200 miles. What should I expect to find when I tear the motor down? Scored cylinders maybe? If the cylinders were scratched up, wouldn't the compression numbers be worse than they are? Would it be any cheaper to buy after market rebuild parts rather than buying oem? Any experienced advice would be appreciated. Thanks....bullett
 

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7200 miles is a long time without a rebuild. I'm not sure about the compression numbers, but they don't sound too bad to me. Being 5psi off from eachother is a little odd. Being a fan cooler though, re-ringing would be a simple task. You say it's underpowered, what are you comparing it to? If to your 800 or 670 it will seem underpowered. Also conditions play a big factor on the fanners. They won't be screamers on warm days.

If it has 7200 miles and it's never been apart, I'd say it's time for a rebuild.
 

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Discussion Starter · #3 ·
Nah, there is definitely something going on. It is real boggy and it feels like the brake is on holding it back. My daughter also has a safari 377, even that sled will run right by the 500. If you stop the 500 at the bottom of a fairly significant hill, it has a hard time getting to the top. I know it is not comparable to my sleds power wise but it should go much better than it does.
 

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How does it start? Does it have a primer, or a choke? Have you had the carb/carbs apart? Taken a look at clutching at all? It could be so many things...
 

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Discussion Starter · #5 ·
I have taken both carbs off and cleaned them. I did that in the fall when I bought the sled. I also did a little rear suspension work and a grease job. Everything looks fine in the suspension. I haven't had the clutches apart yet. It seems to start pretty good. I have been searching around on the internet looking for f/c compression numbers and I can't seem to find much of anything. I am still guessing that my numbers are lower than they should be.Thanks.....
 

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rebuild!

110 is too low in my book.

my gf's sled has 145psi (99 mxz 500)

BUT, my buddy has an 93 indy triple 600 with 110psi in each cyl and it runs great.

If its runs good/ starts good/ i would say get the clutches checked out/cleaned.

Maybe if it has rave valves, get them checked too.

edit: check track tension also.
 

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Discussion Starter · #7 ·
Unfortunately, sounds like the rebuild is probably the answer but I will pull the clutches off first and go through them. A buddy of mine has a touring 380 and a touring 440 and has over 10,000 miles on each one and they are still going strong so I was figuring on atleast getting the rest of the winter on this sled before tearing it down. Oh well. I just don't want it out of commission for a couple weeks.
 

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You might want to check to see if something IS holding it back. Take to belt off, lift the track off the ground and see how easy you can turn the track by hand. Should turn but with some resistance. Is it consistant resistance for a full revolution? Also, is it boogy from the start and then has good top end or vise versa. Starts and idles OK? Any change after it warms up. I'm not real familiar with fan cool either, but I've heard it takes alot of power to run the fan. I'm not sure if it has a belt to drive the fan, but maybe check that also.
 

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You might want to check to see if something IS holding it back. Take to belt off, lift the track off the ground and see how easy you can turn the track by hand. Should turn but with some resistance. Is it consistant resistance for a full revolution? Also, is it boogy from the start and then has good top end or vise versa. Starts and idles OK? Any change after it warms up. I'm not real familiar with fan cool either, but I've heard it takes alot of power to run the fan. I'm not sure if it has a belt to drive the fan, but maybe check that also.[/b]
Check the fan bearing also.
 

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I just rebuilt a 95 formula SL 500 fan, and after the rebuild it had 105 psi on both sides


i think your fine, but then again every compression tester is different. I'm having the same problems with this sled. It runs okay on a lift stand, but when riding the sled it bogs bad and barely has enough power to move itself.
 

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A trick for 4 stroke engines, and it should work on a 2 stroke as well. put the piston to tdc, pour enough oil in it to get to the ring groove all around (not too much though) and test it again. If compression jumps more than i think 15 or 20 psi from the dry test to the wet test, its an indication of rings being worn.
 

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I owned a 440 safari fan and it pulled along very good now own a formula 500 lc with 10k+ miles never touched motor it has 140 psi anyways I would clean your primary clutch remove it take the outside section off and clean the shaft it probably has some built dirt on it not allowing your clutch to engage at the rpm it should and put a new belt it makes a world of a difference good luck
 
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