Need help fixin' smoething

[dubeffect]

Recently bought a 99 summit, previous owner claimed the motor was upgraded to the 700 and only had 200 miles on it. Rode it for the first time today...bought it in August.

Sled starts fine off the trailer and will run for about 15 mins before it begins to lose power, then backfires and dies. After I let it sit for a while was able to get it started again and ride for another fifteen minutes?

Any thoughts on what the problem could be?

Thanks

 

[corncrackerjimmy]

After it dies. Drain the float bowls and see how much gas is in them. If they are empty you're looking at a fuel pump issue.

 

[capen4]

After it dies. Drain the float bowls and see how much gas is in them. If they are empty you're looking at a fuel pump issue.

or after it dies pull the plugs and see if theres to much fueling when it goes bang are you just cruising or is it when you are in the throttle heavy and you let off then goes bang and dies if it acts like that, thats and indication of to much fuel.

 

[winter brew]

Look for a plugged or kinked fuel tank breather....or loosen the gas cap and see if the problem goes away.

 

[icr]

spray ether at the crank seal while it's running, does it increase RPM?

 

[dubeffect]

thanks for the advice, let me know if you think of anything else

 

[2manysleds]

I had the same thing happen. I had a 99 600 that I bought and was told it had been rebuilt. After riding it, it started leaking coolant. So I took it to the dealer and when they got into it they said the pistons were shot and needed to be replaced. So I did. Went to pick it up sounded great ran great onto the trailer. Went out riding and it started dieing. Let it cool down and it would start and run great for a while. Ended up towing back. Took back to the shop. they started looking at it and found that the first time it was rebuilt they used some off the wall piston and bore it out. We ended up having to resleave the walls to fit stock pistons. It has run great since. What was happening is it would run great until it warmed up then the pistons would shrink and it would lose all crompression. Then when it cooled the pistons would expand. You might want to look at that.

 

[JustinB]

Does it run fine then when you get on it it cuts off and dies? my 02 did I had similar problems. I found I was running NGK br9 plugs You have to run the BR9ECS plugs not sure if that is it but it solved my problem.

BTW anyone need any I found them for 5.50 a plug
http://www.mfgsupply.com/m/c/BR9ECS.html?mv_arg=2

 

[JustinB]

I had the same thing happen. I had a 99 600 that I bought and was told it had been rebuilt. After riding it, it started leaking coolant. So I took it to the dealer and when they got into it they said the pistons were shot and needed to be replaced. So I did. Went to pick it up sounded great ran great onto the trailer. Went out riding and it started dieing. Let it cool down and it would start and run great for a while. Ended up towing back. Took back to the shop. they started looking at it and found that the first time it was rebuilt they used some off the wall piston and bore it out. We ended up having to resleave the walls to fit stock pistons. It has run great since. What was happening is it would run great until it warmed up then the pistons would shrink and it would lose all crompression. Then when it cooled the pistons would expand. You might want to look at that.

Not saying your wrong but doesn't metal expand when hot and contract when cooled? When your run your motor the pistons expand thus the reason for you rings being slightly bigger to allow the expansion as it get s hot. I could be wrong?

 

[2walla]

I think what he was saying..

The pistons heat up quicker than the motor- Can you say cold seize.. What I think 2manysleds was saying was that when everything came up to temp, the cylinders were too large for the pistons and it lost compression.

 

[2manysleds]

Yes sorry I switched them. I guess I should slow down and reread.LOL Needless to say my sled was doing the same thing. The only way they found this problem was by Micing the walls and pistons. Once we got the right parts it has run great and have not had a moments problem.