J Man
New member
Ok, so I've been reading through all the posts and can't seem to find my problem. I'll describe the issue and then list the sled setup. The sled is setup for high altitude 6500 feet according to the service manual. The sled is in good condition but had been sitting for a couple of years, so I replaced the fuel lines, fuel filter, cleaned the carbs, fuel pump, and fuel tank. Changed the chain case oil and the engine oil along with priming the oil pump until the new oil was coming out. Compression was 120 psi in both cylinders and still is. I currently live at 5000 feet and got the sled tuned to start and idle (1800 RPM and pilot screws 1 3/4 turns, it had a slight bog off idle at 1600 rpm and 1 1/2 turns) at this altitude. All the cables were adjusted to the service manual specs. I also checked for any air leaks or bad crank seals when I was tuning it and didn't find any. Took it for a ride around the yard and it drove fine. I then took it up to the mountains where the trail starts at 8000 feet. It started fine, let it warm up about 15 minutes, drove about a quarter mile to the trail head about 5-10 mph without any issues. Hit the trail and was driving it about 45 mph between 4000-5000 RPM for several miles without any issues. I was still around 8000 feet and had to stop to fix the gear in my luggage rack. This is when the problems started. As soon as I got off the throttle and slowed down, the engine just died. After fixing my gear, I could not get it started unless I held the throttle full open. Even after it started, it would die if I let off the throttle. After messing with it for awhile, the only way it would stay running was with the pilot screw at 1/2 turn and the idle adjusted up to 2500 rpm. After these adjustments, it then had a bog when accelerating from about 4000 rpm until about 5000 rpm and it sounded like a diesel engine brake when it bogged down. I drove it up to around 10000 feet and did some ice fishing and let it cool down. Again, I had to hold the throttle full open to start it, and it would idle at 2500 rpm and had the same bogging when coming down. Checked the choke, and the engine would die when I opened it, as well as if I pulled on either individual one. Each plug was light brown in color. And I'm assuming the bog was because of the pilot screw setting. Pulled the carbs again and can't find anything obvious, so here I am. Any help would be appreciated.
Sled setup:
AAEN pipe with stock airbox. No visible leaks around engine (amazed it was this clean when I got it!) no boot or crank seal leaks that I could find.
Carbs are the Mikuni butterfly, 1.5 float seat, float height set at 11mm, 80L special primary nozzle with correct hole alignment, 2A main nozzle, 135 main jet, 95 pilot jet (plugged along with center tube), pilot air jet 1.5, spark plugs light brown after the drive (didn't do any of the checks shutting the motor down).
Primary clutch spring Red Pink Red with 3 shims and no rivets, Secondary spring is black (couldn't find a brown mark), set at 70 degree twist angle, 1 and 6 (couldn't see the part number for the cam angle. Gearing is 16-33.
Think I have all the info covered, sorry for being long winded. Thanks ahead of time for any help anyone can give.
Jeff
Sled setup:
AAEN pipe with stock airbox. No visible leaks around engine (amazed it was this clean when I got it!) no boot or crank seal leaks that I could find.
Carbs are the Mikuni butterfly, 1.5 float seat, float height set at 11mm, 80L special primary nozzle with correct hole alignment, 2A main nozzle, 135 main jet, 95 pilot jet (plugged along with center tube), pilot air jet 1.5, spark plugs light brown after the drive (didn't do any of the checks shutting the motor down).
Primary clutch spring Red Pink Red with 3 shims and no rivets, Secondary spring is black (couldn't find a brown mark), set at 70 degree twist angle, 1 and 6 (couldn't see the part number for the cam angle. Gearing is 16-33.
Think I have all the info covered, sorry for being long winded. Thanks ahead of time for any help anyone can give.
Jeff