80 LF Bogs when warm

[OhBigDaddy]

I just acquired an 80 LF. Nice and clean sled. Had compression check at 120psi per hole. The guy I bought the sled from said he had the sled serviced and the carbs cleaned and set up at a shop. His kids ran the sled a few weeks until they broke the pull rope. (He mentioned that the sled didn't seem to idle well. Low rpm and had to feather the throttle to keep it running.) When I brought the sled home I took it for a short 3 min drive and it seemed to have good power (popped a bit) but it idled rough. The next day I tried to adjust the low idle by turning in the low idle screws. I also checked the carb sync and they were way off. The mag side carb cylinder rose way before the pto side. So I adjusted them so they started together. The idle was real fast then (3-4g) but it had NO power. Couldn't even engage the track.

Next day I took off the carbs and cleaned thoroughly. Set the idle screws (3 turns after contact with the cylinder) set the air screw 1 1/2 out. Started the sled and it idled nice 3g, lots of power. Took it for a hard drive, which lasted about 5-10 min. (it popped a bit) but had lots of power. When I stopped at the house, it began to bog again. Checked the plugs and noticed one plug not much color on it. (New plugs) When I touched the mag side plug wire it shocked. Switched the plug end cap and it still was bad. (with sled running on one cylinder the mag plug wire without a plug in it was arching on the frame. I noticed the ground wire on the coil was broken. Redid that so it was grounded on frame. But still bog.

Do you think it is a coil/wire issue that would cause the sled to run well when cold but die when it got a bit warm? Any help appreciated. Kind of new to the LF. (I did order coil which should be here later this week)

[acesillini06]

I got a 83' liquifire with rebuilt motor and carbs cleaned and snycronized, rebuilt cdi, new stator and still having problems with the idle at or below 3,500 rpm's. It just won't idle but when driving it runs great, just have to keep the rpm's up. Once let go of thottle it die's.

[427cobra]

With your 80LF you want to set the idle around 3 - 3.5K.

Installing the purple spring in the primary clutch is recommended with "B" weights.

Make sure the drive chain is tight. You may want to tighten up the secondary spring that may help eliminate the bog.

A bad CDI would cause a bad bog when warmed up and cause hard starting when warm. Happend to my buddies 80 LF last year.

Good Luck!

[OhBigDaddy]

I understood that the CDI either works or it doesn't. I finally took the sled to a local guy who works on these. He thought 95% that it was the stator. (A problem if it works when they are cold and begin to bog when they get warm) It is too easy to start plugging in parts without a clear diagnosis... I thought the external coil...... We will see.

[acesillini06]

We put a new stator on the 83' Liquifire from Bob at Image for $185 dollars. It did not help the idling issue. It's at the second pro mechanic right now, it's got everyone clueless as to the problem. Besides the idle it runs great.

[Danzig]

Who is this "second pro" ? Locally in Rochelle?

Did you ohm out the stator?

CDI was rebuilt? By whom?

I am local to you and would love to help..

[AirborneX4Special]

I am inclined to think you might have crank seal issues. Change that coil and see what it does, but don't push it. I was on a similar regimen with an 80 and an 81; both sleds had a bad mag side crank seal. Luckily, I only burned one down! Good luck!

[Danzig]

unhook the rev limiter too..

[Kulture Vulture]

I would pressure check it and make sure it`s not a bad crank seal. Some of your symptoms where the same as my 81 LF, when the mag side seal went. You definately don`t want to burn it down.