Let me start by saying this is my first experience with a two stroke. I bought my son a 1985 LT50 out of a barn and started him on it when he was two. After a couple of years he got pretty good on it and started to complain about the lack of suspension. So, I bought him one of the late models with suspension. Now he's five, 4' tall and about 55lbs.

Right from the start it was obvious that the older bike had a lot more power. I figured it had been derestricted, so I swapped everything over between the bikes. Exhaust, carb, intake, etc. but the new bike still doesn't seem to have the power that the older bike had. I'm wondering if the older bike might have a shaved head.

Anyway, after swapping everything over, I've been trying to get the bike tuned as well as possible. I've read tutorials and have it running out pretty good on the top end. As a matter of fact the top speed of the bikes seems to be about the same.

Here's my problem. It doesn't seem to have anything on the low end. Sometimes he can't get it going without a push even on the slightest inclines. So, I'm wondering what to do. One thing I've noticed is that if he has trouble starting and holds the throttle without moving for a few seconds the clutch seems to heat up or something and then it makes the problem worse. But at the same time, it doesn't seem to rev off idle like it should.

What do y'all think? Carb jetting? Does shaving the head make that much difference? Change the sprocket? Clutch worn out? I'm at a loss.

I like the size and weight of the LT50 for him and I don't want to go to anything else just yet. We aren't looking to go racing, but it is frustrating for him not to be able to get rolling from a stop.

I'd really appreciate any insight I can get.

Thanks.

 

I've swapped the engine on from a 2002 to a 1985 and the 85 to the 02 and they are the exact same. I did it to make one good atv till I could rebuild the 85 frame and 02 motor.Yes they can be restricted and that would make a difference, but if it was running fine prior to moving it nothing should have changed. The 85 frame is lighter though. When my girls started riding the 02 they had to learn to shift their weight and rock the atv over some obstacles in the woods and trails, but once they got use to having to accelerate going up hills before the obstacles then they were fine. My youngest was 3 when she started riding and her friend is 7. I just repaired a 06 polaris predator and my daughter (test rider) got bored on it because of the speed so she went and rode her 1985 lt50. Check some of the older post and hopefully LT80 will comment and give you dome ideas for improving it.

 

I would swap the clutch between the units, doesn't sound like the new bike is letting the engine start revving before engaging.

 

I hadn't thought of that! I actually ordered a clutch kit for it last week. If that doesn't work I may try that. Thanks.

 

So was it running fine when it was in the older frame? If so it's not the clutch it's the exact same clutch thru all those years.

 

MIght be the same, Doesn't mean its working right.

 

But if it was working prior to being swapped then it's not the clutch.

 

true. But he did not swap the Clutch.

 

He said in his first message he swapped everything. So I would have thought he swapped everything including the entire block. So that's why I had asked that question.