1986 125m engine swap?

[troyky29]

New here, been looking at this site for a while, but finally registered. Here's my story. I have a 1986 125m. Nice looking trike, needs seat recovered. Engine turns over and sounds like it has compression. I took it to a guy who works on four wheelers and he said it sounds like it needs a top end rebuild. Quoted a price of $300 if it needs to be bored and everything else is not damaged. He took the cdi cover off and told me the motor was junk and it would need an all new top end. Of course I took it home. Before I sell this thing, I was wanting to see if an engine off a 1987 TRX 125 would bolt on my frame. They look the same but I'm not sure if the bolt pattern is the same. any help on this would be great and if anyone has any thoughts on the engine on it that would be great too. I don't know alot about the internal parts so maybe someone could tell me if all this sounds correct.

[shortline10]

Same motor . Harness plugs might be different but it should bolt in with no issues .

[PerryS]

Whats the advantage of swapping to the trx125 motor? Do they have mpre power? In the future i would like to get some more power out of ny 125m and this may be a good way to go.

[shortline10]

No advantage . These motors are known for the cam journals to go bad if not maintained correctly .
to get a little more pep out of a 86/87 125m you can do a 200x cam upgrade .

Whats the advantage of swapping to the trx125 motor? Do they have mpre power? In the future i would like to get some more power out of ny 125m and this may be a good way to go.

[PerryS]

I dont want to thread jack but will the 200x cam upgrade work for an 84. I have the 84 with the 4 speed and hi and lo

[shortline10]

No it wont work . WEB cams used to make a nice preformance cam for that model if you want an upgrade .

I dont want to thread jack but will the 200x cam upgrade work for an 84. I have the 84 with the 4 speed and hi and lo

[troyky29]

I take it the TRX engine will fit without an issue, now I have to decide if it is worth taking a chance on. Engine suppose to be good but has been sitting in a shop for a few years. Does anyone have any thoughts on the old engine? I believe it was the camshaft that he said was moving up and down. After that he said it will need a completely new top end.

[shortline10]

Before you buy the motor pull the cam cover off and see if the cam has play in it . Very common prob with this motor .

I take it the TRX engine will fit without an issue, now I have to decide if it is worth taking a chance on. Engine suppose to be good but has been sitting in a shop for a few years. Does anyone have any thoughts on the old engine? I believe it was the camshaft that he said was moving up and down. After that he said it will need a completely new top end.

[troyky29]

So if the cam has play in it, does that mean the top end is trashed? There is quite a bit of play in the old engine. Don't think I want to take a chance on the other engine since its on ebay and the seller is not giving a guarantee. If the engine is trashed, I guess I will try to sell the thing.

[malibulvr]

I just put a 125m in my kids TRX125 and had no problems, bolted right up. The only thing I lost was reversed but gained hi/low. One plug was different well it was the same but instead of male it was female so I just switched with the old engine.