Hi I'm just new to the forums here and it looks like their is a lot of good info here. My question is as follows:

I have a 92 Trailboss with a 350L, I was wondering if anyone has tried to do a 4 stroke engine swap in these machines. I love the bike, It's in great shape, but I think the 2 stroke is getting a little weak in the bottom end, but rather than junk the machine I was thinking of putting a 500 4stroke in the old girl. Am I wasting my time?

 

The 2 stroke 350 and 400 engines are basically the same engine. Other than the bore, Very few differences physically. The 4 stroke 425 and 500 engines are basically the same engine.

Looking at the model ID numbers for a 2 stroke 400 and a 4 stroke 425, they use the same frame ID. Theoretically this should work.

Now, this being said, there is a lot more to swapping to a different engine - Frame mounted electronics specific to the engine and the exhaust system will be a couple of obvious changes.....

In my opinion, if you have purchased all these parts to change to a different engine, you have basically paid for a complete used quad, especially if you consider your time and labor in making the swap happen, and then any unforeseen frame differences that may pop up.

I would recommend just rebuilding the 350 engine from the bottom up.

 

No I havn't bought anything to do a swap I was just wondering if anyone had tried and what the difficulty level would be like. Point well taken, your buying all the stuff to do it you might as well just buy and use the other bike.

The 350 still runs good and has good compression, but is a little noisy in the bottom end. Are these engines typically terrible for fuel consuption? I'm only getting about 40KM to a tank of fuel. I am having trouble with it over fueling a bit, any insight on these engines would be great

thanks

 

Your lower end noise is probably primary clutch buttons. IMO. Rebuild that 350, unless you really like the work. Doc