trx 90 mod engine suggestions for 90 2s/125 4s class

[nastynotchback1]

Why do you want to build your own frame?

[Hybrid Iceracer]

Why not, just because I can. I build all my own stuff for my 250s and spring is about a month away here in the NE so I have plenty of time.

[oscarmayer]

Vince at T-bolt really knows his stuff, I would contact him and see what he says. He can probably either build you the engine you need or at least provide all the parts you need. I bet he even has a stroke setup to make it into a 125cc vs. the 114cc. also just an FYI, increasing compression dramatically increases performance int he torque area and response. On the 4-strokes we used to run, I ran up to a 15:1 setup and ti was night and day compared to a 12:1. response was much faster and crisper. you will have to run minimum of 112 but preferably 116 octane race fuel. We accomplished this by using the v2 head with the smaller chamber and had it machined to fit the piston exactly. so with a thin metal HG we got a total of .010 clearance between the piston and the head. I also had to do a lot more custom work than you will with the timing area, but it worked. Also Vince can get you a really powerful cam to go with it. I do also highly recommend getting the head ported to match the intake and exhaust. Run the FMF exhaust setup as it is larger and allows for better flow. BUT, little motors need some back pressure to make power, so ensure you don't try to run w/o a muffler or it will loose all torque and fall on it's face. (lesson learned the hard way during a race when it fell off. lol)

[Hybrid Iceracer]

Making some progress

[Hybrid Iceracer]

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made good progress hopefully after this weekend it will have steering.