110/125m frankenbuild

[forkintheforest]

Now I know there are some purists are on this bored so, *dons flamesuit* I thought I had read a while back about someone putting a 200s/m head on a 110 or maybe it was a 125m. (I'm looking to purchase either or right now both roughly the same price) I was looking at different ways to improve performance. However, when I was reading through the brochures it looked like the 200(s/m) had a bore of 60 something whereas the ATC 110 can be bored to 55 and the 125 is 55(ish). How would that play out when doing a head swap? (if it can be done realistically) I'm not worried about it raising compression, in fact I'd also like to know if you can use a different piston to raise compression. Or is milling the head your best bet? Is there a sticky with other tips and tricks?

Thanks,
Nick

[0GravityMX]

the 200/185 head only works on 86/87 125m they had a vertical motor ...83-85 is way diffrent

[Jason Hall]

I put a 84 125m head and cylinder on a 110 bottom end, and It didn't work out like I wanted. I used the 125 head along with the 125 cylinder ( 125 bore Is 55mm). I found that the 125 cylinder Is quite a bit taller than the 110. I was using a Big stroker crank, so It almost worked out sweet. I had to mill about 100 thousandths off the top surface of the 125m cylinder to make a 61mm stroked crank level with the top of the piston. The timing chain was also a hassle, as It was a 1/2 a link to long or short. What finally made me scrap the entire project was I could not use a 110 cam In the 125m head. The rocker arm geometry was totally different, because the rocker shafts were way higher In the 125 than the 110. When I rotated the 110 cam around In the 125 head the valves hit each other. With the 125 cam Installed the valves opened perfect. I did not want to run the stock 125 cam because I scored a SWEET 110 cam from my Buddy Ol Pal Kasey. Shortline10 also Informed me that the exhaust port angle was different, so the Supertrapp pipe I had would need to be modded. The 125 head Is ALOT more restricted than a 110. The 110 head has Way more potential for porting and flow than a 125 anyday!