Post by oliver on Jul 15, 2024 11:01:09 GMT -5
Hey guys. Got a horizontal minarelli with a china 70cc kit on it. Cylinder was dressed by me and port shapes and heights verified to be a decent performer. cyl head is a polini copy with a o-ring groove and very small squish band. Running no base gasket yields piston at bottom of ports at BDC. Squish is large at ~1.55mm. Compression seems good and it starts easily. Carb is a 19mm PHBG clone. Exhaust is stock with what appears to be no restrictions and the dummy tube removed. Factory air box with snorkel removed. Transmission is stock with no mods. Wants to pull the front wheel off the ground on launch.
At WOT with a 85 mj, w16 needle, 50 slide, I was getting lots of smoke and studder, went out and took it for a wot run and it only saw 220 degree CHT and ran bad. Came back and put a 75 main and it ran much better. Long wot run led to same-ish temps, I felt like it was a little lean and plug color confirmed, changed to 80 jet and lowered needle one notch lean, went for a long wot run and still low 220-230 degree temps.
My wot runs are done on a steep incline that's about 1/4 mile long and I hit about 40mph, on flats it can do 50+mph. Is my gauge bad or possibly the exhaust is just completely limiting what this thing can do? I'll probably change to a 17.5mm phbn carb as it will fit perfectly in place of the stock 12mm carb. Sorry for the long post.
At WOT with a 85 mj, w16 needle, 50 slide, I was getting lots of smoke and studder, went out and took it for a wot run and it only saw 220 degree CHT and ran bad. Came back and put a 75 main and it ran much better. Long wot run led to same-ish temps, I felt like it was a little lean and plug color confirmed, changed to 80 jet and lowered needle one notch lean, went for a long wot run and still low 220-230 degree temps.
My wot runs are done on a steep incline that's about 1/4 mile long and I hit about 40mph, on flats it can do 50+mph. Is my gauge bad or possibly the exhaust is just completely limiting what this thing can do? I'll probably change to a 17.5mm phbn carb as it will fit perfectly in place of the stock 12mm carb. Sorry for the long post.
