So I've been tinkering around with this engine for a month now, I wasn't completely familiar with the plugs that they took so when I went to get a new one to replace the stock plug I requested a bpr6hs and the guy behind the counter handed me a champion b6hs. He said it was the equivalent. I didn't ask any questions and took it home. It led me to be chasing a bunk plug for a week. Trying things to get it to run right and just would not get just right. Finally put in a proper ngk bpr6hs, protruding tip and it runs very well now.
In that time I had opened up the exhaust port with one single bit, I couldn't go all the way through with the big bit so stopped about 5mm from the cylinder wall and completed the rest of the top part with a grinder bit.
My top speed went from 28mph@6500 to 38mph@ 9000. A staggering 30% increase. I'm running a 41T rear. The bike will not take anything bigger than a 58 jet, a 60 or bigger drops my top speed. 32mph with the 62 jet. 15mph with 68 jet. I did also get the straight short intake instead of the stock one.
My main issue right now is my damn spokes keep coming loose. Get them just right and ride less than a mile at WOT and I need to stop and tighten them back up. It's a real pain. I'm just waiting till I have enough dough to get mag wheels from bike berry.
Engine has a 5.5cc head and .030 squish with gasket. Has the expansion chamber pipe. No reeds, stock carb.I think it would hit the head without the gasket. Good thing for us the piston always has down force on it from above on every stroke. Probably helps. A 4 stroke has that exhaust up stroke where theres no pressure above the piston, allowing it to go as far as its able upwards.
The picture of the port still has shavings all over it. Excuse that. I have a compressed air blower I use to clean them up before installing. I really didn't care about the polishing bit. I just need it opened up, I'm not interested in the extremely minimal gain if any that would come from polishing. It's what I call engine polished. The residue in the 2 stroke exhaust will fill up all the little spaces and cracks. Lol.
I'm pretty happy with going from 28 to 38. That's a huge increase!!! I can stick nearly my entire pointer finger into and through the port. It seems to actually like the higher rpm now, some vibration went away.
In that time I had opened up the exhaust port with one single bit, I couldn't go all the way through with the big bit so stopped about 5mm from the cylinder wall and completed the rest of the top part with a grinder bit.
My top speed went from 28mph@6500 to 38mph@ 9000. A staggering 30% increase. I'm running a 41T rear. The bike will not take anything bigger than a 58 jet, a 60 or bigger drops my top speed. 32mph with the 62 jet. 15mph with 68 jet. I did also get the straight short intake instead of the stock one.
My main issue right now is my damn spokes keep coming loose. Get them just right and ride less than a mile at WOT and I need to stop and tighten them back up. It's a real pain. I'm just waiting till I have enough dough to get mag wheels from bike berry.
Engine has a 5.5cc head and .030 squish with gasket. Has the expansion chamber pipe. No reeds, stock carb.I think it would hit the head without the gasket. Good thing for us the piston always has down force on it from above on every stroke. Probably helps. A 4 stroke has that exhaust up stroke where theres no pressure above the piston, allowing it to go as far as its able upwards.
The picture of the port still has shavings all over it. Excuse that. I have a compressed air blower I use to clean them up before installing. I really didn't care about the polishing bit. I just need it opened up, I'm not interested in the extremely minimal gain if any that would come from polishing. It's what I call engine polished. The residue in the 2 stroke exhaust will fill up all the little spaces and cracks. Lol.
I'm pretty happy with going from 28 to 38. That's a huge increase!!! I can stick nearly my entire pointer finger into and through the port. It seems to actually like the higher rpm now, some vibration went away.
