Any suggestions for upgrades?

DieselTech

Well-Known Member
Local time
1:49 AM
Joined
Sep 18, 2021
Messages
6,089
Running a reed valve without high enough intake duration or a windowed piston can cause a decrease in power due to the intake restriction.
Rocket you mentioned a high enough intake duration for running a non windowed piston. What kind of intake duration would a guy be looking at to do so. Thanks.
 

ImpulseRocket

Moderator
Staff member
Local time
1:49 AM
Joined
Apr 16, 2014
Messages
2,948
Location
Omaha, Nebraska
Rocket you mentioned a high enough intake duration for running a non windowed piston. What kind of intake duration would a guy be looking at to do so. Thanks.
Depends a bit on the engine, but between 140 to 150 degrees is getting aggressive enough that you can run piston port without a reed, but it may be able to run with one without taking a hit in power. Past 150, It starts to become more necessary. The blowback becomes significant enough that you start to see a loss in power, thus the reed helps recover it.
 

DieselTech

Well-Known Member
Local time
1:49 AM
Joined
Sep 18, 2021
Messages
6,089
Depends a bit on the engine, but between 140 to 150 degrees is getting aggressive enough that you can run piston port without a reed, but it may be able to run with one without taking a hit in power. Past 150, It starts to become more necessary. The blowback becomes significant enough that you start to see a loss in power, thus the reed helps recover it.
Ok thanks, it's a 49mm steel bore engine that I raised the jug almost 2mm then decked the cylinder. .7mm squish. I'll just have to try a reed just to see what happens. It runs real good now, so that will give me a idea, if it falls on its face with reeds & non windowed piston. Thanks
 

ImpulseRocket

Moderator
Staff member
Local time
1:49 AM
Joined
Apr 16, 2014
Messages
2,948
Location
Omaha, Nebraska
Ok thanks, it's a 49mm steel bore engine that I raised the jug almost 2mm then decked the cylinder. .7mm squish. I'll just have to try a reed just to see what happens. It runs real good now, so that will give me a idea, if it falls on its face with reeds & non windowed piston. Thanks
In my own experience with reeds, I first installed one on a lightly ported 66cc. I neither gained or lost power. It felt no different. The only real benefit I got was a mild increase in torque down low and a less oily air filter long term.
 
Top