running hot... overheating 2 stroke

[HumanPerson]

This is a picture of my bicycle, not much but it gets me around comfortably and economically.

https://motoredbikes.com/attachments/img_20190323_175112-jpg.86524/

 

[HumanPerson]

I'm new to this so don't take what i say for granted lol

 

[BIG BOBBY]

This is a picture of my bicycle, not much but it gets me around comfortably and economically.

https://motoredbikes.com/attachments/img_20190323_175112-jpg.86524/

mega exhaust pipe

 

[HumanPerson]

mega exhaust pipe

1 1/8" Inside Diameter tube.

Crazy story starts here

Stinger Length?

Alright, so i have a few SBP expansion chambers laying around. I cut out the 1/2" wide by 2 1/4" long stinger that was on the expansion chamber when i took the silencer can off. Now, i am going to braze onto the expansion chamber a 5/8 wide tube. Is there a length to go by or am i ok with my...

motoredbikes.com

Just keep safety first. Make sure you can get ahold of someone or one of us here if you have trouble.

You can do it, just keep the speeds down and cruise while taking in the energy and projecting some popsitive Vibes yourself

 

[BIG BOBBY]

yeap. positive waves.

 

[Hell on Wheels]

Resonating with what people said above, if your plug looks good and she isn't melting pistons, heads, etc then that's fine. 40:1 is good for 25 mph. I tend to go faster so I need alot more oil. Synthetic has better film strength which I hear helps with closed throttle, high rpm but idk about reducing oil amount. I'm running 20:1 on regular oil, 91 octane non ethanol for my break in. Idk what I'mma set it to after.

 

[BIG BOBBY]

thank you for the input. ill take every opinion I can get.

I think the pros here would tell you to go straight to 32:1 after break-in,.. since your gonna be mashing it.

 

[CrazyDan]

Tune your engine to get the most power in low rpms and stay around there to keep your engine running longer. Prolonged high rpms is what kills engines. I got a shift kit just so I can get up to speed then shift into a higher gear to maintain that speed at a much lower rpm. Remember: It takes more horsepower to get to a certain speed than to maintain that speed. HP=torque*RPM/5252.

 

[BIG BOBBY]

agreed. I want to cruise slow. as slow as i can without making the motor buck/jerk. I don't like going fast just to keep the motor smooth. I do realize, however,..that the motor's rpm's need to be varied,.. almost continuously.

 

[Hell on Wheels]

Tune your engine to get the most power in low rpms and stay around there to keep your engine running longer. Prolonged high rpms is what kills engines. I got a shift kit just so I can get up to speed then shift into a higher gear to maintain that speed at a much lower rpm. Remember: It takes more horsepower to get to a certain speed than to maintain that speed. HP=torque*RPM/5252.

I used to have my pipe tuned to hit @4-5k rpm and cut at 7,000 rpm but I couldn't keep up with traffic and the hills around me. Even then, the cylinder got scored up (bad casting) and the bike frame I was using snapped (multiple reasons). So I'm gonna give it to her. Make her scream and replace the cylinder and head as needed. My first build blew the wrist pin bearing (weaker variant). My second still had bearing material in the crankcase so it locked immediately. Third build was ground up with Fred bottom end and machined down/cleaned cylinder with low-mid rpm range pipe tune. I'm breaking in my top end rebuild with a higher rpm header and I need a different rear gear (28/10 is too small for the power band, going to 41 to judge engine characteristics then down to 36 probably).

The goal is lower than 11k rpm as, from what I hear, that is when the connecting rod bearing dances too much and shoots out the side of the piston.