80cc 2 stroke wont reach full rpm

[Shadow57x]

I just got done with a project wit a new engine kit and the bike fires right up and run great intill I hit 18 mph then starts four stroking. I've check for air leaks there is none and played with the jetting and put a different cdi box on it. seems like no matter what I do it's still four strokes the only thing I changed was the intake and like I said I have no air leaks could my intake be to long? I'll include a photo. Any suggestions is greatly appreciated. Thanks

 

[GW's Motorized]

Nice job with the fitment. I don't know about the length on the intake being your problem. Did you adjust your carb needle?

 

[Shadow57x]

Thanks it was alot of work. It's got the hp carb with all of the jets. Tried the 70, 75. And the 80 and still nothing. I'm running out of ideas.

 

[DieselTech]

Nice job with the fitment. I don't know about the length on the intake being your problem. Did you adjust your carb needle?

I believe that's a flat side dellorto 15.15 sha, they dont have a needle.

 

[DieselTech]

Thanks it was alot of work. It's got the hp carb with all of the jets. Tried the 70, 75. And the 80 and still nothing. I'm running out of ideas.

Try a 67 or 68 main jet.

 

[GW's Motorized]

I believe that's a flat side dellorto 15.15 sha, they dont have a needle.

My bad, I should have looked closer at the pictures.

 

[DieselTech]

My bad, I should have looked closer at the pictures.

No problem here. Stuff happens. I do it all the time!!!

 

[Shadow57x]

I went out and stole a jet from one of my pocket bike hp carbs and it's running to lean. I tried that because I have another bike with the same set up as this green one and it runs great and I believe that other bike has a pocket bike hp carb on it. Now I'm thinking about putting the jet back in that carb I stole it out of and trying the whole carb because that inlet is smaller?

 

[DAMIEN1307]

No problem here. Stuff happens. I do it all the time!!!

Yep...Except with Diesel, he does it with the written word though...lol...Reading is fundaMENTAL ya know...lol.

 

[Axl Myk]

It's a brand new motor? They have to be broken in for a few tanks of gas. Some say 20 to 1, I say 32 to 1 is good. 4oz oil /gallon.
Start hotrodding it right off the git-go is bad for it.