Re-assembly 60cc with port matched setup - Very low power

[DanielMaia]

Hmm, very nice..

The fact is: even at low RPM's, if i WOT all the way, it revs really good, with a perfect 2 stroke sound, but in high rpm's it makes 4 stroke (in 3rd gear (equals to 44 sprocket) at 44, 45km/h, it 4 strokes a bit..

With the throttle from 0 to 50, 60%, it 4 strokes a lot..

 

[Norman]

if it is 4 stroking at wot the main jet dia is a little to big. most carbs work with 0.70mm or stock size going to a 0.65 mm will help lean it out at high rpm.
You might need to check the mm size of the main jet first use the butt end of the drill bit if it will go through the hole with a small amount of drag then that is probably the size of the jet. Then you can decide which way to go on making the engine learner or richer. Smaller hole is lean bigger hole is rich. The jet affects only wot.
If your running a non stock air cleaner that can affect the amount of air into the engine. If your air cleaner is stock but has a lot of oil in it that will act like the choke is partly on simply wash out the air cleaner in warm soapy water wring the filter out as best you can stick it back on the engine with out oil and run it for a while/short ride if the cleaner was causing the 4 stroking with it now clean and less oil it should make it run better. Don't worry about no oil in the cleaner it will get plenty of oil on it as it runs.
These engines will spit a small amount of fuel back into the cleaner as it runs,oiling the filter.

 

[DanielMaia]

Yes, the main jet i already put a smaller size. Stock is #70 as you said, if i remember its #60 now.

Other thing, the spark plug is between the chocolate and dark, but what i dont understand is: the engine gets really hot (a lot higher than my 66cc)...but, in other hand, it 4 strokes at high rpms..than it needs a smaller jet, BUT, a smaller jet --> leaner mixture --> more temperature, am i right?

 

[shellshock]

I had to get a new piston for my 60cc grubee, piston rings, and cylinder body. I also bought a high compression head that runs "cooler". I put it all to gether and when I try to bump start it the piston makes crazy noise I have never heard before. I took one piston ring off my 60cc flying horse and got another one in the mail. I dont know what else to do. help!

 

[Mr.Gadget]

Out of time,,, but undergoing a rebuild myself. I'll post later with questions and details.

 

[Mr.Gadget]

OMG!!!!
That little engine fought me tooth and nail, and I was rolling around on the garage floor like I was fighting an aligator!!!!! LOL!!! But I finnaly got the entire engine apart. I am the 3rd owner of this engin, and it was abvious, someone had been in there before. I was surprised to so much debris inside there. Tonight I will clean up all the parts and pieces and begin the rebuild.

My first question is, After break in, is it bad to remove the cylinder??? would this not mess up the seating of the piston rings?? I have seen alot of people here with the cylinder removed,, Once you put it back on,, do the rings go back to the same seated position?

 

[skipu]

just guessing but i think you had a base gasket leak maybe maybe not just saying from the symptoms its happened to me a few times now i really take the time to lap the case and cylinder after my porting and the thinest layer of black rtv im running grubee gt5's tweeked cns and billet head and intake on a 36t sprocket hitting a consistant 46 mph after three motors experimenting got a good combo