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Mighty_Max

New Member
I have been somewhat concerned with my engine for a little bit. It keeps 4-stroking and i'm losing out on some power that i feel should be there. I have the SBP shiftkit and in first gear it only goes about 21 mph. In fitfh gear it only goes about 26 and at 7th gear i actually lose speed because there isnt any power anymore. I was expecting it to go faster than this and i decided to tinker a bit. The exhaust pipe (standard) wasn't perfectly sealed against the gasket because the end of the pipe was hitting the frame so i kept tightening the nuts to bend it a bit. That was still leaking so i tried to double gasket the pipe and that seamed to seal it better, so after i went for a ride and everything was hot, i decided to tighten it a little bit and the post came right out along with a coil of threads from the block.

so I have 3 questions:
Can i just jb weld it back in place and get any kind of longevity out of this?

In lieu of that am i going to have to retap the stud hole? Is there another option?

:-||Does anyone know why my engine keeps fourstoking and making me lose out on all this power? I've heard of people getting near or over 50mph with the shift kit and a stock engine and im just barely doing half of that

Engine is the Grubee Skyhawk 2012 GT5 69cc. First tank of gas still, running 20/1 fuel. Only modifications to the engine and related components is the shift kit and a replaced plug boot and plug contact clip. I suppose a pulled exhaust stud counts as a modification too. dammit.
 
you can retap the hole to 1/4-20 pretty easily.

your exhaust needs to seal. you need to bend it to clear the frame. this vould cause your 4 stroking.

other causes could be mixture, jetting, bad plug... there's a lot of things.

i've never heard of anyone doing 50 with a shift kit and a stock motor. or a modified motor. the biggest advantage of a shift kit is low range. non-pedal starts and hills.
 
I think I might have a tap and die set in storage somewhere. Ive sort of been putting of doing anything to the exhaust because i knew i was going to get an expansion chamber, unfortunately, there wont be a cushion in my wallet for a few weeks yet. When i do get the chamber I'm gonna have to do a full diagnostic test and see whats acting up.

Those speed figures might have been exagerated in passing rumors that I had heard, and i didn't expect that, but i don't think 35mph is too unreasonable.
 
You cannot expect much performance during break-in. Give it three or four tanks before you worry about top speed. ALL china girls are blubbery rich from the factory. Once your engine is fully broken-in, you can jet it leaner to get full potential and less four-stroking. Don't bother trying to jet until it's broken-in as it will not stay consistent.
Helicoil is better than new once installed correctly. It's not too hard.
 
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I was being stubborn and lazy when i posted before. A couple months ago, during the cold snowy month of February, I caved in and bought a helicoil kit from Napa auto parts (the only place I know of that carries them in this size) and it worked beautifully, and it was pretty painless. As for my performance problems elsewhere, the problem lay in the CNS carb. It came direct from factory jetted way too rich. Every possible mod for the carb left me upset and with no improvements so i bought an NT carb and high airflow filter. All of my problems vanished the instant i put the new carb on. Thank you for all your help(s?) even though it took me forever to listen to you guys.
 
Congrats, MM! Personally, I believe the CNS is a terrible intro carb. I suspect it may be great for a racing kit where you're continually tuning it, but that's not my bag MAAAAAHN. My welcome to MBing was a kit with the "high-performance" CNS3. I shan't get into a carb debate here, but switching to an NT solved my teething-pains too. I actually did get the CNS running reasonably well, but I think for an everyday rider where minor atmospheric changes can noticeably affect performance, simple is better, and the NT is stupid simple. I am 280#, carry about 30# in my backpack on a 40# bike. I run a 66cc X with a 44T on 29" wheels, and am cruising on a VERY broken-in engine @ 30MPH & ~80MPG. This with the standard NT. You can basically plug it in, adjust via plug-checks, and forget it. At sea-level, I've only needed to change the pin by one notch from 17-deg F to 80-deg F.
 
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