new 48cc jug big bore??

JerboaJohn

JerboaJohn

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Interestingly, I got a new jug and piston in for my 48cc HT and since I don't trust anyone or anything I thought I better measure all the specs
wholly unexpected, this is the bore, calculating CCs it is not gonna be legal haha. I'm gonna port the beans out of this!
really good casting by the way (tho the int/ex flanges are not symmetrical they are workable)
20180924_161149.jpg
 
decided not to get carried away porting lol. the bike wont see much WOT. just cleaned up the ports and left the piston alone. I'd still like to bore the pin but idk. next weekend if it's still nice enough, base test the original jug and then swap this one.
online calc says it'll be 54cc
 
I think this link works. it's from boygoesfast lol
.
https://www.ebay.com%2Fulk%2Fitm%2F190933567467
 
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Do you know if anyone makes a plus one or plus two crank for that engine?
 
joecass said:
Can I buy just the topend kit or is the stroke also different
Click to expand...
You can not put a 47 mm diameter piston 66cc cylinder on a 48cc case that had a 40 mm diameter piston.
The cylinder stud spacing is different.
Buy a complete motor.
 
I’m going to try and port this one because I’m just looking for something to pull me up hills I’m not looking to go fast. Plus it doesn’t cost anything
 
ok here's a few pics part way thru. I didn't open them up, just smoothed the ports. exhaust side needs more smoothing and then polished.
it's a b**ch getting the bottom of transfer ports. they are bad design bcs its a right angle right before streets the cylinder. I'll get that narrow bump out but can't correct the angle farther in on transfers
I didn't want to risk nicking the cyl wal until I can get a right angle grinder.
basically keep ports small for more air speed so not to lose torque at the expense of high rpm power. that's a different game
intake_mod1.jpg
20181005_080310.jpg20181005_080443.jpg
green areas on the intake are material to remove. just to smooth the flow and let the fuel mix get in faster. lots of little things like this that's not hard to do
 
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