full circle crank

howdy, im rebuilding my 49cc engine with a sleeper head kit i think! Anyway i am looking at replacing the bearings and seals and i am also looking at a full circle crank like this one....

do u guys think it is worth buying one? How much modifing will i need to do to get it to fit? cheers

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49cc F7, sleeper head, fully polished internals, reed, timing key, modded carb=speed

the full circle crank is the way to go for top performance gains as it reduces crankcase volume which in turn increases crankcase pressure, these cranks must be balanced with the piston fitted to eleviate all vibrations, slight machining of the crankcase internal wall areas may be required.

who can i get to balance it, and machine the crankcase walls? isnt the crank already balanced?

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49cc F7, sleeper head, fully polished internals, reed, timing key, modded carb=speed

RD RACING Might Be Able to Do It IF You Ask Him Nicely, Im Getting Some Awesome Engines Built By Him.

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www.MiniRiders.com.au


Scott@MiniRiders.com.au

Kool, i'll giv it a shot :wink:

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49cc F7, sleeper head, fully polished internals, reed, timing key, modded carb=speed

the kt100s and j engines have ful circle cranks, so id say they would be worth the money

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Since when did the KT100 J or S engines become high performance engines ? :roll:

Neither of them rev hard or make half the power of a high performance kart engine.

Both are piston port 100cc 2 strokes. The J makes 9 hp and the S makes a wopping 17 :roll:

Even compared to good piston ports they are slow , real piston ports make 25hp and rev as high as 19,000 rpm.

A real high performance 2 stroke not only has a full circle crank but the rod end has nylon stuffer blocks as well.

As kart engines go some of the prototype Formula Super A engines made 36hp and rev to 21,000 rpm every lap.

You can't just take an engine designed to have a half crank, bolt in a full circle and expect it to tune up just like that.

Fitting a full circle crank to a CAG engine will help it rev, not only because of the weight of the crank but because it reduces the volume of the crank cases. This increases crank case compression and therefore the engines ability to transfer fresh air.

This is at the cost of bottom end power.

Given that the clutch engages at very low revs on a CAG and the porting isd not up for big revs, not to mention the igniton gives up at 10 grand, you'll have your work cut out making it go properly.

If you want to throw enough money at a CAG to buy a real bike just fro fun then go for it. But if you don't want to buy a carby, 4 petal reed, new exhaust to suit, trick igniton, a head kit and more just to make the crank work , then don't bother.

CAG engines are made to GRUNT . Tune them to pull tall gearing and run clean.
:wink:

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ZPF Central Queensland
ZPF bikes
Euro parts
PMT\'s & Sava\'s
Hi performance water cooled bikes
Engine Blueprinting

didnt say they were high peformance all i said is they are good. ffs

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who says the ignition coil on a cag gives out at 10,000 rpms, how do my engines run at 14,000 rpms plus, maybe the engine takes over after the 10,000 limit? also full circle cranks [after balancing] are a must for a moded cag or piston port engines if you want them to go how they should go. and nylon for rod stuffers? i would think teflon.

kawasaki use nylon in kx's :lol: Hence they dont work for long on methanol.
I made my first FC cag crank by welding on some rolled mild steel and filling the gap with silicon it went 14600rpm, I pulled it out after 3 months of abuse and it was still together? :lol: