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Discussion Starter · #1 ·
From IP2.

this current crank is already too much work, it originally tested with 38 grams JCC piston (39cc)

now the other pistons weight more (some 40cc pistons weights 50 grams and some biiger set ups weight up to 65 grams) so it be out of balance because one side will be heavier so ballancing required by drilling 10 to 12mm holes on both side of crank main pin and filling with expoxy

but even after reballancing vibration will still too high because of flaw in design of these bikes as bottom plate welded only on one side and not suported on the front therefore vibrate , we had to weld supports bars for engine plate to reduce vibration , the engine mount bolts are only 6mm so we had to retapp to 8mm

thats why even stock 40cc cag vibrate , pipe cracks on stock bike , stock 48.3 is worse , you can only expect lot more vibration when going to higher displacment

also drastic jetting changes required when going to FC crank , reason is displacment and timing changed and intake pulses being stronger

be aware stroker crank needs lots of work :

ballance
split case
trim case
install with new gaskets
set squesh clearance to 0.5 mm
lower exhaust port to match
weld support for front of bottom plate
jet

this item is not a bolt on and intended for experience tuner only
 

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WFO Racing said:
From IP2.

this current crank is already too much work, it originally tested with 38 grams JCC piston (39cc)

now the other pistons weight more (some 40cc pistons weights 50 grams and some biiger set ups weight up to 65 grams) so it be out of balance because one side will be heavier so ballancing required by drilling 10 to 12mm holes on both side of crank main pin and filling with expoxy
more info on this please.
i thought it was already balanced. i figured they would balance it with the big bore piston since thats what most people would run it with.
 

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you think if when i get my big bore kit i assemble the crank, rod and piston and take it to a machine shop they can balance it perfect? or is it too small.
 

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Discussion Starter · #4 ·
SUX2BU said:
more info on this please.
i thought it was already balanced. i figured they would balance it with the big bore piston since thats what most people would run it with.
That's all I have really. It was or is balanced for the 39cc but because of the longer stroke there is more vibration. It's even worse with the big bore but there are things that can be done to calm them down. I did..........

Rubber/metal (sealing) washers between the motor and frame and behind the screws.
Same on the rear pipe mount.
1/8'' rubber between the seat and frame.
Progrip gel grips.
Stiffer upper motor mount with sealing washers on fasteners.
 

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is the off balance so bad with yours that it affects performance or is it just anoyying vibration?
 

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Discussion Starter · #6 · (Edited)

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so you have to drill, looks like three holes and remove that big *** chunk of the flywheel? that seems like alot.
 

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i think i want to contact those people to see if they can balance our stroker cranks and pisto assembly. we should find a place that sells the case seals for our engines also. i have a feeling mine are going out also. well this is turning into the biggest mod i have had to do to this engine yet. weld frame, balance crank and piston, and others.damn
 

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It sounds like its not a balance issue. If you look at the bike design and think about what is happening inside the motor. Piston going up and down. Motor bolted to a plate that is only supported at the rear. Its like you standing on the end of a diving bord and jumping up and down. Its going to vibrate. If you added a support to the front of the mounting plate you could get rid of some of this. No amound of balancing the reciprocating parts is going to help here.
 

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so is anyone thinking about balancing there assembly. it seems like it would solve a lot of problems with these bikes. would not have to reenforce frames and bolts would stay in. and pipes would not break.it going to be a pain in the *** though. i want to talk with remnant and maybe another pocketbike manufacturer to see if they balance there set-up. i bet polini does.
 

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i got my crank in and working today. before i even got a feel for it. my header bolts and engine mount bolts popped out. it does vibrate a little more.

one thing though is that i cant think of a way to put some supports on the front of the engine plate. anybody have some ideas to route the supports? remember i have the ip2 pipe also.

but this thing revs like CRAZY. feels like its gonna blow up if i hold it WOT. it is also running a little richer, gonna have to re jet.

i have the 39cc so this is balanced with the piston right?
 

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Hey Mike

I just saw this writeup. Been out for a few days. That cutting out a part of the flywheel looks pretty crazy. Since the flywheel is lightened, I would think you would get even more revs. Wow. Let us know how it goes.

P.S

I sent you an email. Laters



mike93eh said:
i got my crank in and working today. before i even got a feel for it. my header bolts and engine mount bolts popped out. it does vibrate a little more.

one thing though is that i cant think of a way to put some supports on the front of the engine plate. anybody have some ideas to route the supports? remember i have the ip2 pipe also.

but this thing revs like CRAZY. feels like its gonna blow up if i hold it WOT. it is also running a little richer, gonna have to re jet.

i have the 39cc so this is balanced with the piston right?
 

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Damn...you guys are working with some dangerous stuff there. Is there a possibility for the piston to just shoot through the cylinder and the gas tank? Wouldn't want that...

I can't think of any other support method that wouldn't put stress on the upper frame.
 

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snowboardgeek1 said:
Hey Mike

I just saw this writeup. Been out for a few days. That cutting out a part of the flywheel looks pretty crazy. Since the flywheel is lightened, I would think you would get even more revs. Wow. Let us know how it goes.

P.S

I sent you an email. Laters
yup it does look pretty crazy :)

i guess im going to have to trust him on it. since that is what is needed to take off the flywheel when using a big bore, im going to start by just taking that big chunk out and not drilling those 3 holes and see what that does for the vibrations, since were using a 39cc and not the big bore.. wfo said it cut down on vibrations about 50%. ill find out tommorow.
 

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Vbp6us said:
Damn...you guys are working with some dangerous stuff there. Is there a possibility for the piston to just shoot through the cylinder and the gas tank? Wouldn't want that...

I can't think of any other support method that wouldn't put stress on the upper frame.
yea it revs up so crazy now, it feels like the piston is going to shoot through the head and going flying for a couple miles.

and i already figured out some extra supports for the engine mounting plate. i welded on some small angle iron on the bottom of it and welded it to the frame. it helped with the vibrations.
 

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mike93eh said:
yea it revs up so crazy now, it feels like the piston is going to shoot through the head and going flying for a couple miles.

and i already figured out some extra supports for the engine mounting plate. i welded on some small angle iron on the bottom of it and welded it to the frame. it helped with the vibrations.
Let's see some pics of these supports.
 

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Any word yet from anyone attempting the balancing flywheel mod?




XtremeEng said:
Possible, although you would have better chances of getting struck by lighting and then winning the lottery twice. :p

Mike39eh, lets see some pics of the engine mount supports. I am thinking of welding some mounts on myself.
 
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