Smolik minarelli hybrid motorized bicycle kit.

The YD 100 head bolt spacing is different than the 66/80cc engine.
you are right about the yd100 cylinder bolt spacing. it will not work on a menirelli cylinder. also a stock cylinder is 6 mm studs. you have to drill out the cylinder heesd onto a yd100 bottem end that's for sure

ad bo get the hlt holes to accept 8 mm bolts. but you will not
 
I guess that is the end of the story here huh ? Well I'm thinking of doing it to. Just not sure if I should be worried about balancing the crank
 
I guess that is the end of the story here huh ? Well I'm thinking of doing it to. Just not sure if I should be worried about balancing the crank
I would just get a balanced crank thru Arrow. Heres a few.
Screenshot_20230920-191524_Chrome.jpg
 
I guess that is the end of the story here huh ? Well I'm thinking of doing it too. Just not sure if I should be worried about balancing the crank
If you do not properly balance the crank you will not achieve full potential out of your engine.

The vibes will be so bad up around 9k you won’t get past it without out problems.

I have a Mineralli engine with an RDM 40mm stroke crank.
It was advertised as prebalanced.
It needs balancing.
My correctly balanced China crank will run circles around this RDM crank engine and both engines are identical.
If you spend the money to build the engine balance your crank to the top end kit you use.
 
If you do not properly balance the crank you will not achieve full potential out of your engine.

The vibes will be so bad up around 9k you won’t get past it without out problems.

I have a Mineralli engine with an RDM 40mm stroke crank.
It was advertised as prebalanced.
It needs balancing.
My correctly balanced China crank will run circles around this RDM crank engine and both engines are identical.
If you spend the money to build the engine balance your crank to the top end kit you use.
The issue with pre balanced cranks is you need it balanced to your piston weight.
 
The issue with pre balanced cranks is you need it balanced to your piston weight.
Yes.. this crank is supposed to be matched to the 47mm kits.
My kit is one of the popular kits so I made the mistake of just installing the crank. I don’t know if I’m heavy or light but I can’t take the engine past 40 mph the way it is now.
It’s been sitting on the bench for months.
 
The issue with pre balanced cranks is you need it balanced to your piston weight.
As a whole, the pre-balanced cranks will work sufficiently for most of the 47-49mm pistons and the weight difference between the slightly larger piston won't likely be enough to have a huge impact on the balance factor and will work sufficiently.

The real fun would be to not only lighten the pin side of the crank, but actually add weight to the opposite side by drilling and pressing in tungsten weights. For larger bores (52mm or more) it would be the safest and most practical way to achieve a BF higher than 50%.

There are other ways to adjust balance factor without machining the crank counter weights. I wouldn't suggest them without a "do at your own risk" disclaimer though. That means removing weight from the piston side of things. I have seen people do some crazy stuff in the quest for balance work (I have done it too) - up to and including boring the center of the wrist pin out larger (that was the me thnig), matrix grinding the underside of the piston crown (cutting criss-cross patterns) all for the sake of a couple grams. Not recommended for reliability sake, although it could potentially last.
 
As a whole, the pre-balanced cranks will work sufficiently for most of the 47-49mm pistons and the weight difference between the slightly larger piston won't likely be enough to have a huge impact on the balance factor and will work sufficiently.

The real fun would be to not only lighten the pin side of the crank, but actually add weight to the opposite side by drilling and pressing in tungsten weights. For larger bores (52mm or more) it would be the safest and most practical way to achieve a BF higher than 50%.

There are other ways to adjust balance factor without machining the crank counter weights. I wouldn't suggest them without a "do at your own risk" disclaimer though. That means removing weight from the piston side of things. I have seen people do some crazy stuff in the quest for balance work (I have done it too) - up to and including boring the center of the wrist pin out larger (that was the me thnig), matrix grinding the underside of the piston crown (cutting criss-cross patterns) all for the sake of a couple grams. Not recommended for reliability sake, although it could potentially last.
I thought I was only crazy 1 thinking about tungsten plug weights in a CG crankshaft. On honda gx & predator cranks, we go as far as welding on a ¼ thick plate on the side of the counter weight. Mostly big block stuff with the balance shaft removed.
 
I thought I was only crazy 1 thinking about tungsten plug weights in a CG crankshaft. On honda gx & predator cranks, we go as far as welding on a ¼ thick plate on the side of the counter weight. Mostly big block stuff with the balance shaft removed.
Oh, I'm crazy too lol. I also considered rifle boring the center of the rod pin. That would be a great place to remove some mass.
 
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