I was talking to a few guys who supposedly think that if you do any sort of big bore kit you are REQUIRED to do bottom end/crank work because the stock equipment wont handle the extra power. Is this true? Anyone had issues with a stock bottom end and a big bore? Currently looking at the Fuel Moto 107" for my Road King.

Thanks
Josh

 

Nope..........not required at all...........build it!!

 

Call Jamie at Fuel Moto and talk it over with him. There are many, many 107"s out there, no bottom end work done and no problems. The bottom ends are very strong, now if all you do is drop the clutch all day for burn outs and wheelies .......

 

The correct answer is you won't know till you break down your motor and do inspections of oil pump and do crank run out checks. If your crank is out of tolerance...you will want to have the crank true, plugged and welded. If the crank is fine and the oil pump is fine...thyen you are good to go to use what you have.

I just did a 103 stage III upgrade and my crank was inspect, but, I'll check it again at the end of this riding season.

 

Like speakerfritz indicated, you should let the current crank run-out determine if you should have the lower end re-worked. When I built my 103" my TIR was .0045. I checked it again last year after about 16k miles. Still at .0045. My 103" is making 114/120 and I don't baby it. I also don't do burnouts, wheelies, hole shots etc.

Zach

 

I talked to jamie about the same thing awhile ago and he said the bottom end dont need to be touched unless your running gear cams which then your crank run out would need to be .003 or less. Plus on 08 and newer bikes harley upgraded to roller chain and hydraulic tensioners

 

The roller chain and hydraulic tensioners actually came in 07 with the 96 motor.

 

go for it

 

What year bike do you have?

 

While the larger runout #s of the newer bikes is fine for chain cams, it also effects the oil pump, cam plate and primary chain tension (clutch/trans input bearing). All in a bad way. How bad is the ?? There a couple shops here in town that won't do motor work if runout is over 3???? Others don't even bring it up????