7 mil stroker motor

[blowout169]

hey i was just going to build a 85.5mm bore stock stroke motor for a freestyle superjet but i just bought a 75mm stroker crank used and i not sure of the cond. or if i should do a 85.5mm bore x 75mm stroke motor. Has anyone made this motor or done a +7mm stroker motor and how did it go

 

[waxhead]

A 7mm stroke on a std cylinder resleeved or not is going to have radical port timings unless you run the pistons out of the cylinder and that is not a very good technical idea

 

[Millertime]

ADA used to do some 7mill strokers back in the mod days, but don't think it was a stock cyl.

 

[#ZERO]

Post a picture of that crank and the rods.

 

[blowout169]

here it is what do you think keep it or sell it

 

[#ZERO]

That's a stock crank with offset welded pins but I'm not certain about the rods.

What's the inside diameter of the upper rod journal, also see if you can measure the rod length from center to center journal.

Also how wide and deep are the domes cut in that head?

 

[blowout169]

That's a stock crank with offset welded pins but I'm not certain about the rods.

What's the inside diameter of the upper rod journal, also see if you can measure the rod length from center to center journal.

Also how wide and deep are the domes cut in that head?

the domes are 85mm and i dont no the cc and has soon as i get the crank i will post the spec what do you think this crank it worth

 

[Matt_E]

I sold one just like that one a couple years back for $500.

 

[blowout169]

ok good i got the crank and ada head with 85mm domes for $250

 

[MTRHEAD]

good deal. You probably have 133mm Kawasaki rods on it that use the 20mm yamaha piston pin. Nothing wrong with that setup. You can use a stock cylinder but you will be lifting it very high, at least around .375" if you use OEM pistons. If you use Kawasaki pistons, which are what R&D,RIVA,and other bigbore flat tops are, you will be lifting less because they are shorter.

 

[blowout169]

good deal. You probably have 133mm Kawasaki rods on it that use the 20mm yamaha piston pin. Nothing wrong with that setup. You can use a stock cylinder but you will be lifting it very high, at least around .375" if you use OEM pistons. If you use Kawasaki pistons, which are what R&D,RIVA,and other bigbore flat tops are, you will be lifting less because they are shorter.

thanks what kawasaki pistons will work

 

[#ZERO]

Use the Riva flat tops because you'll have a problem with the ring pin alignment hitting the auxiliary transfers on your stock cylinder using the Kawasaki 750 small pin pistons.

 

[blowout169]

ttt

 

[MTRHEAD]

Use the Riva flat tops because you'll have a problem with the ring pin alignment hitting the auxiliary transfers on your stock cylinder using the Kawasaki 750 small pin pistons.

I always use OEM kawasaki pistons in GPR's. I bet every pro in Havasu in the 2000-2004 era used OEM kaw's in the Yamaha cylinder on the GPR1200.
Yes they do wear more over time because the ring ends clip the roof of the rear transfers but it will work. Tons of Lameys are also out there with OEM Kaw's or Wiseco Kaw's

 

[BombThreat]

A 7mm stroke on a std cylinder resleeved or not is going to have radical port timings unless you run the pistons out of the cylinder and that is not a very good technical idea

my stroker was built to run out of the cylinder around 2mm. whats wrong with that other then needing custom domes cut?

 

[waxhead]

Well the std cylinder is an open deck and the sleeves move around a bit
this is why the lamey cylinder bridges them together and the to the side of the casting as well
It will work but its no ideal
I would be interested to see your port timing as well on a 7mm stroke crank with a stock cylinder as its going to be very radical

 

[waxhead]

Im using kawasaki pistons on my 8mm stroke lamey as well

 

[waxhead]

On another note
looking at the crank pin thats welded it doenst seem to be to offset to the casting
are you sure its a 7mm stroke crank ???

 

[blowout169]

i am not sure yet thats what i was told

 

[BombThreat]

Well the std cylinder is an open deck and the sleeves move around a bit
this is why the lamey cylinder bridges them together and the to the side of the casting as well
It will work but its no ideal
I would be interested to see your port timing as well on a 7mm stroke crank with a stock cylinder as its going to be very radical

Mines a 5mm, sorry. I know it uses a slightly thicker base gasket then stock and 44cc domes for 180psi and 42cc for 200psi