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Hot Rods Stroker Crank CRF250R

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when Hot rods states there is machining to be done in order to run their mini stroker setup... what are they talking about machining?? i have read the cylinder head needs to be machined somewhere...

anybody have any experience with the stroker??

balance??

stuff like that...:thumbsup:

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If its a true stroker then the piston has to travel lower at BDC and higher at TDC.

How do they do this with no modifications? I would think the piston crown would protrude above the top of the cylinder, and make contact with the head.

When we had 80's we used to put a spacer either under the cylinder or at the top to turn them into 112's.

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If its a true stroker then the piston has to travel lower at BDC and higher at TDC.

How do they do this with no modifications? I would think the piston crown would protrude above the top of the cylinder, and make contact with the head.

When we had 80's we used to put a spacer either under the cylinder or at the top to turn them into 112's.

Shorter rod

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i put one in with a wiseco piston. you must make sure that your piston will clear through out the stroke. you may have to shave some of the webbing out of the bottom of your piston. this does not decrease the integrity of the piston. i did mine with a dremel tool you could probably get it done with a file and a little time. just be sure tokeep it clean and make sure there is enough clearence.

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thanks guys....

the hot rods website had a big disclaimer saying that head modifications would be necessary to fit the stroker crank.... didn't make sense since they just shorten the rods on all the other strokers

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thanks guys....

the hot rods website had a big disclaimer saying that head modifications would be necessary to fit the stroker crank.... didn't make sense since they just shorten the rods on all the other strokers

This only applies to two strokes not four strokes

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yep..but the only prob with shortening the rod is it takes away clearence for piston webbing. does not effect skirts or anything..just be sure it clears. i know that the stock honda one does not clear nor does a wiseco

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maybe when hot rods meant there were head mods needed, they meant piston webbing mods to clear the stroked crank

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no the head mods are required ffor some two strokes. the 4 stroke ones just say machining required

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guys... i know all about the 2 and 4 stroke difference... i run venom performance and have built zillions of engines both 2 and 4 stroke over the last 30 years....

hot rods...in the info specifically for the CRF250R 4-stroke....stated that head machining was needed to fit the stroker...

i was asking if anyone had bought / used / installed one of their CRF250R stroker cranks and had insight as to what the machining note was actually referring to....

some members had said the crank was a drop in... as are the ones used in the 450 honda and yamaha quads...

thanks for that, guys...

now...

in my own experences, the yamaha 450 stroker cranks all needed balancing to the piston weight...or the machine had SERIOUS vibration issues....

the Honda 450 strokers had no such vibration problem...

i wanted to know if anyone had any hint of increased vibration with the CRF250 stroker cranks.... it would be terrible to have vibration on a 13,000RPM single cylinder..1

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The vibration issues Hot Rods had with their stroker cranks has been resolved several years ago. However, anytime you increase stroke vibration will go up - and no amount of balancing can change this. The improved Hot Rods stroker cranks have considerably less vibration compared to the first units produced years ago.

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the yfz450 stroker cranks will still vibrate like a one legged paint mixer if not balanced...

but sent with a piston to crank works of arizona for balancing and trueing... they are smoother running than oem....

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if you look at the crf250r stroker cank ad on crf's only....

it still says head machineing mods are a MUST DO to fit the crank.... doesnt seem like a great selling point .... im sure its a misprint

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if you look at the crf250r stroker cank ad on crf's only....

it still says head machineing mods are a MUST DO to fit the crank.... doesnt seem like a great selling point .... im sure its a misprint

yes it most definately is. like i said it has no effect on the head the just shortened the rod so it doesnt hit the head but it didnt give the piston a lot of clearence and the wiseco and stock you will acually just have to shave some webbing. i believe a jp however will clear check either way. good luck and no noticable vibration

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