644 circle crank with 35mm big end

I remember vaguely reading something on these forums about it not being possible to put the bigger pin in the old crank. I cannot remember why, but something about the oil feed comes to mind??? I could be wrong...

Just got my 06 "pork chop" crank today, after my 04 destroyed the mains, and the big end had some play. Rather than replace the rod I went with a whole crank out of the later model which doesn't seem to have as much trouble with it's lighter weight and bigger crank pin making it stiffer and putting less stress on the mains. I too went by the JBS racing website where they recommend the later 35mm crank, although couldn't really find any solid references of it being done before.

The crank as a whole looks much better designed, I haven't done much measuring yet other than placing them side by side, and they look pretty much identical other than the full circle/pork chop design. The metal of the webs around the big end seems much beefier, hopefully that means stronger. I will be going overkill and getting this brand new crank balanced and welded. I still have to do some measuring with the old piston to check deck height, but seems like it should be fine because the 04 piston supercedes to the 06 anyway.

I would save the headaches of making the old crank suit the new rod, and just get the later crank. Even getting it shipped internationally, it only cost me $700 all up, for a brand new complete crank. Which is quite cheap I think

Here's a comparo of the 04 and 06 crank side by side. Took it outta the packet and snapped some phoot's, but haven't been able to do any real measuring yet.

I got to thinking this myself because I have on extra crank that needs a conrod.

So any info about 32mm pin being replaced by a 35mm pin?

Wouldn't want to buy a new 628cc rod kit and find out it can't be fitted.

I've done two of these cranks. one was balanced at 65% for no balancer and the other we didn't balance at all and just sold the crank. I've heard nothing back from either party. one was a Husaberg 666 in a Cannondale Quad OR chassis changed by me to roadrace use. I spent h-o-u-r-s getting the chassis right. ducati rear shock.

anyway, my concern is the shear SHORTNESS OF THE ROD when added to a 85mm stroke. 135mm C to C is a ratio of 1.588 to 1. the books I have read talk of 1.65 to 2.2.

by use of a combination of packer and various cam chains be it standard, 53 or 219 chain you can get it sorted. a longer liner is needed if only to seal the liner around the original rim inside the cases.

there is a speedway rod that would bolt straight in at 164mm C-to-C. whilst I don't know how good it would be for sustained road or road race use I know that with some 'non-destructive testing' you could get through this period.

in some ways I want to have a crack at this myself but I have curtailed all evening work at the moment. life's sweet!

regards

Taffy

I have curtailed all evening work at the moment. life's sweet!

Click to expand...

i take it: "it was good for you" :cheers:

I'm well now thanks!

I talked to the trees, they tried to take me away....

:lol: :lol: :lol:

Taffy