42mm stroke cranks are here now!     

This ad is for the Street version crank with 4 balance holes per flywheel giving approx. 52% BALANCE FACTOR.  

 FYI:  Due to Tariff increases it now cost 78 cents per dollar of China goods to import  just in US Customs Declaration only, not even including ocean freight and truck shipping cost from port.  We had to pay $3270 tariff to Uncle Sam just to get you these cranks plus shipping charges. 

This is a 2mm longer stroke crank for your SkyHawk Avenger, Olyin Avenger 85 or YD 85 engine. It is accomplished by moving the crank conn rod pin outboard by 1mm. 

Makes 89cc displacement out of a stock Avenger 85cc engine.   

Comes with a extra cylinder bottom gasket to move the cylinder upward by 1mm.  

With just this crank change turns 40mm stroke 85cc into 89cc.  How much more power difference will it make? Only God Knows!   We have no dyno and YuanDong didn't tell us the performance curve! 

Made for a 12mm diameter WRIST PIN. 

NOTE:   42mm stroke Cranks will be offered in 2 versions.   

RACING 5 holes and Street 4 holes.                See Pics. 

This ad is for Street version with 4 balance holes.   

If you prefer to NOT have the OCDT Drill Starting accoutrement like found in late model SkyHawk engines just let us know with note to seller at check out and we gladly supply according with a slotted beveled gear attach screw suitable for  Olyin 85Avenger or CDH YD85 engines. 

If in addition you order an OCDT counter clockwise, CCW, drive tool with this crank denoted on the same order, we will also include the necessary 8-1CCW grade 10.9 hardened bolt made for OCDT right side CCW cranking. 

Please do not order the Racing version crank unless you plan to race at SoCal or some other race track where engine rpms need to be higher than Street 10,000 max rpms.  Racing engines so modified can reach as much as 14,000 rpms so we are told by internet self-appointed experts.   Making a motorized bike produce this kind of 14000 rpm performance for street use is not a wise thing to do.  "The squeeze is not worth the juice".

Note: We believe 5 hole Racing cranks tend to vibrate too much at the lower RPMs, so hence the reason why we have 2 versions. 

If you're wondering if this crank will fit Olyin 85 Avengers and CDH YD85 engines , the answer is, "Yes sir, it will".  

DISCLAIMER:  As with any China made engine, they are tolerance variables to contend with that require fit & finish modifications to obtain a 1mm desired piston "Quish clearance".   Experienced builders know this and can adjust build and balance accordingly.   

If you don't know what you're doing do not attempt to change out a crank on your kitchen table.   Best send your engine to a reliable engine builder to have your 42mm stroker crank installed.   

For example:  Should you be sending your engine to Don Butler and want us to send a 42mm crank of your choice to him for installation in your engine just let us know with "Note to Seller" at check out or call us at 580 775 4496 to discuss.