nmrichardson

im thinking Std crank and some porting will be best ?

doesnt the spacer affect port timing?

not sure on rod length as I don't have a crank yet so I guess could be either at this stage so standard crank probably best here ? 50mm stroke , 110mm rods ?

hey all I'm working a bit backwards on this build haha I've picked up a new cool head with 19cc std bore domes, I also picked up a new std bore cylinder/piston kit now I need to source a crank..... question is, now that I have std bore cylinders, std pistons and std domes am I limited to a std crank? or is there a way to make a 4mil crank work with my other bits? I realize this isn't the best way to tackle a build but the other bits came my way at a good price and now i just need to decide which crank will be best ...

last question for today i promise haha i see blaster only goes upto 68.25 so where do you go from there if you have a failure?

out of interest sake, then what do the guys do when it comes to big bore kits? as 795 pistons only go upto 66mm ? i know they go over to Blaster pistons , but the 573 blaster pistons are not offset, so the piston would crown 7mils ? Or are those barrels machined to suite?

gotcha, so the 795 pistons counter the +5mil on the rod, but the +4mil stroker crank will still have the piston crown 2mil above the deck

so then the 115mm rod only alters port timing? has no bearing on stroke or displacement? which is why you need to run a 5mm base gasket to counter the extra 5mm on the rod?

are you saying a 4mil crank can be 110mm rods, or 115mm rods? I (probably incorrectly) assumed that all 4mil stroker cranks have long rods.

thanks for the responses so far... I should mention I'm based in South Africa, so getting all these great parts you mention becomes difficult, also using people to port the barrels is a logistical nightmare, so I need to keep it as close to ''bolt on'' as possible, I can do some porting work myself, I port all my motors, but its more of flowing, polishing and case matching than actual porting, I'm not sure we have the expertise here for proper porting jobs like you guys have in the states. I can easily get Wiseco and Hotrods parts here, hence the reason for mentioning those parts. @sleeper I would be happy for anything north of 80BHP, my last build (and current track bike) is a TZR250 1KT which I managed to squeeze 60 ponies out of, so I'm sure 80BHP from the banshee motor will be achievable ​ I don't want all the power at the top, I want more mid range and more usable power getting on the power out of corners, but she should also make some up the top, pipes are going to be a challenge as the 3MA is a reverse cylinder, and the 350 is normal, so ill have to find a way to route a set of custom pipes...

Hello all, First post here, so go easy on me spend more of my time on the road bike forums, I own quite a few 2 stroke road bikes including 2 x RZ350's YPVS and LC's anyways enough of that, my next project bike is a TZR250 3MA rolling chassis with a banshee motor, I have already bought the shee motor, it needs a complete rebuild top to bottom, I think I have made my mind up on the 4mil crank, (unless someone can convince me otherwise) so now a few questions how is the port timing on std barrels if I run a 4mil crank ? I have done some research and see the cub port timing is around 10 degrees lower/later than the stock, does this make a huge difference? If I run a 4mil crank and 795 pistons, can I run a std head? if I run a 4mil crank and standard pistons, can I run a cool head with stroker domes and be done ? anyone else here run a banshee motor in a track bike ? I think the gearing will be more suitable for track than the 31K motor , the gear ratios are more evenly spaced out on the banshee. anything other advise will be greatly appreciated ! a couple pics of the initial mock up below: