Banshee crank in rd400

[RDSingh]

Has anyone tried using banshee stroker crankshaft in rd400. Its +4mm that is I think equal to stock rd400 connecting rod. I understand its long made for banshee cases but we can modify the side covers. Crankcase volume will increase for sure. What else. Can we use it anybody tried it.

[m in sc]

too wide wont fit cases unfortunately, from everything ive read.

Im running an lc (4l0) crank in a set of ac 350 cases but as you said, had to mod the side-covers.  luckily the crank wheels are the same width. maybe an lc stroker crank? UK would be your best bet to find one.

could you make it work? sure but the time and effort would outweigh the benefits i think.

[teazer]

A Banshee cranks is a couple of mm wider than an Aircooled RD crank - and presumably an LC crank.  It's too wide for the crankcases, but that doesn't mean it can't be made to fit.

You may have to get the cases trenched to clear the conrod and if so, get the cases machined to clear the flywheels. Crankcases inside faces are not usually parallel, so be sure to measure twice and cut once..........

A stroker crank (+2mm in this case) means that the piston will be 1mm higher up at TDC and equal at 90 degrees BTDC or ATDC and 1mm lower at BDC.  You may need a 1mm lift plate of port the motor to suit.  Calculate the port timings with stock stroke and then with the stroker crank to see the revised port timings before you start raising everything by 1mm and not getting teh answer you were looking for.

Banshee pistons are available with different wrist pin positions because of the change in stroke and conrod length (115mm vs 'Shee 110mm), so that's another variable to throw into the mix. 

You could also probably machine the outer flywheel faces, but you would have to check all the dimensions and confirm that.

You can't fit a banshee or RZ transmission though, but you could fit a banshee side cover if you use a Banshee kickstarter shaft with a bush and IIRC the RD spring. That gives you space for a lock up clutch or just a clear cover to see the trans oil getting dirty.  You also have to blank off the water pump inlet/outlet if you go down that road.

[m in sc]

to confirm:

you can fit an LC crank in a set of aircooled cases with no mods to crank. rz and banshee cranks are wider as stated.  However, you Do have to deal with the primary gear side being longer.  also, you get the larger taper on the ign side. this does allow a banshee or rz cdi to bolt right in. and, they do. 





yes, the stator plate bolts right on.



I eventually went to an HPI as i saved almost 4 lbs. 

added for banshee ign pickup.



all of this will also apply if modding/adding a banshee or rz crank to aircooled 400 case AFTER  you get it all fit up, so it is relevant. Im pretty sure you can get stroked LC cranks out of the UK new. at least the webs fit. .02

[RDSingh]

Wow. excellent work. So it can  fit in rd400 cases also. But rd400 crankshaft webs are quite big as compared to rz350/banshee. That means if we fit rz350 / banshee crank the crankcase volume will increase. Will it effect the overall performance.

[m in sc]

yes, I'd think it would be prudent to stuff the cases  if you wanted to go thru all the trouble

[patastinky]

 :metal:wow that's killer

[teazer]

yes, I'd think it would be prudent to stuff the cases  if you wanted to go thru all the trouble

Agree.

[m in sc]

i also have to add: i certainly dont think its worth all the aggravation to get stroker crank, there's other ways to get it done id imagine? . But, it could be done. 

[teazer]

one could always consider a stroker crank into a set of RD350/250 cases with an RD400 top end to go say 66.25 x 64 for 438cc, but to get to say 499 needs closer to 70mm piston and to feed that enough mixture would need more transfer area and much bigger reed box, but anything is possible for the right class.

An RZ with CPI top end and a stroker crank is a much more HP dense solution. 

[m in sc]

id imagine you'd be back at trenching the cases but at least the c.c. volume would be right.  or at least way better.

[teazer]

But that would be a small crankcase volume and not necessarily well suited to a large capacity motor.  I recall seeing a billet +10mm crank a wile ago with RD400 flywheel dimensions but the price was eye watering and way beyond my pay grade.

[rodneya]

Gonna be easier to put that banshee stroker crank in banshee cases and stick it in your frame.

[bhh1989]

Digging up old thread here - What would the performance benefit to a banshee crank be? Are they lighter?  It would be nice to have banshee ignition options but that alone wouldn't be worth the trouble.

[bitzz]

Lighter and you can buy one off the shelf

If you have a RD400, you can run a 3J7 crank (Canadian RD400 Daytona F or G model) which has the same taper as the RD-LC or RZ/Banshee... but the keyway is 90 degrees off, but that's simple... and run any modern ignition.