Banshee Track Bike

[nmrichardson]

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:

 

 

Edited February 15, 2017 by nmrichardson

[ClaudeMachining]

Great built!!

[trickedcarbine]

.018 to .020 base gasket, 4 mil crank, and Weisco 795's are the common combo. It will require domes be custom as the piston crown will be above the deck a bit.

 

Other possibilities would be to use the new Driveline pistons, and run a Wicked 5mm crank. May be worth hitting up Roger at Wicked Motorsports as he is quite familiar with your type of build.

[trickedcarbine]

Is the 5mm crank for sale? Thought it was still in testing.

He's put the combo in a couple motors. I wouldn't think it needs much testing other then fitment as long as it's been put together with similar components to his other cranks.

[sleeper06]

How much hp you looking for. What rpm range are you looking for.whats your competition. You can make this bitch fly. No Matter what you build I hope your gonna spend the coin on custom pipes to put the cherry on top

[nmrichardson]

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...

[nmrichardson]

I would suggest running a serval or driveline top end. A 421 serval can make some good usable power.

 

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.

[nmrichardson]

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?

[nmrichardson]

No, the long rod uses a certain piston to offset the extra length in the rod. This will also not change port timing.

 

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

[nmrichardson]

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?

[nmrichardson]

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?

[trickedcarbine]

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?

Stock cyls will only go to 66-67mm max. You'll need sleeves to go bigger in stock cylinders, but that is a lot of work for a not so great product. Look around on some of the site sponsor pages. Some of these guys are distributors for just about any thing you could need/want, and are capable of shipping international.