After installed KFR Ex.big valve. This motor has webcam high lift camshaft.
We checking valve clearance by clay just to make sure.
Plenty of clearance.
IN:0.0827" (2.1mm, right side of picture.)
EX:0.114" (2.9mm, left side.)
When KFR designed this exhaust big valve, it had little story.
Idea was started from year of 2010. Koji had two triggers. One was he got his own TW. And another one was his friend Shinji Kazama who made North pole ridden by TW200 based bike. Koji met him again when he visited the US in summer time. It happened almost same time.
He rode bicycle that time from Indianapolis to Toronto, Canada. (And that ride ended at Sweden, Europe!! He is the challenger forever.)
We had couple of condition. But most part is this,
"Higher performance and stay in reasonable."
So, valve material choice is stainless steel, and valve size goes just over 0.039"(1mm).
This cylinder head has more space for exhaust side so we could go more larger. The larger valve size will be better if we going to get more horse power but we did not want to replace valve seat ring. Also light weight titanium valve will make good effect on high revolution but this solid material is aggressive to seat ring. Seat ring replace is very sensitive work and lot's of labor. Just replace the valve will be so much cheaper and easy work.
This thought is same even national race class motor. Those engine builders changed from titanium valve to stainless steel big valve.
(*Over size valve is not allow on GNC singles class any more.)
We decided design by this reason, for more durability and "total" running performance.
KFR exhaust big valve can install only by seat cutting job. We are welcome to service your cylinder head if you don't have any place to work on it. Just let us know.
Also we service WPC treatment to KFR valve and other engine parts with additional price.
This motor has much more possibility so, of course we can make more horse power if you want but just don't forget one thing. It is TW.
Having coffee break with "special cylinder head" TW.
Contact mail to Koji : furuhashiracing"AT"yahoo.com