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Quote:

Originally Posted by Kenny (Post 81896)

Thanks guys,
This is a straight drop-in and is easily reversible. You will probably want a new head gasket, which the Yamaha factory piece is the best AND cheapest. It is also re-usable for the adventurous types. Higher compression by itself is worth more power and torque. 11:1 is only 1 point higher than what you have, but that 1 point combined with the tighter squish area work together to make a more efficient, and responsive engine. They are good for 2 hp or so and a similar gain in torque. The 12.5:1 is worth another 1-1 1/2 hp over the 11:1, but requires higher octane gas. Yes, I will ship them anywhere(even Greece). I decided to build these pistons knowing that I will never sell one in this country. I am waiting to find out a positive lead time for production. Hopefully we will be looking at 2 weeks. The trick is gonna be collecting orders and putting it all together. I will talk with Wiseco tomorrow to get a definite.

Hi Kenny,

You can put me down for one - not sure which compression ratio though. Can one run the 12.5:1 on high octaine (98) pump gas or are we talking race fuel here? If I can get away with high octaine pump gas I'm in for the 12.5:1

Quote:

Originally Posted by Gravityfreak (Post 81916)

I am gonna have to do some research to figure how the octane is rated over there. I think it is rated differently than ours. If yours was measured the same way as ours, you could most certainly get by with 12.5:1(on 98 octane), but I don't think that is the case. I hope someone on here can properly inform me.

I'd be up for one. Thinking 11:1 X 100.

THe Higher octane is available in UK under the heading of Super Unleaded 98RON
The two major suppliers are:

BP Ultimate
Shell Ultimax

Kenny, will these pistons come in a Wiseco box or not? If so, maybe I can have a chat to some of my contact over here to see if they don't want to buy a few. At the moment you only get stock Yamaha pistons here, so a nice aftermarket unit might come in handy.

Also, question. Why does Yamaha make the pin location off centre? Surely they have a reason for that?

Quote:

Originally Posted by Freez (Post 82003)

FREEZ!! I hope all is going well!! Yes they are gonna come packaged in full Wiseco garb. They will have a part number and label denoting that they are a KDS Racing custom piston.

Great news Kenny. :signthankspin:

I tried to get JE pistons to make up pistons for us last year, as I had all the measurements they asked for to make them, after a few weeks of E-mails they were not interested.

One thing with the XT, is the ignition advance is more advanced between 2000RPM & 3500RPM then the Raptors & will tend to ping if the compression is above 11:1. With my 11:1 JE piston it pings really badly if 98RON fuel is not used so much it will damage the motor, so I only use 98RON. Marcel has found similar results with his 11.3:1 mod. Just some info for you.

Quote:

Originally Posted by Freez (Post 82003)

Kenny, will these pistons come in a Wiseco box or not? If so, maybe I can have a chat to some of my contact over here to see if they don't want to buy a few. At the moment you only get stock Yamaha pistons here, so a nice aftermarket unit might come in handy.

Also, question. Why does Yamaha make the pin location off centre? Surely they have a reason for that?

Kenny please correct me if I am wrong, as fare as I know the pin center are off set for a quieter running motor from cold, you have less piston noise in the warm up faze. The down turn is with a off set pin the piston is forced to one side of the bore which reduces HP & causes more wear in the bore.

Quote:

Originally Posted by Kev (Post 82021)

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Kenny please correct me if I am wrong, as fare as I know the pin center are off set for a quieter running motor from cold, you have less piston noise in the warm up faze. The down turn is with a off set pin the piston is forced to one side of the bore which reduces HP & causes more wear in the bore.

You are correct sir! The cold noise only lasts a few seconds, but creates a bunch of warranty claims. The higher wear from the offset pin doesn't show until after the warranty is long gone. Smart business move I guess

I am quite interested, but would need to get the work done by a mechanic.
Do we have any UK (London area preferably) mechanics on here? Or anybody with links to any who would stock this item and offer installation service?