Originally Posted by motonacio (Post 81899)

Sounds good to me Kenny - put me down for a 100mm 11:1 and I shall pay you up front if you wish - I'm guessing $190 with carriage or let me know. I know you are honest and trustworthy so anyone can order with confidence from you.

David

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.

Originally Posted by Gravityfreak (Post 81916)

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

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?

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?

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.

Originally Posted by driesie (Post 82078)

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?

Originally Posted by driesie (Post 82078)

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?

Originally Posted by Kev (Post 82116)

We have one in Brisbane Australia.:smilies0345:

Originally Posted by CaptMoto (Post 82118)

Dries, if the replacing of a piston is descrived as a simple "drop in" just as Kenny and Kev explained, then it can be performed by any mechanic with the right tools, you will need a new head gasket, which is about a tenner, so if you want to do this I know a couple of people around London that can do the job for you.

Originally Posted by Freez (Post 82145)

Kev, you sure that is a ping noise you are hearing on the 11:1 piston.

I hear that on my stock XT motor under some conditions.

Also, on the raptors that I have done, we have played with the ignition timing on a big way, advancing low RPM timing on the raptors by 10 to 20 degrees in some areas. These motors run between 11:1 and even as high as 13:1 and we don’t get ping noise, even when using 95 Octane fuel.

One thing I would love to figure out.

Why is Yamaha reducing the Raptors low end timing so massively. I compared the raptors ignition timing versus the older raptor 660 timing as well as the Grizzly 700 timing, which basically uses the some top end as the raptor 700's, and it is way different.

Kev, what A/F ratio do you run at 200 to 3500 RPM?

Originally Posted by Kenny (Post 81852)

Okay guys, I just got done striking up a deal with Wiseco to build custom pistons for the XT 660/650 Pegaso..... I need to buy an initial order of 50 pcs, that I can divide between a new Raptor line and the bike line-up. I am interested in selling some for cost, which is just under $150 US. I will have a choice of 11:1 and 12.5:1 in 100 and 102mm bore sizes. With the economy so rough, I need help with the initial order.

The features that will be added are explicitly designed for maximum durability and power production without marketing gimmicks that run the price up.

The main improvements over stock(and many aftermarket) are;
1) True compression ratio increases. The piston actually makes it's advertised compression
2) 2618 piston material that is far stronger than the standard 4032
3) Corrected deck height for knock resistance and higher combustion efficiency
4) Ample valve reliefs to handle future upgrades to the head or cam
5) Centered piston pin for reduced cylinder wall stresses and friction

Of course they will be complete with pin, rings, wire locks and retail packaged.

Let me know if any of you guys are interested.

Kenny

Originally Posted by drade (Post 82199)

will this mod affect reliability in any way? From what I know these mods affect reliability in many cases, is this the case for the xt/pegaso engine?

thanks

Originally Posted by Kev (Post 82178)

Freez I am running 12.8:1 from 2000 to 3500RPM.

When standard my bike pinged a little a low RPM's, but now with the 11:1 piston if I use 95 RON it is so bad I know I will damage the piston, must remember I live right on the coast at sea level not like you up at a higher altitude, so my pinging would be worse then yours.

I reckon the Raptor are design to make its HP mid to up top & the XT is made to make it's power low to mid range & that could be the difference in the ignition timing. I would love to try an ignition module on the XT on a Dyno, just to if any more gains could be had.

Originally Posted by Dan71 (Post 82227)

G'day Kev, how do you think the 12:5:1 piston will go with australian premium unleaded (pinging)?

Originally Posted by Dan71 (Post 82282)

Thanks Kev, Ill be looking at getting the 11:1 piston then.

Kenny, could you put me down for a 11:1 piston to suit the standard bore size. I do have a limit of about $200 AUS though but if Ive done my conversion correct I think I will just scrape in there. I will await further instruction from you on where to send money and when.
Thanks
Dan

Originally Posted by Kev (Post 82284)

Sorry to say Dan, 200 Oz money would not even buy you a JE piston never mind one of kenny's

http://cgi.ebay.com/ebaymotors/JE-PI...Q5fAccessories

http://cgi.ebay.com/ebaymotors/Wisec...Q5fAccessories

Originally Posted by Dan71 (Post 82315)

They sure look the goods! I really want to put my xt motor together with one of these, some head work and further tuning. But if they are US$270 I'm out of the game. I'm praying that they are one of the cheapest kits in years.

Thanks heaps for the gasket prices Kev. They are a bit more then I thought, but I can wear the extra even if I have to wait a few pays to get them, but if by some miracle these piston kits are US$150 I CANNOT miss out!

Dan

Originally Posted by Kev (Post 82300)

I think there must be some sort of miss understanding.

Kenny can correct me, I think his Raptor pistons are around US$270.00 mark + postage, I know he sold the first batch for US$200.00 but they were a one off special. Kenny's pistons have gap less rings which offer better sealing, that is something I am very interested in.

You will also need AUD$90 for a XT660 head gasket & AUD$60 for the base gasket.

I will be great if Kenny can sell the XT pistons for US$150 shipped, they would be the cheapest piston kit I have seen for years.

Difference between a 10:1 standard XT piston on the left & a 11:1 Raptor piston on the right. The XT piston is slightly concaved where the 11:1 has a raised dome.

http://i201.photobucket.com/albums/a...stonheight.jpg



http://i201.photobucket.com/albums/a...ptorpiston.jpg

Originally Posted by Kenny (Post 82617)

Here is a perfect example of how aftermarket pistons are incorrectly designed. Notice how the installed height of these 2 pistons is the same. The added compression comes from the addition of a dome. Both of these pistons sit too far down in the cylinder (.050"), when added to a gasket thickness of .028", it comes out to .078" piston to head clearance (we call it quench). My piston is .035" taller, which makes the piston to head clearance .043". This difference in quench makes for more mixture motion in the chamber as the piston reaches top dead center. This makes the engine less octane sensitive and more efficient. Another benefit is the taller deck height allows the same compression with less dome, which improves chamber shape for proper flame propagation, especially on higher compression engines.

Originally Posted by Dan71 (Post 82287)

Seems I better figure out how much the piston will cost me in OZ dollers or the missus will have me sleeping on the couch for ever.