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)?