Originally Posted by Kenny (Post 67406)

First, let me thank you for the compliment! To be grouped with the likes of Kev and Freez is quite an honor! I hope to earn the reputation.

Okay, the first thing on the agenda is to get everyone in a different mindset. So here goes...... This engine design is tested and proven in the Raptor market as an absolute dead reliable engine. The are no real inherent weaknesses. Anything that would be considered a weakness is readily replaced by stronger aftermarket parts. The only real failure I have seen is the factory piston(in race conditions), and occasional cylinder wear. This is few and far between in extreme conditions, on very high hour engines.

If you watch the Raptor forums and realize that there are hundreds,if not thousands of modded Raptors out there......the fact that everyone is shocked at the occasional catastrophic failure says a lot. We have guys routinely spraying nitrous without drama. I have a half dozen or so 70+ horsepower stock bore engines getting the snot beat out of them regularly without issue. These engines rely on a factory rotating assembly and plated cylinder. We are working on a new cam which should put us at 80 hp on the same builds. We are only concerning ourselves with specific power output since durability is never really an obstacle. Enough said.

That leaves us to power output, which there are many weaknesses in factory form because of production compromises. Almost anything you do to this motor is worth power, and that part in return will add cumulative gains as the build gets more aggressive. For example, a good performance oriented valve job alone can be worth a stunning 30 CFM gain (@28"). Our CNC ported head is worth over 100 CFM of improvement. This will bring about the obvious question of port velocity. This is not your average motorcycle engine. This engine has a rod/stroke ratio of 1.6:1 and lack of velocity is not a problem, as a matter of fact, we need to add runner volume. I will go into my design theories at a later date. At the moment I need to get a cam and supporting hardware so I can design and start producing the parts for these......Then we can get a couple of different dyno proven packages together.:028:

Originally Posted by Freez (Post 67615)

We have one major problem on the Xt's that you don't have to worry about on the Raptors which could put a damper on the engine mods we can do.

The XT's rev limiter kicks in at 7200 RPM, where the Raptor spins all the way till 9000 RPM.

At this stage, we are not sure if a rap tor's ignition module from dynojet (powercommander) or the Dynatek ignition will sort out the problem.

The Xt also run coded keys and more advance ECU's with anti theft protection that the Raptor don't and if you cannot get the RPM limiter extended, then even the plain old stage 2 or 3 Hotcams become useless on the XT as you cannot reach the RPM peak those cams are designed for, let alone a special high RPM cams with major port work added.

Also, and this is maybe useless info, but I did some spot checks with just some basic tools and the Xt’s cam (lobe high and width) is closer to a Grizzly 700 stock cam than the 700 Raptor’s stock cam. I would not be surprised if Yamaha used the same type of cam setup for both.

Also, the Xt does not suffer from the same ignition mapping problems as the rap tors, so if we can sort out the limiter problem, we can do some major work on the XT’s

Originally Posted by Kev (Post 141400)

The throttle cables are different between the bikes. I know the Raptor 700 throttle bodies are much cheaper in the USA than buying a XT660 throttle body. You would need to modify your XT's throttle cables to suite the Raptor throttle body.

Originally Posted by zaburtante (Post 141484)

Thanks mate I see but Xt oem body 46mm raptor oem body 44mm or aftermarket body 54 mm :)

Originally Posted by Kev (Post 141488)

I have just realised I made a typing mistake, the XT660 has a 44mm throttle body & I bored mine to 46mm. The Raptor 700 & XT660 have the same size standard size throttle body 44mm.:coat: