what is Raptor 660 compression?

[250X_project]

Hi, I am the new (but not proud) owner of an '02 Raptor 660 that was said to have a 720 big bore hot cam and K&N filter. Now that I own it it, of course, it will not start. It has spark and you can give it fuel in the intake but no fire! What should I read for comp. PSI?

I went to go in reverse and stalled twice, not being used to the rather tall gearing. The second time it made an almost popping sound. After this she would not fire. I mention this because as I wrote the previous article I started to wonder about the flywheel key. Is this common in a rappy with the power of a 720? I know it's possible but is it practical?

Also has anyone ever heard of a reverse shift pattern mod? This is odd to me. Thanks!

[250X_project]

Don't any of you Yami fans have any info for me??

[jmann660]

THE REVERSE ON THE RAPTOR HAS A REV LIMITER IT WILL POP AND BACKFIRE WHEN TRYING TO BACK UP. I'VE HAD MY RAPTOR FROM NEW AND IT DOES THE SAME THING.

[jmann660]

YOU COULD BUY A REV BOX THAT ELIMANTES THE REVERSE LIMITER (JUST DONT BUY THE WHITE BROS REV BOX)

[QuadManiac]

Regarding the reverse RPM limiter: remove the green/white wire from the reverse switch (just under the front sprocket) and ground the wire or just run a ground wire to the existing connection. The reverse limiter will now be locked out with no ill effects except your reverse light will no longer work and you can kill yourself doing 40 in reverse!

When you put bike in reverse kick it down twice, it doesn't always catch the first time and sometimes makes a loud clunk when you release the clutch when it hasn't engaged fully.

Regarding your fuel, spark and yet no fire... compression at starter speed should be around 130psi. The real compression is much higher, around 180, but there's a decomp mechanism that reduces compression at startup RPMs. The Raptor is real finniky about starting conditions. Check your valve adjustment and try some starting fluid.

Woodruff key shearing is heard of, but not real common. You can check for proper ignition timing by using a standard automotive inductive pickup timing light and looking at the timing mark (a wide H, right is TDC, left is max advance) thru the timing inspection cover near the top of the left side case.

Good Luck!

[250X_project]

Well I found out what it was. It was the carbs popping out of the intake boots.

I fixed that now it needs the starter rebuilt or replaced. :mad:

Stupid Yamaha :rolleyes:

[QuadManiac]

Great! I shoulda recognized your "popping" sound as a backfire which can blow the carb boots off... I was fixated on reverse instead.

What are your starter symptoms?

[250X_project]

Actually it wasn't a backfire. I think it was just the sucksion from the carbs to the boots.

I have juice to the starter, but it just clicks. This is not the case when the plug is not in and the engine is free. Then the starter will crank it over. :rolleyes:

[QuadManiac]

Rebuilding is pretty easy, maybe an hour of work. Good tutorial at

http://www.raptortranny.com/index.php?option=com_content&task=view&id=27&Itemid=35

First use a voltmeter to make sure that your getting close to 12V at the starter so it's not in the solenoid or wiring to the starter. Anything less than 10V at the starter's lug when cranking (or about 1V less than at the battery while cranking) and I'd look eslewhere first.

[250X_project]

Hey thanks

[hubie000]

try www.raptorforum.com

LOTS of good info!!!!:) :)

[QuadManiac]

Yep, that's where I hang out most of the time.

[250X_project]

Oh, okay. Thanks guys!