Why not go with bigger valves!! It can't hurt. Why not go the whole ten yards. If I'm going to fully port and polish the head to improve the flow wouldn"t bigger valves which also improve the flow be an excellent addition to the port and polish job. Ya I now they are only 1mm. over stock but every little bit helps and there must a market for them or kibblewhite wouldn't be making them. They are also made of titanium, not hardened steel (stock 30mm), not stainless steel (ferrara 30mm),......... Titanium (kibblewhite 31mm). The same stuff kibblewhite makes their heavy duty valve springs out of. Besides the valves are only $30 each the same as oem Yamaha valves, no BS. Ya, sure I could stay with my stock 30mm. hardened steel valves but why not step kibblewhites titanium 1mm over valves and stop wondering what could be when the job is done and it is time to ride. By the way instead of Yamaha making their raptor intake valves larger than their exhaust valves like many other head configurations ol' Yamaha just added a third intake valve for more intake flow rather just enlargening two intake valves resulting in a five valve head with five 30mm. rather than a four valve head with bigger intake valves than exhaust valves. The kibblewhite aftermarket titanium valves are 1mm over stock resulting in a 31mm valve that can be used for both intake and exhaust replacement. Besides I heard that Yamaha went to a better valve style halfway through the 2002 model year, that means all the 2001 raptors and some of the 2002 raptors have Yamahas Model A valves which were replaced and improved halfway through 2002 and stayed the same for the rest of the 660r's production. Besides it is the same price to cut the valve seats for the 1mm over valves as it is for the stock valves which any type stock sized valve will work in, new or old Yamaha type, Ferrara, or whatever. Thanks If anyone has anymore useful information on my future project it will appreciated. Thanks again guys.

 

you only need +1mm valves if your boring into the 730 range, then their necasary. your wasting you money. you going to be puting to much air into the motor. i got my head ported for $100 by my buddy and it run excellent. My opinions, trash the valves idea, if anythign get titantium valves but stock sizes. the money you save on the valves have a pro port your head.

 

Thanks CT, but I don't think just going 1mm over on my valves is going to be putting too much air into my engine. I mean come on 1mm isn't all that much of an increase, I'll look farther into it. Theres a guy on ebay selling a tricked out raptor head with bigger valves, also ported, cammed, and HD springs which was on a running 660cc raptor with high comp piston but a high comp piston doesn't change the amount of air vaccum an engine can handle when the bore is still the same it is still 660cc's with a bit more compression thats it, not a bigger engine. So you had your head home ported you say, how did it turn out, you said you noticed a positive difference in performance, how so? How much material did you remove and where did you remove it from. Thanks for the information bro... past, present, and future.

 

Just thought I'd throw this out there........but I don't know anything about the rappy.......but on the pred the heads a very particular on porting. If you take too much or in the wrong spots, you can actually loose power......

 

Thanks Brad, Are those Preds reliable and fast.

 

Yeah I'd say they are pretty reliable(like anything you always hear about the bad ones......).........mine has never given me any trouble(other than what I deserve).......and I'd say they are pretty fast too. In stock form they are in the top 5 anyway......and in full mod form they are right up there too(starting to be quicker and quicker)........the rappys are still faster, but I think the pred is right behind them......

 

I had a chance to buy a 2003 stock predator because the guy was only asking $2500 obo. I never saw the thing but I talked to him over the phone and he said that it was in good shape and he was selling it because he thought it was to fast for his 15yr. old son. But he also said that it was on its third factory motor and the second motor blew after only a few miles which turned me off on the whole predator thing. Bat I have seen one racing a yfz up a sand hill in the dunes on yfz.central.com did you see that clip. I was impressed, the pred it lost though but nice sounding motor on both bikes no doubt.

 

sweet...........yeah its not faster than the yfz until really modded..........and like any other quad has has trouble........

 

Yeah, I wish I had a Predator because thier light too. But at the same time I wouldn't want the motor to blow up on me. But that guy that was selling that one was the only time I heard about engine problems with the pred but he is also the only dude I ever talked to about a predator in person, those bikes are kinda rare to see.

 

yeah.......all depends on where you live.......they aren't rare here.......trust me!!! One guy has about 6 of them.....my dealer.......of his own........