2nd Gen SV650 Oversize Valve issues

Has anyone ran 1mm oversize intake valves on a SV650 and not have issues?

We put in Ferrea valves and have had 2 intakes cup on us. The exhaust valves have been fine.

We're getting really good at removing the heads now.

We'd like a resolution to this problem. Any known good brands out there, Manley, REV, DelWest, KibbleWhite?

Thanks!

 

Also for what it's worth, we are running R&D HD valve springs.

 

The springs could be your problem. Every time I have checked a RD spring for an sv they were like 80# of spring pressure. Might want to check spring pressure and see where they are

 

We were aware of the springs being low cause we checked them before we installed them. They were shimmed up since we talked to R&D when we found out they were less than stock.

With shimming the springs, we were above the stock closing pressure.

 

What are you seeing in gains out of oversized valves?

 

Well, we did the valves, slip on and busa pistons an made 77hp. It also has some mild porting.

We hope to be in the low 80's with a full system.

On the Moto-ST dyno with the totally stock exhaust, it made 67hp.

 

why not stock valves then?

 

Because the guy who did our heads wouldn't do just a valve job like I wanted. He insisted on getting the bigger intakes.

We are now paying for it with these issues.

He did do the work for free as well as helping to get this resolved. All we've paid for is the parts. These are the first SV's that he's played with.

 

I have a used rear cylinder head from a 2003 SV650 available for sale. Might as well just start from a stock head as your head obviously is making your power worse.

 

You're wearing the valves out how fast? What seat width? And why the R&D springs with, assuming, stock cams? I'm not too big a fan of any of the aftermarket valve train stuff for SV's. I've had decent luck w/Ferrea and REV valves, KBW not so much. All the aftermarket spring/retainer kits are junk, IMO, I only use them when I have to. (coil bind w/cams and stock springs) You are about 5hp shy of where you could be with all stock parts and a proper SS build, and it would be mostly bulletproof.

 

Really because I would expect a SS build to put out 80-85hp.

 

WE went woth the springs cause Ferrea said that's why we cupped the first valve. The first one lasted for one practice day and 2 CCS Team Challenges.

The second one lasted for one practice day, a GT race, a Team Challenge, and a track day. I then checked the valve clearance and found one about .008" tight. This is with the R&D springs which is what Ferrea recommended.

I'll ask what the seat width is. Thanks JD! Wally sez hey.

I think we'll be getting the REV valves.

 

sounds low hp to me too. my ss motor makes a good bit more power than 77.

 

Yea but thats a cheater ss motor

 

i hear that almost every weekend.

 

Some of my riders too.

GPZ, I think you possibly have issues that don't really relate to the valves. IE, valve seats that aren't cut correctly or maybe worn valve guides, something like that.

 

no way!

 

Speaking of Valve springs
Anyone know where I can get a YEC comparable set for a Yamaha R6?

 

JD,

The seat width was cut to about .020 ~ .025".

 

That is very thin for an endurance motor, I dont go any less than .8mm on anything that has to last a while.