Setting valves and horsepower

[Traumahawk]

Edited for content

 

[blaxmax]

I like loose because they will tighten.

 

[blaxmax]

http://www.vmaxforum.net/showthread.php?t=12853

http://www.vmaxforum.net/showthread.php?t=12855

exhaust .012in

intake .006in

 

[Traumahawk]

Edited for content

 

[Traumahawk]

LOL...you added the specs will I was typing my post.

 

[adambweird]

When i did mine i set them a lil closer to the loose side since i know they will tighten up. Id imagine though that setting them closer to the tight side of the spec will allow for a little more lift and potentially more power at the expense of more frequent valve checks. I dont think though that with stock cams it would make much difference though. I could be wrong... after all, im not an engine builder, just a reasonably well educated enthusiest with poor spelling skills, lol.

 

[blaxmax]

25 and 48 mins apart.
I make a living racing- Hard for me to give optimum but I do.

 

[Damon]

On a fresh rebuild I always use .006 intake and .010 exhaust, once the engine has approximately 2K ~ 3K miles I'll go back and re-set the intakes to a .004~.005 to help quite things down.

Well thanks for those, but trying to see if there is an optimum number. On Maleko89's spread sheet its gives the figures that I believe that are stock specs.

.11 -.15mm on the intake
.26 - .30 mm on the exhaust.

Now, what Ive found on the forum though is Damon says .006 intake, and .010 exhaust...and Maleko89 says .004 intake and .011 on the exhaust. Both of those people are very sharp, and Damon says that with those numbers, you should get between 27-30 Kpa of vacuum with those settings.

 

[Traumahawk]

Edited for content

 

[blaxmax]

Eric, I could never see a reason to set valves tight only loose and personally would never let a stealership do anything to my bike. Last time I did that I was 15 years old. Lovely to know exactly what is going on by my own hands and no one else's.

 

[Traumahawk]

Edited for content

 

[blaxmax]

If you need help again I'll be happy to run over there.

 

[maleko89]

Eric, sorry for missing your phone calls last night. Feel free to give me a call this afternoon.

What I was taught was to set intakes to a loose .004 where .005 will not slide in. In my experience intakes barely change clearance at all once set. These days I set to .005 and call it good.

Exhaust values do tighten over time although I was originally taught that intakes tighten, exhaust loosen. I would set to .011 and 26,000+ later they would be .006-.008.

The key thing is to set the lash of all intake valves to the same thing; same with exhaust. Once this is done sync'ing the carbs and vboost is even easier.

IMO.

Mark

 

[Traumahawk]

Thanks Mark.

What really started this thread was the thought that like most "production machines" a lot of the values of something is in the middle....so there is always room for improvement. So now the question is....how much improvement?

This is the first bike that Ive had, that Ive really gotten knee deep into.

Do you think that you will make it to Eureka Springs this year? I'm really trying to get Steve down here for this year.

 

[maleko89]

Thanks Mark.

What really started this thread was the thought that like most "production machines" a lot of the values of something is in the middle....so there is always room for improvement. So now the question is....how much improvement?

This is the first bike that Ive had, that Ive really gotten knee deep into.

Do you think that you will make it to Eureka Springs this year? I'm really trying to get Steve down here for this year.

I've wondered that myself. Unfortunately it's not easy tuning valve clearances. I've had loose intakes and tighter intakes but does it noticeably change bhp and torque? I believe engine size, combustion chamber shape, etc all have a factor. Also, can having more clearance for intake valves (more intake charge) help or hurt depending on exhaust valve clearance? Probably. I guess I'm lazy...I'll keep the valves the same and make sure they are within Yamaha's spec.

I'm not sure on Eureka yet. Truthfully, I haven't given it much thought but it would be great to see y'all again.

Mark