[Drew]

I just bought an 06 250R and the guy didn't have the manual. Does anyone know the service limit measurement for the clutch springs and friction plates? Thanks

[Asmith]

Springs 38.00mm

Discs 2.85mm

Plates 0.10mm

[Drew]

Thank you! do the valves set on 11 and 5 like my 05?

[Asmith]

Thank you! do the valves set on 11 and 5 like my 05?

Yup, although the NEW school of thought dictates 8 and 4. More duration and less impact on closing. More better power and more better longevity.

[Drew]

Thank you!

[124]

Thank you! do the valves set on 11 and 5 like my 05?

Yup, although the NEW school of thought dictates 8 and 4. More duration and less impact on closing. More better power and more better longevity.

OK...gimme the scoop. 8 & 4?

[Asmith]

Thank you! do the valves set on 11 and 5 like my 05?

Yup, although the NEW school of thought dictates 8 and 4. More duration and less impact on closing. More better power and more better longevity.

OK...gimme the scoop. 8 & 4?

Here goes...with the tighter tolerance, the valve intersects the cam lobe at a point lower on the ramp. This causes the valve to open sooner. It continues it's ride of the lobe until it finally releases from the lobe at a point further down the ramp of the lobe, causing the valve to close later. The velocity of the valve would be much less, as it's "freefall" time would be much shorter. Less Velocity would equate to less impact force against the seat.

Longer duration = mo betta power

Less impact force = mo betta durability

[124]

OK. So you are increasing duration and effective overlap without changing lift or valve separation angles (designed overlap). But I would have to see some data to fully "buy-in". My side of the 8 & 4 theory:

In general, increasing duration and overlap has benefits to high-RPM and detrimental affects to low-end and idle. (For others following think about a muscle car burping and chugging at an idle - ba-la-lup, ba-la-lup, etc ). I think you would lose power in the usable range for the average "X" rider. A pro MX'er...maybe this could benefit.

As you know, cams are a tradeoff. They only work perfectly at one RPM. Your changing the duration and overlap (in this case increasing it) to improve durability? This has more holes in it than meets the eye imo. I would be skeptical to buy in to this one without some data to speak about. Maybe that's just my engineering tendency to doubt the manufacturer and design engineers. Not that they are all-knowing, but purposely changing the specs usually comes with consequences.

I could be persuaded to understand the slower velocity/improved durability, but...I don't know...could it be neglible? I would want to know what the effective decrease in valve velocity would be...the delta. If I had the cam profile, that would a relatively easy calculation. And along those same thoughts, what the effective change in duration/overlap.

I'm not drinkin the kool-aid yet...

[Asmith]

OK. So you are increasing duration and effective overlap without changing lift or valve separation angles (designed overlap). But I would have to see some data to fully "buy-in". My side of the 8 & 4 theory:

In general, increasing duration and overlap has benefits to high-RPM and detrimental affects to low-end and idle. (For others following think about a muscle car burping and chugging at an idle - ba-la-lup, ba-la-lup, etc ). I think you would lose power in the usable range for the average "X" rider. A pro MX'er...maybe this could benefit.

As you know, cams are a tradeoff. They only work perfectly at one RPM. Your changing the duration and overlap (in this case increasing it) to improve durability? This has more holes in it than meets the eye imo. I would be skeptical to buy in to this one without some data to speak about. Maybe that's just my engineering tendency to doubt the manufacturer and design engineers. Not that they are all-knowing, but purposely changing the specs usually comes with consequences.

I could be persuaded to understand the slower velocity/improved durability, but...I don't know...could it be neglible? I would want to know what the effective decrease in valve velocity would be...the delta. If I had the cam profile, that would a relatively easy calculation. And along those same thoughts, what the effective change in duration/overlap.

I'm not drinkin the kool-aid yet...

Damn Dogg!!!

just take a sip...you'll like it.

All the conjecture so far as I can tell is anecdotal in nature.

" I run at 8 & 4 and my valves are like new after 10 years of racing..."

It is however, the setting of choice by both Ron Hamp of RonHampCycles and Dave Harryman at MRD Racing (pipes). They are both strong proponents of the setting and swear by it.

They know more about valves and cams than do I, so I figured it was worth taking a look at.

I think the increase in duration is negligeable, the main benefit is the reduction in impact force on the seat, especially when going to Stainless valves with their increased masses. As you know, even a small increase in mass results in a large increase in force. F=MA.

[124]

Like I said, I could be persuaded into the durability side of the theory. But performance is still in the air for me. Intentionally creating new nominal specs comes with consequences. I'm sure you're well aware of the laws being in engineering. Murphy's laws as well as the law of tradeoffs is always present!

I would trust what RHC and others say because I'm not a cam/valve expert either. I'm data driven though and kinda skeptical in nature about those types of theories.

Thanks for the lesson AS...I'm gonna wash that for little bit though.