[Donger]

I set the intake openers to .004" and the exhaust openers to .006". I set all the closers to .003".
This was Pat's clearances that he set for his shims at the 15K miles for the SBK in my DIY 15k belt change/check valve thread back in 2012
I no longer own the 848 but bought the 2010 SF S instead.
Question I have is is it possible that I could set my tolerance to the SF's engine? Since they are technically the same but different airbox/AF tuning?
Quackquack, and others who have been working on their bikes, you guys are more than welcome to chime in.
Cheers.

 

[Tchase]

Do both bikes shop manuals state the same? If they do I would think you could.

 

[pat1098]

Unfortunately the recommended settings are a range, not a specific measurement.

I offered these settings as they work for me, and make sense. (I have done many thousands of miles on them before recommending them to others).They are actually similar to settings I have used on various models over the last four decades.

The opening clearances (.004" inlet and .006" exhaust) I have used on everything from bevels onwards. Even the pre-Desmo models.

The closing clearances (which I used to set at nil - .001" on the early models) I have increased to .003" as later models rev harder.

The factory has long recommended 'looser' closing clearances on its R models for this reason. That and the fact that they run 'harder' cam profiles. (A base 748 - 916 they recommend .002", whereas the R they suggest .004").

My rationale is that by setting the clearances to an exact value, rather than just checking they are 'within range', they can be left for longer, on the assumption that they should take longer to get outside the recommended range.

I leave mine for 18,000 kms, rather than attending them at the recommended 12,000 kms (7,500 mi). Worth the extra work to both know they're dead right, and to be able to leave them for longer.

Setting the valve clearances on these is a PITA if you've done as many as I have.. I am now at an age where I just want to ride!

 

[Donger]

^why I asked..because I do remember when I posted my DIY 15k miles for the 848, I thought my valves were in spec, but after reading your post it makes much more sense.
The SF will be my permanent bike and I do plan on keeping it for long. The bike is only at 3500 miles right now. So it will be a while until I hop back onto this topic.
Future plan is to do a full system with custom map ( I love the way the termi cans look, but the damn header alone is impossible to find unless I wanted to cough up $3k for the full system, this is after discount I got from my friend at the dealer--and we all know how tedious this task is.
If only Austin Racing makes the full system with twins cans I'd be all over it. Their GP2R system sounds really good, not to mention the weld quality.
I am still trying to look for a local fabricator to see how much would it cost to have him make my tank with Aluminum since Motowheels orders are on B/O with unknown date. Or if the CF Tank won't suffer the swelling I might go that route.
Money pit lol..but we all love it, don't we?

 

[pat1098]

For those not sure why there has to be a clearance between the rocker and valve - it is to accommodate expansion due to heat.

The exhaust valve has a greater clearance as it gets hotter.

If there is insufficient clearance the valve may 'ride' when it's hot. Exhaust valves are at risk of burning out in this situation, with hot combustion gases being forced past their thin edge, and running is compromised due to a loss of compression.

The natural trend of wear at the valve face and valve seat will reduce the opening clearance, necessitating the periodic adjustment. The same process will increase the closing clearance.

This is why car engines usually have hydraulic lifters, to avoid this job. But of course they limit possible cam timing and performance.

The Desmo system allows pretty radical valve timing and cam profiles, and of course maintains timing and valve 'obedience' more accurately. A great system, except when you have to spend a whole day maintaining it!

 

[Superfly999]

One of my exhaust closers was .23mm or .009" checked at about 10 degrees Celsius. I realize that's almost at the max book value but what is suppose to happen if it gets too loose?? Because it was an exhaust valve I figured it would get hotter and close up the slack a bit but I'm not really up on what happens. The engine seems to run fine

 

[pat1098]

This won't cause a running problem, but if left may eventually cause a wear issue.

If the opening gap is too great, it may cause a faint rattle, but with as much engine noise as these make, it won't be obvious!

Of course the valve isn't being opened quite fully if the opening clearance is excessive, and the valve's reciprocating movement is not being controlled as accurately by the camshaft. And of course the duration of that valve's opening will be reduced.

The take-up against the greater clearance could ultimately cause some wear, and increase the clearance further, with a slight hammering action against the valve.

But it will need to be remedied, as it is getting close to going outside of the (greatly increased) 'acceptable range'.

I hope this is of assistance - not trying to be a 'prophet of doom'..

 

[pat1098]

Sorry - just realised you said closing clearance.

Different story.

This being loose means the Desmo or closing rocker isn't controlling the valve's closing as accurately as the camshaft permits.

Don't let it get too loose though, as you could hammer your half-clips and break them. Or they could fall out at revs..

Just put it right as soon as you can.

 

[Superfly999]

sorry I miss typed the clearance. the exhaust closer on one was .23mm which is getting loose as per the book. as per you guys its real real loose. The cam wear on the lobes looked great though so I guess that's a plus. I'll prob shim it next time I open it up...

 

[Donger]

^one of my 848's horizontal closer valve was at .19mm..but i buttoned it up due to not having the knowledge about clearance vs range/tolerance.