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Cam Timing for '99 R6

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ice

Cam Timing for '99 R6
« on: January 29, 2003, 11:36:40 pm »
My '99R6 used to be super-fast, but I had it rebuilt middle of last season and now it seems much slower.  
I really should have had it on the Dyno prior to the rebuild, but......

The motor was originally done by Moto-Tune, but was rebuilt by another outfit.  The rebuild was primarily pistons, rings, and valves.

The motor is stock with the exception of a milled head.
 
The bike runs smoothly and carburates well, but it just seems to be missing that extra hit.

I've been told that the cam timing is likely the difference.  The rebuilt motor cam timing is set to original Yamaha specs.

Does anyone have any cam settings that are different from stock that have improved engine performance???

Any other ideas??????  
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mdr14

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Re: Cam Timing for '99 R6
« Reply #1 on: January 30, 2003, 05:36:02 pm »
I would check both compression and leak down, That will tell you the sealing condition of the rings and valves

I would also test the bike on a Dynojet model 250 dyno. Those dynos are for sure using the hardware stack ( gathers all the weather data so accurate and repeatable correction factors are calculated) and the windows software. The windows software also determines SAE corrected hp better than the old dos based software that still may be used by some dyno shops.

You might be able to play with cam timing to see if a gain is availble. It is possible that perhaps the cam timing is not at a good specification, or even at a stock Yamaha spec.

If you are really concerned about cam timing, and you are in the midwest, and your feeling froggy (whatever that means) You could pull your motor out swing by the shop, and I can check & or adjust your cam timing while you wait, with an appointment of course.
« Last Edit: January 30, 2003, 05:39:43 pm by mdr14 »
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Matt Drucker
MD Racing
www.mdracingstp.com

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R6Chris760

Re: Cam Timing for '99 R6
« Reply #2 on: February 04, 2003, 07:47:12 pm »
4 degree advance is the best i believe (pretty sure it's best for the R6).  Anyone disagree?

Chris
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tcchin

Re: Cam Timing for '99 R6
« Reply #3 on: February 05, 2003, 02:55:50 pm »
Where will that leave the lobe centers?
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ice

Re: Cam Timing for '99 R6
« Reply #4 on: February 05, 2003, 10:30:37 pm »
Chris,

Thanks for the advice.  I have been talking to quite a few R6 owners and this seems to be what everyone is saying.  I actually heard stock settings were 8 degrees on the intake and 4 degrees on the exhaust and the recommended cam timing was 4 degrees advance offset at 4 degrees intake and 8 degrees exhaust.  
I don't have a clue if this makes any sense since I don't really understand how the cams are adjusted.

Are there separate adjusters for the intake and exhaust cams?

Tim,
Can you explain what a lobe center is?

I assume that it would be that it is the part of the cam that is at maximum distance radially from the center of the camshaft.  If this is correct, then I don't really understand your question?

Matt,
One of my sponsors said he would take the bike to the local dyno to check it out.  I'll come see you if there is no progress.  Thanks for the help.
« Last Edit: February 05, 2003, 10:41:02 pm by ice »
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tcchin

Re: Cam Timing for '99 R6
« Reply #5 on: February 06, 2003, 11:38:09 am »
Lobe center refers to the angular midpoint of the cam lobe, not necessarily the location of maximum lift. For example, on intake cams, it's calculated by subtracting the opening point from the closing point, adding 180 and dividing by 2. So, cams that open at 40 BTDC and close at 80 ABDC would have (80-40+180)/2 = 110 degree lobe centers.

Lower lobe center figures reduce overlap and promote higher cylinder pressure, enhancing low-speed power. Higher lobe center figures allow for more overlap and cylinder scavenging, enhancing high-speed power.

The only way to accurately measure lobe centers is to use a degree wheel on the crankshaft and a dial indicator on the tappet. Typical lobe center figures for roadracing bikes vary from 95-105 ATDC.
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