[benp]

So I finally had a bit of time today and tore into my 2011 Daytona 675R to check the valve clearances. After checking a few, I began to wonder what effect the temperature of the engine has on these clearance measurements. I know that the valve clearances are meant to be checked with a cold motor, but I thought this typically meant that the motor hasn't been run recently.

It was probably mid 40's (Fahrenheit) in the garage today, but the bike engine could very well be close to freezing. So, before I order any shims, does anyone have any insight as to whether my clearance numbers could be off because I'm checking them on a near-freezing engine? If anybody is curious, I've listed the clearance values below:

.35 .35 ----- .35 .35 ----- .28 .28 --- Exhaust (Spec: .275-.325)
.13 .13 ----- .15 .15 ----- .15 .13 --- Intake (Spec: .10-.20)

Additionally, if the temperature isn't a huge factor, why would my exhaust valves be so loose? I thought they tended to tighten up with use. FYI, my bike has 12000 miles on it with 3000 of those as track miles.

 

[MGFChapin]

Metallurgically speaking, 40 F is the same as 70 F to a motor whose oil circulates at 250 F. Your measurements are fine.

Loosening is normal. Here's a good explanation:

 

[benp]

Metallurgically speaking, 40 F is the same as 70 F to a motor whose oil circulates at 250 F. Your measurements are fine.

Loosening is normal. Here's a good explanation:

I was hoping that was the case, but it did raise an eyebrow at the time. Now thinking clearly and actually looking at the numbers, the theoretical change in length of the steel valve vs. the aluminum head is .00066" (.0168 mm) for a valve/head length of 3 inches and a temperature change of 40 degrees Fahrenheit. That's way closer than what I can measure with some feeler gauges. Ugh, I really should have thought about this a bit harder. Thanks for the video though! I appreciate his approach to explaining things!

 

[siq75]

When reinstalling, the service manual says to lube the cam bearing areas of the ladder and the tappet buckets with 50/50 engine oil and molybdenum disulphide grease. Will the engine oil be sufficient, or do you need the moly too?

Also the manual says inspect, and clean the cam journals in the head, no mention of any lube. Is this because the cams will be lubed with engine oil?

 

[MGFChapin]

Oil alone is fine, but this is the good stuff: https://www.redlineoil.com/assembly-lube

You don't need to lube the journals because the cams should be lubed.

 

[siq75]

Oil alone is fine, but this is the good stuff: https://www.redlineoil.com/assembly-lube

You don't need to lube the journals because the cams should be lubed.

Thanks, and that is very good stuff! Use that straight on the cam bearings in the ladder, and the tappets, or do the 50/50 solution as per the service manual?

 

[MGFChapin]

Thanks, and that is very good stuff! Use that straight on the cam bearings in the ladder, and the tappets, or do the 50/50 solution as per the service manual?

Straight, don't mix it. It's nice and thick so it'll stay put wherever you smear it.

 

[siq75]

Straight, don't mix it. It's nice and thick so it'll stay put wherever you smear it.

Cool, I appreciate the tips!

 

[Weiweismart]

Is this because the cams will be lubed with engine oil?

 

[MGFChapin]

Is this because the cams will be lubed with engine oil?

Yes. The cams are the last thing to get lubed and the top end gets the most wear from a cold start. Smearing them with assembly lube prevents excessive wear after starting for the first time in a while.

 

[siq75]

Is this because the cams will be lubed with engine oil?

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