CBR600RR 2008 - Valve clearance

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self_moto

Well-known member
Hello,

I know internets are saying "loose valve is better than tight one", but how much loose is too much?

I finally got to check valve clearance on my cbr (it's track bike), last time valve were checked around 10k ago, I think I put couple thousands (in this 10) on track only. Most of valves are close to spec, but I have one of exhaust valve sitting at 0.35 (0.28 +/- 0.03 service limit).

Here are the numbers(range number basically shows upper limit which hadn't fit at all, so 0.17 - 0.2, means it's less than 0.2 but more than 0.17 obviously):
https://docs.google.com/spreadsheets/d/1-JvegBIQBqkQXyimk9psueb9dQFrsfQy2ZycjopShTM/edit?usp=sharing

To be honest, I want to replace those shims.. but I don't have proper honda tool to get cam chain tensioner off the bike... and it's really tight there (frame is in the way to use other tools), so if you have suggestions on that, it would be great too!
 
afm199

afm199

Well-known member
I'm not exactly sure what that means. If you have an exhaust valve with .35mm clearance, it's close to .014". As exhaust valve clearance goes, that's pretty fucking huge. I'll be running .007 to .011 on most of my bikes. I can't imagine the honda has that much clearance.

I just checked, according to the internet, my clearances are correct for the CBR.

Sorry, reread the question. Button it up and ride it. It will only get smaller. It's a huge amount of work to swap one shim. Unless you're riding it at redline all day, you're fine.
 
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stangmx13

stangmx13

not Stan
the CCT tool is a glorified flat head screwdriver. I made one that would fit by cutting most of handle off of a small screwdriver. u screw it in to release tension on the cam chain. I just make sure to do that before firing the engine so that it can reset the tension.

if you are out of spec, id change the shim.
 
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afm199

afm199

Well-known member
stangmx13 said:
the CCT tool is a glorified flat head screwdriver. I made one that would fit by cutting most of handle off of a small screwdriver. u screw it in to release tension on the cam chain. I just make sure to do that before firing the engine so that it can reset the tension.

if you are out of spec, id change the shim.
Click to expand...

Yup, tiny screwdriver or a cotter pin with the end pounded flat.

I didn't recommend changing it because he has just put 10k miles on it without a problem.
 
stangmx13

stangmx13

not Stan
... whats a little less valve lift on a CBR :laughing

exhaust valve clearances used to get wider and wider as carbon built up. but I think modern fueling and modern valvetrains have fixed. now they pound in just like intake valves.
 
afm199

afm199

Well-known member
stangmx13 said:
... whats a little less valve lift on a CBR :laughing

exhaust valve clearances used to get wider and wider as carbon built up. but I think modern fueling and modern valvetrains have fixed. now they pound in just like intake valves.
Click to expand...

:rofl

That was funny. We used to cut clearance to a minimum to get that tiny bit of extra lift.

Agreed, today, particularly with the higher rpms, they recess.
 
S

self_moto

Well-known member
Thanks for input! I think I'll replace it... but I'm done trying to do things with DYI tools (made without proper tools around :) ) usually it ends up even worse and consume more time. I think 50$ is not that bad for a tool. So I'm going to get a tool (K&L selling those for half the price of OEM tool)
 
afm199

afm199

Well-known member
self_moto said:
Thanks for input! I think I'll replace it... but I'm done trying to do things with DYI tools (made without proper tools around :) ) usually it ends up even worse and consume more time. I think 50$ is not that bad for a tool. So I'm going to get a tool (K&L selling those for half the price of OEM tool)
Click to expand...

Fifty wasted bucks. Get a screwdriver.
 
afm199

afm199

Well-known member
augustiron said:
+10000
there are times and places where specific specialized tools are a must have, this is not one of them.
So badly, the MP tool feels like a scam for suckers.
Click to expand...

Bingo.

I must own a thousand bucks worth of specialty tools. GSXR crank pullers, SV main bearing installers ( talk about a specialty tool), on and on. JPS screwdrivers, Whitworth wrenches.

For that CCT I use a smashed down cotter pin.
 
S

self_moto

Well-known member
So.. i have a problem, decided to post here instead of making new thread - bike turns over but wont start - https://imgur.com/a/HkjnLsO

i did a valve job, and a lot of other stuff. removed kick stand, light controls from left clip on, PAIR system with part which goes to SMOG(https://www.peterverdone.com/archive/600RRpairsmog.htm), disconnected evap purge valve, new spark plugs. I was starting with kickstand switch connected, in neutral. Thoughts?
 
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stangmx13

stangmx13

not Stan
it almost fires, which means its not the sidestand switch.

id check for vacuum leaks first, mostly validating that you plugged everything necessary for the PAIR and EVAP removal. then id start taking it all back apart until I had the valve cover off and could check the cam timing.
 
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S

self_moto

Well-known member
checked spark - it’s there, and fuel pump - is priming. I was able to start it once(with a bit of throttle), but it was running uneven, and died right away. I ended up disassemble whole thing and set timing again, and to be honest, exhaust had a bit offset from parallel with case position... so will report one assemble it and give it a try again.
 
S

self_moto

Well-known member
looks like it was cam timing... set it properly this time, marks flush with case.. put it back together and it’s running just fine now

added pictures cam timing marks before and after (sorry for poor quality), it’s not that much of a difference... (https://imgur.com/a/HkjnLsO)
 
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stangmx13

stangmx13

not Stan
good stuff.

for next time... you can use a paint pen to mark the chain and sprockets so that they go back into the same spot. itll be perfect so long as you dont drop the chain and let it skips a tooth on the lower sprocket.
 
afm199

afm199

Well-known member
stangmx13 said:
good stuff.

for next time... you can use a paint pen to mark the chain and sprockets so that they go back into the same spot. itll be perfect so long as you dont drop the chain and let it skips a tooth on the lower sprocket.
Click to expand...

This! It's so easy to mess up cam timing when the motor is in the frame, as it's so hard to see the exhaust cam mark lined up with the top of the head. A simple mark will make this so easy.
 
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