Valve (Shim Type) Adjustment 02 zx-6r

[ucmgrad]

Hey Everyone,

Tomorrow (4/26) I'm going to start tearing into my commuter for it's long over-due valve check. Bike has a little over 101k miles, last time I checked them was around 30k? But there were within spec since then. Here's a list of what I'm changing:
Spark plugs
Fuel Filter
Cleaning Air Filter
Valve cover Gasket
Engine Side Gasket

The specs/clerances are as follows: (FSM states to measure on a cold engine)

Intake: .11 - .19 mm
Exhaust: .22 - .31 mm

If I remember correctly, valves tighten over time. So after measuring them and swapping shims would it be better to have clearances on the looser side i.e. .19/.31?

 

[dmfdmf]

Take all of this with the caveat that most of my shimming experience is with the Suzuki DL650 V-90 twin motor. The motor in your ZX is quite different but I think these tips should apply.

Since the exhaust valves run hotter the clearance tends to close faster than the intakes. I usually set the exhausts to the wide end of the spec (0.31mm in your case) and the intakes to mid-spec (0.15mm). This will maximize the time between needing to check/adjust them but due to all sorts of variables out of your control it is unlikely you'll get right at these numbers.

Many shim kits come with shims in 0.05mm increments but I just use Rocky Mountain ATV Shims which come in 0.025mm increments which usually allows me to get the gaps spot on.

I don't know if it matters but within each cylinder I try to keep each valve pair set to (roughly) the same gap. For example, in cylinder#1 having both intakes valves close to 0.15mm and avoid one at 0.13mm and the other at 0.17mm. You can't always control this unless you are willing to swap all the shims but it is a soft target. If valve pairs are similar then it supposedly idles better and has better low rpm operation, so I am told.

If you are OCD like me, I use a metric and english feeler gauge sets to measure the gaps. The slight offset between the two measurement standards allows a more precise measurement of the gap. Just use a calculator to convert to metric.

 

[OaklandF4i]

You are correct, valves generally tighten as they wear. I always set my valves to the loose end of the specs. :thumbup

 

[ucmgrad]

dmfdmf - I haven't adjusted the valves in 70k miles but it's ran fine since, I already have a complete shim kit so I know I'll have whatever I need. I also have few different metric feeler gauges I'll be using as well. My plan is to check all the clearances and set them to all the same clearances.

OaklandF4i - I just needed reassurance and backing up from dmfdmf I'll be setting them to the looser end of the spectrum.

Thanks again!

 

[kuksul08]

I find that there is not enough resolution in shims a lot of times. If possible shoot for the looser end. But anything in the range is fine, which is why they give you a range.

 

[dmfdmf]

I haven't adjusted the valves in 70k miles but it's ran fine since

FYI, valve check is a scheduled service because motor runs fine (i.e. no symptoms) until you fry an exhaust valve. Your motor is probably fine but I'd bet more than one valve is out of spec or at the limit. If I know the intakes are at mid-spec and exhausts at wide-spec when I button it up I'll go 40-50K miles without worry. 70K is pushing it.

I already have a complete shim kit so I know I'll have whatever I need.

Shim kits are usually 0.05mm increments so you won't have much control over where the gaps are with respect to the range but you can put them back in spec which is the important thing.

I find that there is not enough resolution in shims a lot of times. If possible shoot for the looser end. But anything in the range is fine, which is why they give you a range.

Agree, anything in range is fine. I do my adjustments in the Winter so don't mind waiting for shims from Rocky Mountain ATV (though they do ship quick) which are 0.025mm increment which gives better resolution to put them where I want.

 

[ucmgrad]

Kuksul08 - That's my plan is to shoot for the looser end.

dmfdmf - I looked at my shim kit this morning (Hot cams shim kit) and you're right, it goes in .05m increments. I bought it years ago and only used it the one time. I'm about to start tearing into the bike, also purchased a manual chain tensioner as well just as peace of mind. I'll report back to let everyone know how bad/good the valve clearances were.

 

[afm199]

Road bikes... Shoot for looser.

Race bikes.... Shoot for tighter.

PS: If you have gone 70k without a problem with your CCT ( cam chain tensioner) just buy a new stock one throw it in. You don't need a manual, and you have to adjust them every 10k or so.

 

[ucmgrad]

afm199 - It's my commuter bike, I wanted to see if this bike would last 100k then I'd purchase another. Well I bought my next bike but now my new goal is to see how long this motor will last before a catastrophic failure. I already purchased the manual chain tensioner so I'm already past the point of no return. But I have a garage and room to work so adjusting the chain shouldn't be an issue. :cool

 

[afm199]

afm199 - It's my commuter bike, I wanted to see if this bike would last 100k then I'd purchase another. Well I bought my next bike but now my new goal is to see how long this motor will last before a catastrophic failure. I already purchased the manual chain tensioner so I'm already past the point of no return. But I have a garage and room to work so adjusting the chain shouldn't be an issue. :cool

You say that now. That motor can easily last 200k. Tell me that after six chain adjusts. :rofl

 

[ucmgrad]

Small Update:

Degreased and have the bike taken apart:
Most of the valves were out of spec, the exhaust much more than the intake valves.

Taking a lunch break before pull off the cams and swap the shims.

afm199 - Based off of all of my Barf experience, I know you're right. And each time I'm going to have to adjust the chain I'm going to be pissed and think of you.:rofl

 

[ucmgrad]

Update:
I buttoned up the bike this afternoon, I set the clearances to the max spec on both the intake and exhaust side. Installed new spark plugs, fuel filter, cleaned the air filter and it idles and runs great. I'll be sure to take it for a test drive tomorrow!:cool

Edit:
afm199 - I didn't use the manual chain tensioner (it didn't fit) and went back to the oem one. Eventually I'll just purchase another but stock it is!

 

[ichabodnt650]

Did you need a Carb/TB sync for everything to idle and run smoothly?

 

[ucmgrad]

Ich: - To be honest, since I've owned this bike (over ten years) and 90k miles I've put on it I've never sync'd the carbs. The bike idle's fine and it's never given me any fueling issues. I helped my friend install a jet kit back when he owned it but that's about it. I'm sure it could use it and I have the sync kit to adjust it. Maybe another weekend I'll go ahead and give that a shot. But for now I'm just riding it as is.

Update:
Well I took it for a spin this morning, rode it 15 miles one way and it's missing (almost as if a cyliner wasn't firing) and also sputtered/occasional pop. Then on my way home I was just cruising along and it started to lose power almost as if fueling was being cut off. So I pulled over, called for a ride and towed it home. I'm thinking its either one of these issues or a combination of all three:

~Gaps for the new plugs were too tight
~Timing is off on the cam shafts
~Valve clearances are too loose

My question, lets say the timing isn't off. How would a motor run if the valve clearances are too loose?

 

[ucmgrad]

Any advice from my last edit/post is much appreciated.

 

[CABilly]

I can't help you with your mechanical issues, just wanted to say those classic Coleman ice chests are dope. Did you know they have almost a cult status and can fetch more than $100 even in not great shape?

 

[dmfdmf]

Update:
Well I took it for a spin this morning, rode it 15 miles one way and it's missing (almost as if a cyliner wasn't firing) and also sputtered/occasional pop. Then on my way home I was just cruising along and it started to lose power almost as if fueling was being cut off. So I pulled over, called for a ride and towed it home. I'm thinking its either one of these issues or a combination of all three:

~Gaps for the new plugs were too tight
~Timing is off on the cam shafts
~Valve clearances are too loose

My question, lets say the timing isn't off. How would a motor run if the valve clearances are too loose?

Got the plug wires crossed up? I'd check that all the hoses and vacuum lines are plugged in and plugged in to the right place before assuming the worst.

Re: Plugs: The plugs for my 'Strom come pre-set but I still measure them and they are always spot on. Did you have to set the plug gaps? Seems unlikely to to me.

Timing: It is pretty easy on the Suzuki to set the cams off one tooth, I don't know about your bike,

Clearances: You checked them on the way out, right?

 

[ST Guy]

Carbs probably not properly cleaned. Still plugged up.

 

[afm199]

Ich: - To be honest, since I've owned this bike (over ten years) and 90k miles I've put on it I've never sync'd the carbs. The bike idle's fine and it's never given me any fueling issues. I helped my friend install a jet kit back when he owned it but that's about it. I'm sure it could use it and I have the sync kit to adjust it. Maybe another weekend I'll go ahead and give that a shot. But for now I'm just riding it as is.

Update:
Well I took it for a spin this morning, rode it 15 miles one way and it's missing (almost as if a cyliner wasn't firing) and also sputtered/occasional pop. Then on my way home I was just cruising along and it started to lose power almost as if fueling was being cut off. So I pulled over, called for a ride and towed it home. I'm thinking its either one of these issues or a combination of all three:

~Gaps for the new plugs were too tight
~Timing is off on the cam shafts
~Valve clearances are too loose

My question, lets say the timing isn't off. How would a motor run if the valve clearances are too loose?

Did it run crappy from the start? You probably have the cam off one tooth on the exhaust cam. Check both.

 

[dravnx]

None of the things you mentioned would cause intermittents. If they were bad enough to cause problems, you would know right away. You have either a fueling issue or an electrical issue. Plug wire not secure, carb boot loose, vacuum hose fallen off
Go back in and inspect everything you touched or was close to touching.