Jump to content

DRZ400S valve clearance query?


Recommended Posts

Just measured the valve clearances on my partners DRZ, not sure if I should change a couple of the shims?

The right hand inlet measures 0.10mm, right on the bottom limit of the 0.10 - 0.20mm range specified in the manual. There's very little drag on the 0.10mm feeler gauge blade which makes me think the actual clearance is 0.11 or 0.12mm.

The right hand exhaust measures 0.20mm, right on the bottom limit of the 0.20 - 0.30mm range specified in the manual. There's some drag on the 0.20mm feeler gauge blade which makes me think the gap is 0.20mm exactly.

The manual states that the above readings are fine & that there's no need to adjust. However the bike is heading off on a 5,000 mile trip through South America starting mid-August. My feeling is that I should adjust both clearances to the mid way setting of 0.15mm (approx) for the inlet & 0.25mm for the exhaust in case the clearances tighten up? This would also bring them in to line with the other two valves.

The idea is that once adjusted the valves shouldn't need looking at again for the duration of the trip. I'm not sure if DRZ valves have a habit of tightening or loosening up as the miles are covered?

All advice appreciated. 🙂

Link to comment
Share on other sites

Thanks for the info.

Removed the cams etc, all's well, will order the shims tomorrow. Only thing different to what I expected is that both exhaust shims are marked up as being 318 (3.18mm) which I've confirmed with a Micrometer? I thought the Suzuki shims only came in 0.5mm increments? Bike's got less 2,700 miles on it since new, I guess theese are the original factory shims that were fitted to bring the clearances in to spec during the build?

Am I better off swapping the current 318 exhaust shim for a 310 to increase the gap to 0.28mm or would I better going for a 315 to take it to 0.23mm? I'm in favour of the larger clearance personally seeing as how the gaps already closed up to 0.20mm but am open to advice. :thumb

I measured up the remaining two shims & noted the shim sizes for future reference.

The bike won't be ridden much before it's shipped to Buenos Aires on 10th August.

Link to comment
Share on other sites

Thanks for the info.

Removed the cams etc, all's well, will order the shims tomorrow. Only thing different to what I expected is that both exhaust shims are marked up as being 318 (3.18mm) which I've confirmed with a Micrometer? I thought the Suzuki shims only came in 0.5mm increments? Bike's got less 2,700 miles on it since new, I guess these are the original factory shims that were fitted to bring the clearances in to spec during the build?

Am I better off swapping the current 318 exhaust shim for a 310 to increase the gap to 0.28mm or would I better going for a 315 to take it to 0.23mm? I'm in favour of the larger clearance personally seeing as how the gaps already closed up to 0.20mm but am open to advice. :thumb

I measured up the remaining two shims & noted the shim sizes for future reference.

The bike won't be ridden much before it's shipped to Buenos Aires on 10th August.

OEM shims available to the factory come in half sizes.. As service replacement parts or aftermarket shims, only in .05mm

Do not shim to OVER the spec, but get it as close as possible.

Unless you had checked prior, there is no way to know if the valve clearance has changed at all since it left the factory.

That may just be what they set it to..

Change um now, ride a bit, check again.. anything less is just guessing.. Best of luck on the trip.

Link to comment
Share on other sites

What happens if you go a bit big? Noise? Wear? I wanted to be near the maximum and ended up just a hair over spec. Should I change it? 0.305 feeler has drag on exhaust.

I just re-shimmed mine for the first time at 16,000km and basicly went 0.1mm on each valve. (since the factory shims were odd values this means some were 0.08 change, etc) At 12,000 they were in the bottom half (intake at 0.14 for example) which is how they were since new and now I have them all near maximum or as mentioned just a touch big.

How much wear is typical? Should I start saving for valves?

Link to comment
Share on other sites

In inches 0.3mm is .0118" and 0.305mm is .0120". The difference is so small it is insignificant. I use inch feeler gages so I use .008 to .012 anyway.

Wear is very slow until it suddenly becomes very fast. So just check once in a while.

I have a 2000 DRZ E. Only shimmed the valves once. Really didn't need it then. Unknown miles but it is a lot. Maybe 30,000.

Link to comment
Share on other sites

Thank you Noble for the idea of getting a 'true metric' feeler gauge set and using both for a closer measure. That would have served me better as I had it all put back together and 1 intake and 1 exhaust were not as close to max as I wanted and the math seemed to say it would accept another 0.05 but when I got those shims from the store it ended up just the hair big. By then the store was closed so I left it. Time to buy a hotcams shim set I guess.

I am familiar with the slow then quick wear from helping a friend on his RM250F. Pretty sure he used the wrong technique on his air filter(wash in gas, shake out, let mostly dry, then oil) . Didn't like my more time consuming method (varsol, soapy water, rinse, completely dry, oil with foam air filter oil ONLY). Now that several valves have failed he is reconsidering his method.

What I am curious about is now that my valves have worn about .05 mm each is this the beginning of the end? (actual wear since new even though I shimmed more to get to the upper end of the range) Are there owners who have shimmed several times and continued to see a slow wear over an extended period? When my friends valves go it is a matter of hours.

I have started to rethink putting them at the upper end of the range as I am now right at the 'service limit'. Do bad things happen out of this range like the bucket not making a soft transition from not contacting to contacting the cam? When I saw they were a couple hundredths of a mm below the minimum I rushed to fix it and I guess the same should go for the upper limit? I know they almost always tighten. It isn't that much hassle to change them again but there are many other things i can do with my time if it isn't.

I am probably worrying about this needlessly but I am curious if anyone has info?

Link to comment
Share on other sites

What I am curious about is now that my valves have worn about .05 mm each is this the beginning of the end? (actual wear since new even though I shimmed more to get to the upper end of the range) Are there owners who have shimmed several times and continued to see a slow wear over an extended period? When my friends valves go it is a matter of hours.

You wont know for sure until you measure them again after a few hours of use.

Yes, once they start moving, the wear (valve face wearing, valve receding into the head, clearance getting smaller) You can re shim and get another ride or two, but they will have moved again, often closing the clearance up completely causing a no start open valve issue.

I have started to rethink putting them at the upper end of the range as I am now right at the 'service limit'. Do bad things happen out of this range like the bucket not making a soft transition from not contacting to contacting the cam? When I saw they were a couple hundredths of a mm below the minimum I rushed to fix it and I guess the same should go for the upper limit? I know they almost always tighten. It isn't that much hassle to change them again but there are many other things i can do with my time if it isn't.

I am probably worrying about this needlessly but I am curious if anyone has info?

You are loosing valve lift and some duration by intentionally shimming OVER the clearance spec. As I've never intentionally done that on a motor and seen it comeback after a few hundred hours, I don't know the actually additional wear it might introduce.. Nor do I intend to find out.

Put um in the range 0.10-0.20mm and 0.20-0.30mm and go ride. If the valve face is in good shape , intake tract sealed and properly maintained.. You'll be fine.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Ă—
Ă—
  • Create New...