Interesting observation while adjusting valves

[t3rmin]

So 5 of 8 valves were too tight; all but 1 of them were only one shim step off. I got the new shims I needed and swapped 'em around until they were all in spec (well the one that was two sizes off is still a teensy bit tight 'cause I didn't have the right shim but I'll find one tomorrow).

Anyway, when I was done I noticed turning the crank with the wrench was significantly harder (with the normal hard-easy pattern of strokes). It would seem compression increased enough that I could actually feel the difference. Which means, of course, I've been driving around with pretty crappy compression.

The moral of the story: don't neglect adjusting your valves. This was my first time and I'm amazed such a tiny adjustment can make such a big difference. I can't wait to put it back together after getting that last valve in spec, re-sync the carbs, and see how much better it runs!

 

[t3rmin]

Also a question: how important is getting the clearances exactly the same for all valves? Like say if I have 6 valves at .05 and 2 at .08... Should I leave it at that or be sure to get them all spot on .05?

 

[terry]

I wouldn't be too worried about them being a little on the loose side mate, but as you've discovered, if they're too tight, you're hurting your performance capabilities.

Our bikes suffer from valve recession, so overly tight clearances are common, in bikes that have sat for a while with no maintenance. When I first bought my GS1000S, I couldn't get it to run until I re-shimmed the valves, due to a distinct lack of compression, ha ha!

I know it's a pain in the butt buying shims, so I hunted around until I found a factory shim kit at a swap meet, and just added any missing shims as I went, so now I've got plenty of each size. Keep an eye on Ebay too, I see them come up every now and then, and Motion Pro sell the correct shim tools. (don't use a magnet) Cheers, Terry.

 

[KEITH KRAUSE]

Just be sure you adjusted them exactly per the factory manual procedure.
If you just take the measurements with all the lobes pointing up, (commonly done by some) you'll often get inaccurate readings.

 

[Dan Ruddock]

Keith you are right, I used the old TDC and check both in and ex for the same cyl and got different readings than using the suzuki manual method. This is because of the bending action put on the cam fron the cyl next door to the cyl your adjusting. Dan

 

[DimitriT]

Shameless plug: I've got bunch of shims for swap in the parts sale/wanted section. Maybe we can all add our extra shims to a single thread and have a list for swaps.

 

[t3rmin]

Yeah, I did use the Suzuki method. I suspect the previous owner, if he did it at all, used the Clymer method (lobes straight up), since I got much "better" readings when I used the Clymer method (before I discovered the correct way). I love my Suzuki shop manual. I've also got a Clymer (came with the bike), which is OK, but the Suzuki manual is usually more detailed/accurate and as such it sees alot more use (it's starting to have that well-loved grease-stained look).

Well after I started this thread I got antsy and went back out to the garage. I managed to do some more creative swapping of shims and got all but one valve exactly at .05. Since 7 of 8 are so "right on" I'm going to go ahead and swap a shim at the local powersports shop and get that 8th valve matched up with the rest. I figure balance must count for something since the shims do affect the cam profile slightly and it's super important to get the carbs balanced. I'm also trying to work out the infamous 4k RPM buzz, so I want everything as even as possible.

The crazy thing is, I thought the bike ran GREAT even before adjusting the valves. It was already considerably faster than my friends' Honda 650's and 750's. Of course this is like the 5th time I thought I had the bike running "perfect", only to find out later that it wasn't. It's kind of fun because every time I stand back and think "wow, this thing is amazing", it just keeps getting better. ;-) I've been going crazy with excitement all night/morning and I can't wait to get home and button 'er back up and go for a ride!!!

 

[t3rmin]

One more thing I learned that I'll pass on (even though it's been said before): GET A DIGITAL CALIPER! I picked one up at Harbor Freight the other day for like $15 and I could NOT have done this valve adjustment with the same degree of accuracy and ease without it. Not only were the markings worn off several of my shims (PO put in upside-down), but there was a LOT of variation, even between shims marked with the same value. Instead of recording the marked value, I just used the caliper on each one and recorded the actual thickness. This made things both easier and more accurate. I can see spending hours swapping shims around trying to get things right if you didn't know the actual thickness...

Also, get the right tool for getting those shims out. I tried screwdrivers before I had the tool and managed to get *one* out with extreme difficulty and I ended up gouging the head several times (fortunately in unimportant areas). You've got to get shims out and in many times as you swap them around (at least if you have a bunch of valve off like I did). I can't imagine struggling with wedging screwdrivers in there for all of the many times I yanked shims out yesterday. Of course if you manage to make a tool that works, great, but I got the official Suzuki valve shim removal tool on eBay for $18 and I'm dang glad I did it.

Something else I encountered was, on the lobes on the ends of the camshafts, the tool would sometimes slip off and the tappet would snap back up with a twang (often splurting me with oil). I figured out I could keep that from happening by using a small screwdriver as a lever to put firm pressure (toward the lobe) on the end of the shim tool as I rotated it on the camshaft.

 

[DimitriT]

t3,

For those of us without a Suzuki manual, could you go over the differences with Clymer's as far as shimming.

thanks!

 

[t3rmin]

Sure. The Clymer says simply to turn the crank 'till a lobe is straight up (in relation to top of head), measure, then repeat for all valves. i.e.: the valves are all measured with the cam lobe facing straight up from the head.

The Suzuki method is... (found in the archives):
----------------------------------
turn crank until
#1 exhaust cam lobe pointing forward parallel with the top of the head
- check #1 exhaust
- check #2 exhaust

rotate crank 180 degrees
#1 intake cam lobe pointing up perpendicular to the top of the head
- check #1 intake
- check #2 intake

rotate crank 180 degrees
#4 exhaust cam lobe pointing forward parallel to the top of the head
- check #3 exhaust
- check #4 exhaust

rotate crank 180 degrees
#4 intake came lobe pointing up perpendicular to the top of the head
- check #3 intake
- check #4 intake
----------------------------------

I think it's easier to judge when a lobe is straight up, so for the steps where one lobe is supposed to be sideways, I look at the other lobe and make sure it's straight up (from the head surface). The cam retainer block thingies and bolts are good points of reference.

 

[Nessism]

The Suzuki manual specifies two different allowable positions: straight up or pointing perpendicular to the surface of the head (method specified above). The key thing is to have the base circle of the cam lobe over the tappet shim when you measure the clearance. Some say the readings differ depending on which method is used so this must be due to bending of the cams due to spring load. On my bike I used the cam lobes straight up method just to keep it simple. Seems to work fine.

 

[t3rmin]

Well the readings were quite a bit different on my bike between the "Clymer" way and the strict Suzuki way. Honestly it doesn't make a great deal of sense why this should be so, but I'm more comfortable having done it the Suzuki way. ;-)

By the way I got the last valve into spec with a new shim (all of them at .05mm gap now) and started it up. Haven't driven it yet (need to re-sync carbs) but it already sounded smoother.

I did notice the increased valvetrain noise, but as somebody said, it's a mechanically correct noise and therefore pleasing to the informed listener. ;-)

 

[Dan Ruddock]

Well the readings were quite a bit different on my bike between the "Clymer" way and the strict Suzuki way. Honestly it doesn't make a great deal of sense why this should be so, but I'm more comfortable having done it the Suzuki way. ;-)

There is no doubt in my mind what causes the reading change. You will notice when doing it the suzuki way the two same shaft cam lobe's on the same side of the chain are both in the closed valve position. The clymer way has one lobe in the open valve position pushing the cam against the brg. clearance causing a looser reading on the closed lobe. I have worked on many car and motorcycle engine types and this is the first I have seen to use this procedure. Dan

 

[Nessism]

There is no doubt in my mind what causes the reading change. You will notice when doing it the suzuki way the two same shaft cam lobe's on the same side of the chain are both in the closed valve position. The clymer way has one lobe in the open valve position pushing the cam against the brg. clearance causing a looser reading on the closed lobe. I have worked on many car and motorcycle engine types and this is the first I have seen to use this procedure. Dan

This makes lots of sense to me. I'm going to go back and check my valve clearances again, this time using the proper method to see what kind of readings there are.

 

[KEITH KRAUSE]

The Suzuki manual specifies two different allowable positions: straight up or pointing perpendicular to the surface of the head (method specified above).

It's true that Suzuki says the lobes must be straight up or perpendicular to the surface of the head to take accurate measurements (or to remove a shim), but they are only pointing out that you'll see the cam lobes in only these two positions if you follow the factory procedure exactly. Just start with exhaust 1 at the roughly "9:00" position and you can't go wrong.
You will see a difference. Clymers and other "aftermarket" books lack a lot of info and often include info that's actually bad for the bike. Get a factory manual if you have the chance.
Dan made a good explanation of what happens if you adjust the valves with all the lobes pointing up but I just thought I'd add my thought.