Need my head examined (beware monster pics)

[Nessism]

Ed, thanks for auditing my results. Apparently, things are different for the 850. According to my copy of the factory service manual, standard specs for "valve guide - valve stem clearance" is 0.025-0.055 with a service limit of 0.35 for intake and 0.040-0.070 / 0.35 for exhaust.

Am I misinterpreting the whole standard / limit thing? If so, I'll bust out my indicator and take a more accurate reading for sure.

Dogma,

Don't want you to take this the wrong way but there is something wrong with your manual or the conversions.

The intake spec is 0.025-0.055 mm with a service limit of 0.090 mm or .0035".

Exhaust spec is 0.040-0.070 mm with a service limit of .100 mm or .0039".

Another thing, and again don't take this the wrong way, it looks like those valve seats in your head have a very wide seat width. The spec is 1.0 - 1.2 mm (.04" - .05"). Please check them.

Yea, I'm one anal SOB. It's a handicap some times.

[Dave8338]

Yea, I one anal SOB. It's a handicap some times.

No sir, you have that wrong. To measure correctly is to know. Best piece of mind you'll ever get for free!

[Nessism]

To measure correctly is to know. Best piece of mind you'll ever get for free!

Yup! Agree! (check my signature)

[Dogma]

Dogma,

Don't want you to take this the wrong way but there is something wrong with your manual or the conversions.

The intake spec is 0.025-0.055 mm with a service limit of 0.090 mm or .0035".

Exhaust spec is 0.040-0.070 mm with a service limit of .100 mm or .0039".

Another thing, and again don't take this the wrong way, it looks like those valve seats in your head have a very wide seat width. The spec is 1.0 - 1.2 mm (.04" - .05"). Please check them.

Yea, I'm one anal SOB. It's a handicap some times.

I did think it odd that the service limit is so much larger than the standard specs. I tried to cross-check it against Clymer, but that only says that more than a little is too much. I have to find the "more than a little" marks on my caliper now... 0.35 isn't more than a little, is it? Where did the 0.09 and 0.10 numbers for the service limits come from? It's sorta hard to ignore the service manual published by Suzuki for this model without some convincin'. The inch conversions match the mm numbers in the chart (0.014" for the service limits). The writers of the manual would have to accidentally convert the intake number you give twice to get 0.014", and then accidentally duplicate that for the exhaust limit. And all these numbers appear in two separate charts. I hope the factory manual isn't that bad!

I have to admit, the valve seats look awfully close to 1.2 mm. I'll have to put my calipers on there and see what I find.

So, what are the consequences if there's too much slop in the guides, and the valve seats are too wide? I'm trying to visualize what that would do. All I can figure is performance degradation.

[Dogma]

Carefully on the valve seals, but dont be dainty...

Not dainty... How about two pair of vice grips and a 3 lb driving hammer? I was getting pretty good at it by the 8th one!

[TheCafeKid]

I did think it odd that the service limit is so much larger than the standard specs. I tried to cross-check it against Clymer, but that only says that more than a little is too much. I have to find the "more than a little" marks on my caliper now... 0.35 isn't more than a little, is it? Where did the 0.09 and 0.10 numbers for the service limits come from? It's sorta hard to ignore the service manual published by Suzuki for this model without some convincin'. The inch conversions match the mm numbers in the chart (0.014" for the service limits). The writers of the manual would have to accidentally convert the intake number you give twice to get 0.014", and then accidentally duplicate that for the exhaust limit. And all these numbers appear in two separate charts. I hope the factory manual isn't that bad!

I have to admit, the valve seats look awfully close to 1.2 mm. I'll have to put my calipers on there and see what I find.

So, what are the consequences if there's too much slop in the guides, and the valve seats are too wide? I'm trying to visualize what that would do. All I can figure is performance degradation.

I would think it would QUICKLY wear the valve seals? If every time it opened, that valve could waggle on the back end of the seal...Maybe not.. Where are those specs located Dale? I will double check im MY Clymer, AND the Zook SHop Manal.

[Dogma]

I would think it would QUICKLY wear the valve seals? If every time it opened, that valve could waggle on the back end of the seal...Maybe not.. Where are those specs located Dale? I will double check im MY Clymer, AND the Zook SHop Manal.

Well, the Clymer just talks about wiggling more than a little in the valve inspection paragraphs. The FSM (the pdf scan available on BC's site) lists the specs in the service limits charts at the beginning of the book, and again in the top end inspection section.

You have manuals that cover 850s? I didn't think you had wrenched on any other than Steve's family's.

[TheCafeKid]

Ive wrenched on a FEW 850s...But the Clymer manual covers ALL of the shafties, and Im pretty sure ALL of the heads use the same valve size and stem.. The 8v heads were "over valved" which is why they did so well for so long when other people were going to 4 valve heads, and why you can get away with hopping them up pretty good without a whole lot of headwork.

[Nessism]

Just figured out that the GS850 manual as hosted by Basscliff has the wrong Service Limit values in it. The later version of the manual, which I have in binder form has the correct values, and the GS750 and GS1000 manuals all have the same values as my manual.


This photo is from the 1000 manual. The valve spec values are exactly the same as the 850.

[Dogma]

I went and had a look at Alpha Sports to compare the 850 and the 1000. the guides are the same, the valves are not. I would imagine the 1000 has slightly larger heads on the valves, but with the same guide, it's hard to imagine the stems being different, or that the 850 for some reason can allow 3x the clearance.

It may be a moot point anyway. I went out and got out the indicator and put it on the valve that I thought felt the worst. I measured 0.003" one way and 0.0035" the other way. Keeping the indicator on the edge of the valve wasn't easy, so my measured slop may be exaggerated by misalignment of the indicator tip and the edge of the valve. I wish I'd had a test indicator so I could put the shank of hte needle against the edge of the valve.

So, it's approximately right at the edge of the (corrected) service limit. Considering the time and expense of tightening that up, I'm inclined to let it ride. Any chance of someone scanning that updated service manual?

Oh, and the valve seats are wide, about 1.3 on the intake and 1.5 on exhaust. Another difficult one to measure accurately, but I'm sure it's wider than 1.2. Consequences?

[Nessism]

I went and had a look at Alpha Sports to compare the 850 and the 1000. the guides are the same, the valves are not. I would imagine the 1000 has slightly larger heads on the valves, but with the same guide, it's hard to imagine the stems being different, or that the 850 for some reason can allow 3x the clearance.

It may be a moot point anyway. I went out and got out the indicator and put it on the valve that I thought felt the worst. I measured 0.003" one way and 0.0035" the other way. Keeping the indicator on the edge of the valve wasn't easy, so my measured slop may be exaggerated by misalignment of the indicator tip and the edge of the valve. I wish I'd had a test indicator so I could put the shank of hte needle against the edge of the valve.

So, it's approximately right at the edge of the (corrected) service limit. Considering the time and expense of tightening that up, I'm inclined to let it ride. Any chance of someone scanning that updated service manual?

Oh, and the valve seats are wide, about 1.3 on the intake and 1.5 on exhaust. Another difficult one to measure accurately, but I'm sure it's wider than 1.2. Consequences?

I'm not surprised by the mistake in the service manual. The factory 550 manual I have also has the same mistake. There are lots of them. If I had a scanner I'd take a snap shot to show the updated manual...but as already stated, the spec is as shown in the photo already posted.

Regarding your engine, those guides are ok if they are at .0035" or less. You might want to try lapping some of the valves to see if that pitting on the seats will come out. The lapping will also help define the seat width so you can get a good measurement on it. I'm not sure what the consequences of a wider seat margin are but the specs are typically there for a reason.

Good luck and keep up the good work!

[Dave8338]

Ed, have you forwarded a copy to BassCliff for review?

[Nessism]

Ed, have you forwarded a copy to BassCliff for review?

Dave, I don't have an electronic copy of my 850 manual. It's basically the same thing that BassCliff already has I think other than some of the typos are fixed. Not sure it's worth the hassle to get this one scanned.

[Dogma]

Dave, I don't have an electronic copy of my 850 manual. It's basically the same thing that BassCliff already has I think other than some of the typos are fixed. Not sure it's worth the hassle to get this one scanned.

If it contains something that image and instructions from the 1000 manual, then it is much more detailed than the one on Cliff's site. Does Cliff's site need a copy of that 100 manual?

[TheCafeKid]

Ive got the shop man for the 1000 and the CLymer as well if someone needs something...