90PSI warm on all 4 cylinders, no valve clearance at all

[lemonshindig]

So... since I'm new to this, how do I know what valve shim to replace the old one with, if there's no clearance to begin with? I assume I have to put a smaller shim in to make a clearance, then measure that, and figure out the correct shim based off of those numbers?

My bike might have 12k or 120k, not sure. But there's 90 PSI warm in all 4, and absolutely no valve clearance (although I did check the valves when the engine was warm).

This thing runs like crap once it warms up. I have completely dissembled the carbs, soaked them for several days, sprayed out ALL passages, and reassembled several times now. I also did a POR-15 acid etch and tank coating in the fuel tank, replaced the petcock, and installed a new fuel line with an inline filter.

The fuel tees are also new, as are the intake o-rings.

Now I originally had trouble with the bike overheating after 2-3 hours on the highway. Letting it cool off for an hour put it right back into it's happy place.

But the symptoms have gotten worse, MUCH worse. Two weeks ago it would run like hell right after being started. When I rebuilt the carbs again a few days ago, it ran great for 15 minutes then went back to running like hell. The longer I ride, the worse it gets.

My guess is that overheating ruined the new intake o-rings. I am going to pull them and replace at the same time I adjust the valves. I am also going to replace all of the o-rings in the carbs. They are only a few months old but i've pulled and reinstalled all of them 4 or 5 times now, they may be worn out.

Today I rode for about 15 minutes and checked compression. 90 PSI in all cylinders and 3/4 plugs look lean. Then I checked the valve and found no clearance. I threw a timing light on each wire but they spark so fast that I don't think i could see any abnormalities anyway.

Thanks
-Matt

 

[tkent02]

My guess is that overheating ruined the new intake o-rings. I am going to pull them and replace at the same time I adjust the valves. I am also going to replace all of the o-rings in the carbs. They are only a few months old but i've pulled and reinstalled all of them 4 or 5 times now, they may be worn out.

This is all BS. Adjust the valves before they burn up.

 

[Big T]

Matt

read the Top 10 Newbie Mistakes list and go from there

You've been here for months and you haven't adjusted the valves?????

 

[lemonshindig]

Matt

read the Top 10 Newbie Mistakes list and go from there

You've been here for months and you haven't adjusted the valves?????

I'm doing so now, aren't I?

I still don't think the valves are the only issue. They are definitely too tight, working on that. But I'm not expecting my troubles to go away once they're in spec.

 

[boingk]

Check the valves when its stone cold and still sitting in your garage unstarted that day.

After checking them, adjust them.

Don't jump to conclusions before doing NEEDED and ROUTINE maintenance.

- boingk

EDIT: The symptoms you describe could well be caused by your valves (which will need doing anyway) or your carbs (which you should only touch after adjusting your valves). If it is still running badly once warm then I would check your jetting, sounds as though it may be out.

 

[rapidray]

Valves out of adjustment WILL make an engine run poorly! Adjust the valves & LEAVE THE CARBS ALONE until you see how it runs after the adjustment. You will also need to vacuum sync the carbs after the valve adjustment. Ray.

 

[BigD_83]

You can expect your compression numbers to jump if everything else is good. Case in point, I just picked up a 550es, did the valves, and the compression on #3 jumped from 90 cold to 150. All the others jumped up a few PSI as well. Now it starts like a dream where it was a hard starter to begin with.

Getting the valves sorted first puts you at a baseline where the other issues will be more easily solved.

 

[Steve]

Yet another voice chiming in here to say "adjust the valves" and to DO IT COLD.

All that carb rebuilding says one of two things to me. Either you are not doing it right (even though everything you mentioned is the correct thing to do) or you are trying to compensate for another problem (valves) and are not suspecting it.

Yes, you are correct in assuming that you need a thin shim to establish a starting point. Take a look at your shims that you have in there now. Take the thinnest one out, put a coin in its place (to keep the cam from being damaged by hitting the bucket), move that shim to the other locations to check clearance. If that is still not enough, you will know that you will need a shim that is another one or two sizes thinner.

Whatever you do, DO NOT MOVE THE CRANK UNLESS THERE IS A SHIM (or coin) IN EVERY POSITION.

.

 

[lemonshindig]

Yes, you are correct in assuming that you need a thin shim to establish a starting point. Take a look at your shims that you have in there now. Take the thinnest one out, put a coin in its place (to keep the cam from being damaged by hitting the bucket), move that shim to the other locations to check clearance. If that is still not enough, you will know that you will need a shim that is another one or two sizes thinner.

.

I'll see if I can pick up a shorter shim today.

Thanks
-Matt

 

[eil]

Looks like everyone already beat you up pretty bad about the valve clearances, so I won't.

But I will mention that if you still have overheating issues after adjusting the valves, you might have to replace the intake boots. I thought the boots that came with mine looked great for their age. They weren't cracked or hard. But even after I installed brand-new o-rings, the engine was still running rather lean when hot. That finally went away when I replaced the intake boots with brand-new OEM ones.

 

[Guest]

piling on here, compression test etc is meaningless without valve adjust.

 

[lemonshindig]

Looks like everyone already beat you up pretty bad about the valve clearances, so I won't.

But I will mention that if you still have overheating issues after adjusting the valves, you might have to replace the intake boots. I thought the boots that came with mine looked great for their age. They weren't cracked or hard. But even after I installed brand-new o-rings, the engine was still running rather lean when hot. That finally went away when I replaced the intake boots with brand-new OEM ones.

We're talking intake boots, not airbox boots, right?

You might be on to something there. I was baffled because this is a new issue, or at least an issue that got much worse recently. I remember the first time I rebuilt the carbs, I greased the heck out of those boots which would help seal them to the carbs and the head. I've removed the carbs several times since then and never re-greased them. So I'll adjust the valves first, then try riding, then pull them apart and grease them up again. If I see a noticeable difference, I'll replace them.

I'll probably do the airbox boots at the same time, either that or pods. Z1 sells a set of four intake boots for $135. That's probably the best price i'm going to find. *sigh*

Thanks
-Matt

 

[BigD_83]

I wrote a long response addressing this earlier, but looks like I forgot to post it.

Boulevard Suzuki does some really deep discounting at times. Right now their 1000 intake boots are $29.00 each

EDIT http://www.boulevardsuzuki.com/fich...y=Motorcycles&make=SUZUKI&year=1979&fveh=2147

 

[lemonshindig]

Looks like i have to go down .05mm on all 8 valves. I'm surprised they've worn out that consistently. I'm also surprised that I don't need to change more than a single sizing step. Is that normal? Being off by a single size can result in low compression and poor running?

Thanks for the boulevard link, that will definitely save me some dough.

-Matt

 

[tkent02]

Is that normal? Being off by a single size can result in low compression and poor running?

Yes, here's how it works...

Valves heat up and like anything else they expand, they get longer. The clearances are set cold with this expansion in mind, so the valves can still seal even if the engine gets too hot. Now as the engine runs several thousand miles, the valves contacting the seat eventually wear into the seat. After a while it can go farther in before it contacts the seat, the valve actually recedes into the head. This leaves the stem poking out a little bit farther, hence the clearances tighten up as the miles add up. Not always, there are other things in there wearing too, but they usually get tighter.

The only path for heat to get out of the valve itself is through mechanical contact with the seat, which is connected to the head, and to the cooling fins. Maybe a little bit by contact with the valve guides, but not much. There is no other path for heat to get out of the valve. Now if you neglect the valve clearances, and if they get tighter as they generally do, the valve eventually doesn't contact the seat as well as it should, so the valve doesn't cool itself as well as it should. It gets hotter than it should be. When it gets hotter, the valve stem gets longer, and so the valve contacts the seat even less, and the valve gets even hotter. It is a vicious circle, the valve gets hotter and hotter, longer and longer, and cools less and less...

The end result is a burnt valve. When the valve/seat contact is so poor that actual flames start to leak past the edge of the valve under pressure, the valve gets extremely hot in that one spot. Sometimes the edge of the valve gets messed up, then it can't seal so well. Sometimes a pie wedge shaped piece of the valve burns away, but even if it's not that burnt, it won't seal again as well as it should. The cylinder may still run, at least until it burns more, but it won't run right.

Anything else that makes the engine hotter than it should be makes the problem worse, such as a vacuum leak or other lean running problem, or retarded timing.

Adjust the valves correctly, then check the compression. Hopefully you caught it before any damage was done.

 

[1980GS1000E]

A lot of guys here run the valves at .09-.10 to be on the safe side. A valve with clearance is a good thing.

 

[OMGCat!]

If your bike has no clearance then you are definitely on the right track to getting rid of your running issues by doing a valve adjustment. You're chasing your tail otherwise as no amount of tweaking fuel or air is going to mask compression loss due to valves in the process of burning themselves.
I always set my valves (cars or bikes) to the max clearance or even a touch above if I only have aftermarket shims that go in .05 increments. It might be a tiny bit noisier but you will be a lot better off in the long run.
With valves a little more clearance is MUCH better than less.

When I did the valve adjustment on my FZR600 nearly all intake valves were at no clearance. I started with decreasing shim thickness by the .20 (which is the spec) and went from there. I still had to go back and put thinner shims in several of the buckets. This means 6 of my 8 intake valves were OPENED by around .1mm while the bike was running. This is BAD. The bike needs compression to run and squeezing super hot gas through a small opening is kinda how a cutting torch works.

Hopefully you won't have such severe lack of clearance though. The FZR is known for having valves with the harness of dry play doh and I know I may get one more adjustment before it's time for a valve job.

Suzuki built there bikes a bit tougher, the GS bikes especially.

On my GS700 with the clearance set to max spec I almost doubled my last clearance setting interval (around 14k miles) and when I checked them only three were a touch below min spec.
I usually only set them at 10k instead of the recommended 7 just because I've become aware of the wear patterns in this bike over the years.

 

[Nessism]

This is what the valves look like when you don't adjust them. Hopefully your engine isn't damaged like this one was...

 

[lemonshindig]

This is what the valves look like when you don't adjust them. Hopefully your engine isn't damaged like this one was...

I hope not. But it's possible, I put 800 miles on this bike a few weeks ago, before I had ever touched the valves.

-Matt

 

[Steve]

Is that normal? Being off by a single size can result in low compression and poor running?

Think about it for just a moment. :-k

The minimum clearance is 0.03mm.

The interval in shim sizes is 0.05mm.

You could have a valve being held open by 0.02mm, change it one shim size and it would now be at the minimum clearance.

.