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Large valve clearance. On purpose?

  • Thread starter Thread starter KiwiGS
  • Start date Start date
K

KiwiGS

Guest
Is there any reason some one would run xtra large valve clearances.
I have double and triple checked my clearances and they are all out of spec and all by the same amount.
The top looks to have been off. (bolts had antiseeze on them)
The bike has (allegedly) only done 66000 kms. I find it hard to believe that it come off the line that far out of spec. So that leads me to think some one else has set the clearances.
I am confused.
Cheers
 
How far out of speck are they. I know some are here like try and set them on the larger side just to be safe.
 
chef1366 said:
Valves tend to tighten over time. Someone set them wrong.
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Thats what I think too, but did they do it wrong on purpose?
n1elkyfan said:
How far out of speck are they. I know some are here like try and set them on the larger side just to be safe.
Click to expand...
The range is 0.03mm-0.08mm and mine are a tad over 0.1mm

I am going to leave them at that. As Chef says they will tighten overtime.
See what they are next time.
 
someone might have thought that if they set the gaps larger they wouldnt need to attend to them again in a long time - lol
at 66ooo kms you are looking at overall aprox (and only aprox) 0.3mm down in shim thickness so theres no way you still have factory shims
what sizes are you at? 2.40 - 2.60?
 
It will be noisy and you won't be able take advantage of the full duration.
Other than that I don't think it will hurt.
 
chef1366 said:
It will be noisy and you won't be able take advantage of the full duration.
Other than that I don't think it will hurt.
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Funny you should say that. When I fist got it running I could not believe how quiet and smooth it was.
I have my feeler gauges at work so I can use the engineers measuring equipment to check them. I dont expect them to be wrong. Who knows though.
Cheers
 
I have a couple right at .1 mm, but all of them is a bit odd, especially if they used to probably be even wider than that and tightened since it was done. Dropping a shim size (probably a little wider than labeled too me from .03 to .1.
 
KiwiGS said:
Funny you should say that. When I fist got it running I could not believe how quiet and smooth it was.
I have my feeler gauges at work so I can use the engineers measuring equipment to check them. I dont expect them to be wrong. Who knows though.
Cheers
Click to expand...

If you get the valves adjusted, you're going to be amazed at the difference. I did mine a month ago, it's been 8000 miles and 3 years since last adjustment, and the throttle response improved greatly.
 
You're safe to run a 0.1mm gap but I'd be a tad nervous going wider especially if you like plenty of revs - you could end up spitting a shim out.
 
You're also subjecting the valve train to higher impact force, that noise you hear is caused by the cam lobes hitting the buckets. While it may not cause a problem in the short term, it will increase wear, and decrease performance as mentioned earlier due to a shortened duration.

Keep in mind that the ideal theoretical clearance is 0, with the valves still completely seating. We can't achieve this ideal though because of the large temp range these components must endure, so we add enough clearance when the engine is cold, to allow the valves to fully seat even when the engine is extremely hot. If the clearance is too tight, the valves can't seat when the engine is hot, and the exhaust valves therefore can't transfer the intense heat they're subjected to, leading to imminent failure.

So in short, too much clearance is better then not enough, but the factory spec is there for a reason.
 
Off topic, but man you wanna talk about a godawful noise... The first 5 minutes after replacing a stator before the oil gets to it... that is some scary stuff.
 
I set all of mine between .06 mm and 0.1 mm, and for a street bike, that should be fine. Oldtimers always say it's better to have a LITTLE tappet noise, lets you know the valves are set right. As they will wear tight, it's insurance your valves will continue to close completely for a while. I wouldn't go any looser than 0.1mm. When I first dug in to the valves, it was because all of my cylinders read marginal compression, and they were all tighter than 0.04 mm, which was the smallest feeler gauge I had. But they must have been really tight, because some shims went from a 2.85 to a 2.75 or even a 2.70. Now if I can just get my new AGM battery to work, I'll do a quick compression check, set the ignition timing on the Dyna S, and finish tuning the carbs I just cleaned and installed a Stage 3 Dynojet kit.
 
I guess I'm like some vicious old ill-tempered nun when it comes to valve lash, but spec is spec. If all of your valves are 0.10, then all of your valves are out of spec.

It's true that you don't want your valves too tight, but don't start second-guessing the engineers who designed these things. Do you think they pulled those numbers out of their arses?

It's just amazing to pull the engine apart to check the valve lash, determine that it's wrong, and take no action. Seems pretty pointless...

My advice is the same as the factory shop manual's: set the valves to 0.03 - 0.08, and re-check in a few thousand miles.
 
I guess my philosophy is (and apparently not alone) that if I can't get a .04 under it, then it's .039 or less, so .01 mm from being too tight (which is a very bad thing). Pulling the cover, replacing the gasket, etc... is a bit of a pain. If one is that close, I'm gonna just go ahead and drop it down one shim size. If that takes me to .09 or .1, so be it. Running a little loose for a couple thousand miles is preferable to running to tight or having to go back in a month from now and adjust them again.
 
doctorgonzo said:
Running a little loose for a couple thousand miles is preferable to running to tight or having to go back in a month from now and adjust them again.
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Very true, but are you really going to go back and check it in a couple thousand miles? Because they tighten up (meaning they'll get quieter), and they are already relatively quiet to start with, it will be hard to guess when they reach that magic minimum clearance number. I see robertbarr's point, but I also agree with the majority of the others, I tend to leave them on the looser side. If you were to go to the next size shim on all of the valves, they would still be well within the middle of the range, so it's not really an issue of them getting too tight in a couple thousand miles. Besides, how fast do they change clearance, anyway? I have not noticed any changes worth changing shims for in the last 14,000 miles on my wife's 850, so I feel they have stabilized a bit, but that doesn't mean I never have to check them. 8-[

.
 
I bet they set the clearances using 16 valve specs by mistake!

80 1100E specs are .09 to .13mm
 
Steve said:
Very true, but are you really going to go back and check it in a couple thousand miles? Because they tighten up (meaning they'll get quieter), and they are already relatively quiet to start with, it will be hard to guess when they reach that magic minimum clearance number. I see robertbarr's point, but I also agree with the majority of the others, I tend to leave them on the looser side. If you were to go to the next size shim on all of the valves, they would still be well within the middle of the range, so it's not really an issue of them getting too tight in a couple thousand miles. Besides, how fast do they change clearance, anyway? I have not noticed any changes worth changing shims for in the last 14,000 miles on my wife's 850, so I feel they have stabilized a bit, but that doesn't mean I never have to check them. 8-[

.
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Some of it was working with what I had shim-wise. Example, a .04 wouldn't go under it and it had a 2.60X in it. I didn't have a 2.60, or a 2.55X only a 2.55. So I went from the 2.60X to a 2.55 which took me to .1. I COULD have put the cover back on knowing one was close to being too tight (or maybe already was) ordered a 2.60 and a 2.55X and waited for them to arrive, then pulled the cover again and gotten them perfectly in spec. Instead I said screw it, and put a 2.55 in there.
 
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