valve clearence results- ???

ok just checked my valve clearences. my feeler gauges only go down to .006 I dont have anything smaller.

#1 I= less than .006 (would almost go )
E=same
#2 I=less than .006 ( same as above )
E= .006 ( almost perfect
#3 and #4 exactly like #2

engine cold hasn't run in a couple months.

A fast/short Background-- Bike sat for unknown number of years owner tried to get it running did not have air box so he got some pods, he did get it running but poorly- did a almost fair job of a carb rebuild blamed the carbs as totaly shot and sold it. I bought it followed "church of clean" got a stock airbox and now Im checking valve clearences before I put the carbs back on

 

Your going to need some feeler gauges that go smaller than that if you want accurate results.

 

Hold on now.

Specs are .11mm~.15mm (.004"~.006") intake, .16mm~.20mm (.006"-.008") exhaust.

You can't just go by the fact that a .006" blade won't go in.

Get yourself a proper feeler gauge, metric if you want to make it real easy on yourself; and do it right.

KD Tools' 2274 is widely available: http://www.google.com/search?q=kd+tools ... 00&bih=729

 

Yeah I was getting ready to go to harbour freight or some where to get some, was just wondering if that sounded way off already or not.

 

It's not all that "way off" it's just not accurate. About the only "true metric" feeler around is the one I posted about; you can often find them at Sears. I got mine off the innanet for under $6.

I just got done (tank's not even back on yet, came in the house to cool off) checking my valve clearances for the first time since I put my '83 back on the road, about 5500 miles; and I got:

Exhaust, 1-4: .15, .17, .18, and #3 is somewhere between .19~.20 all in metric.
Intake, 1-4: .14, .13, .15, likewise the #4 intake .11~.12mm.

So it looks like I need an exhaust shim for #1; and need to keep an eye on intake #4.

SO easy with a metric feeler.

 

cool Thanks man. turned out the only thing available close and local was just about what I already had so Ill have to go on in to Pensacola after work tomorrow. I'm just getting anxious to fire it off is all.

 

ok got a Proper set of feeler gauges and the the results are:

Intake #1 thru #4 .127mm (.005in)

Exhaust #1 .102mm (.004in)
Exhaust #2 thru #4 .152mm (.006)

from what I can tell they all look pretty well in spec with the exception of exhaust #1. This will have to be changed I know, is that too far out to get the carbs back on fired up?

 

Let me share a thought with you:

Intake spec is .11 - .15 mm. Since the intake valve stems are exposed to cool intake air and the aluminum head will expand more than steel they probably don't tighten much as the engine heats up. In other words, .11 - .15mm clearance is required at RUNNING temp to cool the valve and get a good cylinder seal.

The exhaust valve stems on the other hand are exposed to hot combustion gasses. That heat causes the valve to expand more than the head - tightening them as the engine heats up. To allow for that Yamaha build an extra .5 mm into the cold clearance of the exhaust valves.

Your exhaust valve is already tighter than the intake spec. How lucky do you feel?

 

As MiCarl says you will be ok for a quick start-up test but don't leave it like that for long.

The spec for inlet and exhaust is for a cold engine and is wide enough that it can be achieved with ordinary tools and available shim increments. The range is set to give minimal clearance at normal running temps plus a little for good measure when the engine gets slightly over-heated.

After all the "ideal" running clearance when hot is zero since it is combustion gas pressure that seats the valve not spring pressure, which is really only there to return the valve against the cam and prevent valve bounce. Running an engine with valves a LITTLE tight will eventually erode the valve and seat with hot gas blowby and will cause imbalanced compression, a major bug-bear for tuning, so fix it before you try to tune.

For XJ valves I've found the steps in the metric feelers are too wide unless you use two of them together (like a 0.08 and 0.04 to give 0.12) a practice which is generally frowned upon by mechanics (a little dirt or a bent leaf can give a false reading). The imperial feelers give the in-between numbers which roughly equate to 0.10, 0.12.5, 0.15, 0.175 and 0.20 and these seem to work well for the 11-15 inlet and 16-20 exhaust ranges.

We also need to avoid chasing false precision. The only available increment for changing the clearance is 0.05mm, which is more than the specified range of 11 to 15 on the inlet, so if it measures at 11 do you change it and make it out of spec (loose) at 16 or wait till it seats a little more (ie. down to 10 or 9 which is now out of spec low) and then change it back to spec by adding the 0.05?

It's a rhetorical question of course, because not only are we unable to reliably measure to +/- 0.005 mm we are unable to increment the clearances by similar amounts without grinding the shims.

I've found a good compromise is to just measure the valves at every tune-up and increment up those that are at the bottom end of spec, leaving the others be. For what it's worth my idea of "bottom end" of spec is 0.10 fits but 0.125 won't (for inlet) and 0.15 fits and 0.175 won't (for exhaust).

 

ALL 4 exhaust valves are tight, one horribly so. Spec is .16mm~.20mm and you're at .152 on 3 of them.

I also agree with not running the motor too much with #1 exhaust that tight.

 

This is one of the sizes that is tough with imperial gauges. His .006 gauge goes, but his .007 does not. So he's more than .152mm but less than .178mm.

Those three may, or may not, be in spec.

Personally I wouldn't lose any sleep over a .152, especially if the gauge slides in quite easily. The factory book for my Venture calls for exhaust clearance of .16-.20mm, but lists the imperial measurement at 6-8/1000".

 

So you guys are the heavies, Ive read a ton of your stuff and much has been learned from you (many thanks). so I thought I was pretty good except for the one, No question now before I fire up Its changed call that done. now as far as the other guys-- should I try to get on the loose end? See what pad numbers I have and drop a size? you guys Know best and I believe that and I appreciate your help, so if it was YOUR bike, what would you do?

 

A lot of SAE sets have a 0.0015" gauge. If yours does you can stack it with the 0.005" gauge. If they'll go in together then the lash is at 0.165mm which is in spec. If you go to a thinner shim you'll be too loose.

In fact, you know they're at least .152 mm. If you go down a shim size you'll be at least .202 - too loose. But not so loose to worry about.

If you do change them remeasure (that goes for all the shims actually).

 

I actually have 2 sets and I can do that, the one Im gonna change now before the new battery hits the cable. can I get the shim tool at harbour frieght or sears? I know she's old but I fell in love with her, so she's gonna get what she needs.