Valve Adjust

[rinkydink]

Bike is a 76 R90/6-----21k miles on the clock.. I have been noticing a ticking from my right cylinder lately so I figured a valve adjustment was due. I have no local dealer anymore so I am forced to tackle this myself. I searched valve adjust on this forum and read Duane's excellent article concerning this. I have taken rocker covers off and at TDC I find the clearances very tight on both sides. I can't even get a feeler gauge in between any of them. No matter how much I fiddle with the crank I cannot get any clearance between the rocker arms and valves. I have the OT mark in the window and understand it doesn't have to be exactly centered. Both valves are closed on the side I'm checking and the rocker arms wiggle some but I'm shocked at their tightness. I rotate 360 deg. and the other side is the same. Could they really have gotten that tight? I am a tad nervous as I've never done a valve adjust before. I am referencing a Clymer manual also so I am not flying totally blind. Any words of wisdom? TIA

[Jean]

Yes, they could have gotten that tight as the OEM specs are REALLY tight.
I have a copy of the 1977 shop manual that shows the normal spec for the valves as I=0.10mm, E=0.15mm. Sometime in 1987, there was a lively discussion about valve setting in the Airheads magazine (I think) and the intake spec was recommended to be increased to 0.15mm and the Exhaust at 0.20mm. This is still pretty tight. Now, this spec was the same for ALL the bikes coverred in the manual for 1977; all from R60/7 thru the R100RS.
Anyhow, This what I've been running since then.
In my OLD Clymer manual, they list the tighter specs for the /7 models and the looser spec for "all other models".
In case you don't have mm gauges, the 0.15mm is 0.006 inches and the 0.20mm is 0.008 inches.

You should check the torque on the head bolts BEFORE trying to adjust the valves. If it's not just right, it could make a few thousanths difference in the clearance you are trying to get. That may be part of your problem now. I think you already know to do all this with a "cold" engine. Right?

I've just checked the 2003 Clymer; all Intakes are listed as 0.10mm although the exhaust is listed at 0.20mm, with NO note that the /7 models are different from the earlier models. Based on the previous discussions, earlier manual, and my experience with the various settings, I think I=0.15mm and E=0.20mm is the way to go.

[SteveD]

I think it was gspd that suggested tighter clearances were ok? Anyone recall?

I've recently done mine at 0.10 and 0.20, but today I'm planning on going to 0.13 and 0.18 which is what the local airhead pros use. They believe the 0.13 gives a better idle, or maybe that was it was easier to set? Can't remaber exactly but it was their preference.

[ME 109]

GSPD liked .1 and .1mm checked regularly.

Fun Bags liked .1 and .15mm, claiming lash was affected by too tight setting.

IIRC............

I run about .1 and .1 for a little more quietness.

It's the exhaust we want to be most concerned about imo, and if we aint going to look in there very often, tight is not the go!

I would recommend .2mm ex and .15 inlet to anyone who was slack/unsure in the maintenance dept.

[chasbmw]

You do need to keep an eye on tappet clearance, because if it continually closes up, then would indicate that you are suffering from valve seat recession. This if left unchecked will result in a dropped valve, which is expensive.

The ticking from your right cylinder is quite possibly end play on the rockers. Can you move the rockers up and down on their shafts? They should be set so there is almost imperceptible up and down play and the rocker is free to rotate.

Various ideas on the web about what methods to use to eliminate the play, however unless you fit the later shimmed rockers the play will come back over time.

Charles

[Kurt in S.A.]

It wasn't mentioned but when checking the valves, it is important to verify that the side you are checking are at TDC on the compression stroke. Ensure this by 1) removing the spark plugs and putting your finger over the hole while turning the engine. When you feel pressure on your finger, you are in the compression phase of rotation...the next time the TDC mark comes by, you can check the valves. Or 2) put the tranny in 4 or 5th gear, rear wheel off the ground. Turn the rear wheel while watch the valve action (say the left side). When the intake valve opens and then closes, you're beginning the compression stroke. Move back to the timing window and bump the rear wheel slowly until the TDC mark shows up again...set the valves on that side. From this point, you can rotate the flywheel 360 degrees for the other side...or repeat the above steps.

As for FH, I recall one of things that he liked to do was use the pitch of the adjuster bolts to set the valves. I forget the exact numbers, but the idea was the the rocker arm tappet and the end of the push rod are not completely flat and will make contact when the high points first meet. He liked to run the adjuster into until it was lightly seated, and then loosen the adjuster the appropriate turns or partial turns to result in the final setting he wanted.

Kurt in S.A.

[ME 109]

As for FH, I recall one of things that he liked to do was use the pitch of the adjuster bolts to set the valves. I forget the exact numbers, but the idea was the the rocker arm tappet and the end of the push rod are not completely flat and will make contact when the high points first meet. He liked to run the adjuster into until it was lightly seated, and then loosen the adjuster the appropriate turns or partial turns to result in the final setting he wanted.

Kurt in S.A.

Ooh, GSPD would be rolling in his grave. Wait a minute, he's not dead. His last post told us so.

GSPD used the adjuster thread pitch, flats and half flats thingy.

Fun Bags is a feeler gauge guy. (amongst other things )

[rinkydink]

Thanks guys. Per your replies I feel confident I am doing everything right so they are indeed that tight. With only 21k actual miles I am thinking I don't have valve seat recession just yet. I will check the head bolt torque (gingerly) and rocker arm play and carry on.

[Kurt in S.A.]

As for FH,

Ooh, GSPD would be rolling in his grave.

Yikes...my bad...apologies to all involved! Mea culpa!

Kurt in S.A.

[Jean]

At 21K miles I could not imagine rocker-arm play would be significant...unless there had been a severe loss of lube sometime in those 21K miles!
0.13mm and 0.18mm sounds nice. Right in the middle.
I am a (touchy) feeler-gauge person. Got lots of metric tools.
Lotsa Km on the old hoss, too.