Adjusting valve clearance

phactory · Post by **phactory** » Wed Jun 30, 2010 10:38 pm

I know this is an old post but I am at the point where I am getting ready to adjust my valves and I found this through a search. I can only find one spec listed for the valves which is 0.08 - 0.12mm, which I will probably end up using 0.10 (or 0.004"). I find it odd that intake and exhaust is set to the same clearance. Is that correct? I would expect slightly more clearance on the exhaust valve.

TIA, Phil

LOUD MOUSE · Post by **LOUD MOUSE** » Wed Jun 30, 2010 11:16 pm

.004 is correct for all adjustments. ............lm

phactory wrote:I know this is an old post but I am at the point where I am getting ready to adjust my valves and I found this through a search. I can only find one spec listed for the valves which is 0.08 - 0.12mm, which I will probably end up using 0.10 (or 0.004"). I find it odd that intake and exhaust is set to the same clearance. Is that correct? I would expect slightly more clearance on the exhaust valve.

TIA, Phil

phactory · Post by **phactory** » Thu Jul 01, 2010 6:10 am

Thanks LM! Do the exhaust valves have a tendency to tighten up or are they pretty stable over the course of the adjustment period?

Thanks, Phil

LOUD MOUSE wrote:.004 is correct for all adjustments. ............lm

LOUD MOUSE · Post by **LOUD MOUSE** » Thu Jul 01, 2010 7:36 am

First I want to comment about an earlier statement that if ya have a 180 crank engine after ya have adjusted the right side valves ya need to rotate the crank 180 degrees (one half turn) to adjust the left side valves not 360 degrees.
If ya have the 360 crank then ya do rotate the crank 360 degree (full turn) to adjust the left side after adjusting the right side valves.

Now for the question at hand.

A good question there!
The exhaust valves have a treated face (stelite I think is the word) which is very hard and doesn't Tulip as the intake valve does. (exhaust valves are non magnetic)
As the intake valve has a soft face (compared to the exhaust) it will tulip (mechanical phrase) which is it will lose it's smooth, flat surface and sort of for want of better words Round In at the contact area.
The seat in the head will Round Out also.
As the two areas change the contact surface the adjustment will change (become less) and will require adjustment.
That said the answer is ya can expect some change of all the valve adjustment but more with the intake than the exhaust as the ends (adjustment point) will ware in at the contact area. ........lm

phactory wrote:Thanks LM! Do the exhaust valves have a tendency to tighten up or are they pretty stable over the course of the adjustment period?

Thanks, Phil

LOUD MOUSE wrote:.004 is correct for all adjustments. ............lm

phactory · Post by **phactory** » Thu Jul 01, 2010 8:19 am

Thanks Lm! Yes I have a 180 degree crank, which I just realized from reading my Clymer. So I set the engine to the "T" mark and adjust the right side valves (sitting on the bike I hope), then spin the motor to the "LT" mark and adjust the left side valves.

Funny about the exhaust valves being more stable than the intakes, as in a BMW twin it is just the opposite and the exhaust get slightly more clearance than the intakes, as they are more prone to tighten up.

Thanks, Phil

LOUD MOUSE · Post by **LOUD MOUSE** » Thu Jul 01, 2010 9:21 am

I'd say ya have the points timing procedure correct.
Ya just want to turn the rotor to LT not a Full turn.
HONDA used a material (non-magnetic) for the exhaust valve but not the intake for some reason.
Once in a while ya will see After Market exhaust valves on eBay made of steel (look like steel not gray like HONDA) which I don't recommend using as they will wear for sure. ........lm

phactory wrote:Thanks Lm! Yes I have a 180 degree crank, which I just realized from reading my Clymer. So I set the engine to the "T" mark and adjust the right side valves (sitting on the bike I hope), then spin the motor to the "LT" mark and adjust the left side valves.

Funny about the exhaust valves being more stable than the intakes, as in a BMW twin it is just the opposite and the exhaust get slightly more clearance than the intakes, as they are more prone to tighten up.

Thanks, Phil

phactory · Post by **phactory** » Thu Jul 01, 2010 9:29 am

LM,

That is how my Clymers reads for the valve adjustment, and when I say spin the motor to the LT, I do mean only 180 degrees from the T mark. But first you have to make sure that both of the right cylinder valves are closed. It seems like the motor wants to fall through the adjustment point, which to me means that I am still off one crankshaft rotation.

Thanks, Phil