Cafe Racer Forum banner

261 - 265 of 265 Posts

·
Registered
Joined
·
5,527 Posts
I don't troll don't think I even really know what that is, is it anything like calling somebody names? That would make calling somebody a troll trolling
:/ just stating the facts for the fella, it don't work the way you said it worked.
 

·
Registered
Joined
·
2,107 Posts
Cyorg, you are talking nonsense, i[/COLOR]f you have a way of measuring valve clearance on a Honda overhead valve engine while it is still at operating temperature, please share with us how that can be done.

re: “there is virtually no clearance when the engine reaches operating temperature” <- Because the valve has elongated due to heat to a point where the valve clearance you previously set at room temperature, is all but gone! As in, close to zero excess backlash between the mating parts as possible, without actually making the valves leak.

re: "
Are there not other SOHC Honda engines out there where clearance increases with heat? No! because then it would not be a valve clearance adjustment, that would make it a pre-tension adjustment.

Well I didn’t quite know what to make of your statement about measuring valve clearance at operating temperature. What exactly is it that prevents you from doing that? Admittedly it would be annoying to do it on the CB400 twin because it has a valve cover as opposed to inspection caps. If one was inclined to do so...In the shop or garage, remove the tank, move the coil wire brackets if necessary, hook up an auxiliary tank, check the clearances cold, reinstall the cover, run it up to operating temperature, pop the cover off, and recheck. In the shop we often used small light air driven impact guns or air ratchets to increase efficiency, so with the tank out of the way, the cover can be removed in less than a minute. So the stem isn’t going to shrink much in that amount of time if that is what you are thinking? If you simply want to establish what operating temperature clearances are, then there are other bikes would be easier. How hard would it be to pop the outboard inspection caps off say a CB750K when it is at operating temperature. If you don’t want to remove the timing cover, just use the starter or rear wheel in gear to bump the engine over until the intake is open and then measure the exhaust (and vice versa). Takes no time at all. How hard is that? That’s why god invented gloves. Less aggravating that doing plug chops on that engine.
How about a GL1000 or variant? After a ride, pop the valve cover off and use the same method to rotate the engine. If you want to line it up to the T marks, leave the sight glass installed before you go for your ride. Again, I have no idea what you think prevents you from checking. Yes they should be set cold and that is probably what makes this a somewhat asinine conversation.
You are certainly not alone in your thoughts as the majority folks think the same way. I feel like I’m not following my tag line which translates into “don’t piss into the wind” , and not sure why I’m repeating myself here.
As previously mentioned, I don’t know where his clearances will end up and I don’t recall what the rocker assembly is made out. Still betting it won’t be virtually zero.
Have a look at the photo, again keeping in mind that the distance between the rocker shaft and the cam comes into play and so does the distance between the valve seat and.. well let’s use the rocker shaft again to keep it simple. Note the amount of aluminum between the valve seat and spring seat. Also note the amount of aluminum between the cam and the rocker shafts. Given that, and the fact that aluminum expands at what? Almost twice the rate of the stem? You can look it up. If you remain fixated on just the stem, then you are missing a large part of the equation. As the head expands, the rocker shaft moves up “and” away from the cam and the valve seat moves away from the rocker arm shaft. Not talking giant amounts, but it adds up. Don’t let the bolts get in the way, they have some stretch. Expansion of the seat and head of the valve itself would cancel out a minute amount of the stems expansion. You want him to have the facts, but you’re making an assumption.
I am by no means an expert on valve trains and a lot of what I was taught back in the day, no longer holds true. I found that out a little while back when exchanging pleasantries with someone who designs them for a living. Anyway you or anyone else on here is welcome to prove me wrong. Learning and dispelling old beliefs is a good thing.
In the meantime I will gladly remain a one percenter of the valve lash community.

BTW. Not aware of any motorcycle engines, but some engines are set hot, some even running.... and when I asked “ are there not other SOHC Honda engines out there where clearances increase with heat” .. that was kind of a rhetorical question.

CD725113-2F7F-42CA-BDFA-68E25AA239AE.jpeg
 

·
Registered
Joined
·
5,527 Posts
Operating temperature for this one is when the thing is running
and you can't set this one when it's running.

We don't have to figure out what expands where Honda already did it for us.
They did it on a room temperature engine I guarantee you, otherwise that would be detailed in the service manual.
 

·
Registered
Joined
·
1,656 Posts
part of valve clearance is the time the valve sits on the seat to transfer heat.
i dont think it goes to zero hot...

or maybe it does. hell if I know...
 
261 - 265 of 265 Posts
Top