HPP exhaust valves.

[evo550]

Anyone know of an exploded view of how this system works. Mine's not, and I'm FIIK why.

[Hoony]

i can photocopy oem manual if that helps.

A common mistake most people make is they expect valves to be closed when cylinder is on bench.

 basically the valves need to be fully open when the cylinder is NOT on the crankcase. the cam on the crankcase holds them shut.

[evo550]

Hoony,
I have a clymer manual, which isn't all that good when showing assembly of the system, lots of words and not many pictures leads to confusion
I think the assembly in the cylinder is good and I knew about the valves being open (because you told me once before) and as I slide the cylinder down onto the cam I have to push the rod across wich allows the cylinder to drop down all the way, at the same time it closes the valves.
I've got a funny feeling the cam isn't moving as the revs rise, now I am pretty sure the mechanism is correctly assembled behind the water pump, but what I'm not sure of is how this then activates the cam in the crank.

[smed]

http://www.powersportspro.com/pages/OemParts?aribrand=HOM#/Honda/CR250R_A_(86)_MOTORCYCLE%2c_JPN%2c_VIN%23_JH2ME030-GC800021_TO_JH2ME030-GC808068/WATER_PUMP/CR250R-86-JPN-A/2Y14KA4EKA48E0400C

This is for 86 CR250,it is a cup & ball type which relies on centrifugal force pushing the balls outwards as the revs rise turning the arm which in turn operates the powervalve,with the cylinder off if working properly you should be able to grab the arm with pliers & gently try to turn it one way or the other against the spring pressure & let it go & it should return by itself back to where it started,don't turn it far though only a tiny little bit & don,t force it,gently,gently otherwise it may spring apart inside,if it flops around when you try to turn it or wont move at all it is not working properly

[evo550]

Ok, so I have taken the clutch cover off and the mechanism behind the waterpump seems intact and the "Y" arm with the ballbearings on one side and a spring on the other side all moves fine (although the spring seems to have alot of tension on it and I cant imagine those small ball bearings over powering it)
The next bit I'm not real sure about, which is the arm that runs up through the crank case. I imagine there shouldn't be much force required to turn this, as the only resistance should be the small springs that return the slides closed/open.

[smed]

With the clutch cover off & the upper part disconnected the arm that runs up through the case should turn with no resistance or very little,part #31 bush maybe sticking.


http://www.powersportspro.com/pages/OemParts?aribrand=HOM#/Honda/CR250R_A_(86)_MOTORCYCLE%2c_JPN%2c_VIN%23_JH2ME030-GC800021_TO_JH2ME030-GC808068/EXHAUST_VALVE_86-87/CR250R-86-JPN-A/2Y14KA4EKA48E0502A

[evo550]

Shouldn't I be able to move arm with the cylinder still on, the only resistance should be the springs #18 and 19...Yeah?
What position should the lever on the bottom of the arm be in, shouldn't it be facing outwards and as the clutch cover is fitted it gets depressed?

[smed]

yeah the springs should be the only resistance felt,checking the arm movement with the upper part disconnected & the clutch cover off just proves that the arm is not binding in the cases.

I don't remember which way the lever should face only that i thought it could only go one way otherwise it would not line up with the upper part in the bottom of the cylinder.

[evo550]

Seems as though the problem lies in the mechanism in the cylinder, once the barrell is off the connecting rod between the bottom end and cylinder moves freely. The valves look half open just sitting there.
Problem is now related to the rebore I just had on it, which has widened the intake port enough to allow the top ring to pop out of it's groove and stop me from pulling the cylinder right off. I am so over this bike.....

[evo550]

So, I got the cylinder off and the valves are opening and closing fine, although I'm not sure what resistance should be there, but once I got a screwdriver up into the base where the activating rod goes it open and close well.
I'm now thinking it could be the spring in the mechanism behind the waterpump, It's real stiff and looks like a valve spring from a V8, did Honda paint them any colours?
But anyhow powervalves are down on the adgenda, as the brand new piston/rebore has melted itself to the exhaust port. and since it was on the last oversize, a resleeve is required.....did I mention I was over this F%$#K'n peice of S^%T