KIPS main valve jamming up

[TheRadBaron]

I'm doing the top end on my '89. When I got this bike the left and right subvalves were snapped and not functioning but the center main valve worked smoothly. In the process of doing the top end I bought new subvalves and collars, and had the cylinder replated by Millennium.
I'm putting everything back together tonight and I'm having trouble. Everything works smoothly until I tighten down the cover for the center main valve. When the cover is tightened down the valve jams and locks up the mechanism. I took out the wave washer and tried it and it's the same thing.
With the cover off, if I push hard against the aluminum carrier that the center valve shaft rides in with my fingers, everything gets tight. It almost seems like the aluminum carrier is being jammed into the KIPS actuation shaft when it's tightened down that last little bit. It seems like I might be missing something obvious since I haven't changed anything with the center valve and it was working when I took it apart, but I can't seem to figure it out. Can anyone shed some light?

[Keystone]

Did you put the spacer (circlip part#92026) back on? All your kips o-rings are there and in good shape? The gears on the operating shaft are facing the right direction? Left and right subvalves have slight differences, are they in the right place? Everything is lined up according to the manuals diagram? Just thinking of all the obvious stuff.

[KDXGarage]

Any chance there is a plating build up on the cylinder? A guy I know had that happen on his H model.

[TheRadBaron]

I came to the same conclusion about a buildup of plating and it seems very likely that that is the problem. I think some plating got built up on the bottom face of the exhaust valve bore and it's reduced the operating clearance enough to jam it up. I'm communicating with Millennium now to see what they think.
Do you have any idea how the guy who had this problem on his H went about fixing it? I'm not sure what the best course of action to take is and I really want to get this bike up and running. Thanks.

[Joshmcmillan]

Did you cover everything with 2 stroke oil or grease before assembly? If you throw it together without lube it jamms up pretty well.

[TheRadBaron]

Yeah, everything was lubed up well and everything was verified as being in the proper locations and orientations. At this point I'm 99% sure that the plating buildup is the problem. I can see wear marks on the bottom of the valve bore where the face of the valve has been rubbing when the cover is tightened up.

[TheRadBaron]

So my next question is in regards to fixing the problem. There's not much thickness that's causing it to bind at all. Maybe a few thousandths. I'm thinking that a bit of work with a Dremel will clear everything up, but I'm not sure how much end play there should be. I don't want to remove any more material than is necessary but I don't want it to be too tight either.
I think I need someone's help to figure it out. I'm thinking the best way to tell how much clearance should be between the face of the valve and the bottom of the valve bore would be for someone to remove the cap that covers the valve and do the following:
-push the valve shaft inward until it's tight against the open-sided locating clip and take a measurement of the distance from the end of the shaft to the face of the aluminum shaft holder. This could be done with a caliper with a depth gauge on the end.
-next, remove the locating clip and push the valve shaft inward until it bottoms out on the bottom of the bore. Then take the same measurement. The difference between the two should tell me how much clearance should be present between the valve face and bore face.
Would anyone be kind enough to do this figuring for me? The frame might interfere with getting a caliper in the position to take a measurement but I'd even take a good guess at this point. Like "it looks like it pushes in about 1/4 of the thickness of the locating slot in the shaft" or something like that. I'd really appreciate any help since I'm kind of at a loss. Maybe Millennium can shed some light on it, though.

[KDXGarage]

Is it possible to sand/lathe down the KIPS part??

Is the area where it rides OK to sand/file??

[TheRadBaron]

I could remove some material from the face of the valve and this would probably solve the problem, too. It might be the easier option, in fact. I'm waiting to hear back from Millennium before I do anything, though. I'm hoping that they might have a slick way to remove the plating from the area in question. I sent them the first email on Friday, so hopefully I'll hear back from them on Monday.

[TheRadBaron]

Well, I heard back from Millennium the other day and they assured me that they can fix the problem. I'm not sure how they plan to do it. Maybe they have some method to strategically remove plating from an area. They sent me a prepaid UPS label, so I boxed up the cylinder and sent it their way. Hopefully they get everything fixed up. I have faith in Millennium. They seem to be a stand-up company.
I'll report back when I know more.

[6 Riders]

Did you send the main valve in w/your cylinder the first time?
Just curious, I've been told that you should, just like sending the piston with it.

[KDXGarage]

sulfamic acid