Valve fixture ideas for 4 valve motorcycle head needed.

[SWAirflowServices]

I need to do a bunch of testing on 2 particular heads and would like to build a fixture just for them. I could use some design ideas. The top of the head is kinda like a Harley only with 4 valves.

KTM450 2.jpg

KTM450.jpg

[Michael Moore]

It looks like that piece near the middle sticks up above the rest of the gasket surface. Is that correct?

If you modified a dial indicator to incorporate the pusher as I did for the Honda 160/175 heads you could make a fixture like the attached active PDF file. Move the post that holds the dial indicator from hole to hole/side to side on the vertical wall.

You could use a gasket to lay out the base, and the only thing that needs to be at all accurate is getting the holes for the indicator in the same plane as the valve guide bores, and then have the hole in the indicator post offset to be centered on the bore.

An alternative would be to bolt the indicator piece to another bit of flat stock and then lightly clamp that stock to the center wall and shuffle it around until you get alignment with the guide, then clamp it more firmly. That would be more fiddly as you'd have to unclamp/reclamp as you moved to each guide, but it does reduce the precision needed in making the fixture.

The attached PDF will go "active" if you click on the image, allowing you to zoom pan rotate the image with the mouse.

cheers,
Michael

[andykaw1]

Oh, thats my same problem.... for Kawasaki 250 and 450 is possible to build this system? Do you have some other image or picture as example?
regards,
Andrea

[Michael Moore]

I had a thought that the post that holds the dial indicator in that quick model I did today should have a longer threaded section. Then you could have a nut on either side of the vertical bulkhead and that would give you some lateral adjustment.

cheers,
Michael

[SWAirflowServices]

The top of the head is totally flat. The part I am particularly interested in is the how to move the valve and measure the movement. I have seen where the a screw moves the valve and the dial indicator has a foot the rests on the retainer. Another where the dial indicator rests on the end of the adjustment screw and another where the screw moves the dial indicator which in turn moves the valve (like Michael's). Michael's seems like the simplest way to go but I am working with 2 intake valves at a time. Should I have them adjustable independently or might someone have a good set up to move them in unison?


Oh, and don't forget that I am making this solely for just this style head and not worried about it being universal.

[Michael Moore]

That cover hole/boss to the 2 o'clock position of the upper left guide looks like it sticks up above everything else. Maybe that's just an optical illusion in the photo.

If that doesn't stick up then your fixture plate doesn't have to jog around it making that part even easier.

Shouldn't you try to have the ability to measure each valve separately, and then both I or E valves together to bring in the full port?

If you have a bar that spans both valves of a pair you probably need a solid foot on one side that hangs down a little below the bar, and on the other side have an adjusting screw. That would let you accomodate valves where the tips are not dead level with each other.

Another thought is if these are DOHC operating through buckets (no finger followers) then make a faux cam of round stock and drill and tap two holes on the guide bore centers. Clamp the bar in the cam bearing spaces. That gives you independent adjustment of the two guides in a pair, but you might need two indicators if you are trying to lift both valves. If your intake and exhaust valves have different center distances then you'd need a fixture bar for each side.

Putting the screw on the end of the indicator does simplify some things. It lets you eliminate threading of the fake cam as all you need are some reamed holes to match the indicator housings and a set screw coming in from the side.

The import indicators are relatively inexpensive. If it were me I'd go with the fake cam (if it is possible to fit one and get it clamped firmly) and two indicators and not try to lift both valves from a single pusher/indicator.

cheers,
Michael

[SSR]

The top of the head is totally flat. The part I am particularly interested in is the how to move the valve and measure the movement. I have seen where the a screw moves the valve and the dial indicator has a foot the rests on the retainer. Another where the dial indicator rests on the end of the adjustment screw and another where the screw moves the dial indicator which in turn moves the valve (like Michael's). Michael's seems like the simplest way to go but I am working with 2 intake valves at a time. Should I have them adjustable independently or might someone have a good set up to move them in unison?


Oh, and don't forget that I am making this solely for just this style head and not worried about it being universal.

Sorry for speaking in Metric (I don't know what increments in inches you guys use), but when making a valve opening fixture of this type I use a thread pitch of 1mm, this means one turn = 1mm of valve opening. Two valves can then be opened equally and easily - you can keep a check on one with a dial guage if you want.
Looking at your head would it be relatively easy to bolt on some steel plate and use a magnetic stand with the dial gauge?

[Michael Moore]

Over here that's commonly done with a 1/4"-20TPI bolt as each pitch is .050".

If using that method without a dial indicator it would be good to have a fairly large diameter head and clear/sharp markings/pointer on the bolt to ensure you can get as exact of a full turn as possible. It is the same idea as using a larger degree wheel instead of a smaller one, you get more lateral motion at the edge with the big one for a given angular change than with the small one.

Being a little off of a full turn could mean a +/- 5% difference in actual lift from run to run and that might give confusing readings if that coincides with a spot where the air behavior is changing noticeably.

Edited to add: a small variance from run to run may be much more significant with a small port/valve/lift engine. +/- a couple thou lift difference on something with a .800"/20mm lift cam and 2"/50mm valve may not be a big concern.

cheers,
Michael

[1960FL]

Here s an example of the one i made to do both Harley TC and EVO heads. it uses a 1/4 - 20 thread, adjuster knob and the dial indicator reads exact thread movement.


Now all that said I know this is a two valve head but you could apply this to a 4 valve if you are trying to open each valve individually or use a setup like this and make a bridge to bind the two valve stems together and open both simultaneously

Rick

[SSR]

Ooh I like that, nicely made!