[eyeore302000]

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Been looking through the forums for the answer but havent found it yet, i'm sure it is there somewhere. Can valve guides and or seals be changed without removing the head ? I saw a couple threads that said something about using compressed air, is this just for the guides and is there a technique listed somewhere ?

 

[GregForesi]

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I believe you will have to pull the heads to replace valve guides (they are a press fit). The valve stem seals can be replaced with the heads in place. An old spark plug can be altered and an air hose fitting welded on top. This special tool has to be long enough to tighten in the sparkplug well. With air pressure on a cylinder the valves can't slide into the bore when the retainers are removed.
I have seen an alternative to air pressure...push a length of clothesline into the sparkplug hole and carefully spin the crank (with the stator bolt) to bring the piston up (remember to leave enough rope on the outside so you can pull it out). That will push the rope against the valves and keep them from going into the bore. When you're done with that cylinder turn the engine backward and pull out the rope. With the sparkplugs out - turning the stator bolt backward for a bit is OK.

 

[RA72]

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There's a lot of difference between valve guides and valve seals.... da

 

[brianinmaine]

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Since you have to take the cam shafts off to change the seals, you have the belts off also, either air or rope is fine in the holes to change the seals. You should be able to spin the motor pretty easy then if both cams are off. I've head that you can bolt a solid bar across the mounting holes for the cam, then use a big open end wrench to compress the spring. Watch those keepers! They like to fly!

Guides look to be a pretty special thing on these heads - I'd probably look to have them done at a machine shop unless you already have the know how and special tools. I thought about it myself, then ended up getting a different engine on a parts bike.
Good luck!

 

[eyeore302000]

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I am green as grass wrn it comes to tearing in to engines I believe the valve seals r wut I need to do. The rope trick sounds pretty genious.

 

[Old Fogey]

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As Greg says, you can hold the valves with air pressure. Good tip by my mate Bill here: http://www.ngwclub.com/forum/viewtopic.php?t=14861

The valve guides are a different matter.
First problem is locating some! They are getting very scarce.
Second, they need to be removed and replaced with the head HOT. Most partners do not appreciate the wonderful smell of cooking heads!
Third, guides need to be reamed out to size after fitting. The valve stems are a very peculiar size, requiring an adjustable reamer to do the job. Unless you have experience in handling a straight flute adjustable reamer, do NOT attempt it.
Fourth, Unless you are lucky and get the guides back in exactly right, the valve seats will probably need to be re-cut.
So, all in all, the answer is first find your guides and then take the heads to a machine shop.
Gives you the opportunity to spend more money by getting the heads surfaced at the same time!

 

[eyeore302000]

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I am gonna give the valve seals a shot. I have 2 spare motors out of grames I can practice on.

 

[machinehead]

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You dont mention the miles on the motor so unless there are mega miles on it i would not worry about the guides.
You can always do the " wiggle test " when you are changing the stem seals ... just try to wiggle the valve stem back and forth as you go through the seal replacements and look for one that is looser than the rest. Hopefully all will be relatively the same with next to no axial movement at all.