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Discussion Starter #1
I had a burned intake valve replaced at 12000 miles. the mechanic said the top of the guide wont hold a seal on, so he put it together without the seal. I think the stem was mushroomed and forced through. he said they remove the seals on racing engines for lubrication? anyone ever have this happen. im thinking of having it done correctly and at the mileage maybe replacing the piston, I think it was run hard because how slow they are on the road. any advise is appreciated thank you.
 

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You are likely wise to replace the possibly mushroomed valve, perhaps a new guide as well and certainly a new guide seal. Inspection of the cylinder might reveal advisability of new rings, a hone and possibly a new piston. They may still have life in them. If you are doing the disassembly yourself the labor saved could well pay for a Wiseco piston and a complete head service & re-build.
 

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Replace your mechanic if he put it together without offering you the option of replacing the guides.. No seals "may" make sense on a drag bike but generally it never makes sense.

If you decide to replace the guide yourself. Heat the head in an oven, they come out fairly easy and you can cook a snack while your doing it.. Don't forget the clip...

Always grind off the top of a mushroomed valve stem or at least file it down before attempting to pull it out through the guide.

Or... buy a good used head off of ebay or someone here.

Chances are the valves were run way to loose due to lack of maintenance and the rocker smashed them into little mushroom tops.
 

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Discussion Starter #5
thanks for the help. I think ill also do the base gasket update. its very lean, takes long to run without the enricher out. Is there any known carb specs that work. its a 08 at 400-2200 elevation. thanks again.
 

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For the fun of it look into the exhaust port. I have seen some heads with a lot of casting flash (???) limiting the size of the exhaust port. Some heads are pretty good. Some aren't. You can compare it to the size of the exhaust pipe where it bolts onto the head. I bet the pipe is a lot bigger.

I opened up the port on one of my heads and it seemed to help the performance. If you are going to have the head all apart anyway and if you have a die grinder it might be something you want to do.

I started opening up the port before I took the picture. Originally it was a smaller hole.
You can see the gasket on the pipe and the same gasket in the head. A lot of metal can be removed.
PA280049 (2).JPG
 

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If you run an intake valve without the seal you will burn a little oil but probably nothing worse will happen. If you run an exhaust valve without the seal, you will probably coke up the valve stem and get sluggish performance especially prior to warming completely up.
 

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If you run an intake valve without the seal you will burn a little oil but probably nothing worse will happen. If you run an exhaust valve without the seal, you will probably coke up the valve stem and get sluggish performance especially prior to warming completely up.
On one of my TW's with a bad exhaust stem seal the back side of the valve was covered with hard carbon about an eighth to a quarter inch thick. A lot of hard carbon had been deposited in the exhaust port / passage too. Is that what you meant by saying "coked upped"?
 

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Discussion Starter #10
thanks for all the input. if it doesn't carbon up on an intake valve I think I will run it this season the way it is. it has over 12000 miles ill do the complete top end over winter, I don't want to tear it apart now anymore. I'm old and slow I really like this bike and the low gearing.
 
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