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ET: Engine (Twin) Decompressor


erik

Well Known and Active Website User
VOC Member
I am now starting to fix the Timing side.Unfortunately I didn`t dismantle the engine because it was a basket case. So I have no idea how to fit the return spring of the valve lifters?especially ,where is the anchor Point of this spring (ET 129)? May be Pictures would help.I heard this could be modified to work better? regards Erik
 

erik

Well Known and Active Website User
VOC Member
this is what i wanted to see.many many thanks ,Erik.
 

stu spalding

Well Known and Active Website User
VOC Member
The right hand end of the spring should go through the right hand end of ET 166. Cheers, Stu.
 

Marcus Bowden

Well Known and Active Website User
VOC Member
The control rod on the left where it exits timing cover has to be a slack sloppy fit as the action is not in a straight line so sealing can be tricky. Trevor S's mod is a good fit and "O" ring seal in the bore of the union then Bowden cable silver soldered into a steel threaded rod. IMG_4311.JPG
 
Last edited by a moderator:

Glenliman

Well Known and Active Website User
VOC Member
Phil's decompressor does look a lot like a hummingbird skeleton. If any of it comes apart, the engine damage is going to be extreme. Ive not read of this happening though?
The thing seems to work on and on like the rest of the bike.
I do like the simplicity of the in head decompressors.
On the other hand, I purchased a new Ossa Trials bike in 1974 and had one of these simple poppet type decompressors fitted to be used as an engine brake. They are very effective when sliding down a mountainside. The rear wheel gives good braking but still rotates just enough to keep you upright.
The decompressor was fitted by Dave Wildman himself, the Ossa/Triumph dealer and Westwood racer.
It came apart on the second day of use, destroyed the piston!
So maybe the hummingbird skeleton is OK.

Glen
 

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