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Mystery - Gutless 400 four

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Clem2112:
There I was hoping the culprit would be discovered and I could cure my gutless engine.
But those marks in the bores look very wrong as others note and tell me the compression will be down.
Hoping to find that its been the valve seats all along with mine.

hairygit:

--- Quote from: Trigger on December 04, 2018, 09:53:17 PM ---Honing too coarse which has already damaged the rings and a good cross hatch is needed if the piston to bore clearance is with in spec  ;)

--- End quote ---
  Not kidding there Trig, almost looks like someone has used a 60 grit flapwheel on the bores to save the cost of having then properly bored. :o :o :o :o :o :o

Northy:
Ok folks  ..here we go

Checked the bore / piston / ring gap no issues there.
Bore honing is not as course as picture makes out (reflecting alot from the flash) and I've  given them and quick whiz with honer (not a homer) and all OK there. See picture a can lie.

However have found the reason for no power ,importantly the cause and things that don't help matters  :-(

Exhaust valves  from 1 & 2  ( 2  blowing badly)



The head ,and the scratch marks where already there , umm
 

Another issue is the valve seats appear to too wide, spec is  1.5 mm

On on the head we find that where the bonded washer sits the ally been domed / squashed , Both of them.

 

How that's happen I don't know but I will get milled flat and already have some new bonded washers.

No play in valve / guides , One shim missing from under valve spring,all spring well within spec.

So logically thinking, the valve stem seal have given up the ghost - having not been replace at the time of the rebore (although softish the holes are enlarged). This mean the engine is sucking in oil, burning it leaving lots of carbon on the valve etc (there in way!). The seats being too wide allow carbon to form on them  . The valve seat blow then mean no compression , poor mixture
   = NO POWER   :o

Does that  sound right ?  at least its not an expensive fix.


BTW spend most of afternoon removing the remains of the base gasket which had been stuck on with some grey cement the like of which I've not seen before , Why ? .             




 

 

Nurse Julie:
Quote
'BTW spend most of afternoon removing the remains of the base gasket which had been stuck on with some grey cement the like of which I've not seen before , Why ? .             

Because whoever did all the work previously was a muppet. That is appalling work all round. They should be shot. Just my opinion.

Northy:
Agree some muppet been there before ..wasn't my mate ...he would given me the engine to work on. Spoke to him (mate) and we  think we have our suspicions it was done by the BMW car dealer were it spend most of it life or handed out for someone to fix up.
But hey who care's now , its should be sorted and back on road in no time ....... then I'll get back to building the special one.


OH Clem2112  might give you a few pointers ,best check you compression first. ...... and don't let muppets lose in garage with spanner.

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