Forum

[Reg]

I've just breathed a deep sigh of relief. After fiddling with the de-compressor cable prior to removing said component, I had one last stroke on the kick-starter, and bingo! Compression restored. I actually tightened the cable, which seems the wrong way to go, but hey-ho, I'm not going to look too deeply into it. Started second kick and went for a short run and all was well. Boy am I a happy chappie. Now I can spend time worrying about OE the piston. Oh the joys of Enfield ownership. Many thanks for all the learned comments.

[Bullet Whisperer]

Good news, then, Reg and it didn't have to cost a penny! Regards, Paul.

[Alan R]

well---- not yet at least (Knowing nod & wink )

[Reg]

Back again I'm afraid, with tales of woe. Compression has once again deserted me. Now the bike is almost impossible to start and revs very fast with throttle closed. Wouldn't shut down using ignition switch, had to use decompressor to stop it. So I'm going to have to go bravely where I have never ventured before, and remove both head and barrel. The thing is, how will I know if the valves need grinding or replacing? Is it good practice to change piston rings, or can I leave them alone if they are free in their grooves? If the valves need grinding how will I know when to stop? Would I be better off taking the head to my local garage to be checked and worked on? I'd really like to change the piston while I'm at it but can't justify the cost of one of the better ones. Could weak valve springs be the cause of my trouble? Bike has done 19,000kms

[Tim NZ]

AHHHHHHHHHHHHHHHHHH!


This time you have managed to trap the throttle cable as well as the decomp.


Replace the piston and rings! Take the head in to your local agent and get them to inspect...

[Bullet Whisperer]

Just free the cables and carry on ...

[Reg]

Don't think it's a trapped cable as nothing has been disturbed in that department. Also I tried your trick Paul, of putting a rubber glove over the intake and moving the piston over TDC. Sure looked like the inlet valve was leaking. I really think I must address this lack of compression, though when the bike is running it seems fine.

[Leon Novello]

Could be lots of fun ahead. Fortunately, the Bullet`s piston went nearly 40000 kms with only a new set of rings. I lost track of it after I sold it.

[Alan R]

Strewth !! LEON---- a rogues gallery indeed...

For those of you not yet acquainted with the OEM piston have a look at Leon's second photo...At the top is the main piston with gudgeon or wrist pin whilst below it is the crown....The area shaped thus}----- ( .... and.... ) ----- is that which has just separated and is the ONLY connection between the crown and main body....Bear that in mind next time you're doing 70 down the Motorway !!


Just a thought REG but is your machine a Bullet '65 ??............A few years ago those models in particular were identified as having had the wrong spec. heads fitted at the factory and were subject to a free head change.....Mine at that time was one of those and Watsonian Squire supplied an exchange head which I fitted.........RE had mistakenly fitted heads destined for their home market and as such they didn't have hardened valve seats....I believe that over time those seats started to compress / collapse, OR would move inwards ( Valve seat recession )... the first indication being the tappet setting closed slightly or completely, thus holding a valve partially open and subsequent loss of compression.......

That engine running away uncontrolled in any other scenario might well be a piston in dire need of a de-coke.....The carbon glows red-hot, ignites the incoming fuel/air mixture despite the plug not firing !!.........SO, it's time to ( yes, I'm going to say it !! ).. bite the Bullet and get that head off...Please bear in mind my earlier warning re}--- a) The inlet rocker housing can be a bit awkward to remove in the very last few mm...........b) the soft washers biting into the stud threads and almost locking the head in place...

Good Luck !!...Mon Brave..

[Reg]

I thought Halloween was last week Leon. But thanks for the warning. Alan R, my bike is a 4-speed Classic 500 from 2005. I bought it with about 3,000 Kms on the clock in 2010 so I have a pretty good idea of it's history. As you point out, it may be one which has slipped through the net with a dodgy cylinder head when it left the factory. The summer before last it made a mighty racket which went on for a short distance then went back to normal.I was told this was most likely a loose valve guide, and not to worry about it(They all do that sir.) Seems possible something has loosened in the head and is causing the problem. I shall investigate. Thanks for all comments.