Hitchcocks Forum

Hello one & all,
Having a spot of bother with the exhaust tappet on my 59 250cc clipper, no matter how many times I adjust it, it still end up with no gap after a run, inlet stay fine at 4 thou, but not the bloody exhaust, when I last adjusted it to 6 thou I also give the adjusting nut a pop with the old centre punch. thinking of trying some lock tight an ideas please.
Cheers.

Loss of adjustment on the exhaust pushrod after the bike has been ridden is often the result of a burnt exhaust valve.

Sometimes the threads become worn and simply won't lock together, try replacing the adjuster. If you were getting a gap appearing from a burnt valve you'd have other performance problems as well!
REgards, Mark

Valve seat regression mayhap? That might burn the valve a touch as well..

Hello Again,
I had the bike out for a run a few of days ago, roughly 50 miles and it went really well, wasn't till I was about 10 miles or so from home when it went a bit flat and I lost the tick over so had to keep the revs up when stopping etc, just managed to make home. Checked the tappets next day and that's when I found no gap on the exhaust.
Cheers.

Sounds like valve seat recession to me...........If the gap has closed but the adjuster remains at the same setting then your valve stem is moving towards the rocker..........Can you obtain a spare head ??? ---- this will keep you on the road whilst you investigate this problem further..........

Those symptoms - slight loss of power, loss of tickover, no tappet adjustment - are all signs of early stage exhaust valve burning. It's a bit of a pain, but I'll stay with my first suggestion! REgards - as they say!

Sorry, but I just can't resist this opportunity to say }---- Hey, PRESTO ( Alright, alright----I apologise !!LoL..)...... I think the general agreement here is that our friend HOWZIE will need to remove the head in any event..............Personally I hope it's the burnt valve as it'll be a whole lot cheaper to repair, BUT....................... ???

Hello all, Thanks for your reply's brilliant as usual, changed the tappet adjuster on the exhaust valve, see how that goes, in not off with the head.
Cheers Howzie.