Have been really pleased with the Beamish since I got it 12 months ago but over the last few events it has starting giving me signs that things were not right, the main one being after the run between sections the tickover races but one it is left to cool down for 3 -4 mins its back to normal. I started to investigate today and noticed the following, any thoughts or comments are appreciated:

1) The exhaust was blowing from the front manifold when the bike first starts up from cold. This is not around the gasket/flange but actually where the u pipe pushes into the manifold flange. Their were no springs locking the u pipe to the flange or on the other end to the main expansion chamber

2) When stripping it down it become clear that one of the exhaust manifold threads had been either been helicoil's or drilled, metal filled and tapped as I could not tighten down on it. Looks like that needs to be re-helicoil'd or welded and tapped

3) Have checked the reed valves and these looked in a good state

4) The air mixture screw was set at 3/4 turn from the fully in position

Any thoughts are appreciated. The engine is out on the bench ready to get the thread sorted but Im wondering if their is anything else I need to take a look at?

Rob

Hi Rob, it soulds like you may have an air intake leak judging from the engine racing and the air screw being 3/4 turn out.

You should have a spring holding the U front pipe into the manifold, you may find that the is a lot of carbon in the fitting where the U pipe slots into the manifold stopping it go all the way in, this needs to be cleaned out and a spring fitted from the ring welded to the U pipe and the hole in the manifold.

Check your base gasket and fit a new one anyway when you replace the barrel after sorting out the thread problems. Check the rubber inlet manifold to ensure it is not perished and ther are no cracks around where the rubber is bonded to the metal. Re-assemble the reed cage with a new gasket between it and the barrel. If your reeds are steel REPLACE THEM! They are almost certainly original and if you read the manual, it is recommended that you replace these every 6-12 months. Crooks have fibre reeds for £15, they inprove the performance of your engine and won't damage it if they break up unlike steel ones.

If you are on a standard bore (80mm) think about replacing your rings while you have the barrel off, these are £7.50 from the Beamish Owners Club at the moment for genuine rings. Check your pilot jet too, the Club have new ones for 50p at present for a 20 pilot jet, they also have the rubber manifold should you need it.

Check all other possible sources of an air intake leak.

Hope this helps.

Jim, many thanks. A nice little shopping list there to give it some TLC. Really appreciate the guidance. The reed block looked like it had fibre ones in it but their was no gasket either between the head and the block or the block and the manifold. Have googled for the right gaskets but could not find any? Do you know a source or are people now using instant gasket for these type of things?

So shopping list is as follows:

Springs for exhaust u pipe (both ends) - where?

Base gasket - Wemoto?

Reeds - Crooks

Reed block gasket - ?

Rings - Beamish club

Jets - Beamish club

Manifold - Beamish club

anything ive missed?

Thanks once again

Edited May 5, 201313 yr by slogger

Hi Rob,

Reed block gasket - Crooks

Single spring from exhaust manifold to U pipe - Crooks

Base gasket - Crooks (as soon as they get some in) or make one

Anything you find you are short of let me know through the website and I am sure we can sort you out. There is a manual on there which is a free download PDF.

Why do you think there is more than one spring?