Surging Engine

[gsmoke]

When the mechanic eliminated the spark, is that to all four plugs?
I had something similar and it turned out to be a dodgy ht lead to one plug.
First thing I would do is take out each plug in turn, Re-attach ht lead and place the plug so that the tip of the plug touches a bit of metal on the engine (to earth it). Turn the engine over for a few secs and see if the plug fires.
It wont hurt to check that your timing is correct.

[jason k]

are you on carbs or fuel injection?

[kevtherev]

shame though that you opted for webers

when you could have fitted some go go tubes from Delorto.
boy do those things make you smile for a while.

[jason k]

not the best kit out there to be blunt.
but if needs must after all then fair play.
one thing though please go get it jetted on a rolling road as it will be lean out of the box.
lean mixture on a Aircooled = a very dead one soon
it will go better and be better on mpg.

[jason k]

Great but all that mechanic can do is set up your idle speed and mixture. He cannot up the jetting to suit your particular motor as he has no rolling road to get the required measurements . So basicly you are running on the manufacturers supplied jets which are sized for many applications and nearly always are lean towards the top end.
A session on the rollers is about 80 quid. How much were pistons and liners again?
If its lean you will kill it sooner or later.
Your choice.

[jason k]

without a rolling road you can only check mixture statically which is likely fine as he can adjust to suit however he cannnot know the mixture when the motors running under load.
pennywise and pound foolish as my old mam would say.
dont say you werent warned.

[CovKid]

I wonder if the accelerator diaphram is split. I've seen many carbs on the v-dub range and setting aside comments on rolling roads, if its run great up to now it could just be something like a split rubber or an air leak. Be useful to get some compression readings though - just to rule that out.

On the other side of the coin unless the engine has been rebuilt in more recent years, it could have other issues. Tappets adjusted correctly? And is that a 009 dizzy? Points set correctly? With no vacuum advance you need just the right gap on those or it will tend to govern the rev range. The heel of the points soon wears down and the gap drifts, particularly as points burn over time. Feeler gauges not a lot of use unless points brand new. Dwell meter is essential to get them right. Don't need a rolling road to get it running satisfactorily. Just check the more obvious.

[R0B]

I think you need to wind your neck in mate.Jason was giving you his opinion.You can take it or leave it.Theres no need to accuse him of ruining our forum.or to call him names.(I have removed that bit) Personal attacks are not allowed on this forum.

There is always one who has to ruin a forum and you seem to be it on this forum