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Re: Thorspark Electronic Ignition on a VH

Posted: Sat Jun 15, 2019 12:22 pm
by BobWard
[img]
5BB91068-3BF4-4546-B223-C137860B17FD.jpeg
[/img]These baffles are from Brit bike bits

Re: Thorspark Electronic Ignition on a VH

Posted: Sat Jun 15, 2019 6:44 pm
by Steven.Carter
BobWard wrote:These baffles are available from VW car spares and come in different sizes, their fitment is in the end of the silencer by means of one screw so you will have to drill a hole on the back of the tail pipe so it doesn’t show. Bob


That's what I did Bob

Re: Thorspark Electronic Ignition on a VH

Posted: Mon Jun 17, 2019 9:29 am
by Keith.owen
Hi Bob,
I originally had an Armours silencer; bought in 1978. It was not correct. Towards the end there was a baffle, basically a plate welded across the body with holes drilled in it. It was too restrictive and things improved when I punched a big hole in it, but at the same time the bike made so much noise that I could hear the exhaust not echoing off cars coming in the opposite direction! I don't know what they are like these days though...........

The new one that I have just recently fitted is from Feked and is a true replica of a Burgess. It is quite noisy but the bike runs well.

On the subject of carbs. I have a 30mm concentric fitted (the inlet on n the head had been bored out to 32mm by a previous owner). The jetting etc. is standard and everything seems fine. I marked the twist grip at 1/8, 1/4 and 3/4 open and I seem to do most running at between 1/8 and 1/4 - I can chunter along at 50ish on between 1/8 and 1/4. I have tried snapping the throttle open by different amounts and from different points and the needle jet size and needle position seems fine i.e. the engine does either falter or pick up and then fall off.

I'd be interested to know how my throttle openings compare with those on other VH's.

Keith

Re: Thorspark Electronic Ignition on a VH

Posted: Mon Jun 17, 2019 11:54 am
by Bob.Murphy
Well, I have ordered a simple baffle that will be held in the silencer tailpipe by a single bolt. It will be interesting to see what effect it has.

Nothing is ever simple of course, the nearest baffle diameter I found was 35mm - but the ID of the tailpipe is 37.65mm (1.482 inches - presumably 1.5 inches without the carbon ;) ).

I'll try to 'expand' the baffle sleeve under the hydraulic press and if that doesn't work I'll make a cylindrical spacer and press the lot together.

I have a spare 32mm concentric that I bought back in the 1960s (when converting my 350 AJS to 500cc :D ). It has a brass fuel metering jet for the idle whereas nowadays there is just a drilling in the body - food for thought.

Life, of course, has got in the way of my 28mm carb strip-down. Yesterday was 'Fathers' Day ( :roll: ), daughter & family came over, then their car broke down on the way home (who thought that putting the electric fuel pump inside the fuel tank was a good idea !) so I have lost my Ford Focus. Today I have peace so I'll get on with it . . but the grass needs cutting . . in fact I could do with a Silage Cutter its so long . . Hey Ho.

No wonder Classic Bike Fettling takes so long.

Bob.

Re: Thorspark Electronic Ignition on a VH

Posted: Mon Jun 17, 2019 12:35 pm
by Simon.Gardiner
Bob.Murphy wrote:I have a spare 32mm concentric that I bought back in the 1960s (when converting my 350 AJS to 500cc :D ). It has a brass fuel metering jet for the idle whereas nowadays there is just a drilling in the body - food for thought.

Back in the 1970s I had no end of fun trying to sort out the idle settings on a concentric with a brass idle jet. Reading through all the various docs on these a few years ago before deciding on splashing out on a new 'premier' concentric I found somewhere that they'd changed the idle layout maybe twice and I think the current advice is the throw the idle jet away if it's fitted.
Also I think I found that the threaded hole for the jet is still there even in the current new carbs.

SG