Thorspark Electronic Ignition on a VH

[Bob.Murphy]

A bit of an update . . .

I looked at my neighbour's 3GL Matchless - he has a single magnet in his rotor and different instructions .

Amazon delivered a nice, good quality, 'Silva' compass and I did some checking.

I tested the Matchless:- The North-pointing end of the compass points to the outer edge of the magnet.

I tested mine:- Both magnets have the same orientation with the North compass pointer pointing at them. This makes sense if the rotor is for a twin - both sparks will be identical.

I have ignored the instructions and removed one magnet; the bike has been running.

The exhaust is still very loud. I put this down to the increase in compression after I machined the barrel top face and fitted a 7.5:1 piston. I will remove the silencer and see if there is anything in there . . . . . If not, its a call to Armours .

The carburation isn't good. I swapped the 200 main jet for a 180 and the exhaust isn't showing black smoke any more, I have even had it ticking over but it won't pick-up cleanly from idle. I need to experiment with the air screw, needle position and throttle slide cutaway.

Is anyone else out there running an alloy 'VH' with a 28mm concentric '928' carb and a 7.5:1 piston . . What carb settings are you using ??

Getting there slowly .

Bob.

[Eero.Korhonen]

I have iron head VH with 28 mm concentric, piston is from a car 84 mm(Datsun 180 SSS), probably compression
is about 8. Main jet is 180. Normal magneto ignition.
Br, Eero

[Keith.owen]

Hi Bob,
Are you sure that the problem isn't with the float chamber level? If the level is too low the whole carb will run lean; if too high, it will run rich.

The main jet will have no affect at throttle openings below 3/4 - in fact on low throttle openings below 3/4 you could run without one fitted. Are you sure you didn't disturb something else when you changed the jet? Sorry to state the obvious, but are you sure the gasket is around the right way?

Factory default settings should be pretty ok., at least as a starting point. For 4 stroke concentrics these are 106 needle jet. no 3 cutaway. needle in middle position. Only the mainjet changes in size from a 28 to 32 mm.

Perhaps the attached might give you some pointers?

Let me know how you get on!

BR,
Keith

[Bob.Murphy]

Thanks folks.

Eero, I had noted in the past that people were running 180 main jets, yet mine had a 200 in it. Higher compression means more efficient running so I bought a range of jets and went down to 180. It seems to be running cleaner now.

Keith.

I have disturbed a whole load of things and the motor feels quite alien now . The top end has been decoked, valves ground, head torqued down three times and the tappets adjusted again. The plug is new.

I stripped the carb and put all the bits in my Ultrasonic Cleaner with the cleaning fluid. It all looked good when it came out but I'll strip it down again and use the air line on the passages.

I have replaced a few carb parts (jets, screws gaskets) and the float needle seems to be working (fuel on, wait, press tickler and after a few seconds it floods). Not easy to check the level, the Monoblock was easier with the clear plastic float cover!

Thanks for the 'Tuning Secrets' I've printed it and will settle down with a mug of tea and see what I've done wrong .

I'll report back.

Bob.

[Bob.Murphy]

Keith,

You have just fitted a silencer from Armours . . . I'd like to compare notes.

My '58 VH has an "Ariel motors' silencer, and very nice it looks too:

It has always had a fair 'Bark' and will rattle the windows if I open it up - even motorway bridges aren't immune .

Since modifying the motor, the noise is totally unacceptable, so I took it off to investigate . . .

Design approved by Her Majesty's "Ministry of Noise" I presume:

Investigation revealed a perforated tube - but nothing to get in the way of that shock wave:

What are the Armours Silencers like inside? The two I bought from them for my Panther have perforated tubes but with the far end blanked off. I tried to fit one to the Ariel to see how it sounded but the shape is totally different .

I have to do something as I can't ride it as it is.

Bob.

[Steven.Carter]

In an attempt not to annoy my neighbours I bought this off ebay, it didn't fit because I bought the wrong diameter but the correct one in my Huntmaster certainly calmed things down.

[ian.scott]

I think they are marketed by Hitchcocks.

Ian

[paul.jameson]

The Ariel Motors Limited silencer should have a "tea leaf" just inside the inlet pipe. If your silencer has a rattle when shaken, the tea leaf has fallen off, as is common. If it doesn't rattle, the tea leaf was never fitted ! Either way, a "pepperpot" on the inlet into the silencer sounds like a good plan.

[Bob.Murphy]

No rattles and no tealeaf !

I have had a search on e-Bay and also watched some u-tube vids but I'm still confused as to where these things fit when one has a simple pipe and silencer.

The perforated pipe that Steven bought looks the thing - but does it go into the pipe before the silencer is fitted ? How is it held there - a screw would foul the silencer input sleeve ?

The 'pepperpot' design . . does that go into the pipe or over it before the silencer is slid on ? The diameters are quite tight so an extra sleeve in the silencer input isn't going to work easily.

I'm sure its blindingly obvious when I see the actual item in use .

Bob.

[BobWard]

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