Just posting for general info. There is a 2 stroke version and a 4 stroke version of the Mikuni 38-9, with very little difference between them. I have learned today that the only difference in the body is the 2 stroke idle adjustment needle adjusts air delivery, whereas the 4 stroke adjusts fuel. Apart from this, the differences are all jet, needle and slide differences. The drilling for the idle air adjustment is slightly larger than that of the 4 stroke fuel orifice, hence the need for a slightly larger pilot jet if using on a 4 stroke. The Carby I have was supplied with the correct main jet, needle, and slide, but wrong needle tube, so I have the right needle tube plus the next 2 larger size pilot jets coming from Mikunioz in Townsville. Might as well do it right. The needle tube should allow me to return the needle clip to the center position, and a larger pilot jet will restore some adjustment back into the length of the needle for fine tuning. And the supplier has agreed to replace the faulty rotor for one with both magnets, although it will take a couple weeks to arrive. So, good, if slow progress. In the meantime, I'll go back to the Suzuki Hustler, as well as fix a flat on the 23 Model T Ford.

Here's one for single fire coil.

And one for dual fire.

It seems to work ok, even with the magnet I installed myself. Looking forward to getting the right one tho. The single fire has the single magnet with two sensors, and the dual fire coil has the two magnets for the one sensor. They just mixed mine up a bit.

If you decide to get one of these, the black wire goes to the +ve on the coil along with the wire from your switch, and the yellow wire goes to the negative post of the coil, replacing the old points wire. This is dual fire. Single fire would be similar, except two negative posts.

Carby bits arrived and fitted and now not a single backfire at idle or throttle blip. Off to get a clear plastic timing plug this morning to check the accuracy of my static timing. Timing light has decided to work after new spark plug fitted. Very happy with the Mikuni.

Can you wind them in till they nearly touch or do they not go in that far?

Never had any success with them.

Because I'm running points I check timing quite a bit, got a tool that bolts onto the points cam and locks the centrifugal advance into full advance. I take the timing plug out, pull the spark plugs out so I'm only turning the engine against valve spring pressure, put a radio tuned off station close to the bike, and slowly turn the back wheel and listen for the tchk radio signal firing as the advanced timing mark, single dot, is centred in the inspection hole.

Detaching the ignition condenser makes the tchk louder.

Stuart, can't do it on 4 speed Evo Sporties, they only have inspection covers positioned to inspect primary chain tension, and to adjust clutch. Pretty sure that 5 speed ones are the similar, athough attachment method of the primary tension inspection cover was changed and the screw in clutch adjuster cover was replaced by a full size detachable derby cover.

Is this way correct, or backwards?

"Used a test light and it lit just as I turned the motor to the "Dot", which is the idle mark. I then set it onto the "Line", the advanced mark, and when I manually turned the cam as far as I could to simulate advanced timing, the lamp lit again."

They reversed the timing marks on Sporties in 1980. Early 1980 bikes or earlier are different to late 1980 and after bikes.

On mine, 1990 4 speed Evo, the dot is 40° advanced on front cylinder, the line is TDC for front cylinder.

There's a good page about it on Sportsterpedia.

Thanks for that Steve, I'll stay with what I've got then.

Steve has lots of tricks up his sleeve 😁

And Hilly, I had to find a better way. There I was in 1971 with a POS C15 BSA, I reckon it was BSA's worst bike ever. The service notes told me to determine points opening by being able to pull a cigarette paper from between them; and I didn't smoke. Read about the radio method in a mid 70's Yank bike mag and used it until I bought a timing light during my Norton days.

It works better if you have a copper wire cored HT lead. I have one in the shed for timing purposes.

And no officer, I don't run it on the road like that, why that might interfere with people watching TV, and govvys of all stripes won't allow that. Why, if people didn't watch TV they won't be able to absorb the ads, and they might stop consuming and start saving. Shit, that might crash the economy!

Or maybe I'm just an old hippy that lived in the bush with no TV reception for 40+ years.