Hitchcocks Forum

Hi Chaps

This may be a stretch of your collective experience, but here goes!

I've just finished Rusty, my latest project, which is a 350 Superstar, 1992 vintage. BW has breathed on the head, opening up the inlet to around 30mm and has opened up the exhaust port too. Because I happened to have a 29mm CV carb in the shed left over from upgrading my Electra-X, I thought it would work nicely on Rusty. Before running it, I raised the needle to top position, figuring the AVL engine is lean-burn, so Rusty would need more juice

I've just had a test run and although Rusty starts well and ticks over nicely, he's running poorly in the mid-range - not pulling at all well. Having looked at the plug after the run, I know he's running quite weak (I have a conical filter on).

My questions are about jetting.

1. Does anyone have any experience of this setup, and where would you suggest I start?

2. I figure I need a larger needle- and possibly a larger main-jet. MrH only lists standard jets in the online parts book, are these jets interchangeable with the standard range of Mikcarbs fitted to Bullets or with Amal concentrics?

3. Any idea where I can get these jets, or should I just drill out the standard ones? What size?

Any help or suggestions most welcome!

Thanks, Stephen

Rics post may help.


http://tinytim.forumcircle.com/viewtopic.php?t=634

Stick with the std jets as per Electa X for the time being. They should be very close to what you want.


You wont need a different needle, but MAY possibly want a another needle jet, and or a 115 mainjet? Mikcarb main jets are different, but flow the same and can be used at a pinch...


Make sure that the screw driver you use to access the needle fits the screws PERFECTLY. They are tight and are easy to damage and are NOT readily available as a spare part. Besides adjustment of the needle is only one up or down and wont get you far as acceleration is limited by the slide operation (CV)


But why bother with the CV when a 30mm Amal fits straight on and you wont need a manifold adapter.




Change your thinking about Lean-burn: Think more of the old design motors as being SUPER RICH burners.

B.W. is a dab hand at sorting out Amal Mk2 carbs, I'd get back to him and see what he recommends. I know it seems a shame to waste the Electra's CV carb, but I would go down a more traditional route for your Superstar. I once had very good results on a tuned BSA B40 using a VM32 Mikuni with 350 Goldie jetting.

Thanks chaps, most useful. I also have a Mikcarb 28 (500 Bullet spec) but it fouls on the lug where the rear of the tank fixes to the frame, presumably because of the extra long rubber flange-thingy I'm using to fit it. Maybe I'll try this again - I have a feeling that if I fit it with a 10deg clockwise twist it might clear the lug. Providing this doesn't mess up fuel levels in the float bowl it will probably be easier to jet correctly.

Any thoughts?

Stephen

You need the one piece mounting flange rubber, if our hosts don't have one the right size try Allens' or Motocarb who supply Mikuni carbs and accessories. It will need 2" (50.8mm) mounting stud centres for the 350 head, and you will need to measure the O/D of the 28mm Mikarb at the engine end and select flange that fits that carb, making sure the inner bore of the flange is 30 or 28mm. There should still be room for a tufnol spacer to prevent heat transfer from the head.



A.