Excalibur jetting

[Russ]

I need a bit of advice about 350 Excalibur carburation.
How and why I have an Excalibur when I had no intention of buying one still puzzles me but these things do happen from time to time.
The previous owner told me he thought the carbs needed balancing, after riding a 100 miles or so home I was in full agreement that was the least it needed. I stripped down the carbs, one of which had the top on backwards, the carbs are PHBL25 HS jetted :- Slide cutaway 50, needle D31 on 3rd notch down, atomiser 262 FC, idle jet 48, main jet 85 and choke jet 50. So the first thing is are these correct to begin with?
If they are what changes should I make to allow for an after market exhaust, already fitted to the bike when I bought it and the tech tips mod to the air filter which I intend do.
Any and all suggestions welcome.
Russ

[Steve Brown]

With a different less quiet exhaust and the airbox opened up I would expect just the main jet would need raising. A 350 Strada/Sport would have a main jet of 110/112/115 so that would probably be as large as needed. It may only need 95 or 100. You'll have to experiment I'm afraid as the exhaust requirements will be an unknown as well as the airbox mod. Some bikes don't need much changing. Our resident Custom bike Village person is away in Portugal at the moment but I'm sure he'll be along here soon.

[3potjohn]

Go back to the front page of this website and about halfway down is a link to the Morini club.nl pages. In Technical/carburettors is a table of settings. This might be of help. My experience with the air box housing is the opposite of the oft suggested benefit of removing the flowerpot etc.Also with non standard silencers. Running particularly at a steady throttle was greatly improved by returning the airbox to standard. This on a Coguaro.
In the first instance I would get the jetting as per standard then go from there. Reducing the idle jets from say 50 to 48/45 /43 or so can be worthwhile.

[Russ]

Thanks for the replies. The problem I had was that the set up shown on the Dutch website and other places were either for VHB carbs or PHBL carbs fitted to 500's; that's good for idle & main jets but no help for needle or emulsion tube sizes. I have now found a chart on the forum that suggest that needle size D31 & tube 262 FC should work, I'm still playing with needle position as that combination is close but a bit rich at the initial needle position.

[3potjohn]

I marked the twistgrip with a series of different colour paint lines to help me, 1/8 ,1/4,1/2 . Above about half I was not concerned about as it was up to half that affecting my steady throttle response. Both on the 350 and the 507 I have experimented with the idle jets sizes from 50 through to 43.
I would make absolutely sure the chokes are not leaking when closed or you can be chasing “ false” richness.
I also made careful notes (on my phone ) of all changes as it is easy to forget.

[Steve Brown]

Thanks for the replies. The problem I had was that the set up shown on the Dutch website and other places were either for VHB carbs or PHBL carbs fitted to 500's; that's good for idle & main jets but no help for needle or emulsion tube sizes. I have now found a chart on the forum that suggest that needle size D31 & tube 262 FC should work, I'm still playing with needle position as that combination is close but a bit rich at the initial needle position.

I've had good results on my road bike and trail bike by raising the throttle cutaway to weaken the area you describe. That takes effect prior to the needle and jet. I filed the slides to suit and was prepared to buy new replacements if it failed, it worked though!