Carbration advice...34mm Dellorto

[Hillt68]

Hope someone out there can help.
I'm building a Mugello 225 engine for the GP (for Touring)
I've been given a brand new 34mm PHBE (BS) Dellorto
currently set up with
Main Jet 120 (seems about right??)
Atomizer AB270 (seems abit big/rich?)
Needle K3
Choke 30
Idle 70 (i think, stamp abit near top, so top of 70 cut off)

Mugello 225, (116mm) with standard head (not low compression)
on a ScootRS steel pipe (for now...want a JL3 or something later..)

I've only ever played with 30mm Delly's and 34mm Amals so not sure?
I saw from Dans RB20 thread he had the same carb..
I need to know ball park (and I mean roughly) how close or far away I am from what I need.
i.e. I don't want to blow a hole in the piston??????
And who sells parts for these..?
Thanks for any help you can offer..any help would be welcome..
Tone

[J1MS]

Used lots of dellortos, But only for useable road riding. So I never went bigger than 32mm, but the main jet you have to me seems miles too small for a 34mm carb, and the needle jet seems at least one size too big.... Others on here will have used 34 mm dellortos and they might come up with a better guestimate.....All the best .................... BTW I use a 148 main jet in my 32mm dellorto......

[byron]

I'd go with that main jet being far too small.
are you planning on running the carb with a filter ?
I have a 130 main in an open intake VHSA28 on a Mugello 186.

[Hillt68]

Thanks for the input guys.
I have got several main jets from 120 (that was in the carb when I was given it) all the way up to a 146.
I am intending to run with a mesh filter (which has 1mm holes) so this will affectively bring down the main jet size due to reduced air flow... I'll go safe I think and start with the 140 jet I've got and do a plug check..
In my other scooter, I've a 28 Delly and this has no filter on a Indian 200 with a PM pipe, the main jet is a 120 and this runs abit rich.
Thanks again...

[shocky]

my old 240 ran a 36mm dellorto and a 180 main in the evening and a 170 in the day or when it was better weather so id say a 120 was way to low id try the `146 for starters with the neddle high

[Hillt68]

Hi again :bouncyeng:
The reason I am using the 34mm round slide Delly is cos it will have a gauze on the bellmouth affectively reducing the air flow, making it comparable to a 30mm Delly
Finally got the engine in, started with the 146 main with the needle set to rich..
This setting was by far too rich...ran like it was on choke (didn't need choke on to start it)
I checked the choke just to make sure it was operating ok..
I then put a 125 jet in (as it's the closest one I have to the 146) this is still a tad too rich (better but still running as if choke is half open)
I would agree to some degree with the comments posted about 122 being too small on an open mouth but was supprised to find in practise that the 125 (without gauze) was still too rich.
I'm going to fit a 122 jet (with gauze cover & side panel on) as I feel this will be close, then play with the mix screw and needle hieght to hone it.. constantly checking the plug for that chocolate brown colour....wish me luck.
on the initial run (with the 125 jet) quarter throttle in 4th pulled 40mph, Im hoping that I've got the gearing right.. running an ViJay II 150 on 17/46 (giving 5.0 according to stickies figures) with a scootRS steel pipe for now...I'll post how it goes, as it may help someone oneday.. :baddevil:
Thanks again for the thoughts

[J1MS]

Keep us posted...

[rog60]

As I also have a Vijay 150 M2 gearbox any comments on the spread of gears would be interesting. I propose to use it on an Indian GP200 Stage 4 with SH2/22 123 main/48pilot and an Indian 42mm big bore. Considering 16/46 sprockets.

[Hillt68]

Hi again :biggrin:
I've taken the 34 phbe off for now whilst running in. after some closer investigation I found
that the Atomiser was an AB270 ( ideally should be a 264 + or - 2).

Have found the Dellorto Dealer is only in Reading, so am going to pay him a visit...
Meanwhile the 28 delly PHBH I've got is jetted to the rich side (AV266 Atomiser, 123 main jet )
scooter runs and putters along quite merrily (rich) in 1st, 2nd, 3rd and 4th
but I feel it may struggle a bit 2 up on a steady climb,
although with the carb not jetted correctly it could be a false impression....
so wont know till it's run in and the correctly jetted 34 is back on..

Also checked my timing and it's 18/19 btdc may retard to 19/20 not sure yet


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