rb250 Dellorto settings

Check here for a list of various carb set-ups to help with jetting and all aspects of carb trickery!
AndyS
registered user
Posts: 96
Joined: Thu Jan 08, 2009 7:05 pm
Location: Halifax, West Yorks
Contact:

Is anyone running an RB 250 with a Dellorto 34mm fitted.
I have jetted it as per AF's spec sheet but it is really boggy up to 1/2 throttle.
Setings are
K21 needle
DP267 atomiser
Main 198 ( but have not actually got to this so far)
Pilot 55
Choke 60

Have tried a DQ266, it is slightly better, but still very boggy.

The gearing is SX200 with 16x46 sprockets ( 4.5)
Exhaust is franspeed tourer.

Due to runnig it in I cant go above 55 mph for a while, and with the gearing the throttle is only about 1/3 open.
Any help would be appreciated
Knowledge
Dealer
Posts: 957
Joined: Sun Jan 11, 2009 12:49 am
Main scooter: GP
Location: Ipswich
Contact:

I agree that you should not have hit the main jet circuit yet, but that main jet seems huge. Why not just try a 160 just to see.

What have you got to lose for the sake of a quick blatt up the road.

Also, check that the choke is closing properly, as it might be open all the time. Have a look down the mouth of the carb and you should be able to see the plunger.

Finally, have you adjusted the air screw?
Martin
J1MS
registered user
Posts: 1153
Joined: Sat Jan 10, 2009 12:02 am
Contact:

Why not fit the 15x46 while you run it in, then switch back later......Got to agree with Knowledge the main jet does seem big...
AndyS
registered user
Posts: 96
Joined: Thu Jan 08, 2009 7:05 pm
Location: Halifax, West Yorks
Contact:

The main is what is recomended by AF.
I thought it maight have been the choke, so disconected it, but it was still the same.
I dont think that there are many about a the moment, if a few people have them you can compare jetting and generally get it a bit nearer.
Might go down the Mikuni route, had one last year on my RB225 and it was fantastic.
andyC
registered user
Posts: 3
Joined: Fri Jan 09, 2009 10:42 am
Contact:

hi my rb25 runs
40-slide
k24-needle 2nd clip
dp267-atomiser
195-main jet
45-pilot
60-choke
300-float valve
gp 200 gears/19-46 sprockets
varitronic 25 degrees initial advance
runs clean thru all the gears
hope this helps
AndyS
registered user
Posts: 96
Joined: Thu Jan 08, 2009 7:05 pm
Location: Halifax, West Yorks
Contact:

I think I have sorted it now. It was probably a combination of thgings.
I cut and remade the choke cable so that I am sure it isnt open when running.
There is an inlet on the side othe carb, which I think is for an oil injection, this wasn't blocked, it is now, have dropped the pilot to 45.
I now need to try a DQ267 atomiser as I have a DQ266 on it at the moment and I think that it will be lean in the mid range.
Thanks for posting your findings
I think I maight change the gear ratio aswell, it pulls 4.5 but it struggles a bit if I am not revving it up hill
Bilko
registered user
Posts: 1346
Joined: Thu Jan 08, 2009 12:06 pm
Main scooter: LI150
Location: Belfast
Contact:

How are you getting on with this?

I've the same set initial set up as you and boggy as f@@k up to half. After that it's too lean.

Struggling to find an answer
Bilko's Oily Blog

Directionally dysfunctional since 1966
Post Reply Previous topicNext topic
  • Information
  • Who is online

    Users browsing this forum: No registered users and 2 guests