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350B carb differences

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rd350nick:
I have a spare set of 360-92 carbs that i was going to recon with new jets etc to fit to my 75 B model 350.
 I noticed in the carb specs chart that there is a difference between the slides and needles between the 360 and
522 carbs that i already have on the bike.
 What difference to running does the cut away on the slide actually make?
Looking at the bodies of the carbs they don't seem any different apart from the 360 version hasn't got the brass balls it the venturi.
 I have problems with bike running too rich on low to mid throttle and then possibly slightly lean on top end,
 All the jets are standard sizes.
 When i first got the bike in the early 80's it had K&N filters and no air box, i managed to source a proper air box and filter (baffled type) but it didn't have facility to put the pipes from the carbs into the air box so i just vented them to the atmosphere, would that maybe have any effect on the running?

c50:
You need to say exactly what you currently have fitted and which air filter/main jet combo?

The UK 521/522 B ( not sure where if anywhere else used the same set up and it’s not documented anywhere)  has the carbs with the external air correction to the air box. To go with this they have No 2 slides instead of No 2.5, 5L3 needle instead of 5I4. The Main jet on the 350 should be 105 with baffled filter (standard set up) or 140 with un baffled filter. You could just drill the holes in the air box and grommet them.

The 350 runs very well with either carb set up. It’s the 250B that is prone to bogging if you suddenly give it wot. Did you check the air correction isn’t blocked behind the brass balls? Blow down the pipes, you should be able to with resistance, put some carb cleaner down them with the engine running. 

5port:

--- Quote from: rd350nick on August 16, 2022, 10:17:29 PM ---I have a spare set of 360-92 carbs that i was going to recon with new jets etc to fit to my 75 B model 350.
 I noticed in the carb specs chart that there is a difference between the slides and needles between the 360 and
522 carbs that i already have on the bike.
 What difference to running does the cut away on the slide actually make?
Looking at the bodies of the carbs they don't seem any different apart from the 360 version hasn't got the brass balls it the venturi.
 I have problems with bike running too rich on low to mid throttle and then possibly slightly lean on top end,
 All the jets are standard sizes.
 When i first got the bike in the early 80's it had K&N filters and no air box, i managed to source a proper air box and filter (baffled type) but it didn't have facility to put the pipes from the carbs into the air box so i just vented them to the atmosphere, would that maybe have any effect on the running?

--- End quote ---

Hi Nick,

Yes, we covered most of this with you 5 years ago.  Have a look at your old posts, the info is the same. 
Did you get rid of the x-over and try standard everything? 
What you are saying here sounds just like before?  If you remember, you need to go through everything with carb questions!  ;)
Cheers
5port

rd350nick:
The 521 carbs are all standard spec, what i was wondering was if the 360 carbs would need any alterations to jet sizes etc due to the air correction jet being through the venturi rather than the pipes to the air box.
 I will also have to put the 2.00 cut away slides in as i dont have any 2.5 ones.
 5 port i blanked the balance pipe of so that shouldnt alter things.

5port:
Well,  2.0 slides will not work well with carbs/jetting that should have 2.5 slides.
Overall, your 522 carbs should work well on a 521 350B if all standard.  Although it is possible to jet other carbs to work if you know what you are doing, I think you are barking up the wrong tree to fit different carbs when you have the correct ones.  The Air corrector tubes should be fine fitted into the airbox with grommets.

5port     

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