Recommission of 2c after importing. Need carb help

250 2c- the Wee-WeeVees
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Bedfordowner
Posts: 63
Joined: 12 Oct 2020 12:51
Location: stafford

Recommission of 2c after importing. Need carb help

Post by Bedfordowner »

Hi All,
I bought an imported 1985 2c last week from M and P motorcycles in Newcastle. She needs a complete overhaul but first I wanted to get her running. I have stripped and ultrasonic cleaned the carbs. I have rebuilt them with a new gasket set from Mdina. I replaced the plugs , checked and gapped the valves and changed the oil. I am running from a supplemental fuel tank at the moment as my tank has no taps and needs cleaning.
I got her started today, second kick but have noticed that she really only wants to run with one choke on . She had been standing some time so not too worried, she revs fine but did not want to rev too much until I change the cambelt. I wondered if any ideas as to the air mixture setting. I have backed them both out about 11/2 turns but the carbs have not been balanced .
Really love the sound she makes, probable helped by the rotten silencers and the ease of kicking her over.
All help will be good and look forward to getting involved with the club
Thanks
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Ming
Posts: 798
Joined: 01 Aug 2014 16:32
Location: France
Location: Central France

Re: Recommission of 2c after importing. Need carb help

Post by Ming »

I'm currently getting one of these back on the road (it's been a long journey for one reason or another) so if I can help let me know. The carbs needed a really good clean and o rings on the mixture screws were suspect (in fact missing on one). It does start easily but I still need to sort out the carbs.
mbmm350s
Posts: 666
Joined: 22 Jun 2018 10:18
Location: Reading UK
Location: Berkshire UK

Re: Recommission of 2c after importing. Need carb help

Post by mbmm350s »

Hi,

I think we have already chatted on line and way welcome to the forum!
Iwondered if any ideas as to the air mixture setting.


The screw is a mixture screw as its engine side of the slide, out enrichens (more fuel), in weakens

The reference position is 1 and a half turns, but you should find out if they are functional.
I mean the engine should run nicely between two stumbling points,
and you find the fastest running point between them.

If after further comissioning you find the engine only runs on choke, it's possible that the idle passage, or idle jet is still blocked.
Another thing to consider, and found recently on a bike i worked on , that the spark is failing at low rpm.

Mark
Bedfordowner
Posts: 63
Joined: 12 Oct 2020 12:51
Location: stafford

Re: Recommission of 2c after importing. Need carb help

Post by Bedfordowner »

Hi Mark,
Yes think we have chatted.
I have recleaned the carbs and possible there was a small amount of dirt still in the idle tube. Refitted them and she now runs and holds a high tick over around 2500rpm. Really pleased with how she runs considering how long she has stood and the state of the carbs when I removed them. I need to balance them next and have ordered a Carbtune for that. Not sure where it attaches as there are no bungs or inlets on the inlet rubbers.
There is a pipe on each carb above the float bowl. I presume this is some sort of balance tube between the carbs. I have joined them with a length of pipe and the engine seems to run better. Is this what they are for or am I doing it wrong?. Thanks again

Keith
mbmm350s
Posts: 666
Joined: 22 Jun 2018 10:18
Location: Reading UK
Location: Berkshire UK

Re: Recommission of 2c after importing. Need carb help

Post by mbmm350s »

You should have VHBZ22HS carbs, the H indicates that the body has a vacuum port, fitted with a vertical brass tube. This is where you put the balance gauges. When done balancing the two carbs on a 250 are linked together with a small bore petrol resistant tube.
If this isn't fitted or is leaking then you get a fast idle and revs that wont die down may be as you describe.
The vacuum port isn't used on 250s it is used on later 350s and 501s with different carbs to operate a vacuum tap.

By the way the S stands for Sinistra, meaning left in Italian, air cooled V twin Morinis have two left carbs.
Do check the inlet and air filter rubbers aren't perished. New filters are available they are the same as the 500 (just uses one)
I found a strange white fungus growing in an air filter once :shock:
Mark
Bedfordowner
Posts: 63
Joined: 12 Oct 2020 12:51
Location: stafford

Re: Recommission of 2c after importing. Need carb help

Post by Bedfordowner »

Hi, Quick update.
The carbtune pro turned up yesterday so have now balanced the carbs. Great piece of kit and made the balancing easy. I still get the occasional cut out whilst idling but sure it will clear when I get to ride her. I am near Stafford, so any club member who needs to balance their carbs is welcome to contact and come over. Covid permitting.
I have picked up an unused 350 Fairing so now need to work out how to fit it as there are no fittings with it I think it best to post a request for details of fittings separately incase someone already has one on their bike.
Thanks for all the help

Keith
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