Carb.

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
User avatar
Posts: 192
Joined: Sat Jul 19, 2008 3:05 pm
Location: LEICESTERSHIRE UK

Carb.

Postby davehutch » Wed Aug 13, 2008 2:46 pm

Hi, Need more help again. After buying new jets, carb spacer, needle, studs, for my concentric carb on my G2. It runs a lot better but will not run when choke slide is full open, Ok when ¾ open. Do you think I need to get a monobloc?
Thanks again Dave
----Only a biker knows why a dog sticks his head out of a car window.

Posts: 7725
Joined: Tue Nov 22, 2005 6:01 pm
Location: UK

Carb.

Postby itma » Wed Aug 13, 2008 3:17 pm

no you need to sort the concentric.
well, unless you really want to spend more cash.
you seem to have a fuel supply problem

User avatar
Posts: 192
Joined: Sat Jul 19, 2008 3:05 pm
Location: LEICESTERSHIRE UK

Carb.

Postby davehutch » Wed Aug 13, 2008 3:26 pm

When I pull off the fuel pipe there is a continuous flow of fuel. And when I hold down the tickler it floods the carb and that is what I have to do to start it again. Any ideas?
----Only a biker knows why a dog sticks his head out of a car window.

Member
Posts: 2882
Joined: Mon Jan 01, 1990 12:00 am
Location: USA

Carb.

Postby Don Madden » Wed Aug 13, 2008 4:54 pm

Are you moving the choke lever the correct way? It is counter-intuitive, pulling the cable to raise the choke.

Is it the same size carb? A smaller size will require a smaller main jet.

Do you have the correct main jet? For the same carb size & application concentric carbs require smaller main jets. Follow the set up for a similar engine with concentric fitted, as the B*A B25.

Cheers, Don.

User avatar
Posts: 192
Joined: Sat Jul 19, 2008 3:05 pm
Location: LEICESTERSHIRE UK

Carb.

Postby davehutch » Wed Aug 13, 2008 5:04 pm

Yes Don I am pulling the lever the right way. The carb is 1 1/16 bore which is what the monobloc should be. I have just put in main jet 180 and Needle jet .160
Thanks Dave
----Only a biker knows why a dog sticks his head out of a car window.

User avatar
Posts: 192
Joined: Sat Jul 19, 2008 3:05 pm
Location: LEICESTERSHIRE UK

Carb.

Postby davehutch » Wed Aug 13, 2008 5:56 pm

Sorry .106 Needle jet
----Only a biker knows why a dog sticks his head out of a car window.

User avatar
Posts: 192
Joined: Sat Jul 19, 2008 3:05 pm
Location: LEICESTERSHIRE UK

Carb.

Postby davehutch » Wed Aug 13, 2008 7:41 pm

Been playing with carb. After changing main jet from 200 to 180 and new needle jet .106 it runs better but will not run with coke off. Tried putting back old main jet no different. Changed the new needle jet .106 for the old one .106 and it runs the same as it did before that is back fires, splutters ,and will run with choke off. When looking at both needle jets the old one is shorter and the little pin hole in the side is in the nut part. The new one is longer and the little pin hole is in the tube part.
Any help will be appreciated
Thanks again Dave
----Only a biker knows why a dog sticks his head out of a car window.

Posts: 353
Joined: Sun Oct 15, 2006 4:12 pm
Location: UK

Carb.

Postby jonhal » Wed Aug 13, 2008 8:16 pm

Try Surrey Cycles, they know correct jet sizes when switching from Monobloc to concentric.

Member
Posts: 2882
Joined: Mon Jan 01, 1990 12:00 am
Location: USA

Carb.

Postby Don Madden » Thu Aug 14, 2008 2:53 am

I believe the short needle jet with hole in nut face is for 4 stroke engines, the other for 2 stroke. Be sure you have the correct needle, too, as there are two types for each series of carb & the lengths for them vary according to the size, also.

Borrow a good one off a B25 if possible to compare the parts.

Early 4 stroke & two stroke concentrics used a screw in pilot jet at the bowl gasket joint face. Later, they replaced the screw in jet on four stroke versions with on pressed in jet at the end of the drillway behind the air screw. Two stroke carbs continued with the screw in jet. The pressed in jet is non-removable & difficult to clear as it is deep in the other side of the casting.

Remove the air screw & shine light down the drillway. If the jet is there, it can be seen, albeit with difficulty, as it is brass in a zinc body.

If there, probe with a small wire to clear the jet. Use compressed air, & if clear, pressure can be felt at the threaded hole for the jet. If no jet, install a #25 pilot jet.

If it cannot be cleared, drill out the pressed in jet & use a #25 screw in jet.

The pilot feed is via the nearly vertical drillways in the bowl. Most bowls have L & R sides drilled but I have seen some that are handed with only one drilled. Be sure your bowl has a clear passage up the bowl to the pilot circuit.

This should keep you out of mischief for awhile.

Cheers, Don.

User avatar
Posts: 192
Joined: Sat Jul 19, 2008 3:05 pm
Location: LEICESTERSHIRE UK

Carb.

Postby davehutch » Thu Aug 14, 2008 3:02 pm

Yes it is doing !!!
----Only a biker knows why a dog sticks his head out of a car window.

Next

Return to G2 / Model 14

Who is online

Users browsing this forum: No registered users and 4 guests