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#710317 - 10/02/17 7:54 pm DBD34 Scrambler carburator problems  
Joined: Jul 2013
Posts: 25
mf-zh Offline
BritBike Forum member
mf-zh  Offline
BritBike Forum member

Joined: Jul 2013
Posts: 25
Switzerland
Hi everybody

Maybe somebody can help me on my carb problem. My bike:

1957 DBD34 500ccm
Standard gear box
New scrambler head (ABSAF)
New AMAL Premier 932 Carb with a heat insulator
New Magneto (electronic VAPE)
High level exhaust

My problem: When the bike is hot, the idle goes up and down a lot. You drive 1 mile stop,the bike nearly dies on you. After your next stop, say 300 yards it idles at about 2000rpms. I have put on a other AMAL, the problem is +/- the same. Due to the high level exhaust, I can't fit a Mikuni. The quality of the AMAL is not great, for example the screws and threads don't look as if they match on idle and mixture. And I imagine it is pulling air where it shouldn't. The heat insulator is good and tight.

What carbs you have on your scramblers?

Greetings for Switzerland,

Mike

BSA Gold Star eBay items

BSA Gold Star forum This board is dedicated to BSA Gold Star motorcycles.

#710361 - 10/03/17 2:51 am Re: DBD34 Scrambler carburator problems [Re: mf-zh]  
Joined: Mar 2017
Posts: 19
99cyclone Offline
BritBike Forum member
99cyclone  Offline
BritBike Forum member

Joined: Mar 2017
Posts: 19
Iowa
Does your bike have an adapter manifold to fit the 932 on the DBD head?

My DBD didn't run right with a 932, was too lean. It had quite an idle rise as it warmed up (no air leaks) and ran hot. I didn't bother much with the jetting, as it already had fairly large jets.

Instead, I found a 1036 AMAL that bolts right up to the head. I got the jetting right and filed the slide cutaway until it ran right. These carbs are scarce, but still out there.

It's a bit more work, but it was well worth it for my bike.

You might contact Mark at British Only Austria. He had a 1034 when I visited in August.


Buells and Brit Bikes
#710364 - 10/03/17 3:49 am Re: DBD34 Scrambler carburator problems [Re: mf-zh]  
Joined: Nov 2011
Posts: 3,971
Magnetoman Online content
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Magnetoman  Online Content

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Posts: 3,971
U.S.
Originally Posted by mf-zh
New Magneto (electronic VAPE)
The heat insulator is good and tight.
It doesn't look like VAPE makes a magneto replacement so please give more details about what you have for an ignition system, and especially if the control unit is mounted somewhere where it can get hot.

"Good and tight" makes me wonder if maybe you tightened it too much and warped the carburetor flange or the insulator, allowing air to leak in. The mounting nuts should be "snug" not "tight," with loctite rather than brute force holding them in place.

#710528 - 10/04/17 7:00 pm Re: DBD34 Scrambler carburator problems [Re: 99cyclone]  
Joined: Jul 2013
Posts: 25
mf-zh Offline
BritBike Forum member
mf-zh  Offline
BritBike Forum member

Joined: Jul 2013
Posts: 25
Switzerland
@99 cyclone

I will ask Mark, i know him well. Thanks for the tip.


@Magnetoman

This is the Magdyno I have from Vape: http://www.powerdynamo.biz/eng/systems/7197/719710main.htm. It is not the problem, I am aware about the warping of the AMAL Carbs.

#714382 - 11/09/17 3:11 pm Re: DBD34 Scrambler carburator problems [Re: Magnetoman]  
Joined: Jul 2013
Posts: 25
mf-zh Offline
BritBike Forum member
mf-zh  Offline
BritBike Forum member

Joined: Jul 2013
Posts: 25
Switzerland
Hi Magnetoman

https://www.powerdynamo-shop.com/shop/show_product.php?cPath=2_36&products_id=259

sell the VAPE Magdyno.

Cheers, Mike


Originally Posted by Magnetoman
Originally Posted by mf-zh
New Magneto (electronic VAPE)
The heat insulator is good and tight.
It doesn't look like VAPE makes a magneto replacement so please give more details about what you have for an ignition system, and especially if the control unit is mounted somewhere where it can get hot.

"Good and tight" makes me wonder if maybe you tightened it too much and warped the carburetor flange or the insulator, allowing air to leak in. The mounting nuts should be "snug" not "tight," with loctite rather than brute force holding them in place.

#714408 - 11/09/17 7:19 pm Re: DBD34 Scrambler carburator problems [Re: mf-zh]  
Joined: Aug 2015
Posts: 931
Andy Higham Offline
BritBike Forum member
Andy Higham  Offline
BritBike Forum member

Joined: Aug 2015
Posts: 931
Bolton Lancs UK
32mm is very small for a 500 goldie
I have a 32mm Mikuni on my B31 and the same electronic magdyno, and DBD34 clubman cams. It idles well hot or cold, starts easily and works cleanly at part throttle

Last edited by Andy Higham; 11/09/17 7:23 pm.

1955 BSA B31 400cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350cc
1967 Greeves 360cc Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
Modified Nu-Trak GM500cc sprint/LSR bike "Deofol"
2003 Aprilia RSV Mille "Lo Stregone"

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