BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
  JWood Auction  
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Photo posting tutorial

Member Spotlight
Coco
Coco
Regina Sk, Canada
Posts: 358
Joined: May 2007
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
209 registered members (57nortonmodel77), 1,642 guests, and 556 spiders.
Key: Admin, Global Mod, Mod
Newest Members
revans, Gilly, XTINCT, Bruce Roberts, Brian Ellery
9959 Registered Users
Top Posters(30 Days)
btour 193
koan58 99
Stuart 84
NickL 73
Popular Topics(Views)
438,944 mail-order LSR
Forum Statistics
Forums33
Topics65,290
Posts632,453
Members9,959
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate This Thread
#444928 - 07/16/12 2:34 pm Amal Monobloc - Setting the float height  
Joined: Oct 2005
Posts: 568
Mattsta Offline
BritBike Forum member
Mattsta  Offline
BritBike Forum member

Joined: Oct 2005
Posts: 568
Surrey UK
I gather that the original float cover had a pip cast into it which is used to measure the amount of fuel in the float chamber against a piece of clear pipe attached to the pilot jet.

Unfortunately, my float cover is not original and doesn't have this feature.

Does anyone have an actual measurement for the correct position of this feature or a measurement for the correct amount of fuel?

The carb is a 1" 376 Monobloc.

I ran my Tribsa for the first time in 15 years this weekend

It was running extremely rich. Seems the fibre washer included in AMAL's repair kit is not required for the fuel inlet. It raises the level of fuel considerably before the viton tipped valve stops the supply of fuel.I removed this washer and it runs better but still too rich.

What's the next thing to check after the float height?

Is it common practice to drop the needle a notch to lean the mixture or should it ideally run in the middle notch?

All the jets and needles are new AMAL components but the float is reused. It's a plastic rather than brass float. It doesn't seem to be punctured.

Last edited by Mattsta; 07/16/12 2:42 pm.

1952 Triumph T100 in a BSA A7 Frame
Support Your #1 BritBike Forum!
Membership Type! Free
Member
Premium
Member
Premium Life
Member
Vendor
Member
Site
Sponsor
Recognition No Premium Member Premium Life member (5 years) Vendor Member Site Sponsor Membership
Post commercial threads No No No Yes Yes
Custom title No Yes Yes Yes Yes
Upload avatar & photos No Yes Yes Yes Yes
Link avatar & photos Yes Yes Yes Yes Yes
Private Message Storage: 10 100 100 100 100
Length of signatures 255 600 600 600 600
Removes this very advert island between post 1&2 No Yes Yes Yes Yes
Price Free $12.90/year $105.00 No End
$55.00/5 years
$210.00/year
($17.50/month)
Email
Click on button >>
  Premium Member Premium Life member Vendor Member Site Sponsor Membership
#444942 - 07/16/12 3:41 pm Re: Amal Monobloc - Setting the float height [Re: Mattsta]  
Joined: Mar 2005
Posts: 9,970
John Healy Online content
John Healy  Online Content


Joined: Mar 2005
Posts: 9,970
Boston, Massachusetts
The fuel level "pip" was at the geometric center of the cover.

A long shot is the gasket under the jet block is leaking - again a long shot!
Another long shot is the pilot jet itself. If it isn't fully seated it will leak fuel by-passing the action of the pilot jet. This makes the bike run rich. - again a long shot.

Saying it runs rich is not the way we should be going about this. If it is running extremely rich at all throttle openings you might have the choke on - a long shot, but a common occurrence.

This carburetor has several fuel circuits that could be causing this problem. Each circuit is referenced to by the position of the slide (and the handle bar throttle). So when you say the bike is running rich under 1/4 throttle we can give you the fuel circuits (jets, slides, etc.) to check. In fact the Monobloc (and Concenntric (MKII has three)) is two carburetors in one. The idle carburetor and main carburetor which share a common fuel source but act independently of each other.

So after ypu check the fuel level, check the position of your choke and if both of those don't improve things mark your throttle: 0, 1/4, 1/2. 3/4 and Full and ride the bike and note where the bike is running rich... Then we can sort this carb out.


#444943 - 07/16/12 3:53 pm Re: Amal Monobloc - Setting the float height [Re: John Healy]  
Joined: Oct 2005
Posts: 568
Mattsta Offline
BritBike Forum member
Mattsta  Offline
BritBike Forum member

Joined: Oct 2005
Posts: 568
Surrey UK
Originally Posted By: John Healy
The fuel level "pip" was at the geometric center of the cover.

A long shot is the gasket under the jet block is leaking - again a long shot!
Another long shot is the pilot jet itself. If it isn't fully seated it will leak fuel by-passing the action of the pilot jet. This makes the bike run rich. - again a long shot.

Saying it runs rich is not the way we should be going about this. If it is running extremely rich at all throttle openings you might have the choke on - a long shot, but a common occurrence.

This carburetor has several fuel circuits that could be causing this problem. Each circuit is referenced to by the position of the slide (and the handle bar throttle). So when you say the bike is running rich under 1/4 throttle we can give you the fuel circuits (jets, slides, etc.) to check. In fact the Monobloc (and Concenntric (MKII has three)) is two carburetors in one. The idle carburetor and main carburetor which share a common fuel source but act independently of each other.

So after ypu check the fuel level, check the position of your choke and if both of those don't improve things mark your throttle: 0, 1/4, 1/2. 3/4 and Full and ride the bike and note where the bike is running rich... Then we can sort this carb out.


Hi John

Thanks for your post

Am I correct to assume that the correct fuel level is roughly the centre of the cylindrical float chamber then?

I will check the pilot jet is tightened and that the jet body is not loose in the carb body. The washer is new and I'm pretty sure I checked that the jet block was tightened fully into the carb body

As far as the choke goes, there is no choke fitted and never has been. The bike starts fine without it. It doesn't get used at all during winter. Maybe this is a problem in itself????

Last edited by Mattsta; 07/16/12 3:55 pm.

1952 Triumph T100 in a BSA A7 Frame
#445652 - 07/22/12 7:47 am Re: Amal Monobloc - Setting the float height [Re: Mattsta]  
Joined: Oct 2005
Posts: 568
Mattsta Offline
BritBike Forum member
Mattsta  Offline
BritBike Forum member

Joined: Oct 2005
Posts: 568
Surrey UK
Seems the rich running problem was caused by a dodgy pilot jet. I removed it and inspected and there didn't seem to be anything untoward about it but I replaced the pilot jet with my old one and the rich running problem was cured immediately.

A very strange turn of events yesterday getting the bike running properly

After curing the rich running problem, the bike started to run on one cylinder. I removed the LHS pick up holder from the magneto to discover that the carbon brush had separated from its spring.

My first thought was SHIT! because I now have a carbon brush sitting in the bottom of the magneto body which would mean I would have to remove the magneto, strip it, re-time the engine and such forth. By an incredibly stroke of good fortune, I removed the rear pick up holder and the carbon brush was sitting intact on top of the rear pick up moulding! LOL! Phew!

Fortunately, I have a couple of spare pick up brushes. Fitted a new one and the bike still didn't fire on the LHS cylinder.

My mate suggested I fit another spark plug so I replaced the (new) one with and old one I had in the shed and bingo! She fired and ran properly for the first time in 15 years.

How odd to have a magneto brush AND a new spark plug fail simultaneouly!

Just a couple of things to sort out now before I get her MOT'ed.

The dynamo isn't working so I will test that today and see if I can diagnose the problem and I need to do some work on the rear brake pedal which isn't fitting properly.


1952 Triumph T100 in a BSA A7 Frame

Moderated by  Alan_nc 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.225s Queries: 15 (0.009s) Memory: 0.8134 MB (Peak: 0.9519 MB) Zlib disabled. Server Time: 2017-11-23 15:00:29 UTC