A A A
Avatar

Please consider registering
Guest

Search

— Forum Scope —






— Match —





— Forum Options —





Minimum search word length is 3 characters - maximum search word length is 84 characters

Register Lost password?
sp_Feed sp_PrintTopic sp_TopicIcon
B175 Carburettor Jets ?
Avatar
b175er
saltfleetby
Top Gear User
Club Member
Forum Posts: 465
Member Since:
October 18, 2013
sp_UserOfflineSmall Offline
1
July 12, 2021 - 4:31 pm
sp_Permalink sp_Print

One for more knowledgeable Bantamites than me ... I've just had the good fortune to be able to buy an unused Concentric carb for my B175. However, when I put it on it just didn't work. All I had was a healthy spark from a bone dry plug. On examination I found that the carb has the correct number, slide and main jet for the B175 but the removable pilot jet, needle and needle jet for the earlier D10/14 models. After numerous stripdowns, cleanings and blowing outs, kicking and running down the road in second gear - all to no avail - I fitted the (longer) needle and the needle jet from one of me old carbs and hey presto; off it went. I understand that the 626/17 is a two stroke carb (Amal catalogue) and I know now that it needs to be fitted with the longer needle and four stroke needle jet for it to work.

So, my question is this. What is so different about the B175 engine that prevents the carb that works on the D10/14 providing any fuel through either the pilot system or when the throttle is opened  on a B175 engine ?

Please enlighten me.

two B175s, a C15 and a CB360.

Avatar
sunny
Norfolk
Top Gear User
Club Member
Forum Posts: 1911
Member Since:
January 9, 2013
sp_UserOfflineSmall Offline
2
July 12, 2021 - 5:15 pm
sp_Permalink sp_Print

to  be  very  honst   bantams   have  a  sort  of   long  term  everlotion     and  each  part  chang   along  the modles   like  race  engine   thay  get  moor  tricky   to start  up and thay     change   as  thay   wear  in and  out  much   faster  .,.,.  so  abit  moor  temprementle    ,.    im  not  very  shor  ther  is  a 
B 175  modle   is  corect        as  far  as  i  know  its  D 175   and   D 175 B   [  the  B for  Bushman  ]      so  just  have  fun  in the knolage  you  have  beet  it   nasty   trix   its   played   on  all  of   us   from  time  to  time  

Avatar
b175er
saltfleetby
Top Gear User
Club Member
Forum Posts: 465
Member Since:
October 18, 2013
sp_UserOfflineSmall Offline
3
July 12, 2021 - 5:28 pm
sp_Permalink sp_Print

Thanks Sunny. You're right, I'm pleased to have got the better of it; but I'm a bit bamboozled by it !

two B175s, a C15 and a CB360.

Avatar
cocorico
Central France
Top Gear User
Site Member
Forum Posts: 3450
Member Since:
June 23, 2013
sp_UserOfflineSmall Offline
4
July 12, 2021 - 6:35 pm
sp_Permalink sp_Print

Well, I don't think its been talked about in the past few weeks, but...** Please log in to view **

Avatar
b175er
saltfleetby
Top Gear User
Club Member
Forum Posts: 465
Member Since:
October 18, 2013
sp_UserOfflineSmall Offline
5
July 12, 2021 - 7:15 pm
sp_Permalink sp_Print

The thing is that these posts are telling what I know; but what I asked is why my carburettor was supplying no fuel at all (not enough so much as to dampen the plug let alone make it fire - even when being run off) when fitted with the two stroke jets whereas after fitting the four stroke needle and jet it started first kick !

There must be a reason.

two B175s, a C15 and a CB360.

Avatar
Sponge
Lancashire (A chip shop somewhere near Preston)
Top Gear User
Club Member
Forum Posts: 703
Member Since:
November 6, 2016
sp_UserOfflineSmall Offline
6
July 12, 2021 - 7:45 pm
sp_Permalink sp_Print

I still think it would start ...even with the wrong needle and needle jet. So long as the needle is liftinv the B175 should start. The changes from the D14/4 were to accomodate the slightly lower compression ratio and to make it run cleaner through the rev range. 

If you want my theory I would suspect a sticking float needle on the new carb which would prevent any fuel getting through. When you stripped the carb to inspect it and change the needle jef you probably unstuck the float needle at the same time. 

Alternative theory is a bit of debris/gasket goo blocking up the pilot jet or one of its airways. Once again when you stripped the carb the problem ended up amongst the iron filings, old washers, and dust on the workshop floor.

Thats my theory anyway. And I am pretty sure that if I took the carb off a D14 and put it onto my B175 it would start up fine....it would just run like it was fuelled on kangaroo urine. 

Happy days and well done anyway. As Sunny says at least you beat it and you have the peace of mind knowing it is all cortect now. 

Avatar
cocorico
Central France
Top Gear User
Site Member
Forum Posts: 3450
Member Since:
June 23, 2013
sp_UserOfflineSmall Offline
7
July 12, 2021 - 8:23 pm
sp_Permalink sp_Print

b175er said
...what I asked is why my carburettor was supplying no fuel at all ... 

If we could give a definitive answer to that without actually inspecting the carb we could all buy lottery tickets! As you should know from previous posts, there are many aspects of Bantams which have no definite statement "why", such as the 4 stroke carb and flywheel plates.

Avatar
sunny
Norfolk
Top Gear User
Club Member
Forum Posts: 1911
Member Since:
January 9, 2013
sp_UserOfflineSmall Offline
8
July 12, 2021 - 9:45 pm
sp_Permalink sp_Print

very  sorry   i  mist ed   that  part  of  the gestion   so  here  gos   in  the factory  each  part made is  set and tested  useing  jigs ,.,  after the  parts are asembled  the  hole  asemberly  get   rejiged   to  fit in on the next  part  of the asemberly     so  a rackn pinyon  stering  rack   has   2 or3  jigs to go  throw  befor  fiting  to  a car or bus  ect     ,.,  if any  parts  are  chaned   the  total   asemberly  has  to  be rejiged       likewize    with  the    bantams 

carb  thay  need    to be  rufly  set up   first    ,then   set  up to  start  the engine  if  the thing  dosnot  run   proply      reseting   or refiting  of jets  may

 be needed    usly   moor than  3  times   so   all in all  good   fun  a

Avatar
b175er
saltfleetby
Top Gear User
Club Member
Forum Posts: 465
Member Since:
October 18, 2013
sp_UserOfflineSmall Offline
9
July 12, 2021 - 11:04 pm
sp_Permalink sp_Print

Yes, good fun - once it's sorted out, Sunny !

Thank you all for the replies.

two B175s, a C15 and a CB360.

Avatar
BASIL
Hamstreet,Ashford.
Area Rep
Club Member
Forum Posts: 908
Member Since:
October 1, 2011
sp_UserOfflineSmall Offline
10
July 13, 2021 - 8:37 am
sp_Permalink sp_Print

Hi, once again here are the settings for a B175 carb, it should be a 626/17 with a fixed pilot jet 3 1/2 slide, 180 main jet and FOUR STROKE NEEDLE and NEEDLE JET, believe me if the engine is fully B175 with no other parts fitted they do not run very well without these settings I have had 4 in the past and they will run with different settings but not very well. Regards Basil.

Avatar
Number6
Lincolnshire
Top Gear User
Club Member
Forum Posts: 535
Member Since:
January 18, 2020
sp_UserOfflineSmall Offline
11
July 13, 2021 - 12:51 pm
sp_Permalink sp_Print

" ...what I asked is why my carburettor was supplying no fuel at all ...  "

Going off-topic but maybe an amusing anecdote - I recently rejected a (new) petrol camping stove for not working properly - basically, you put petrol in, pump it up, then light it - except it keeps going out. Try to relight, it blows the match out. There was just air coming out. I was getting through an alarming quantity of matches. Still can't understand how a tank nearly full of petrol and then pressurized, only blows out air with no petrol in it. http://livinginthepast-audioweb.co.uk/imagex/misc/idunno.gif

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

Avatar
Sponge
Lancashire (A chip shop somewhere near Preston)
Top Gear User
Club Member
Forum Posts: 703
Member Since:
November 6, 2016
sp_UserOfflineSmall Offline
12
July 13, 2021 - 10:20 pm
sp_Permalink sp_Print

Are you supposed to use priming paste to get a peimus type stove lit? The ones I used in the 1980s wouldn't stay lit until they had warmed up. There was also a sort of choke that richened up the mixture to get it lit. Rich mix plus priming paste and away you go. Used up about 1/4 of the fuel tank getting lit.  Once warmed up you could set the mixture lean and it ran very well. 

Brings back happy memories of spilled petrol all over my doss bag and chinese fighting suit. Still I suppose there are worse things to smell of ?

I still have my Coleman stove....it was working when I put it into storage about 35 years ago. Must get it out cos its great for motorcycle camping trips....you just fill it up from your bike ...no need to buy gas or wood. 

Avatar
cocorico
Central France
Top Gear User
Site Member
Forum Posts: 3450
Member Since:
June 23, 2013
sp_UserOfflineSmall Offline
13
July 14, 2021 - 7:51 am
sp_Permalink sp_Print

My parents had a Primus stove, used on days out. I remember that there was a dished ring under the burner, which was filled with meths and lit before turning on the 'gas', obviously warming the burner and also lighting the gas.

I don't think it would work on AMAL carbs, though!

Forum Timezone: Europe/London

Most Users Ever Online: 223

Currently Online: GlenAnderson
20 Guest(s)

Currently Browsing this Page:
1 Guest(s)

Top Posters:

cocorico: 3450

Cornish Rooster: 2917

Blue Heeler: 2434

bart: 2430

David Dale: 2144

Sprung Chicken: 2121

sunny: 1911

Piquet: 1846

Mags 1: 1753

mike p5xbx: 1672

Newest Members:

BantamFife

Forum Stats:

Groups: 9

Forums: 48

Topics: 10831

Posts: 95169

 

Member Stats:

Guest Posters: 1367

Members: 3442

Moderators: 0

Admins: 3

Administrators: Bantam-Super, JMD, Stoo63