I thought jet size numbers were based on drops of petrol per certain period of time. It seems like @Magnetoman has addressed this. Also, Amal jet sizes after the pre-monoblocs changed along with their style, so that complicates things.
Misc: Everything Else Starting Problem - Series 'C' BIG Single
- Thread starter Jez Nemeth
- Start date
There is also the Bernoulli Principle to consider.
Flow thru a venturi increases at the square of the velocity of the air flowing past the venturi.
So mainjet size and engine displacement are not in a directly proportional relationship.
Glen
Flow thru a venturi increases at the square of the velocity of the air flowing past the venturi.
So mainjet size and engine displacement are not in a directly proportional relationship.
Glen
Last edited:
The title of this thread didn't seem relevant to me so I'm only looking at it now for the first time, as a result of Bruce's post causing it to be flagged. I've not read all 72 pages of the thread (or even 71 of them...), so I apologize if this has been mentioned before, but 1000-series Concentrics were constructed for 2-stroke use, and it's not just simply a matter of substituting a few components to get them to work well for 4 strokes. See the following thread for full details on modifying a 1036 to work well on a Gold Star:
www.britbike.com
Jetting a 1036 (or 1038) Concentric
Note: because of the 5 images/post limitation this will be spread over four posts. Jetting a 1036 (or 1038) Concentric for a Gold Star Charles Falco Background: The 1½" AMAL GP supplied on Clubman Gold Stars has an almost unrestricted bore for flowing large quantities of air s...
Yup..let's stick with what we got Bill -you know I tend to dance around problems throwing out all sorts of possibles before honing and focusing in on what needs to be done...and still get it wrong!
Go with your advice mate -it's all good...next time we'll take it up gently, tentative testing step by step, we'll get there -let's just start too rich and work backwards -remember the fun we had with the 930 Premiere? And after a complete and utter headache, head scratching, kicking the can around -finally found the sweet spot and it turned out to be a really lovely smooth ride, first time kicker and uber reliable...
And we got this one to be a first time kicker -which is what was the original objective.
I have absolutely no doubt we'll sort this as well, the new aim is -well we all know what it should be...anyway enjoying each problem as they come up -this is the enjoyment of a challenge- working out what will/won't work...I too read that info in depth on the carb, but didn't reflect what was going on with this one, were in uncharted waters... where the laws of what's gone before don't quite sit with the components we've got to play with...steer left to turn right!!
Last edited:
Your entry to the conversation, or whatever this thread has now become is most welcome, especially when bringing info like that at the right moment to the party. Had read it before when researching the carb originally before deciding to buy it, but had gone completely out of mind -knowing more about it, that thread absolutely more relevant now than then.The title of this thread didn't seem relevant to me so I'm only looking at it now for the first time, as a result of Bruce's post causing it to be flagged. I've not read all 72 pages of the thread (or even 71 of them...), so I apologize if this has been mentioned before, but 1000-series Concentrics were constructed for 2-stroke use, and it's not just simply a matter of substituting a few components to get them to work well for 4 strokes. See the following thread for full details on modifying a 1036 to work well on a Gold Star:
Jetting a 1036 (or 1038) Concentric
Note: because of the 5 images/post limitation this will be spread over four posts. Jetting a 1036 (or 1038) Concentric for a Gold Star Charles Falco Background: The 1½" AMAL GP supplied on Clubman Gold Stars has an almost unrestricted bore for flowing large quantities of air s...
That carb is where the drama is taking place, although there are other factors with the TP head coming to light, many of the other issues are being sorted - (BTW thx for TP head info Glen, it's 40mm -we're using a 36mm Carb...there's a clue there possibly?)
Oddly, found a converted and bored 1034 Amal on ebay earlier and flagged it, sounds very similar to what's being outlined in that shared thread link-for a Goldstar possibly?! But mentions a 2 stroke spray tube? might be a mis-identified Norton style cut?...Much of it fits, which now makes sense from what you've indicated.
As for the rest of the thread, I wouldn't bother reading back -I'll precis it...
Bought very big engine, installed in bike, fixed reluctant starting, appeared to run ok, thrashed and blew out one side of piston and rings on first road test before we'd worked out the correct tuning for petrol rather than alcohol + Nos, now diagnosing what happened, solving issues, proposing next move to avoid repeat...
There, that's pretty much up-todate
Last edited:
On an earlier post I spoke about the 3 mm wide slot at the inside of where the petrol comes in the float chamber,
To aid fast flow, once past the float needle, Concentric !.
It might only be me that didn't know about it, Was not on the old ones,
But the years have got away from me, Not long known about the Mk2,
Which have been out for many years !,
Just to show you what I mean and hope it's already on Jez's Carb' ?,
But I still think for the amount of petrol He needs , He should go for a remote Good Float Chamber ?.
To aid fast flow, once past the float needle, Concentric !.
It might only be me that didn't know about it, Was not on the old ones,
But the years have got away from me, Not long known about the Mk2,
Which have been out for many years !,
Just to show you what I mean and hope it's already on Jez's Carb' ?,
But I still think for the amount of petrol He needs , He should go for a remote Good Float Chamber ?.
Attachments
A thorough and in depth review of these concentrics -absolutely invaluable if owning one, this has really helped.The title of this thread didn't seem relevant to me so I'm only looking at it now for the first time, as a result of Bruce's post causing it to be flagged. I've not read all 72 pages of the thread (or even 71 of them...), so I apologize if this has been mentioned before, but 1000-series Concentrics were constructed for 2-stroke use, and it's not just simply a matter of substituting a few components to get them to work well for 4 strokes. See the following thread for full details on modifying a 1036 to work well on a Gold Star:
Jetting a 1036 (or 1038) Concentric
Note: because of the 5 images/post limitation this will be spread over four posts. Jetting a 1036 (or 1038) Concentric for a Gold Star Charles Falco Background: The 1½" AMAL GP supplied on Clubman Gold Stars has an almost unrestricted bore for flowing large quantities of air s...
What I find with this 1036 carb is that most parts were 4 stroke set up, had to change main, and spray tube (106 -but will be increasing to 112 but is 4 stroke ). The Jet holder was 2 stroke, now 622/128 installed...so a mix.
Just to know I'm on the right track, drill out air constriction to same bore along whole length of the channel for 4 stroke application if not done?
As you mention, and I'm the same as most, I like to more original look of the 1000 series, and don't want the full GP or 10TT9 racing carb experience, but looking at fitting a remote float as its advised will help to supply a more even fuel supply from 1/2 to full throttle.
112 needle jet (upped from 106),
4 stroke spray,
No3 Slide (could be made 4#),
600 main,
55pilot
Last edited:
Where did 112 needle jet come from Jez,
Just looked up Goldie G.P.
109 needle jet and 350 main.
Just looked up Goldie G.P.
109 needle jet and 350 main.
Might be wholly wrong about this, and really working with limited knowledge/experience -Based on engine size Bill -figured that ratio-wise, it would need to be upped from 106 , and 112 was available...thought might be a good choice?...experimenting here...
Maybe the 380 main is ok, it's other factors that are affecting the running -remote, open fuelways,...
Maybe the 380 main is ok, it's other factors that are affecting the running -remote, open fuelways,...
112 sounds a bit too much,
But I can see why you would go that way,
I have done some guessing with mine,
Thinking 350 to 400 main, But that is with a smaller Carb',
Thinking yours could be 450 to 500 ?,
Tricky Game !.
I am lucky , I have a few main jets from my Racing days.
But I can see why you would go that way,
I have done some guessing with mine,
Thinking 350 to 400 main, But that is with a smaller Carb',
Thinking yours could be 450 to 500 ?,
Tricky Game !.
I am lucky , I have a few main jets from my Racing days.