32 mk2 amals

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ozcruiser

ozcruiser

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Are 32 mk2 amals worth the trouble fitting to my 1972 commando. A good mate has offered me these carbs cheap not sure its worth the trouble fitting these as need new manifolds air cleaner etc. After reading some threads they look very hard to set up where not sure what there off thinking triumph t140 but unsure.
 
Are you certain they are 32mm ? I thought the t140e carbs were 30 mm
 
There is nothing difficult about them. Just make sure they are set up to 4 stroke spec with the correct parts. Check the base spec on Amals web site. The needle jet is MK2 specific as is the needle & the air jet. Also, make sure the enrichment plungers are seating properly. Other than that they are just a more modern version of a MK1.

Martyn.
 
There left and right no marking on the carbs at all but after your tip there's three models in the 32mm Amal range that I can find
4 stroke
3 Cutaway Slide
240 Main Jet
106 Needle Jet
25 Pilot jet

2 stroke
3 Cutaway Slide
280 Main Jet
107 Needle Jet
25 Pilot jet

2 stroke Alcohol
3 Cutaway Slide
600 Main Jet
120 Needle Jet
25 Pilot jet
I will stripe the bowls and see what I have from what I read the 8 valve t140 tss had 34mm mk2 carbs so not off one of them.
 
Matchless said:
There is nothing difficult about them. Just make sure they are set up to 4 stroke spec with the correct parts. Check the base spec on Amals web site. The needle jet is MK2 specific as is the needle & the air jet. Also, make sure the enrichment plungers are seating properly. Other than that they are just a more modern version of a MK1.

Martyn.
Click to expand...
Does that imply that the MK2 should be jetted the same as a Mk1 for a given engine ?
 
ozcruiser said:
There left and right no marking on the carbs at all but after your tip there's three models in the 32mm Amal range that I can find
4 stroke
3 Cutaway Slide
240 Main Jet
106 Needle Jet
25 Pilot jet

2 stroke
3 Cutaway Slide
280 Main Jet
107 Needle Jet
25 Pilot jet

2 stroke Alcohol
3 Cutaway Slide
600 Main Jet
120 Needle Jet
25 Pilot jet
I will stripe the bowls and see what I have from what I read the 8 valve t140 tss had 34mm mk2 carbs so not off one of them.
Click to expand...
Some years ago I purchased a friends 71 750 Roadster ,it was running 32mm Mk2 Carbs,he had only recently put them on so they were brand new. One day he started up the bike in the garage and then all broke loose in the engine when the back half of one of the pistons fell off as it was one of the dreaded sloted oil ring type.
Anyway I rebuilt the engine and the rest of the bike.but kept the carbs,manifolds rubbers etc to maybe one day fit to my 850.
The jetting is as follows and the same as what was written on the end of the original Amal box-
# 3 Cutaway Slide
240 main
106 Needle
25 Pilot Jet
A fellow club member was running the same jetting on his 750 and said he used the middle groove of the 5 for the clip.
Regarding air filters ,Old Britts web site has some info on modifying a pair of K & N air filters to suit or Uni filters can be used.
The other thing I noted that it has Anodised alloy slides not Chromed brass, anyone know anything about this.?
Brett
 
Rosey said:
The other thing I noted that it has Anodised alloy slides not Chromed brass, anyone know anything about this.?
Brett
Click to expand...
Amal says Anodised Aluminium in their generic Mk2 spares section. http://amalcarb.co.uk/generic-2900-series-mk11.html

Other than a proper enrichener rather than a choke, I'm not sure the Mk2's are going to gain you anything for the same size carb. But tinkering is fun.
 
Yes, anodised slides were standard in the MK2. Heavy chromed brass slides are available today and give better throttle closing IMHO, but it’s a minor point.
 
NickZ said:
Does that imply that the MK2 should be jetted the same as a Mk1 for a given engine ?
Click to expand...
Not necessarily, but they will be close. The best way to set them for any engine is to start off with the standard base settings for that particular size of MK2 & adjust from there. I've fitted a pair to my Atlas & another to my Royal Enfield 612 Big Head Bullet in the last eighteen months, & they both ended up close to base settings. Both bikes carburate perfectly.
 
Matchless said:
Not necessarily, but they will be close. The best way to set them for any engine is to start off with the standard base settings for that particular size of MK2 & adjust from there. I've fitted a pair to my Atlas & another to my Royal Enfield 612 Big Head Bullet in the last eighteen months, & they both ended up close to base settings. Both bikes carburate perfectly.
Click to expand...
The 1972 Interstate Combat I acquired a couple years ago came with 32mm Mk2 Amals. I installed the Old Britts modified K&N cone air filters. Standard Interstate exhaust. I wasn't sure what the correct jetting / set-up should be. The Amal application listing recommendations for 1972 Combat using Mk1 calls for 220 main jets, 106 needle jets, #1 needle position, 3 cutaway slides, I'm running 240 main jets, 106 needle jets, middle needle position, chromed brass slides with 3 cutaway, 622/196 deep floats and 25 pilot jets. Seems to start and run ok, but not sure if it is optimal. I'm not real keen on doing WOT plug chops these days.
 
NickZ said:
Does that imply that the MK2 should be jetted the same as a Mk1 for a given engine ?
Click to expand...
That would be the best start point.

Because, although the parts differ in detail, the calibrated holes are the same.

The flow isn't much different. I was disappointed to discover that when I changed a pair of 36mm Mk1s for a pair of 34mm MkIIs back in '77 when the carbs were just being released by Amal.

Just two race meetings before I had the 34mm holes bored out to 36mm, which just suited my motor better. Overall there was a small improvement at 36mm, but as much as anything in the starting, cold or hot.

This was a bigger benefit than it sounds today, but remember we push started race bikes in those days, a quick starting bike could gain you several places into the first corner.

There was also a physical benefit in using an over bored 34mm as well because the 36mm MkII is physically bigger/heavier and slightly harder to accommodate.
 
NickZ said:
The 1972 Interstate Combat I acquired a couple years ago came with 32mm Mk2 Amals. I installed the Old Britts modified K&N cone air filters. Standard Interstate exhaust. I wasn't sure what the correct jetting / set-up should be. The Amal application listing recommendations for 1972 Combat using Mk1 calls for 220 main jets, 106 needle jets, #1 needle position, 3 cutaway slides, I'm running 240 main jets, 106 needle jets, middle needle position, chromed brass slides with 3 cutaway, 622/196 deep floats and 25 pilot jets. Seems to start and run ok, but not sure if it is optimal. I'm not real keen on doing WOT plug chops these days.
Click to expand...
Nick
your jetting is pretty much the way my combat with Amal 1 are set up.
From the workshop manual
32 mk2 amals
 
ILLF8ED said:
Nick
your jetting is pretty much the way my combat with Amal 1 are set up.
From the workshop manual

Thanks ILLF8ED.
Click to expand...
The stock 2932/300 & 301 Mk2s I am running came with 240 mains. Looks like I should switch the mains to 230. I am assuming that the standard Interstate silencers (the low ones) do not have mute.
Does anyone out there know if that assumption is correct?
 
NickZ said:
The stock 2932/300 & 301 Mk2s I am running came with 240 mains. Looks like I should switch the mains to 230. I am assuming that the standard Interstate silencers (the low ones) do not have mute.
Does anyone out there know if that assumption is correct?
Click to expand...
Hi Nick,
Stock to me means as supplied by the original manufacturer.
1972 750 combat engines came with Amal Mk1 R932/19 and L932/20 carbs. The factory manual was written when premium pump gas was over 100 octane leaded. With E15 gas the correct main jet is probably 240.
 
ILLF8ED said:
Hi Nick,
Stock to me means as supplied by the original manufacturer.
1972 750 combat engines came with Amal Mk1 R932/19 and L932/20 carbs. The factory manual was written when premium pump gas was over 100 octane leaded. With E15 gas the correct main jet is probably 240.
Click to expand...

By that definition, the MK2 carbs were "stock" as supplied by Amal, but not "stock" for this bike. I am concluding that the exhaust system I received with this bike is aftermarket and not "stock" even though it is in the original configuration for '72 Interstate. The right side pipe is longer than the left side and I needed to construct a custom bracket to fit it on the bike and the exhaust appeared that it had not been run yet, but the bike had 19,000 miles on it.

I am also mainly using Sunoco Optima 95 octane fuel which has no ethanol. I sometimes have to add some pump gas for longer rides.

With the 240 mains it does feel a little bogged down when I have had WOT for short periods of time. I'll try the 230s & report results.
 
Interesting discussion. I have just acquired a 1972 750 with a Combat engine. It has been sitting neglected for a number of years and I am just beginning the process of bring it back to life. I am rebuilding the Amal 932 carbs and I find that the have 200 size main jets and 107 size needle jets. The bike is an "S" model with side pipes and reverse cone mufflers and it had a K&N air filter on it when I got it. The needles were in the middle position. Any idea why the main jets were so much smaller than stock? Please enlighten me as I am rather ignorant about carburetor jet sizes. I assume that a size 200 main is smaller than a size 230 or 240. Any ideas what the number refer to? Likewise that 107 needle jets that I have are most likely slightly larger than the 106 jets mentioned above.
 
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