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Discussion Starter · #1 ·
73 TR7RV with a Amal 928. Since I first got it running I could not make it run lean at all. Always too rich(Reading in the book 1.5-2.5 turn out to start). I tried puttin in a .170 jet and re-adjusted everything several times. After turning the air mixture screw(the horiziontal one) all the way IN. It is still running rich. Recently I read that if you have the adjustment screw ran all the way in and it is still running rich, the screw is too short. Has anybody dealt with this, or do they know the right part number???? I could just order another one, but then I already have three and they are all the same size. I have a coulple of Amal 930 bodies but they are the same size. I wonder if the 928 takes a longer adjustment screw and the one I have are from a 930 or 932??.

TangoMike
 

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The regular screw is Amal part 622/076.
However I see a supplier reference to a "pilot air screw extended" as part # 622/168.
However, This is the air screw for the starting system, after 1/8 throttle the pilot system no longer comes into play. If you are running rich, you're either going to have to rejet or reset your needle or both.
 

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1 928/930/932 carbs all use 622/076 screw

2 622/168 refers to extended (outside the carbs)air screws with hex heads. (622/169 is the part number for extended for the throttle screw)

3 You no say what cutaway or needle jet you are using. SUGGEST you use a 930 carb with maybe a #3 cutaway and a NEW 106 needle jet AND A NEW needle set rich. Maybe a 270 main jet.

4 If you dont believe me get a factory parts book and see what they called for.
 

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Discussion Starter · #4 ·
I don't see any reason not to believe you. I have a 3-1/2 cutaway and a .170 jet. It had a .190 in it. The needle has three notches and I have set it down to clip the top notch, giving it the lowest setting. I did not mention how rich it is running. I foul out the plugs in about 75 miles or so, and it smells rich, but no real black smoke. Does that say anything?? No sure. you mentioned a 106 jet?? Can you tell me which jet is a 106(you know in cc/hr like .190 .210, etc..)
 

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Discussion Starter · #6 ·
OK a 106 needle? Are the different needles different diameters or taper angles or anything like that, or do they only differ in the number of notches??

PS Float levels set at .080 on the money.

Tangoike
 

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Needles are different diameters and tapers, the notches are the same. if your motor is in standard tune you should not be far out with your STD needles. you should adjust the floats to the 60thou limit. and give it a shot. it is a fairly easy adjustment to make, using and 1/8 drill bit shank through the hole in carb under banjo bolt, warm the bowl up a bit and tap the needle seat it will adjust.
Do you have "Viton" tip needles fitted?
 

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Discussion Starter · #8 ·
Oh, that is the first time I heard there was any difference besides the notches. Thanks. That may give me something to go on. I will also adjust the float down to .060. I will get as close to that as I can. I can drift that brass piece, but never as precise as I like. After about 6 attempts it landed on .080 so I kept it. Do you where I may find more information on the Amal needles diameter and taper angles?? Actually I may have that, I will look tonight.

Tnaks
TangoMike
 

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tango
I did a little quick checking my '73 US parts book call for a 930 carb. A 3 1/2 slide, 106 needle jet, and a 280 main jet. Then I grabbed a '73 Factory manual it calls for a 930 (930/89) carb, 3 1/2 slide,106 needle jet (number will be stamped on the jet), std needle on #2 position, and a 280 main jet.

da followin is jus my pinion, granted I dont know your setup stock /choped, stock exhaust/TTpipes, with/without air filters.

your 928 carb may give better low end response due to intake velocity but it will restrict top end. I'm no genius but the factory put a 930 on the bike when new and since my bikes a mostly stock thats what I use. The main jet operates from 3/4 thru WFO so unless you are going gonzo WFO for 75 miles the change you did to that item makes no difference. Needles and jets wear that's why I said fit new ones. Due to the fact where I live all you can get is Ethanol fuel I have RAISED my needles by one position to try to compensate for the 10% alcohol I have also INCREASED my mains by one size. So to recap the way I see it you are fouling both plugs in about 75 miles your main jet is to small and your needle jet is set lean and you appear to maybe have the correct cutaway on the slide which is lean also but you are running rich. Also from from things you have said I gather you are new to these bikes/carbs. We are assuming your charging system and timing are up to par I think your idle mixture is set to rich (been there/got the Tshirt) . Humor me reset your idle mixture/speed screws (mixture screw out is leaner).

Like I said jus my pinion
 

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Shout! tangomike

Oh, that is the first time I heard there was any difference besides the notches. Thanks. That may give me something to go on. I will also adjust the float down to .060. I will get as close to that as I can. I can drift that brass piece, but never as precise as I like. After about 6 attempts it landed on .080 so I kept it. Do you where I may find more information on the Amal needles diameter and taper angles?? Actually I may have that, I will look tonight.Tnaks
TangoMike
tangomike Have you done your float levels yet, as I have said adjust them to 60thou from your 80! I am wrong as this will richen the mix! what was I thinking of sorry.
It sounds as you are having the same hassle as me, always sooting plugs + I get a misfire around 4000rpm, and a couple of mates have said it stinks of petrol when they are riding behind me:confused:
 

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These pages are from a zipped file. I dont know where they came from but they are useful. I have to use 2 replies?? more than 4 images. And I`ll probably be in court soon for violating copyright.



 

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Discussion Starter · #13 ·
Also from from things you have said I gather you are new to these bikes/carbs. We are assuming your charging system and timing are up to par I think your idle mixture is set to rich (been there/got the Tshirt) . Humor me reset your idle mixture/speed screws (mixture screw out is leaner).

Like I said jus my pinion
Good call. New touched them before I stumbled upon this purchase. I am trying to learn, but it is slow. Sometimes I have to have parts of the manual translated into english. Where I live parrafin is a wax and a twist grip is a throttle. The real problem though, is getting what I thought was basically a 73 Triumph Tiger, and what I got was a 73 engine with everything else coming from multiple year/models/makes of Triumphs(and Harleys). So every non-motor part I have tried to order is wrong. Won't fit. Toss in the wrong carbs, exhaust, cables, etc. and what a learning experience. It is slow but sure. After the post from Plewsy(thanks) I got to thinking and looked again at the documentation I have collected. I have finally grasped the needle jet size after I saw a "106" stamped my needle jet. I am building a 930 so maybe I can get that one right. Thanks for the 930 specs. All I need to do is order a .280 main jet.

Thanks
TangoMike
 

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Discussion Starter · #14 ·
OK, I found one more little unknown thing(for me) on the Amal 930. The older model 930(do ask me what an older model is) the is a pilot jet that screws into the carb body above/inside the float bowl. It took me a while to realize that the carb I am rebuilding had a threaded hole and was missing the pilot jet. The one I had for study just has the hole with no threads so I did not realize it was missing a part. With that pilot jet installed, it DOES NOT run any leaner. Maybe a dumb statement to people that know these carbs, but I was hoping to sovle the richness prolem I have. I have since ordered a needle, needle jet, jet holder and main jet.

TangoMike
 

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Twice now I have seen a pilot screw that was 'worn out' and was basically acting as if it were too short. Replacing it fixed the issue both times. It's a super cheap part ...
 

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Discussion Starter · #16 ·
Twice now I have seen a pilot screw that was 'worn out' and was basically acting as if it were too short. Replacing it fixed the issue both times. It's a super cheap part ...
****, I gues I should have ordered it anyway. I had run it all the way in and it stop any air flow while I blow thru it, so I assume it will be ok.I made the mistake of ordering from Rask Cycle. I am still waiting for parts. I have never seen anybody ship so slow.
 

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Discussion Starter · #17 ·
****, I gues I should have ordered it anyway. I had run it all the way in and it stop any air flow while I blow thru it, so I assume it will be ok.I made the mistake of ordering from Rask Cycle. I am still waiting for parts. I have never seen anybody ship so slow.
Ok after two weeks Rask Cycle shipped my parts and I got them yesterday. Too bad is was the wrong damned part! Between the last order and this one, they have lost my business.

TangoMike
 

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Discussion Starter · #18 ·
Like I said, wrong parts. I was sent a .105 needle jet instead of the .016 I ordered. It was even marked .106 on the shipping invoice. I actually order a .230 main jet when it should have been a .280(That was my fault. Old eyes). So I put the 230 main jet the 105 needle jet and a new needle it. Fired it up and there was quite a difference. It runs much much leaner. Actually too much, as it craps out about half throttle. The needle jet and or needle was the source of my super rich buring carb.

Thanks fo al the help
TangoMike
PS I found the 280 main jet and the 106 needle jet locally. Doh!
 

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73 TR7RV with a Amal 928. Since I first got it running I could not make it run lean at all. Always too rich(Reading in the book 1.5-2.5 turn out to start). I tried puttin in a .170 jet and re-adjusted everything several times. After turning the air mixture screw(the horiziontal one) all the way IN. It is still running rich. Recently I read that if you have the adjustment screw ran all the way in and it is still running rich, the screw is too short. Has anybody dealt with this, or do they know the right part number???? I could just order another one, but then I already have three and they are all the same size. I have a coulple of Amal 930 bodies but they are the same size. I wonder if the 928 takes a longer adjustment screw and the one I have are from a 930 or 932??.

TangoMike
Hi TangoMike,

I'm a total newb when it comes to tuning these things, however I'm pretty sure that if you want to lean the mixture you need to turn the screw OUT, not in as you mentioned doing. Turning the screw in richens the mixture. Has nobody noticed this bit?
 
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