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RetroRob
07-30-2012, 6:11 PM
got a new 930 amal on my 66 Triumph 650, single carb, recent rebuild. open pipes. .040 over, hot cams. velocity stack.
Bike starts and idles nice, runs well at speed, but stalls when I get off the gas. If I go 50 then slow down for a red light, i have to keep bliping the throttle or it stalls. Ive had the needle in all the positions, played with the idle and air screw. I think I might need different jets, but dont know what to get. Help !

PS still having problems finding neutral, bike shifts fine otherwise,new clutch plate, springs, rubbers. ball ramp is good, rod looks OK, not mushroomed, I dying to put some miles on this thing, but am getting frustrated after weeks of problem solving.:banghead:

Torch
07-30-2012, 9:27 PM
you say you rebuilt the carb,.... so that means you had it bored and re-sleeved and replaced the needle and needle jet? ...or did you clean it and put new gaskets in it?
Amals carbs wear out, the slides wears out the inside carb body until there is a lot of play between the slide and the body and there goes the ability to properly mix a steady air/fuel ratio off of the needle jet at lower RPM operation. At a higher RPM the slide is further up inside the carb body and the slop of the slide is no longer a big issue.
and the biggest mistake people make when "rebuilding" an Amal is they don't replace the needle and needle jet, these things have been banging around in there for years and are no longer in the correct shape to meter gas correctly.

Frankly, there is no subsitute for a new carburetor.

Do the math.....boring and sleeving = $90 plus $10 shipping, "Amal carb repair kit" containing new gaskets and needle, $55. new needle jet, $12 total = $167.....or a whole brand new carb is about $180

RetroRob
07-30-2012, 9:54 PM
Sorry I miss lead you. The engine is rebuilt, the carb is brand new !

Torch
07-30-2012, 9:59 PM
ok then sorry for the rant...
But, did you buy a TR6 carb, or a Bonneville carb.?

The difference is a Bonneville carb has a 3.0 slide and a 200 main jet
A TR6 carb has a 3.5 slide and a 230 main jet.

and the last thing with todays gasoline containing 15% ethanol ( alcohol ) it sometimes necessary to richen up the pilot mixture by turning the mixture screw all the way in, and then 1.0 to 1.25 turns back out. then raise the idle speed screw until it idles well and then give it a quick rev to see if it revs up without a flat spot or poping.

RetroRob
07-30-2012, 10:28 PM
I've got 3 slide and 200 main. Maybe that's my problem

Torch
07-30-2012, 10:30 PM
you can make a 3.5 slide out of a 3.0 slide by shaving .060 more off of the angle cut on the slide.

RetroRob
07-30-2012, 10:40 PM
Cool I'll try it

SacredSteel63
07-31-2012, 7:24 AM
Not to hijack the thread but mine does the same thing so I'm watching this one. I just ordered a new 930 carb because that's whats on mine now. The old carb was rebuilt and they put in a 230 main jet and a #3 slide. The new 930 carb has a 200 main jet and a 3 slide. The 932 carbs come with a 230 main jet and 3.5 slide. What do the 650 single carbs normally take? a 930 or 932?

RetroRob
07-31-2012, 7:31 AM
I don't know, but mine seems starved for gas, make sense if the carb was meant to run as a pair. I thought I had ordered the right one. I'll add this to my long list of fuck ups on this bike.

Torch
07-31-2012, 8:09 AM
Not to hijack the thread but mine does the same thing so I'm watching this one. I just ordered a new 930 carb because that's whats on mine now. The old carb was rebuilt and they put in a 230 main jet and a #3 slide. The new 930 carb has a 200 main jet and a 3 slide. The 932 carbs come with a 230 main jet and 3.5 slide. What do the 650 single carbs normally take? a 930 or 932?

the 932's were normally for the Norton 750/850 used in pairs with a 3.0 slide and a 200 main, and they were also used on the Triumph TR7 single carb 750 with a 3.5 slide and a 230 main.
The Triumph TR6's usually have a 930 with a 3.5 slide and 230 main.

RetroRob
07-31-2012, 11:01 AM
Thanks Torch, found a 3.5 slide and 230 on ebay, should be here in a few days.

Any ideas about the difficulty finding neutral ? Clutch works great, gearbox shifts well on the bench. but I go right past neutral to 2nd every tume I use my foot. If I reach down and jiggle the shifter I can get it into neutral after 2 or 3 tries.

Torch
07-31-2012, 2:01 PM
try thicker gear oil, straight 90 weight or even ad some STP or Lucas oil stabilizer in there and see if that can slow the gears down enough to find neutral.
But the Leaf spring trans in 71 and 72 has issues with finding and holding gears and all the left side shifts 76/up always had problems finding neutral while running.

SacredSteel63
07-31-2012, 3:16 PM
you can make a 3.5 slide out of a 3.0 slide by shaving .060 more off of the angle cut on the slide.

Torch,
Could you please elaborate a little on this? What would be the best method, file, sand paper?
I'll have an extra #3 slide when my new carb comes in and may try this.

Thanks

Torch
07-31-2012, 5:10 PM
take a set of calipers and lock them on .060. then using the sharp edges of the calipers scribe a line that is .060 up from the existing angled slide cutaway, Then using a flat file you can file off all the way to the scribe line.

if you fuck it up throw it as hard as you can at the wall and drink two more beers and go get on eBay.

RetroRob
07-31-2012, 9:34 PM
Ok, finally got the gearbox to shift to neutral. Tonight I realized how hard shifting to all gears were, even with the clutch working correctly. I jacked the bike up and starting backing out the plunger. Altering loosing it up a bit I tried shifting and amazingly everything shifted great, even found neutral with no problem. So I removed the plunger and was amazed how stiff the spring was. I cut about 5/16" off the spring , then stretched it out a bit. Reinstalled everything and put the 90 weight oil in the gearbox and went for a ride, hitting all the gears with ease. Figured if I fuck anything up all I ruined is a spring. As long as things do jump out of gear I think I'm all right. :killerjob:

dazegoneby
08-02-2012, 1:08 PM
yeah rob ,those damn plungers/springs can give you fits ,,some of those like the one i had, was too pointy on the end) so with wisdom from the cult(brit guys),,I rounded the plunger a bit , shaved a bit off the quadrant,was a good day,,,,well goes to show ,the smartest guys" I don,t know" are here,,the cult saves old bikes on a daily basis ,thanks to all the limey gearhead gurus

RetroRob
08-02-2012, 9:15 PM
Here's an update on the carb, today the mailman brought an Amal 230 jet and 3 1/2 "" slide. Installed everything and moved he needle to the bottom groove. HOLY SHIT !!!!!
The bike ROARED to life like never before , unbelievable sound from the drag pipes. Incredible power and throttle response, ran awesome. Took it out and gave it a great work out. Running Fucking Fantastic. :):):)

Got home and realized I had no liscense plate :( bracket broke off somewhere on my high speed romp. Off to DMV for a new tag tomorrow, at least the bikes running well. Now that most the bugs are worked out I'll get a chance to take some decent photos :) all the months of trouble shooting and problem solving are worth it. I feel like I should send Torch a check for a consulting fee. Thanks everyone here for all the help.

starwolf
08-03-2012, 4:55 AM
[QUOTE=RetroRob;358705...................... I feel like I should send Torch a check for a consulting fee. Thanks everyone here for all the help.[/QUOTE]

I'm sure he wouldn't turn it down, hehe :cheersmate: glad ya got her goin' !