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diamondog777 04-12-2013 03:41 PM

Amal 932 and Triumph TR6

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Hi, guys.
Last year I built my first Triumph, but I'm not happy about the way she rides. She starts easily but she lacks torque and top speed. I think some of the problems can be related to carburetor adjustments or perhaps I have the wrong carburetor? The amal concentric is brand new and so far I have done nothing changes to the main jet (220) or the needle jet (106). The engine is not original. The bottom end is from 1971 and the top end is from 1963. The Morgo Big Bore Kit has 0.20 overbore. Any suggestions?

Glider 04-12-2013 05:14 PM

Re: Amal 932 and Triumph TR6

Main jet may be too small. The manual calls for a 230 for the 650 TR6. You might start with a 240 or 250. You might also try raising the needle one notch. Carb should be an Amal 930.

Either way, all troubleshooting starts with a proper tune-up: Valve adjustment, ignition timing (using degree wheel and strobe—if you're not strobing it you're just guessing), carb settings (including float level, jets as per the manual, etc.). How do the plugs look? Is there oil inside the exhaust pipes? The list goes on....

When I put a Morgo kit on mine I just looked up the jetting for the 750 and jetted accordingly. Never touched the carbs since.

If all the basic stuff is okay, you might want to check your cam timing.

Daddy Boy 04-12-2013 08:12 PM

Re: Amal 932 and Triumph TR6

What Glider said.
'63 has smaller valves, same as pre unit. Do a plug chop.
Wrap masking tape around the throttle and mark where 1/8, 1/4 and 3/4 is and mark a pointer next to that so you can look and see the exact throttle opening when you do a plug chop on the road.
3/4-full is main jet range.
1/4 to 3/4 is needle jet.
1/8-1/4 is throttle slide.
0-1/8 is pilot jet
Ideally start each 'chop' with new plugs when you check each range

Just installed a new premier carb, they gave me a 260 main, told em bike specs for 68/750. Will soon see, not ready yet.

oilfield money 04-12-2013 09:10 PM

Re: Amal 932 and Triumph TR6

I'd go with new plugs and even though it's probably tabu electronic ignition and replace breaker shaft seal just a little oil on the points makes a big difference , kind of had the same issue and took compressed air and blew points clean and made a huge difference but went ahead with the big leap (EI)

Mr.Pete 04-13-2013 12:28 AM

Re: Amal 932 and Triumph TR6

I'm surprised you haven't melted a piston,with a main jet that small.The 930 carb uses a 230 main jet.A 932 carb can flow 14% more air at the the same test vacuum.You need more fuel too,if you want to keep the mixture right.
To put it another way,the velocity will be down 12% at the same air flow.Vacuum on the main jet will be down to about 77%.The jet will flow less fuel for the same airflow.That puts you a lot leaner than you should be.

The valve size will hardly make much difference,even if you are lucky enough to still have the original small valves (which is unlikely after 50 years).

I wouldn't use less than a 260 main jet,but it could be closer to 300.
Try a 300.If it 8-strokes at full throttle with a 300,try a 290.If it runs clean with the 290,fit a 270 and ride it.It will be close enough.

Daddy Boy 04-13-2013 04:08 AM

Re: Amal 932 and Triumph TR6

T120= 120mph. When they had small valves. Single carb was a twentieth of a second slower over a 1/4, or was that a mile?

Good info on the carbs Pete, just learnt somethin new. A plug chop is still the best way to find out for sure which jetting you need.


dandruff 04-13-2013 02:19 PM

Re: Amal 932 and Triumph TR6

I'm in agreement with Mr Pete about the jet size, try 300 and see how it runs. You may need to go bigger even. I would also double check your total timing, if the bike has no balls the ignition may not have enough advance. Here in California we have the worst quality gas ever. In Norway if you are running 99 octane try advancing the ignition to 40 and see how that works out. I have a feeling it may be good. Hope this helps.

Daddy Boy 04-14-2013 03:51 AM

Re: Amal 932 and Triumph TR6

Unreal, 300 or more!?? I did a chop doin the ton when the 32 was on the bike and a 270 main jet had good lookin' plugs.
Maybe we need to discuss plug colour, all the different fuels could be giving us confused readings to what we think as tuned.
The way the bike performs is obviously an indicator but what a man determines as the right colour is debatable.

BTW went for a spin with new 30mm Prem today,
bike ran like it just rolled off the show room floor.
No big diff to what I had before,
just that little bit smoother and beautiful everywhere!!
Felt fucken good!! Never bought a new carb before.

Truckedup 04-14-2013 05:40 AM

Re: Amal 932 and Triumph TR6

Type of gasoline affects performance. I don't know about gas in Norway,but in the US most fuel is oxygenated and requires a richer fuel mix than non oxy fuel.And in theory every spark plug color check should be done with clean plugs.Lower speed part throttle mixtures can be fairly lean for fuel economy and clean running. So long as the engine responds smoothly and doesn't run hot the mixture is ok even if the plug color is on the light side.Full throttle is more critical, main jet size as described by Pete....

diamondog777 04-21-2013 01:47 PM

Re: Amal 932 and Triumph TR6

Thank you for all great advice - preciate! I think I will try out a lot of the suggestions. I will go for 98 or 99 octane instead of 95 and also buy a bigger main jet. I haven't done the strobe timing yet, but I think it will be necessary before a take her out for a plug chop on the road. By the way, I bought a new sparx rotor and a stator (200w output) the other day. The battery (almost new) gives only 12,2v and I think that's not enough. Hopefully all this together will do the job! Finally the snow has disappeared here in Norway and I'm looking forward to some really great rides..!

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