Triumphrat

12-25-2006

I've got a 1976 T140-V, the engine was rebuilt 600 miles ago by Baxter Cycle, the carbs were replaced with new corrrect Amals a few months ago and the bike has been a joy to ride up until yesterday- the bike starts easily, idles evenly and accelerates smoothly right up to 3000 rpm then it starts cutting out and sputtering , if I upshift and bring the rpm below 3000 it is running fine again. but every time I get er up to 3000 rpm - its over Johnny! I have new in line fuel filters, and I just had the carbs off a week ago - disassembled them and blew compressd air through all the orifice's ,put it back together and it ran like a champ. Now this . Any Ideas? Any help would be appreciated :???: Thank You

[ This message was edited by: mailman on 2006-12-25 12:52 ]

jimballard · 12-25-2006

BEFORE YOU GET INTO ANYTHING LIKE THE ELECTRICS ETC, A SIMPLE QUESTION...ARE THE CHOKES PULLING ALL THE WAY OFF? REMEMBER, THEY ARE HELD UNDER TENSION IN THE OFF POSITION AND A BROKEN CABLE WILL DROP THEM DOWN AND CAUSE A SITUATION LIKE YOU'RE EXPERIENCING.

FROM THE BAD MEMORIES OF THE "VILLAGE IDIOT": JIM

OzBloke · 12-25-2006

Mailman,

Jim raises a good point.

I'd also check the fuel filters - modern filters are designed for fuel under pressure from a fuel pump, while yours is a gravity feed system. I'm thinking there's maybe not enough fuel seeping through to keep the revs up. You could take the filters out of line, and run it without them for a while to see if it improves.

Another thing you might check is how the carbs are plumbed. Do you have double banjoes on both carbs, with the main fuel line going to one carb, then a pipe from one carb to the other, then the second one going to the reserve tap on the tank? - a loop if you like. If this is the case, you could open up the reserve while up at 3000 rpm, and see if more fuel flowing (from both main and reserve) helps. If they're not plumbed this way, then please describe how they are.

I don't think it's electrical at this stage.

You could take the plugs out and check their colour. If they're black and sooty, it's most likely the choke Jim mentioned. If they're white, it more likely fuel starving.

Hope this helps.

Pete

[ This message was edited by: OzBloke on 2006-12-25 16:38 ]

Mecchanica · 12-27-2006

If I understand correctly...the bike was running fine when you took took the carbs off and blew them out? If so, why? And if so, I would suspect that one or both needles have come out of their clips and are sitting in the main air chokes. Take the tank off when you install the carb slide/needles in place, to avoid loading the needle as you push in the slide. It should just drop into place. The needle can hang up on the edge of the emulsion tube and be pushed up and hang up in the spring, or be popped out of it's clip and it will fall into the needle jet.

12-27-2006

Well boy dont I feel dumb ! After reading your responses I remembered it was a cold morning when I had started the bike, so I ran to the garage to check my choke and it was full on! It is too late to go out for a ride now but tommorrow I'll give er a test ride and I'm pretty sure everything's gonna be fine. Thanks for the input. By the way Meccanicha asked why I had my carbs apart, It had become very hard to start after the weather became cold and I thought I must have a blockage or debri in my carbs. What I finally figured out was that the ticklers on my new carbs flood the bowls much slower than the original carbs, I just wasn't giving it enough time. Thanks Again :chug:

GrandPaulZ · 12-28-2006

Yep, Jim had it right from the git-go...

jimballard · 12-28-2006

NOW, SOMEDAY I'LL HAVE TO TELL YOU ALL MY STORY; BUT FIRST I'LL HAVE TO GET A LOT OF KETCHUP (NOT HEINZ), MUSTARD, MAYONAISE ETC. TO HELP THE CROW I'VE GOT EAT GO DOWN.

HAPPY NEW YEAR FROM THE "VILLAGE IDIOT": JIM

12-31-2006

Well I just thought I'd give you all the the follow up. The bike runs fine, just like the joy it was before. Thanks for the input, you saved me from tearing into the electrical system. All the bike needed was a smarter pilot!

johnnypence · 12-31-2006

i've been thinking about getting a smarter pilot for my tiger. let me know how yours works out.

oldebonnie · 01-05-2007

I need a smarter mechanic for my bikes (and probably a smarter pilot too). You have to be calmly and persistently logical to be a good mechanic. Absent obvious issues like a rod sticking out of the cases, the process is always the same. Gas? Spark? Nominal settings? Nominal readings? I usually find that when I discover myself up a blind alley I got there by failing to follow the process and jumping to an incorrect conclusion .

Remember the scene in Slingblade where the guy brings in the tiller that won't run? First thing the mechanic did was take off the gas cap. "No gas in it." That is how a mechanic thinks, and I know that was exactly what I thought as I watched the scene unfold for the first time: Check the gas! (Umm, now that I think of it, that mechanic turned out to be a seriously disturbed homicidal type. Maybe not the best example. But you get the idea.)

You can take pride in building something up that runs and rides well and looks good, but there will be some truly humbling moments along the way. You know, the kind where you screw around with an apparent problem for hours before discovering the simple solution that was before your eyes all the time. If you are going to be a good mechanic, it helps to be humble, presume nothing, and follow the process.