Throttle Issues on 2003 Speedmaster. Help? - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 3 (permalink) Old 11-30-2012, 10:06 PM Thread Starter
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Throttle Issues on 2003 Speedmaster. Help?

So I've been getting some great rides in (1000 miles per month) which have included interstate travelings with speeds upward of 70mph. Last week I went on a ride with a group and she was performing great. Problems started when speed limit went from 45mph (which I had been at for 20+ minutes) to 60 mph. She lurched backwards, felt differently and sounded differently all at the same time. She wouldnt go above 4000 rpms even with the throttle pulled completely down. I pulled over at the nearest gas station. Completely cut everything off and started her back up. After some hard revs she started acting normal again. Same thing with similar scenarios append twice on the ride home.

I'm no genius with engines but I figure it had to be something with bad gas or bad spark plugs. But the plugs are less than a month old. Any help on diagnosing or solutions?

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post #2 of 3 (permalink) Old 12-01-2012, 09:38 AM
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Originally Posted by drhutton92 View Post
I'm no genius with engines but I figure it had to be something with bad gas or bad spark plugs. But the plugs are less than a month old. Any help on diagnosing or solutions?
From what you said it could be fuel related. There are a couple of things you can check before taking carbs apart. There is a screen for the petcock in the tank and there is a "hidden" fuel filter it the T pipe at the end of the fuel hose. The "hidden" filter can cause issues if it clogs. How many miles are on the odometer?
There are ignition things that can almost seem like fuel flow issues so do some searches here for your symptoms. Little things like opening the fuel cap to make sure it's not a vacuum or tank vent problem can show up. Good luck with it.

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post #3 of 3 (permalink) Old 12-02-2012, 01:16 AM
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MattyMo's advice will get you off to a good start. Here's another person's pic of that filter you need to check.

There is also the screen on the petcock inside the tank, but I'd exhaust the other checks before bothering with that.

The crack-the-gas-cap trick will tell you if it's a clogged breather tube, but you might as well get under there and check/modify the breather tubes for the tank and carbs:

If it is on the electrical side of things, start with the easy stuff like clean and dielectric grease the connectors(everything, but particularly the spark plug wires and the wires feeding the coils), coil check(resistance checks), spark check.

Not quite in line with your symptoms, more of a problem at lower speeds when they go bad, but check the vacuum caps/lines while going over everything. 4 nipples to check total, 1 carb side and 1 manifold side for each carb. Still have the air injector system on it?
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