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Senior Member
SuperStock
Join Date: Apr 2002
Location: Strzlecki Ranges, Southern Australia
Posts: 275
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Last weekend I took the Thunderbird out for it's first decent spin in several months. Together with a bunch of mates (all on Harleys) we rode some brilliant roads to a pub in the middle of woop woop where we had the place to ourselves before riding back the next day. Covered around 700kms.
The problem was that the Thunderbird was plagued by an intermittent problem, where it would unpredictably only run on two cylinders, popping & farting, sometimes responding to more throttle by cutting back to 3 cylinders, sometimes bogging down, or going on to one. Sometimes just cutting out. On each occasion, if I stopped & scratched my head for a couple of minutes, it would restart again & run fine, sometimes fore several kms, sometimes for several hundred metres only. Pulling the plugs & checking for sparks didn't reveal anything untoward. At this point you are no doubt thinking fuel tank vacuum/sticky tip-over valve. At least that was my next thought, so I removed the tip-over valve & blew through the tank's overflow pipe. No difference to the problem. By now I was thinking either crud or water in the carbs. Problem was I didn't have a 3mm allen key required to drain the float bowls (Keihin). Finally got to a garage that had some tools (sometimes running fine, sometimes on one or two cylinders & sometimes coasting down hills without the motor running, anything to save having to push it), & drained the two outer carbs, couldn't get to the middle one (needs an extra long 3mm allen key). After this the bike ran perfectly for another 120kms, starting to play up again just a couple of kms from our destination. Parked the bike up for the night, & drowned my woes with the blokes. Next morning the bike started & ran fine..........for 15kms. :cry: I stopped at the next town, borrowed another allen key, & went through the carb draining procedure again, this time also squirting compressed air through the fuel line. After this the bike ran flawlessly for almost another 200kms, & I had a ball. I hoped that if there was any crud in the carbs, that I'd managed to stir it up, & that it had been sucked through the motor.
50 kms from home, it all started again. Got to a mates place, repeated the drain & blow process, & again the bike ran fine the rest of the way home.
Today I decided that I needed to pull the carbs in order to remove the float bowls. This is the 'furthest' that I've been into this bike, but I was armed with both a Triumph & a Haynes manual. As far as removing the carbs goes, it all seemed a bit of a palaver just to clean out the float bowls, but basically it wasn't too difficult or fiddly. If I'd needed to remove the throttle cable from the carbs I think it would have been a real***** of a job, but I didn't need to. Took off the float bowls one by one. Each had a little 'mud' (very fine red sediment) in the bottom, but not as much as I'd expected. I removed each main jet & blew compressed air through them, plus squirted air through all the passages, & whilst I was there removed the airfilter from the airbox & cleaned it. I don't understand why Triumph say that you cannot re-use these filters. It cleaned up fine with compressed air & gentle use of a toothbrush. I couldn't work out if the airbox halves had a gasket between them or just silicon. Anyway I removed the old seal & resealed it with silicon. I also eventually located the inline fuel filter that triumph fit, I knew it was there somewhere, but when you don't know what something looks like it can take some time to find. It too had a small amount of fine red sediment in it, but nowhere near enough to block it. After replacing the carbs etc, I turned my attention to the fuel tank............. after cleaning a little more 'mud' trapped in the aftermarket in-line fuel filter I fitted when the bike was new. After draining the tank, I removed the fuel tap, & swilled some fuel mixed with methylated spirits (just in case there was some moisture in there, even though I hadn't seen any water in the fuel I'd drained) through it, tipping it out onto a clean rag. Sure enough plenty of little red paint flakes, some little red globules, which when touched spread under the finger, and believe it or not, a large drowned spider! How the f**k a spider got in there I just don't know. I kept swilling until no more crap came out. I'm not really sure why the fuel tap is mounted on a 2-piece mounting, but the 'hollow in the middle of it was also full full of crud. I guess that there may have been enough to restrict fuel flow on reserve, but this hadn't been the problem. I also pulled the fuel tap apart, but no crud in there. After everything went back together, the bike fired up first hit of the button & purred like a kitten. A quick blast of just a couple of kms up down the road got her snarling ;-) & she behaved impeccably. I was even more impressed with myself after checking & finding no leaks anywhere ;-) It'll need a longer run to determine if the problem is solved, but I'm hopeful, despite not being totally confident that the crud that made it through 3 filters into the carbs, was sufficient to cause the problem.
The red paint flakes in the tank had me scratching my head too. My bike is a green/gold Thunderbird, & I *had* expected to find green flakes, from around the filler. No green, just red. Hmmmmm. Aha! the jerry can? sure enough, red paint on the interior & flaking. The culprit revealed. Lets hope.
Finally a question.
Do I *need* to synchronise my carbs, given that I have not changed any of their settings whilst removing them?
Regards
Ian
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