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Misfiring, no power, stalling once warmed up

3201 Views 15 Replies 11 Participants Last post by  stu, 
S
The Bike
<BR>
<BR>2006 Thruxton. Airbox replaced with K&Ns.Jets = 150/42. TORs AI removed, Cal emissions removed. 7 months old 10500miles (running with no problem for first 10000miles)
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<BR>
<BR>The Problem.
<BR>About 4 weeks ago bike started coughing and spluttering at cruising speed. Thought it was a tank of bad gas (been to a different gas station). Drained tank. Continued to cough and splutter, usually after about 10-15 miles riding. Idles fine when it happens, but gently rolling on the throttle increases revs til about 2500rpm then revs just drop quickly to about 2000rpm and fluctuate between 2000 and 25000. If I leave the bike to cool a bit (10-15 mins) It's back to normal. At first I could continue the rest of my commute (another 15 miles), but it has gotten to the stage that it's happening every 2 or 3 miles after the initial time on a ride.
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<BR>Yesterday I drained the tank completely again. Pulled the carbs and checked and cleaned everything - appears to be fine. I installed new spark plugs and a new fuel line. Re checked fuel filters and checked all electrical connections.
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<BR>It happened again this morning on the ride to work.
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<BR>Has anyone else experienced this? Any suggestion?
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<BR>Could it be a problem with ignition coil/leads?

[ This message was edited by: steelcap on 2007-01-22 11:44 ]
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I pulled the petcock yesterday while the tank was empty and checked the filters - both were fine. I ran some clean gas through them (backwards) to make sure though.
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Thanks Greyghost, I'll give that a try this evening.
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On 2007-01-22 18:17, AVMECH wrote:
I had a similar problem after doing the airbox removal. After about 10 min at cruise would cut out and couldn't maintain 60, Sputtered out after 2nd gear at high revs. I set fuel floats to 16mm, one less than the factory 17 but still within the +/- 1 in the manual. No problems since. Also, 150 main seems a little high. I'm running 138/42 TOR's one shim and it runs great. The 150 would suck that bowl down even quicker than a 138. How long since airbox removal?
Click to expand...
Airbox was removed at about 650 miles - same time as TORs installed and AI removed. So it's been running great for 9000+ miles.

I'm just in the middle of checking the carb mounting boots for a vacuum leak - just about the last thing on the air/fuel side of things.

I checked the float height yesterday and it was 16mm, so I left it at that.

Also the engine temp definately has something to do with it. I let it cool for 2 hours then took it for a spin. After 1.5 miles it started doing it again. I limped homespluttering and coughing. It was still acting up in the garage. I left it for an hour, didn't touch a thing and it fired right up and revved with no problem.

Once I've checked the carb mount I'll ride it round the neighborhood and see what happens after a mile or so.


Thanks to everyone for the help and advice so far.
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Just for future reference - first the dealer replaced the ignition coil and although it improved the situation slightly, it didn't cure it. This week I had the pick-up coil replaced and so far (after 150 miles) it seems to have fixed it.

Thanks to everyone for their advice/suggestions and hopefully this will help someone in the future with this problem
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