sammyd173 Posted September 22, 2014 Report Share Posted September 22, 2014 I'm at my wits end... any suggestions appreciated. I have an '04 TXT Pro 280. Took her to her first trial last weekend. The bike pops at idle so badly that she surges forward with each pop. Not helpful when trying to negotiate full lock turns. What I've done: -Cleaned all the jets and every hole in the carb with compressed air -Fiddled endlessly with the fuel screw (Dellorto VHST 26mm) -Cleaned and re-sealed the exhaust header gasket -Cleaned and re-sealed the intake -Checked the reeds -New plug -Put in fresh gas, clean filter, clean coolant -Repacked the silencer -Checked the jetting compared to suggested jetting Only thing I haven't done is clean out the mid-pipe, but the bike pops right from a cold start through to when she's hot. If there is an air leak elsewhere it's beyond my capabilities to check. I've had the bike for a week, maybe I just need to flip it? Only $1,900 so I don't want to put too much money in to her. The only option from here I can think of is to ship her to Lewisport to be checked out, but that's not a cheap proposition. Any ideas? Ignition? Quote Link to comment Share on other sites More sharing options...
dadof2 Posted September 22, 2014 Report Share Posted September 22, 2014 Uneven low speed running can have so many causes it is difficult to advise over internet. You do need to carry out a pressure check, its not hard. All you need is a bung for the inlet and a blanking plate with a shrader (tyre) valve for the exhaust port at the barrel. Can you borrow a known good HT coil? On a 2004 my suspicion would be crank seals and piston / ring / bore wear. Quote Link to comment Share on other sites More sharing options...
sammyd173 Posted September 22, 2014 Author Report Share Posted September 22, 2014 Thanks so much for the reply. The bike has so much bloody compression that I didn't think about the top end. Considering however it really doesn't make more power than my Beta Techno this could a culprit. I think the bike has had a lot of use. I can do a top end myself but someone else would need to tend to the crank seals. Can I cheat on the top end and just put a new ring in to see if that is a step in the right direction? Quote Link to comment Share on other sites More sharing options...
lineaway Posted September 23, 2014 Report Share Posted September 23, 2014 Ever thought about checking if the jets are correct for you location. Quote Link to comment Share on other sites More sharing options...
copemech Posted September 23, 2014 Report Share Posted September 23, 2014 Lots of bikes pop and surge at low speed, are you sure it is abnormal? You cannot just do full lock turns without using clutch to smooth things! Has anyone else looked at it? Quote Link to comment Share on other sites More sharing options...
t-shock 250 Posted September 23, 2014 Report Share Posted September 23, 2014 What copemech said, sounds normal! Get someone experienced to ride the bike for a second opinion, though you need to use the clutch on these bikes when turning tight. You have chosen possibly one of the most inappropriate bikes to learn on. Quote Link to comment Share on other sites More sharing options...
lee_28 Posted September 23, 2014 Report Share Posted September 23, 2014 if you nuke it please post a video 2 Quote Link to comment Share on other sites More sharing options...
jam Posted September 23, 2014 Report Share Posted September 23, 2014 Have you tried the fuel mix screw? 3.5 turns out with a tick over. Main jet + pilot jet all clean? Got to be worth a shot. Quote Link to comment Share on other sites More sharing options...
totalshell Posted September 23, 2014 Report Share Posted September 23, 2014 timing? Quote Link to comment Share on other sites More sharing options...
huski Posted September 23, 2014 Report Share Posted September 23, 2014 It should be a lot more powerful than aBeta Techno I'd get a second opinion from a more experienced rider They weren't a bike for an inexperienced rider when new doubt it's better now Unfortunetly it seems like wallet thinning time hard to diagnose it without seeing or hearing it but previous replies sound a good place to start Quote Link to comment Share on other sites More sharing options...
melba26 Posted September 23, 2014 Report Share Posted September 23, 2014 Suggest:- Test ride on similar bike if possible to see if different or way it should run although if less power than a techno something is wrong. Check with previous owner for any changes made? How good is petrol/oil mix you are using, could it be contaminated/left for long time. I had a bike run badly and flushed out the petrol and it ran fine - although petrol was "new" it must have been a bad batch. Might be worth trying a different batch. Is the octane ok - not sure what gassers need. Set mixture screw - with reasonable tick over - screw mixture in until revs drop, screw out until revs drop - set between these 2 points. If revs do not drop either way or screw is right in or out could be jet sizes, air leak or other issues. Check timing as mentioned above - might have been retarded to soften power. This is not a big job but requires a puller and tool to hold flywheel. Carbs can be difficult especially if worn - any chance of borrowing one off a different bike which runs well and testing with this. After that it is more difficult things like air leaks or swapping electrical parts from other bikes. Good luck Melba Quote Link to comment Share on other sites More sharing options...
petert Posted September 23, 2014 Report Share Posted September 23, 2014 If it's a pro the timing is not adjustable on the stator. My 300 pro had a similar issue and although had what I thought was plenty of compression. When the ring gap was checked it was found to in excess of specs, bore was fine and within tolerences and a new piston and rings cured it all. Also unfortunately on the pro engine ou have to split the cases to change the main seals if that proves to be the problem. Quote Link to comment Share on other sites More sharing options...
sammyd173 Posted September 23, 2014 Author Report Share Posted September 23, 2014 if you nuke it please post a video I'm having trouble locating the enriched plutonium. 1 Quote Link to comment Share on other sites More sharing options...
sammyd173 Posted September 23, 2014 Author Report Share Posted September 23, 2014 If it's a pro the timing is not adjustable on the stator. My 300 pro had a similar issue and although had what I thought was plenty of compression. When the ring gap was checked it was found to in excess of specs, bore was fine and within tolerences and a new piston and rings cured it all. Also unfortunately on the pro engine ou have to split the cases to change the main seals if that proves to be the problem. This. I'm pretty certain the timing is stock and hasn't been fiddled with (an assumption). The problem is at idle with throttle closed. I talked to someone about a different pilot and he said the fuel screw covered the range of several pilot jets so if the screw is not getting me any benefit this is not the problem. The fact that the bike just sounds a bit clapped out and makes unremarkable power makes me think the top end is shagged. Now the worst part. A top end kit was quoted as $350. However these older bikes apparently used a discontinued piston and rings and so I may need a new cylinder too, total cost $650. Many thanks for ALL the replies, they were all read and appreciated. Quote Link to comment Share on other sites More sharing options...
zippy Posted September 24, 2014 Report Share Posted September 24, 2014 (edited) I'm having trouble locating the enriched plutonium. Maybe you should check with Marvin Edited September 24, 2014 by zippy Quote Link to comment Share on other sites More sharing options...
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