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TXT Pro 250 ('07) won't start


shokrefumi
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Hate to join a new forum and make my first post a problem one, but that's the way the cookie has crumbled.
I come from the beautiful country of Croatia, where, bar one Ossa and another GasGas owner, trials is as a foreign word as Okonomiyaki. I really enjoy it and love these bikes, but mine is being a stubborn idiot at the moment.

So this is my story. Bought the bike in '12, rode it carefree for a few summers and then stopped using it for a year while I changed jobs and moved house. Got it to the new house last July, rode it once and then during one ride it just cut out and died. Bike had no spark, I tried all the usual things but in the end I had to order a new CDI. While I was at it, I ordered a new voltage regulator as well, because you never know. The bike has Ducati electrics and electronics all round (which is strange, as GasGas states that only the 300 should have Ducati electrics for that year), so these parts were as rare as hen's teeth. I had to wait 6 months for the parts to show up.

During the waiting period I did some maintenance on the bike: changed the piston, linkage bearings, cleaned the carb etc. 
The parts delivering Gods decided to have mercy on me and sent me the ordered parts, and to my total joy, after fitting the new CDI, the bike started 3rd kick. 

Now to my real troubles. Yesterday I went for a ride and managed only 250 m riding. It cut out and died again. But this time it has spark (with every kick). It also has a ton of compression when spinning the back wheel in 6th. I took the carb apart again and checked the jets; 36 pilot and 118 main, no clogs, set the float height to 16 mm (with the carb upside-down). Still won't start.

What's causing my issue? The carb is not overflowing, there is compression (I had a doubt as it's not too hard to kick over, so I pulled the exhaust to check if the rings were stuck, but they seem fine; they have a spring feeling when pushing on them through the exhaust port), and there's spark. I also checked the flywheel. It looks a little bit rusty in a few places, but it shouldn't be causing the problem, as there is spark. What about the ignition timing? I checked and the key is in place.

Please help!

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Sounds a tricky one, because you obviously know your way around bikes having looked in all the right places. Keeping it simple, theres two requirements, a spark and fuel, and since you have a spark it sounds like you are short on fuel. Is the carb definitely getting fuel, is the choke working, could you maybe try a taste of fuel down the plughole...

Edited by faussy
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Since writing here I've tried a new voltage regulator and checked and rechecked the carb. Maybe I'm missing something really simple. Also, changed 4 plugs (one used and 3 new), even tried gapping one down to 0.3 mm. There's enough spark to get a much larger engine going, but by now I'm worried that it's throwing a spark at the wrong time. Does anybody know when the dug out in the rotor needs to pass the pick up (how many mm before TDC)? Although, the rotor hasn't spun, and it did start three times before the ride...

Does anybody have the settings for the Dell'orto carb? I've tried a 45 pilot jet, but no change. Where should the idle and mixture screws be? I've been trying 2,5 turns to 4 turns out with the mix screw and every position known to man with the idle screw.

Thanks for the help, I'm really keen to get riding!

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If you left fuel in the carb, and your petrol is as carp as ours, I would clean it again. A small amount down the plug hole, as suggested above should fire it up if it's  a petrol issue, 10mm approx.  Is the plug wet after trying to start it ?

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Just went to check for this; no, they are in the correct way. Even with 10 cc of fuel down the plug hole she's not firing. Leads me to suspect timing. Which is terribly odd if it fired up yesterday and if the key is in place. Very, very strange. Off to the petrol station to see if brand new fuel solves it.

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5 minutes ago, oni nou said:

If your bike was working/running at first then it does not need larger jet sizes to supply fuel..think float height should be 18mm if my memory is correct..also from what you say it sounds like you have a blockage in your carb through it being stood for a while.....people use ultrasonic cleaning baths to deep clean their carbs  take out the jets and it should clear/clean any blocked passages internally

Go through your fuel system one part at a time ......if you are using the old fuel that you stored it away with then that may be the reason it will not fire ......if so change for fresh fuel and before filling up take out the fuel tap and flush the tank of debris..then take fuel tap apart and make sure it is clean make sure fuel tubing between tank and carb has no debris in it [once I had a fuel restriction caused by a small  piece of rubber that had come off the tubing while inserting the fuel tap into the tube....this caused erratic running starting problems] Next total carb clean up check floats have not taken on fuel rendering them useless at floating properly to shut off the fuel supply to the bowl get a carb gasket set and fit all new o rings etc to make sure you are starting out  with the best chance of success  If you still do not get anywhere after doing all this then the next thing I would check would be earthing points for electrics then the ignition pick-up module that sits above the flywheel and sends timed pulses to the cdi as the metal bar on the flywheel passes buy ....this has been known to fail in your year of bike ....they used to supply an aftermarket one at electrex world you will find them on the internet.

My flywheel hasn't got a metal bar, but a channel dug out in it. Do pick-ups go crazy and read a wrong position? What about the distance from the pick up to flywheel? How much should the clearance be? 

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Why not try bump starting ?

Make sure the throttle is shutting, check your kill switch works then select 4th gear and get a mate to push like mad, dump the clutch and you may find the engine spinning over fast enough to start.

also spray a bit of 'easy start' into the air box (need to remove the seat/rear mudguard ) but looks like you already know that.

good luck

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I have the same bike with Ducati ignition. I replaced the regulator/recitfier 3 times. The fan quit once and the ignition quit twice. The last time it would start cold, then after about 20 minutes it would die with no spark. After it cooled down it started again and then die when warm.

I got fed up with Ducati and replaced the whole ignition with Kokusan and haven't had any problems.

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Lots of clever advice here. And an ultrasonic cleaning bath is a lovely thing to use for anything regarding carbs, injection and so on. In the old days we didn't know about them, but still got our engines running, so you don't need it if you do your homework well.

However, there could be another possible source and that is your magnificent Ducati electrics. The CDI units in particular has always been prime suspects when mysterious things happen. When I raced Husqvarnas and Cagivas, we had to deal with these often unreliable parts and always kept plenty of spares available. When my son bought himself a GasGas 125 to play with in 2009, the old Ducati story was repeated. Before he sold that one, he used 3 CDIs in less than 20 months. Terrible!

So, if you are absolutely sure your carb is OK .....please, check everything on the ignition side of life.

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