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Mattc5455

GasGas txt 300, 2017, excessive smoke when hot

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I have just bought a GasGas txt 300. 
it runs fine and has lots of compression etc. When riding it on a loop on the woods for 15 minutes or so and getting it nice and hot, it starts smoking excessively a blueish smoke. If I stop and let it cool for 5 minutes the smoke stops, until I get it hot again. 
 

I'm thinking (and hoping) this might be excess oil built up in the exhaust, has anyone had any experience of this? 
 

The bike gets warm to the point where the fan goes on for a few seconds here and there when riding, but I’m pretty sure it’s not over heating. 

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Rather normal.

Don't over do it, or might end up with a melted end cap

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Yep, had a few fires in the silencer of my 2003 300 GasGas.  Got hot enough it started melting the outer decorative plastic up by the airbox.

 

Packing looks horrible too

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Awesome thanks for all of your comments, I would like to be able to ride it for 30 minutes non stop if possible. Is that not ok on a trials bike? 
 

I come from a motocross back ground, but have bought this for a bit of fun and mid week fitness etc. Wouldn’t mind entering a couple of local comps too! 

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I think it would be best for to re-pack the silencer. When the packing gets old it is oil soaked, loses sound deadening and it's thermal insulating properties as well.

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Ok I will try re packing the silencer. 
it’s only 2 years old and the last (2nd owner) only road it 4 times in 6 months. So does seem a little odd that the packing has broken down? 

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do you know what the previous owners were running for an premix ratio?

Possible they were running a high(er) amount of oil which would foul the packing sooner than 80:1

OR it's possible the crankshaft seal has gone bad and is sucking in gearbox oil.

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1 hour ago, zippy said:

do you know what the previous owners were running for an premix ratio?

Possible they were running a high(er) amount of oil which would foul the packing sooner than 80:1

OR it's possible the crankshaft seal has gone bad and is sucking in gearbox oil.

 

I am running it at 50:1 as that is what is stated in the manual online.. is that too rich?

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2 hours ago, Mattc5455 said:
 

I am running it at 50:1 as that is what is stated in the manual online.. is that too rich?

Yes far too much oil. You want 60ml of 2t per 5 litres of petrol. I use Putoline mx9 which seems to burn better than others Ive tried. Also super unleaded fuel from either BP or Shell makes a difference.

 

Best case scenario is that all of your silencer packing is soaked in oil which is why it smokes when hot. Worst case is crank seal has gone. If it was the crank seal then you could tell from the smell of the burning oil and your gearbox oil would be low. If thats ok then personally Id go a few miles down the road on it then (when cools down) repack the silencer. Trialendurodirect.com do this which is dead easy: https://trialendurodirect.com/product/expanding-exhaust-packing/ and this which in my view is better but a lot more involved: https://trialendurodirect.com/product/silent-sport-exhaust-packing/ 

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1 hour ago, bumpy_ltd said:

Yes far too much oil. You want 60ml of 2t per 5 litres of petrol. I use Putoline mx9 which seems to burn better than others Ive tried. Also super unleaded fuel from either BP or Shell makes a difference.

 

Best case scenario is that all of your silencer packing is soaked in oil which is why it smokes when hot. Worst case is crank seal has gone. If it was the crank seal then you could tell from the smell of the burning oil and your gearbox oil would be low. If thats ok then personally Id go a few miles down the road on it then (when cools down) repack the silencer. Trialendurodirect.com do this which is dead easy: https://trialendurodirect.com/product/expanding-exhaust-packing/ and this which in my view is better but a lot more involved: https://trialendurodirect.com/product/silent-sport-exhaust-packing/ 

Thanks again, what a friendly and helpful bunch you are! I will have a tinker with it and see what conclusion i come to, then will report back.

Very intrigued that a few of you suggest to lean out the oil to fuel ratio, against the manuals recommendation! 

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1 hour ago, Mattc5455 said:

Thanks again, what a friendly and helpful bunch you are! I will have a tinker with it and see what conclusion i come to, then will report back.

Very intrigued that a few of you suggest to lean out the oil to fuel ratio, against the manuals recommendation! 

Less oil, richer fueling, more oil, leaner fueling. Best to stick with the recommended mix if jets are the ones supplied by the factory.  A lower flash point oil will produce less sponge for most riders.

Art  

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1 hour ago, Mattc5455 said:

Thanks again, what a friendly and helpful bunch you are! I will have a tinker with it and see what conclusion i come to, then will report back.

Very intrigued that a few of you suggest to lean out the oil to fuel ratio, against the manuals recommendation! 

 

50:1 would probably be ideal when running on a dyno but the reality is that most of the time we are riding round just off tick-over. 60ml of oil has worked for me riding GG for 20+ years and I haven't seized one yet.

 

24 minutes ago, sherco70 said:

Less oil, richer fueling, more oil, leaner fueling. Best to stick with the recommended mix if jets are the ones supplied by the factory.  A lower flash point oil will produce less sponge for most riders.

Art  

 

Standard carb settings aren't far off for the UK. Ive run 45 pilot, 125 main and (std) needle lifted up one notch (std slide) for years. 

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80:1 seems to be the normal ratio for the majority of modern trials bikes.

Also with GasGas Pro engines the crank bearings are lubricated with the gearbox oil, not the premix.  Premix is only lubricating the piston and con-rod bearings

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