My beta 250 sometimes sits for a couple of months without use if Im busy at work and I don’t find time to get out . Im not very mechanically minded to be honest but I’ve just had a mechanic clean the carb for me as it’s been sat . And he said I should drain tank and the carb if I know it’s going to sit for any length of time or even if it’s being used most weeks I should at least drain the carb the day before a trial . Your guys advice on what is best and what you do would be most helpful . Tia 

I strip and drain the carb after every trial, they always run better with everything clean and fresh fuel in.

Run good fuels and you shouldn't have to go through the hassle. 

Non Ethanol (most important) 

Race

Avgas 

Thirty days should not be a problem. 

28 minutes ago, hillary said:

I strip and drain the carb after every trial, they always run better with everything clean and fresh fuel in.

I always drain tank and use fresh fuel but I’m not mechanically  minded enough to strip down carb myself !  and it would cost me a few quid if I needed to take to a mechanic every week to do that , so I’m just trying to find a happy medium so that I could carry out the maintenance myself . 

Use super unleaded instead,it doesn't go off like normal petrol 

What your mechanic advised could never be considered as bad practice,

But reality is that if you have a clean fuel system and good, no ethanol gas, fuel in the bowl will do no harm.

Fuel/Oil separation in the bowl over time could be an issue.  I always rock the bike good to help

 

Or you could use Aspen fuel which has a 5 year shelf life. No need to clean carb or drain at all then.

As pointed out above the biggest problem is fuel with ethanol. If you're not in the US that's probably not a problem as you have no corn lobby to bribe politicians to require ethanol in your fuel. If you are using pump gas, before you put your bike away, turn off the fuel tap and start the bike. After a few minutes the revs will come up and that let's you know the fuel in the carb has started to run out. You can then shut the bike off and any fuel in the float bowl will just evaporate after a few hours. No need to clean out the carb. If you use non-ethanol gas like racing fuel just shut off the tap and put it away until the next ride. No problem.

Ethanol, when left to sit, forms a waxy residue which is what gums up the works in a carb. It takes time for this to happen but even "premium" pump gas with ethanol will do this. The good news is that if you don't leave fuel in the float bowl of the carb no buildup will occur. The ethanol will evaporate out with the rest of the fuel. As for the fuel in the tank that is another story simply because it is a much larger volume. Aside from the waxy goo from hydrogenated ethanol (think margarine) ethanol has a higher affinity for water than it does for other hydrocarbons including oil. In practical terms the ethanol in the fuel will bond with atmospheric water and separate out of solution into an alcohol/water mixture which is heavier than gasoline. This can sit in the bottom of the tank so when the engine is started after a long time it will be fed ethanol/water with no oil in it. One reason why a sealed gas can is a happy gas can. So draining the tank is one option. The other is a fuel stabilizer which will "preserve" the fuel for a while longer. The third is of course to use racing fuel but that gets expensive (But it's so worth it, I've had bad experiences with pump gas. Trials translation, I've crashed my ass off from crappy fuel.)

It is ironic that the "common wisdom" of pre-ethanol fuel was put it away with a full tank. Now ???

Now having said all that I typically do a disassemble and clean on my carb twice a season for the Keihin as it has many tiny holes that can get blocked by dirt or even water and to keep the bike running properly at low throttle settings those passages must be clear.

But just as a general rule of thumb ride it. If it's running good it's fine and you don't need to clean the carb out every time you take it out of storage.

Edited February 10, 20188 yr by dan williams

23 minutes ago, dan williams said:

As pointed out above the biggest problem is fuel with ethanol. If you're not in the US that's probably not a problem as you have no corn lobby to bribe politicians to require ethanol in your fuel. If you are using pump gas, before you put your bike away, turn off the fuel tap and start the bike. After a few minutes the revs will come up and that let's you know the fuel in the carb has started to run out. You can then shut the bike off and any fuel in the float bowl will just evaporate after a few hours. No need to clean out the carb. If you use non-ethanol gas like racing fuel just shut off the tap and put it away until the next ride. No problem.

Ethanol, when left to sit, forms a waxy residue which is what gums up the works in a carb. It takes time for this to happen but even "premium" pump gas with ethanol will do this. The good news is that if you don't leave fuel in the float bowl of the carb no buildup will occur. The ethanol will evaporate out with the rest of the fuel. As for the fuel in the tank that is another story simply because it is a much larger volume. Aside from the waxy goo from hydrogenated ethanol (think margarine) ethanol has a higher affinity for water than it does for other hydrocarbons including oil. In practical terms the ethanol in the fuel will bond with atmospheric water and separate out of solution into an alcohol/water mixture which is heavier than gasoline. This can sit in the bottom of the tank so when the engine is started after a long time it will be fed ethanol/water with no oil in it. One reason why a sealed gas can is a happy gas can. So draining the tank is one option. The other is a fuel stabilizer which will "preserve" the fuel for a while longer. The third is of course to use racing fuel but that gets expensive (But it's so worth it, I've had bad experiences with pump gas. Trials translation, I've crashed my ass off from crappy fuel.)

It is ironic that the "common wisdom" of pre-ethanol fuel was put it away with a full tank. Now ???

Now having said all that I typically do a disassemble and clean on my carb twice a season for the Keihin as it has many tiny holes that can get blocked by dirt or even water and to keep the bike running properly at low throttle settings those passages must be clear.

But just as a general rule of thumb ride it. If it's running good it's fine and you don't need to clean the carb out every time you take it out of storage.

Thanks Dan great reply and most helpful cheers 

Assuming you're in the UK and stuck with ethanol fuel unless you are prepared to pay for Aspen, in which case you can afford to pay a mechanic anyway, I would definitely drain the carb if it is going to stand for two  months just to be safe (cleaning the gunk out the carb is a real pain).  I never bother with the tank for a period like that but if the bike won't start then you will need fresh petrol as it loses volatility.  But it is easily drained at that time if necessary.

A few years ago a pal was selling a TY 250 that had lain unused for about 8 years - it started second kick on the fuel that had been in the tank. Proper petrol.

I use bp ultimate fuel only and according to their website that fuel does not contain ethanol . 

Edited February 10, 20188 yr by shorty1978

20 minutes ago, 2stroke4stroke said:

Assuming you're in the UK and stuck with ethanol fuel unless you are prepared to pay for Aspen,

Bp ultimate is ethanol free

BP website seems to be silent on the ethanol content but it depends where in the country you buy petrol as to exact ethanol content. Deeper investigation has BP saying Ultimate will never have greater than 5% ethanol content until January 2017.  Presumably it's gone up since then.

I run 4 strokes & my last run of the year is the Scott Trial in October, it then sits until April or May, due to cold & white finger, when it starts second or third kick after flooding the carb & a few priming strokes on the kick start.

I fill it with the cheapest fuel at whatever petrol station I find when I need fuel.

Seems the problem may be with two stroke oil separating from petrol when standing & oil blocking the carb. 

Two stroke guys, drain the carb & slosh around what is in the tank to remix.

Now't wrong with basic petrol!!!!

 

22 minutes ago, dick said:

Now't wrong with basic petrol!!!!

In most cases most likely true but the bad batches I got may have been a dodgy station owner. Who knows? Since I've been using VP C-12 I haven't had a bike hiccup yet and it's been probably two decades now. Damn, I'm old!