Should I drain the carb

[pjw123]

Nothing wrong with basic petrol !!!!. I beg to differ. Just ask the legions of folks who run GRP tanks on their classics.( Been there. Modern ethanol based petrol makes them go soft. Old school O rings prone to swelling. I 've even had a fuel tap pack in due to swollen O rings. I seal my GRP tanks & empty them after every meeting, with the top off, so any residue can flash off. Works for me.

"It's all the same, it all comes from the same refinery " I hear  someone say. Not necessarily true. Raw petrol goes through a petrol blending process, where various additives are mixed in prior to going off to road/rail.. Guess who goes for the cheapest blending runs. Yep, mr Supermarket Chain.   

So,,,,,,,,,, Its Shell V power or BP Ultimate. Best of a rapidly deteriorating bunch. The odd splash of Av Gas mixed in from your local private airfield doesnt go wrong on highly strung motors.

As you may be aware, old fuel can be used for all sorts of things,i.e cleaning, etc but take care : BENZENE. Google it !!!!! 

[tonymoore]

Easiest thing to do is turn the fuel off and run the engine til it cuts out every time you finish. Motorbikes, outboards, 2 and 4 strokes, its good practise.

 

Tony

[dadof2]

One of my bikes had not been started since June until 2 days ago, and I can't even remember when I had the carb off - 2013 I think. It started 3rd leisurely kick. Fuel BP ultimate with optima fully synthetic racing oil at 30:1.

I always make sure there is no water in my petrol tank either from condensation or fuelling in rain. I empty the carb after each ride by turning the fuel off and running then engine until it cuts out due to fuel shortage.

[jon v8]

There is alot wrong with basic petrol now including the fact there is so much cr-p in it. For a long time I refused to believe that enthanol in petrol was having an effect.Then after a while I found the fuel cap on my old Yam was getting hard to unscrew, then the pilot jet was always blocking up. Next was the throttle sticking,followed closely by blistering of the fibreglass tank.Shame as is was signed by Mick Andrews...

Small bits of the tank were breaking away inside and causing the problems,the tank is now an ornament. I've also had to repair Stihl chainsaws and strimmers where carb mount rubbers and fuel hoses have literally fallen apart when fuel was left in them over winter.

Some bulk at the price of Aspen fuel,but for how much a trials bike uses I can't be bothered to worry about it.The plastic cans it comes in are completely clean inside,so once your bikes tank is clean there is no need to do any carb maintenance - more time to ride ! The fumes are much less toxic too,ask Network rail - H and S will let them use Wacker plates in tunnels when run on it. 

[section swept]

Drain carb and tank even if it’s a case of the bike standing for only a week. It’s not like your having to deal with gallons of fuel. Better to have the fuel out of the bike altogether, stops pond life from riding yer bike away if they nick it! Leave carb drain screw/cock open during storage and attach a label to throttle to remind you to close it off when refilling fuel tank. If leaving the bike for some time then a few shots of silicon spray into the throttle slide and down into the carb float bowl will stop any white crusting occurring that you often get. WD40 tends to dry out although it has its uses?

[2stroke4stroke]

Running until the motor stops does not fully empty the float bowl.  There's enough left to cause gumming problems if left long enough.

[NAD1]

What an amazingly unhelpful thread of answers. highlights all that is wrong with forums. You'll get a multitude of answers all of differing opinion and still be scratching your head. Best bet, check with your trusted dealer

Guess it depends on what bike you have and how old. For my tuppence worth, if a modern bike then draining fuel and cleaning carb after each ride is time consuming, expensive and most importantly pointless as well as you running the risk of not putting back as was - needle in wrong place, knock the floats etc etc

Fuel will be fine if you use good fuel and good oil - if not using good fuel / oil then safe to assume skimping on other areas of bike and maintenance
Carb is a a sealed unit - i.e. nothing can get in or out - all you do by removing it and cleaning it is break that seal and risk contamination. If bike running fine you can be pretty bloody sure that the fuel and carb are fine. I'll bet you those that have carb issues are those that constantly have it on and off..

Running your bike dry wont actually get all the fuel out of the carb either so largely a pointless and ancient practice (IMO).

If you know what you're doing, have the time, space and equipment and know all your carb settings then I guess you wont really do any harm constantly stripping, cleaning, rebuilding and reinstalling. If not and bike runs well you're potentially creating a problem where one did not exist.

[jon v8]

15 hours ago, nickday1 said:

What an amazingly unhelpful thread of answers. highlights all that is wrong with forums. You'll get a multitude of answers all of differing opinion and still be scratching your head. Best bet, check with your trusted dealer

Guess it depends on what bike you have and how old. For my tuppence worth, if a modern bike then draining fuel and cleaning carb after each ride is time consuming, expensive and most importantly pointless as well as you running the risk of not putting back as was - needle in wrong place, knock the floats etc etc

Fuel will be fine if you use good fuel and good oil - if not using good fuel / oil then safe to assume skimping on other areas of bike and maintenance
Carb is a a sealed unit - i.e. nothing can get in or out - all you do by removing it and cleaning it is break that seal and risk contamination. If bike running fine you can be pretty bloody sure that the fuel and carb are fine. I'll bet you those that have carb issues are those that constantly have it on and off..

Running your bike dry wont actually get all the fuel out of the carb either so largely a pointless and ancient practice (IMO).

If you know what you're doing, have the time, space and equipment and know all your carb settings then I guess you wont really do any harm constantly stripping, cleaning, rebuilding and reinstalling. If not and bike runs well you're potentially creating a problem where one did not exist.

Really? So you add your "Tuppence" and muddy the waters even more. The whole point of forums like this is to get individuals to relate their own experiences. There is no single correct answer, for instance you suggest using good fuel and oil - so what do you suggest IS good fuel and oil ? Maybe I'm missing something here ?

[b40rt]

16 hours ago, nickday1 said:

What an amazingly unhelpful thread of answers. 

Carb is a a sealed unit - i.e. nothing can get in or out - all you do by removing it and cleaning it is break that seal and risk contamination. If bike running fine you can be pretty bloody sure that the fuel and carb are fine. I'll bet you those that have carb issues are those that constantly have it on and 

"Sealed unit"  what are the vent hoses for ? Dirt and water can enter through the air filter, so sealing that is also a routine maintenance task. 

Edited February 13, 2018 by b40rt

[baldilocks]

I was lucky in that my dad had a shop and taught me a lot about maintenance. "Some people have lost the trial before they get the bike off the trailer as it's not prepared properly"

Removing the carb on a beta is a bit more of fiddly job than on other brands but we are really talking about a couple of jubilee clips.

Have a go at removing the carb. Clean the bike thoroughly first as you don't want any dirt getting into the reed valve intake. I'm sure someone with a Beta can take you through the process. The benefit is you can then start fixing the bike if it breaks down at an event instead of being stranded.

With practice you should be able to clean the carb in 15 mins.

Alternatively on a Beta you might actually be able to get the drain bolt out without removing the carb ?

Finally a Beta has an aluminium tank so at least you don't have to worry about the plastic tank expanding if it reacts with the petrol. 

[NAD1]

2 hours ago, jon v8 said:

Really? So you add your "Tuppence" and muddy the waters even more. The whole point of forums like this is to get individuals to relate their own experiences. There is no single correct answer, for instance you suggest using good fuel and oil - so what do you suggest IS good fuel and oil ? Maybe I'm missing something here ?

That is what I said... get a multitude of answers and everyone's different opinion based on what they do. Also why I said to check with dealer.
Good oil - fully synthetic
Good petrol - super unleaded

Not rocket science surely.
Was 'muddying the waters' on purpose to highlight that you wont get a definitive answer and should speak to dealer if you are not sure / confident on doing this.

[NAD1]

2 hours ago, b40rt said:

"Sealed unit"  what are the vent hoses for ? Dirt and water can enter through the air filter, so sealing that is also a routine maintenance task. 

Agreed. And ensuring the air filter is cleaned and oiled is a much simpler, less faffy task than fiddling with a carb if you are not confident or technically minded.

My point was that if you're not technically minded and bike is cleaned, dried, lubed, airbox is clean and filter oiled and bike is ran up after and running fine then why would you need to strip and clean the carb?

[b40rt]

4 minutes ago, nickday1 said:

Agreed. And ensuring the air filter is cleaned and oiled is a much simpler, less faffy task than fiddling with a carb if you are not confident or technically minded.

My point was that if you're not technically minded and bike is cleaned, dried, lubed, airbox is clean and filter oiled and bike is ran up after and running fine then why would you need to strip and clean the carb?

Can't argue with that, but some carbs really benefit from regular cleaning (petrol screw Dellorto) while amal's are more tolerant. Learning to maintain the bike is a necessity for reliability and cost saving. 

[section swept]

On 12/02/2018 at 3:52 PM, nickday1 said:

What an amazingly unhelpful thread of answers. highlights all that is wrong with forums. You'll get a multitude of answers all of differing opinion and still be scratching your head. Best bet, check with your trusted dealer

Guess it depends on what bike you have and how old. For my tuppence worth, if a modern bike then draining fuel and cleaning carb after each ride is time consuming, expensive and most importantly pointless as well as you running the risk of not putting back as was - needle in wrong place, knock the floats etc etc

Fuel will be fine if you use good fuel and good oil - if not using good fuel / oil then safe to assume skimping on other areas of bike and maintenance
Carb is a a sealed unit - i.e. nothing can get in or out - all you do by removing it and cleaning it is break that seal and risk contamination. If bike running fine you can be pretty bloody sure that the fuel and carb are fine. I'll bet you those that have carb issues are those that constantly have it on and off..

Running your bike dry wont actually get all the fuel out of the carb either so largely a pointless and ancient practice (IMO).

If you know what you're doing, have the time, space and equipment and know all your carb settings then I guess you wont really do any harm constantly stripping, cleaning, rebuilding and reinstalling. If not and bike runs well you're potentially creating a problem where one did not exist.

Draining the carb should not involve anything like the work you suggest. One drain screw or bolt and it’s done. 

Whats unhelpful about giving your opinion on a topic a member has asked help and advice with?

Your ‘trusted dealer’ may give good, indifferent of bad advice. An awful lot depends on the experience of the dealer or in most cases who you ask the questions to. So the forum is an alternative to seek experienced advice from.

[dadof2]

Someone said draining the carb is an easy job, just unscrew one bolt. The unfortunate fact is most if not all modern trials bikes do not have a carb drain bolt. This omission almost certainly cost me a Scott finish and in 2014 I think probably cost Dougie a win.

Running the bike until the engine stops may not remove all the fuel from the float bowl but it removes a very significant amount. If you leave the bowl full the petrol creeps up the jets and evaporates leaving all the deposits exactly where you don't want them, ie in the jets. Also if there is less fuel in the bowl to evaporate it leaves far fewer deposits when it does evaporate and they re in the bottom of the bowl. This method also ensures the float valve is left open and the ealing face unstressed.

Sometimes minute bits of dirt do get through the filter, bits or filter glue break off or dirt gets in the airbox / inlet hose during re assembly. Carb slow speed circuits can generally be one of two designs, and one is more sensitive to contaminated air than the other.