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Bailey V5 idle problem


paul2289
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I have a Bailey V5 with the most recent carb on and it has recently developed a dislike to idleing.

In flight it has plenty of power and runs great it just will not idle without coughing and ultimately cutting out.

At first i thought it was the cold weather but it behaves the same after a 30 minute flight.

I have adjusted the idle screw, checked the valve clearances and replaced the spark plug.

I can follow instructions but my knowledge of a carb is limited, it has been suggested that there are other adjustments that i could make to the carb but the manual only mentions the idle screw which just basically increases the throttle position.

I live 200 miles away from Bailey so any help would be appreciated rather than take it down to him.

Thanks,

Paul

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Hi Paul,

Do you have the CVK carb?

The first thing you will need to do is diagnose the problem:

If you allow the engine to idle for a couple of seconds, then open the throttle quickly, the engine may stop completely, indicating that the mixture is weak at idle, or it may quickly pick up RPM, indicating a correct or rich idle mixture.

If the mixture is weak at idle, it could be an adjustment of the carburettor, although this is unlikely to have happened on its own. It is more likely to be an air leak. Check the carb mounting to the intake manifold and the manifold mounting to the engine.

If the mixture is rich, it could be a leaking float needle. This would cause the float chamber to overflow, particularly when using the primer (without the engine running!).

If all seems well with the above (no leaks), the idle mixture adjustment is on the underside of the CVK carb.

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Hi,

Thanks for the reply. You will have to bear with my lack of mechanical knowledge!

On the ground it will not maintain tickover, i have to keep the throttle open to stop it cutting out. If i let it idle it will splutter then cut out. Going from a small amount of throttle to full throttle is fine and i climbed at over 300ft / min which is good for my wing so no issues with power or power delivery.

I have attached a photo of my carb which is a CVK. Is the screw in the picture the one you refer to? It takes a small allen key.

In terms of turning this is it a case of trial and error or is there a technique to it?

Do you think it might be worth getting a motorbike mechanic to look at it?

Thanks in advance.

fr_1892_size1024.jpg.bcd2030d767d546f3ac

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  • 2 weeks later...

Please do not adjust the mixture screw... 99% of the time it has nothing to do with mixture... "it's not a two stroke!!!"

Have you left the Machine for a long period of time with fuel left in the Float bowl??

Where are you based? If your local you can drop it to us for inspection..

My first thought would be Idle Jet Blocked or clogged with Fuel residue from old evaporated fuel..

If you want some tech advice feel free to call me on 07867317307

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Hi, No it has not been left for longer than a month. The consensus seems to be idle jet blockage. I am based in Lancashire otherwise i would love too!

I am o holiday at the moment but given its a CVK carb found in lots of common motorbikes i was hoping to get a mechanic friend who works on bikes to look at it. Hopefully it will be a case of striping the carb down and cleaning the idle jet which is beyond my comfort level.

Also am i right that you CANNOT run it without the prop on? Out of interest if you had to tune it how would you do that i.e. on a motorbike you could adjust it while the engine is running.

Thanks.

Please do not adjust the mixture screw... 99% of the time it has nothing to do with mixture... "it's not a two stroke!!!"

Have you left the Machine for a long period of time with fuel left in the Float bowl??

Where are you based? If your local you can drop it to us for inspection..

My first thought would be Idle Jet Blocked or clogged with Fuel residue from old evaporated fuel..

If you want some tech advice feel free to call me on 07867317307

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You "can run" Idle it without the prop but i wouldn't...

If my memory serves me right the Mixture screw is 1-1/2 turns out...

why would you try to tune it without the prop on??

You should always try to avoid leaving fuel in the Float bowl for anything longer than a week or two. The Black pipe on the carb will vent vapour out.

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You "can run" Idle it without the prop but i wouldn't...

If my memory serves me right the Mixture screw is 1-1/2 turns out...

why would you try to tune it without the prop on??

You should always try to avoid leaving fuel in the Float bowl for anything longer than a week or two. The Black pipe on the carb will vent vapour out.

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It's not! lol

But its kind of a necessary evil when tuning your carb. You can of course, start it test it, stop it, tweak it, start it and repeat.......

Great amounts of care should be taken either way and should only be attempted when the motor is mounted solidly to something like a fence post.

Most manufacturers will have a place for this to happen in a controlled environment where the mount has been made for specific machines and are bolted into place.

The other thing to consider when your head is close to the prop is to remember your ear defenders!

SW :D

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I guess this situation would be a point scored to motors with a clutch. I wondered if engine builders like bailey would have a flywheel type thing they could put in place of the prop to provide a load for the engine and make tuning easier?

Either way we are lacking manufacturer support up North so a motorbike mechanic will have to do.

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Paul...

you do not need to "tune" a four stroke.... if the valve clearances are correct 0.004 the carb is set to factory settings and the plug is set to 0.6 thats all you need to do...

Tuning without a prop on is IMO impossible... Always do it on your back "simple" you shouldn't be starting a motor on the ground anyway!!!!

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A flywheel is not a load on the engine in the same way that a prop is. At a constant 2000rpm, it might take 20HP to keep the prop turning, while the flywheel requires virtually no power.

The only real alternative to running with the prop would be an engine dynamometer. A dynamometer simulates the prop load (often with an enclosed fan) so that the engines operating parameters (torque, rpm, induction rate, fuel consumption, temperatures, exhaust gas content etc.) can be measured through a range of loads.

Simons approach (run - stop - adjust - run) is the safe approach. If you are adjusting anything, take notes / photos etc. and keep an accurate record of everything you do. That way, when the engine refuses to start :? , you can return to the original settings :wink: .

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  • 1 month later...

Chaps,

What the dickens are you all up to, it is no help to this member to say, it could be, or it could be, or 99% of the time its not....

What i needed here is a systematic diagnostic approach, and base any diagnosis on evidence, not "could be's":

A carburettor is the simplest piece of technology around, start with the basic questions:

1. get a carburettor manual for the exact model, the carb manufacturer web site is where you start.

2. check operation of float chamber valve;

2.a check float level;

3. check all jets, using air to clean and not jet cleaners;

4. check for contaminates;

5. clean as needed;

6. check air filter, clean as required. do not run with it removed, it will run lean;

reassemble, all new gaskets;

if you are competent, re-use gaskets and use fluid (wd40) to check for leaks when running

7. set air screw as manufacturer/bailey specific advise, number of turns from stop (in). check "o" ring to air screw if fitted, and do not over tighten against alloy case/base, it will damage unit.

8. if you are skilled enough, connect a vacuum gauge, and use this to confirm most efficient fuel burn (aka mixture)

9. check plug, visually, and by way of replacement with new to confirm any fault.

10. Importantly, avoid taking advice from those who do not have the pre-requisite knowledge of carburettors/operation, as you may well end up with a lean mixture and heat damage, or rich mixture, washing lubrication from the cylinder wall and destroying lubrication properties of the engine oil.

As if you are stuck, if i can assist, i will.

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  • 2 weeks later...

All,

I am still having this problem. I have tried calling Bailey for their advice / take it to them but they dont answer the phone these days :(

So far i have done the following:

1. Tried adjusting the idle screw (that's the little screw on the throttle cable not the one on the side of the carb), it all the way down atm.

2. I took it to a motorbike mechanic who is familiar with CVK carbs and he stripped it down checking the following:

- Checked the diaphragm at the top for holes splits etc

- Took the float bowl off and checked for contaminates

- checked the float

- removed the idle jet and cleaned it (there was no sign of blockages)

- Removed the main jet and cleaned

3. Checked the valve clearances

4. Did a visual check of the air filter (its a K&N) there are no signs of issues

5. Replaced the fuel for fresh

6. Changed sparkplug and checked gap (the previous one was a normal colour)

As people know the Bailey should idle between 2600 and 2900. If i hold the throttle open at about 3k it runs okay. As soon as i let off the throttle the revs drop off to about 1300 and then steadily roll off until it cuts out.

I can fly it fine and flew for 40 minutes the other day and it still cut out when i tried to idle so it is nothing to do with the engine being cold.

Any ideas?

Edited by Guest
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Just a sudden thought...

I have had spark plugs that fail with very similar symptoms as they warm up.

I am not sure what the mechanical boffins with think to that idea but worth the cost of a plug for a try I recon.

SW :D

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Just a sudden thought...

I have had spark plugs that fail with very similar symptoms as they warm up.

I am not sure what the mechanical boffins with think to that idea but worth the cost of a plug for a try I recon.

SW :D

I forgot to add that to the list, I have changed the plug too and checked its gap.

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Morning,

Do you have the exact carb model number/the manual, i did not see you had checked the float level, float valve operation, or air leak/air ingress. Can you send the manual it to me?

I realise there is some mockery to my suggestion of a systematic approach.... but it is the only approach to use...

If you can pm me, i will assist all i can. If you want me to strip the carb, i will do, and teach you what you need to know at the same time.

Can you get a gasket/service kit for the carb, as for the cost, it is worth replcing all the gaskets etc.

thanks,

I am based in Shropshire.

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No ridicule from me, i am happy for any suggestions.

The carb does not have any manufacturers markings on it (that i can find) but i think it is a Keihin Cvk 26 however i guess it has been tuned by Bailey.

The strange thing is it has plenty of power it just wont hold its revs on idle.

The gaskets seemed fin when we stripped the carb down, bear in mind this has only done about 55 hours so its not an old engine.

Unfortunately I live in Lancashire but that you for the offer. In an ideal world i would just drive it down to Bailey and get them to look at it but they dont answer the phone at the moment :(

I am not sure how much a new carb is but given the cost of driving it down to Bailey i would consider just swapping the whole thing.

Could the fuel pump be causing the problem? It is fed via a vacuum tube off the intake manifold.

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Hello,

Only advice at this point is STOP- and definitely don't start replacing a carb when it may not be that.

This could simply be an air leak/gasket problem not visible to the naked/untrained eye.

You are stuck if the manufacturer is ignoring you, but ask them:

1. The model of carb fitted:

2. any low speed/high speed air screw adjustments they make over the standard setup:

3. any jet size change they undertake/the jest sizes

4. get the manufacturers manual - follow there setup.

You are at a point where you have a choice, get someone who is an expert look at it, or, disaster will follow.

The problem you have is a simple one here, rich mixture (over fuel) washes cylinder bores and will scrap engine, and lean mixture runs hot, and will scrap engine.

Stop using it now.

In my profession, i normally chemically analise the oil to determine engine condition, wear, and narrow defects,

I can put you in touch with the chemist we use if that assists.

I appreciate you are miles away, but you have a stark choice, get an expert to look at it, don't use it, or use it and scrap the engine.

PS, if not running at idle, may be lean of rich at idle, and that condition will manifest through entire engine operating range.

Help if i can, but the next steps are a choice for you now.

Willy Gofar.... or not with a faulty carb!

cheers,

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Hello,

Only advice at this point is STOP- and definitely don't start replacing a carb when it may not be that.

This could simply be an air leak/gasket problem not visible to the naked/untrained eye.

You are stuck if the manufacturer is ignoring you, but ask them:

1. The model of carb fitted:

2. any low speed/high speed air screw adjustments they make over the standard setup:

3. any jet size change they undertake/the jest sizes

4. get the manufacturers manual - follow there setup.

You are at a point where you have a choice, get someone who is an expert look at it, or, disaster will follow.

The problem you have is a simple one here, rich mixture (over fuel) washes cylinder bores and will scrap engine, and lean mixture runs hot, and will scrap engine.

Stop using it now.

In my profession, i normally chemically analise the oil to determine engine condition, wear, and narrow defects,

I can put you in touch with the chemist we use if that assists.

I appreciate you are miles away, but you have a stark choice, get an expert to look at it, don't use it, or use it and scrap the engine.

PS, if not running at idle, may be lean of rich at idle, and that condition will manifest through entire engine operating range.

Help if i can, but the next steps are a choice for you now.

Willy Gofar.... or not with a faulty carb!

cheers,

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Hi paul

I have relied to your post before..

Paul bailey has asked me to post on here for him as he said he has tried to post on this forum before but said his posts never appear???

Anyway.. He is aware of your issue and said if you email pb@baileyaviation.com he will help you with your problem.

You can give me a call if you like.. 07867317307

Regards

Mark

Sussex Paramotors

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