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 Post subject: Carburettor problems
PostPosted: Thu Sep 08, 2016 4:37 pm 
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80 cc

Joined: Wed Oct 16, 2013 5:28 pm
Posts: 16
Location: Dolgellau, Snowdonia
Hi. Having intermittent fuel starvation problems. Bike starts and runs fine, but a few miles down the road it stutters and stops. Beta Alp 4.0. Drained tank, cleaned filter, fresh fuel, checked spark, cleared breather pipe. Just noticed petrol overflowing from float bowl. Now I think Hugh Cleary wrote this up in the past. But can anyone recommend a carb cleaning service anywhere. My local motorbike repair shop has a 2 week waiting list. Cheers. Rob.

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Beta Alp 4.0
Yamaha Serow XT225
Honda XL185


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 Post subject: Re: Carburettor problems
PostPosted: Thu Sep 08, 2016 4:55 pm 
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80 cc

Joined: Fri Apr 16, 2010 3:08 pm
Posts: 54
Hi there,
I do my own now but they are never as good as the first one I had done by these guys: http://www.carbcleaning.com/

Post it to them and it comes back perfect, around £60 from memory.
Good luck


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 Post subject: Re: Carburettor problems
PostPosted: Thu Sep 08, 2016 5:58 pm 
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650 cc Monster

Joined: Sun Nov 11, 2012 7:31 pm
Posts: 3512
Probably the float valve... Easy fix, loads of stuff on you tube about how to set correct float heights.


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 Post subject: Re: Carburettor problems
PostPosted: Thu Sep 08, 2016 8:57 pm 
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650 cc Monster
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Joined: Fri Dec 07, 2012 2:22 pm
Posts: 2439
Location: Romiley
Greetings,

I tried to reply about an hour ago but my previous draft got lost :!:

Your post lists two faults;

fuel starvation - by this I presume stoppage of petrol getting to the carburettor;

switch petrol to on - run the engine until it stops - quickly disconnect the petrol feed pipe at the carb end and check for petrol flow - no flow disconnect the other end from the tap - if flow then pipe faulty if no flow move tap position to check for flow - petrol flows tap needs dismantling - no flow remove filler cap - petrol flows then filler cap vent not working still no flow remove tap from the tank for inspection of filter and internal passages.

I fitted a replacement tap to my Alp 4.0 with a reserve position, the original just has a stupid warning light which you probably would not see even if it was working - mine had been cut out :!:

petrol overflowing

this might be dirt between the flow valve needle and seat; worn float valve; punctured float or incorrect float height
if you have to remove the carb make sure that you thoroughly clean all of the cables and frame of collected dirt first
prepare a clean uncluttered work surface with supply of clean containers - egg boxes/ corrugated paper/plastic microwave takeaway meal type trays; photograph each stage of the dismantling; use only sharp good fitting screwdrivers
take your time and inspect each parts as you remove it such as noting small 'o' ring in diaphragm chamber
inspect the float for petrol gaining access inside the body e.g. punctured
inspect needle valve seat and viton tip for dirt or wear
inspect free movement and float height when inverted under its own weight

The best ultrasonic bath I have used is made by ASNU (http://www.asnu.com) and sold by ProBike but it is expensive, cheaper alternative is that which is sometimes sold by Aldi.

As to cleaning fluid basically an ultrasonic cleaner is best using simple warm soapy water mixture, you could spray every item with carb/brake cleaner as you strip the parts and after cleaning in the soapy solution. The ultra sound causes cavitation and the bubbles and sound waves do the cleaning without physical damage such as scratching.

Proprietary brake/carb cleaner I use is Jaguar BC41 spray (wear eye protection) but others will do, cleaning fluid can be bought from;

Maplin; http://www.maplin.co.uk/p/jpl-seaclean- ... e-1l-a75lg
Mistral; http://mistralie.co.uk/collections/ultr ... hine-parts
ProBike; http://probike.co.uk

If in doubt fit a replacement needle valve whilst the carb is in pieces.

Spray lots of aerosol lube on the inlet stub and air filter connector before refitting the carb, whilst you are at clean the air filter; box and drain tube. I fitted an inline petrol filter into the petrol supply line and fitted extra length breather pipe to loop under the petrol tank out of harms way and water ingress. Lock wire the drain screw so that you do not need to over tighten it and replace screw head bolts with cap screws.

Always run the carb dry after use. Do not store the bike with a full petrol tank, top up the tank with fresh petrol before restarting or going out for the day. Yamaha Marine used to sell a 'fuel stabiliser' but not sure if it is still available.

If you need more info check out previous posts or just ask.

TTFN

Hugh.

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Please note that I am not a National TRF Officer, any views expressed are my own and may not be in accordance with any official policy.


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 Post subject: Re: Carburettor problems
PostPosted: Thu Sep 08, 2016 9:02 pm 
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650 cc Monster

Joined: Sun Nov 11, 2012 7:31 pm
Posts: 3512
Hugh.its called a Petcock...not a tap !....insert gag here....


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 Post subject: Re: Carburettor problems
PostPosted: Thu Sep 08, 2016 10:29 pm 
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650 cc Monster
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Joined: Fri Dec 07, 2012 2:22 pm
Posts: 2439
Location: Romiley
Greetings,

You'll be telling me next that they don't have cork seals :lol: :lol:

TTFN

Hugh.

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Please note that I am not a National TRF Officer, any views expressed are my own and may not be in accordance with any official policy.


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 Post subject: Re: Carburettor problems
PostPosted: Fri Sep 09, 2016 9:46 am 
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650 cc Monster
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Joined: Fri Dec 07, 2012 2:22 pm
Posts: 2439
Location: Romiley
Greetings,

Yes, just using spray carb cleaner can work quite well in many instances but the problems with spraying carb cleaner is that it only removes the larger particles of surface dirt inside the jets, the compressed gas carrier helps to push out tiny specks too, pushing brushes through jets can help provided that one does not scratch or enlarge the surfaces nor break a mini drill or thin piece of wire in a passageway.

The sonic bath method is simply an extra and more importantly a non abrasive tool in the arsenal but one that can more effectively clean the tiny internal passageways that snake through the carburettor body. Which ever method you choose leave the fluid in contact for some time to react. In the absence of a sonic cleaner I have caught spray liquid in the plastic cap and left jets to soak for 30 minutes or so, you will be amazed at the 'sandy' residue left in the bottom of the cap.

I would suggest that carb cleaners are also less environmentally friendly than sonic baths, even though I do use them.

Modern petrols are in my experience reacting in a negative way with the materials used in the construction of flexible petrol tanks; carburettors and injectors, a form of lacquer tends to build up as the 'petrol' passes through and especially when left over periods of time. The volatile component parts of the petrol evaporates more quickly and the liquid that is left does not burn so easily hence why so many folk have problems starting their engines after storage.

You might be interested to take a look at the videos of injector testing on the ASNU site to see the visual result that the deposits have upon spray patterns and quantity of delivery, and that test fluid is under forced pressure not just atmospheric pressure as is the case of a carburettor.

Unfortunately there is no perfect answer only the one that works on the day for that individual, good luck :lol:

TTFN

Hugh.

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Please note that I am not a National TRF Officer, any views expressed are my own and may not be in accordance with any official policy.


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 Post subject: Re: Carburettor problems
PostPosted: Sat Sep 10, 2016 8:55 am 
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80 cc

Joined: Wed Oct 16, 2013 5:28 pm
Posts: 16
Location: Dolgellau, Snowdonia
Thanks for all these suggestions, guys. Especially Hugh. I'll try to be methodical. Intermittent faults seem a beggar to track down, and days can pass before I can get back to the job, by which time I've half forgotten where I started!

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Beta Alp 4.0
Yamaha Serow XT225
Honda XL185


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 Post subject: Re: Carburettor problems
PostPosted: Sat Sep 10, 2016 10:05 am 
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650 cc Monster
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Joined: Fri Dec 07, 2012 2:22 pm
Posts: 2439
Location: Romiley
Greetings Rob,

My Serow recently gave an odd set of symptoms and it took me quite a while, expensive parts and thought to find the actual prime cause, turned out to be that the silencer internals had collapsed and were partially blocking the exhaust gas at higher speeds :roll:

The other 'faults' were all items that would have failed anyway so not bothered, it is back to its original self now and I get almost as much fun out of fixing it as riding it :lol:

I think that you might have been looking for the following post if you want to look at the photos of the carb;

viewtopic.php?f=84&t=18173&p=112694&hilit=beta+carb#p112694

We live and learn, let us all know what you find as the cause/causes.

TTFN

Hugh.

_________________
Please note that I am not a National TRF Officer, any views expressed are my own and may not be in accordance with any official policy.


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 Post subject: Re: Carburettor problems
PostPosted: Sun Sep 11, 2016 12:50 pm 
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300 cc
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Joined: Mon Apr 22, 2013 7:07 pm
Posts: 570
replace the o ring in the carb between the brass seat of the needle vale and the carb body. the needle seats but fuel flows round the whole lot if the orings gone and floods the float bowl. common problem on old dr350s


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