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Carbs...bane of my life!!!


ianl1201

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As mentioned in the last time you rode a bike thread, I gave the Bandit 12 a good ragging on Saturday. This is the second trip in a row where the bastard has decided it no longer wants to tick over. I had the carbs fully overhauled a couple of years ago and it's been running fine, but now won't idle unless I leave a whiff of choke on.

I work away a lot so the bike sits for long periods which makes me wonder if the idle jets are gummed up again or if it's something else? An italian tune-up this weekend didn't make any difference and I know it's getting rattly so a cam chain and valve check is planned for the winter....if this is affecting the timing could this be something to do with it?

Any thoughts from the PB hive mind?

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Timing won't have changed enough with a slack cam chain to make any difference. I'd be looking for blocked pilot jets or tweak the tickover up and see if that helps. 

Possible if valve clearances have gone tight it won't be happy when hot. Fairly simple to do on those luckily as they're screw and locknut adjustment not shim change 

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I had a bike that had sat for a while and being lazy I looked for seafoam in the UK, then I found diy seafoam and made some, I was a bit weary of mixing diesel etc and running the bike on it, I put about 2 or 3 litres in and brimmed it it ran well and cleared the low rpm problems 

It was a cbr600 that had sat for 2 years, I never did take the carbs off

http://hildstrom.com/projects/seafoam/

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  • 2 months later...

Ooof - I'd forgotten I even posted this which shows how much time I've spent with my bike lately! :eusa_think:

 

On 9/21/2020 at 5:12 PM, lesviffer 750 said:

Does it make any difference turning the tickover up, ferk me im showing me age, I meant the idle adjuster.

I'll have a do at this first before reaching for the spanners

On 9/22/2020 at 9:32 PM, wavey said:

Timing won't have changed enough with a slack cam chain to make any difference. I'd be looking for blocked pilot jets or tweak the tickover up and see if that helps. 

Possible if valve clearances have gone tight it won't be happy when hot. Fairly simple to do on those luckily as they're screw and locknut adjustment not shim change 

Ta Wavey - same again. Doesn't seem to make a difference if it's hot or cold. Pilot jets are a thought I had, as unfortunately due to the nature of my job and travelling a lot, the bike does sit for extended periods. I don't really want to have to get the carbs off again, although I am pretty well practiced now!

On 9/23/2020 at 2:47 PM, ssray said:

I had a bike that had sat for a while and being lazy I looked for seafoam in the UK, then I found diy seafoam and made some, I was a bit weary of mixing diesel etc and running the bike on it, I put about 2 or 3 litres in and brimmed it it ran well and cleared the low rpm problems 

It was a cbr600 that had sat for 2 years, I never did take the carbs off

http://hildstrom.com/projects/seafoam/

Interesting stuff. When I get some decent time at home, I'll look into getting hold of the ingredients and have a play with this.

Anyway, thanks for the replies chaps. I was home last weekend and fired up the old girl and it ran up ok after all the cylinders woke up...much like myself of a morning! It's SORN now so over the christmas break (although I've just learnt I'll be working through a fair bit of it) I'll try and get some quality workshop time to get to the bottom of what's happening :thumbsup:

Edited by ianl1201
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There's genuinely no substitute for a full strip and clean of a bank of carbs. Give them a full set of new seals, set the floats properly and return everything to factory settings. That sorts them out beautifully unless the bodies and butterfly shafts are fucked.

It's also a lovely winter evening job if your garage is heated, steadily tinkering away with just a radio and a mug of tea/Hobnobs for company.

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19 minutes ago, Damnthistinleg said:

There's genuinely no substitute for fuckin the whole lot off and throwing it straight in the volcano. 

Awful, awful shite carbs, even 'good' ones. 

Get something modern and better. Anything, a pushbike even, as long as it doesnt have carbs.

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For those who understand and appreciate the art and beauty of perfectly fettled carbs, no explanation is necessary.

For those who don't, none will suffice.

 

 

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Ahhhhh its so clear to me now. 

Where you wrote carbs, you could have written Zeus, or Mohammed, or whatever god you chose. 

No explanation will suffice, thats for sure, and yet for the pious believer, the truth is so self evident.

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1 hour ago, Damnthistinleg said:

For those who understand and appreciate the art and beauty of perfectly fettled carbs, no explanation is necessary.

For those who don't, none will suffice.

While I don't dislike carbs, there's no doubt a good injection system is better. It's just that you can't hold the entirety of an injection system in your hands and make adjustments with a small screwdriver. The counterpoint is that you probably won't need to once it's done right, which tends to be the case from the factory.

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It's all horses for courses until you start talking about state-of-the-art vehicles. The bottom line is that both systems are perfectly agreeable when working and neither has a real flaw where fuelling an engine for general use is concerned. The big problem is the continuous control of that fuelling in a world which is increasingly dominated by emissions.

As for bikes I've owned and worked on, I've genuinely had fairly equal hassle with FI and carbs but the total amount for both is only small.

Funnily enough, the worst offender was my Mille, now I come to think of it. They flood for fun if you don't start them properly.

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On 12/2/2020 at 3:58 PM, Damnthistinleg said:

There's genuinely no substitute for a full strip and clean of a bank of carbs. Give them a full set of new seals, set the floats properly and return everything to factory settings. That sorts them out beautifully unless the bodies and butterfly shafts are fucked.

It's also a lovely winter evening job if your garage is heated, steadily tinkering away with just a radio and a mug of tea/Hobnobs for company.

Very much this and i subscribe to your old yellow newspaper.
I have found much mental stability over the years sorting NC30 and RVF400 carbs to perfection. 
One of the most rewarding and satisfying bike jobs ever. 

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12 minutes ago, CRM said:

Very much this and i subscribe to your old yellow newspaper.
I have found much mental stability over the years sorting NC30 and RVF400 carbs to perfection. 
One of the most rewarding and satisfying bike jobs ever. 

What size is your ultrasuperdupersonic bath? I'm tempted to get one for clogged up carbs too and Santa's not too far away...

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On 12/9/2020 at 4:36 PM, lorenzo said:

What size is your ultrasuperdupersonic bath? I'm tempted to get one for clogged up carbs too and Santa's not too far away...

I have one with a 6 litre tank and whilst big enough for an indivudual carb you couldn't fit an entire bank of carbs in it.

I would measure the biggest item that you think you might want to clean and get one with a tank to suit.

This is my one.

20160417_212226

 

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1 hour ago, Toneale said:

I have one with a 6 litre tank and whilst big enough for an indivudual carb you couldn't fit an entire bank of carbs in it.

I would measure the biggest item that you think you might want to clean and get one with a tank to suit.

This is my one.

20160417_212226

 

Are you satisfied with its performance? I had one of the smallest/cheapest ones and it could hardly cope with bike parts. Then it stopped working altogether.

 

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29 minutes ago, John21 said:

Are you satisfied with its performance? I had one of the smallest/cheapest ones and it could hardly cope with bike parts. Then it stopped working altogether.

 

My one is really good. It was an expensive one (i paid about €500) i bought about 5 years ago. Although prices have come down generally over the last few years.

Works great, the only gripe is the tank is a bit in the small size.

Did these bits off my old nc35 in it a couple of years ago.

20160417_212119

 

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