550j cylinder misfire solved

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barney01
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Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

550j cylinder misfire solved

Post by barney01 »

So i was out on a run the other day and noticed my 550j motor was a little lack lustre, you know when your bike is not running quite right, so when i got home i checked my exhaust manifold temperature. Now i know some of you have these modern gadgets that measure the temperature exactly but i use the age old method. A bit of spit on your index finger and tap the manifold. It should make a unique noise and spit back at you. (Now dont touch it just tap it!) So the right downpipe didnt make the noise and was warm but not hot.
I first checked the plug. Very sooty dirty typical of one thats not firing well. Replaced it with known good clean one. Next connected strobe light to the HT lead, no problem it was firing well. When i examined choke cable it felt tight.
Now these J and K models have independant choke and throttle cables attached to the carbs. There is a 1 into 3 junction box on both units and they are under the tank and do have a tendency to creep pulling tight. So i pulled them back and cable tied them to the frame to prevent a reoccurrence. Went for a run now running well again and downpipes are spitting back at me again!
NO SMOKE .......NO POKE
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Alan H
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Location: Wombwell, Republic of South Yorkshire

Re: 550j cylinder misfire solved

Post by Alan H »

I had something similar with my first 550 back in the 70s. Started fine and then 'lost' a cylinder as the bike warmed up. Picked up at half throttle which was (n't) fun in the rain! Sticky choke slide which just needed a clean - needless to say, I did all 3!
If one's grotty, the others will be.
Proof that four strokes are over complicated
barney01
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Joined: Wed Sep 26, 2012 7:33 pm
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Re: 550j cylinder misfire solved

Post by barney01 »

And so just cleaned and rebuilt airbox and now carbs are going through the ultrasonic cleaner
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NO SMOKE .......NO POKE
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Alan H
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Re: 550j cylinder misfire solved

Post by Alan H »

Not seen one of those fittings on the extension cable for many years Barney. Is it the one with a little lever on so you can select 5a or 15a round pin, 13a square pin as well as flat pins and small continental pins or a multi socket? Mine is the multi plug.
The only other one I've seen is in my garage, but like me, it's retired now that I don't travel all over Europe with work! :lol:
Bloody handy thing over the years tho'.
Proof that four strokes are over complicated
barney01
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Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: 550j cylinder misfire solved

Post by barney01 »

You are right Alan had it for some years. Great if you are a globetrotter! :lol:
NO SMOKE .......NO POKE
barney01
Posts: 3118
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: 550j cylinder misfire solved

Post by barney01 »

Got all the carbs done today! Now looking new again :D
https://youtu.be/srfX2-TIncs
NO SMOKE .......NO POKE
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Harrymail
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Joined: Thu Jul 07, 2016 8:35 pm
Location: East Yorkshire

Re: 550j cylinder misfire solved

Post by Harrymail »

I like the look of that Ultrasonic Cleaner Barney. Might have to put one of those on my Xmas list :D
Currently without a GT, but looking
2003 Yamaha Fazer 600 Blue
2020 Triumph Street Twin Red
1968 BSA Bantam Sports Red
barney01
Posts: 3118
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: 550j cylinder misfire solved

Post by barney01 »

Great bit of kit
Top before
Bottom after :D
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NO SMOKE .......NO POKE
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