Choke question

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wents75
Posts: 262
Joined: Wed Nov 25, 2015 8:25 pm
Location: Colchester Essex UK

Choke question

Post by wents75 »

Hi all
Ok when I use the choke only the centre and right cylinders fire ( get hot. Exhaust smoke)
The right fires up when its on run.
I know the choke only operates on the centre and right
So.....
Is this normal?
Iv done a couple of hot cycles ticking over at 1500 rpm
CCI lines cleared two bubbles with no sign of any more.
So I think there good, :shock: I checked em on the bench before install .
Any thoughts welcome.
Ta
Wents
wents75
Posts: 262
Joined: Wed Nov 25, 2015 8:25 pm
Location: Colchester Essex UK

Re: Choke question

Post by wents75 »

Sorry
Left fires when turned to run.
Choke is on centre and left only .
So something not correct useing choke.
barney01
Posts: 3118
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: Choke question

Post by barney01 »

Hi
Imho there is a problem with the left choke piston. Check that it is not stuck in the bore (plenty of carb cleaner) and that the passageway is not blocked. Also if you look in the float bowl of that carb you will see an upright brass tube. Make sure this is clear. At the top of that tube there are tiny holes that cause the petrol to froth to aid vaporisation. Lastly at the bottom of the upright brass tube there is a small metering jet which can get blocked with sediment. Check all this is clear.
NO SMOKE .......NO POKE
wents75
Posts: 262
Joined: Wed Nov 25, 2015 8:25 pm
Location: Colchester Essex UK

Re: Choke question

Post by wents75 »

Thanks Barney
:D
wents75
Posts: 262
Joined: Wed Nov 25, 2015 8:25 pm
Location: Colchester Essex UK

Re: Choke question

Post by wents75 »

Yo :roll:
Re set the BTDC to 3.37mm strobed it all good ...
Ok checked and cleaned the left carb re adjusted all carb float heights and settings as per the on line service manual.
When on choke it still only fires on centre and right ..
When I turn the choke off ( after its started) the left chimmes in and it idles at 1100 rpm nice revs to 4000rpm and settles back to 1100rpm .
While the chokes on it spits fuel out the left exhaust drain hole like its over fuelled???
Iam not overly concerned but it aint right and if it aint right it must be......Wrong
Any thoughts welcome
Ian
barney01
Posts: 3118
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: Choke question

Post by barney01 »

It is very important to understand that 2 strokes only need a choke or enrichment to get the engine running. As soon as the engine starts push the choke off and rev to warm the motor up. This is not like a four stroke which you can leave the choke on until it idles nicely. Some 2 stroke bikes had a spring loaded choke that had to be held open or they would push off automatically.
NO SMOKE .......NO POKE
wents75
Posts: 262
Joined: Wed Nov 25, 2015 8:25 pm
Location: Colchester Essex UK

Re: Choke question

Post by wents75 »

Hi Barney
Oh I see so it really just enriches for starting only .
Hmm well it starts fine .
I need to get it on the road to see how it runs , check the plugs .
Thanks again.
User avatar
Dutch
Posts: 756
Joined: Thu Jul 28, 2011 8:28 pm
Location: St Helens Merseyside

Re: Choke question

Post by Dutch »

barney01 wrote:It is very important to understand that 2 strokes only need a choke or enrichment to get the engine running. As soon as the engine starts push the choke off and rev to warm the motor up. This is not like a four stroke which you can leave the choke on until it idles nicely. Some 2 stroke bikes had a spring loaded choke that had to be held open or they would push off automatically.
I didn't know this Barney, I've left my choke on for a minute or two at times so what harm could it cause ?

Cheers Jeff
GT750A
barney01
Posts: 3118
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: Choke question

Post by barney01 »

It will just over fuel no harm will be done :D
The two stroke engine needs heavy enrichment to start but then once running the heat from the cylinders improve the mixture enough to aid combustion. Any excess fuel will pass through the exhaust. Once the engine has been started it should not be necessary to use the choke again.
NO SMOKE .......NO POKE
User avatar
Dutch
Posts: 756
Joined: Thu Jul 28, 2011 8:28 pm
Location: St Helens Merseyside

Re: Choke question

Post by Dutch »

Thanks Barney ;)
GT750A
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