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850 Mk3 wont run off Choke

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Hi everyonewell I have just done a engine rebuild and have just stated it up for the first time and the engine is sounding a treat,I had to strip it down and found that the Cam Lobes were Braking up...so on some advice was told to put in a PW3 cam inso I got that from A.N and all seems to have gone ok check all the things that I was also told by Norman White that it would go right in with No problems as the MK3 had all the bigger cutaways for the Tappet Blocks etc but I still checked them anyway, also the piston clearance on the Valves but all were fine other than when I started her Up she ran lovely and as soon as I tried to turn off the choke she would just cut out soon as I put the choke back on first press of the button she would start and again tried to turn off the choke she would stop. checked all the timing and put three more sets of spark Plugs in and still the same thing happen, Now she is fitted with near new Premier carbs and they were fine when I took her off the road in October and I have not done anything to them till Now, so I striped them down and cleaned everything including all the pilot jets outand as there are the Premier carbs they have the improved Idle circuit but the pilot jets which are on the inside between the two carbs have a cross head jet so I found them both were lose, so are they meant to be lose or tight if someone can put me right on that one, also checked that the jets are right I,E Main and Needle jets which are 230 mains with 106 Needle jets and someone told me I should be running 260 Mains which I have just ordered so hope they are right,

so if anyone can shed any more light on this subject I would be most Grateful of any comments.

Thanks Maurice

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I've no experience with a Mk3, a PW3 cam or Amal Premiers. But looking at Amal's exploded image of a Premier I would imagine the idle jets need to be tight (but not so tight as to ruin the O-ring), not loose. That could be your problem right there. If not â? I see you've checked the timing â if you have electronic ignition with a remote box, e.g. a Boyer, have you got the wires to the points position the right way around? HTH

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Hi Yes I am running Pazon Electronic Ignition and yes all is ok with that but thanks I think that the Idle jet should have been tight to so when all is back together when I get the new main jets I will try that.

Thanks

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Hi One more thing is in the float chamber next to the tube that takes the main jet there is a small thread which there is nothing in there, I know that it is for a pilot jet but is there meant to be a jet in there or or not as do the premier carb still need a jet in there or not as they did not come with anything in there.....if so what size should it be or do I just leave it as is.

Thanks

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Maurice:

If it will run with the choke on but not run with the choke off then the logical conclusion is that it is set up too lean.

I would check all jets and all passages, and I am under the general impression that jets should never be loose. Have you checked with the Premier people about the loose jets? If so, what did they say?

Mike

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Previously maurice_cloud wrote:

Hi One more thing is in the float chamber next to the tube that takes the main jet there is a small thread which there is nothing in there, I know that it is for a pilot jet but is there meant to be a jet in there or or not as do the premier carb still need a jet in there or not as they did not come with anything in there.....if so what size should it be or do I just leave it as is.

Thanks

Looking again at the exploded diagram of a Premier,I can't think why there'd be any threads in the float chamber, unless it's an artefact of the manufacturing process that was introduced with the Premier. The exploded diagram again shows nothing in the float chamber that I'm unfamiliar with in Mk1 Concentrics, so I'd leave such threads well alone. HTH

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Hi Maurice

A long shotfor you to check, has the balance pipe across the inlet manifolds blown off or split?

Regards

Katherine Scott

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Previously maurice_cloud wrote:

Hi everyonewell I have just done a engine rebuild and have just stated it up for the first time and the engine is sounding a treat, I had to strip it down and found that the Cam Lobes were Braking up...so on some advice was told to put in a PW3 cam in so I got that from A.N and all seems to have gone ok check all the things that I was also told by Norman White that it would go right in with No problems as the MK3 had all the bigger cutaways for the Tappet Blocks etc but I still checked them anyway, also the piston clearance on the Valves but all were fine other than when I started her Up she ran lovely and as soon as I tried to turn off the choke she would just cut out soon as I put the choke back on first press of the button she would start and again tried to turn off the choke she would stop. checked all the timing and put three more sets of spark Plugs in and still the same thing happen, Now she is fitted with near new Premier carbs and they were fine when I took her off the road in October and I have not done anything to them till Now, so I striped them down and cleaned everything including all the pilot jets outand as there are the Premier carbs they have the improved Idle circuit but the pilot jets which are on the inside between the two carbs have a cross head jet so I found them both were lose, so are they meant to be lose or tight if someone can put me right on that one, also checked that the jets are right I,E Main and Needle jets which are 230 mains with 106 Needle jets and someone told me I should be running 260 Mains which I have just ordered so hope they are right,

so if anyone can shed any more light on this subject I would be most Grateful of any comments.

Thanks Maurice

Maurice

simple check, you are putting the choke on and off correctly, easy to get mixed up, with the Amals it's a reverse of logical thinking. I've taken the chokes out of mine, they don't need them imho

gino

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Previously Katherine Scott wrote:

Hi Maurice

A long shotfor you to check, has the balance pipe across the inlet manifolds blown off or split?

Regards

Katherine Scott

Hi Katherine yes I put a new balance pipe on and I did check it as well

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Previously gino_rondelli wrote:

Previously maurice_cloud wrote:

Hi everyonewell I have just done a engine rebuild and have just stated it up for the first time and the engine is sounding a treat, I had to strip it down and found that the Cam Lobes were Braking up...so on some advice was told to put in a PW3 cam in so I got that from A.N and all seems to have gone ok check all the things that I was also told by Norman White that it would go right in with No problems as the MK3 had all the bigger cutaways for the Tappet Blocks etc but I still checked them anyway, also the piston clearance on the Valves but all were fine other than when I started her Up she ran lovely and as soon as I tried to turn off the choke she would just cut out soon as I put the choke back on first press of the button she would start and again tried to turn off the choke she would stop. checked all the timing and put three more sets of spark Plugs in and still the same thing happen, Now she is fitted with near new Premier carbs and they were fine when I took her off the road in October and I have not done anything to them till Now, so I striped them down and cleaned everything including all the pilot jets outand as there are the Premier carbs they have the improved Idle circuit but the pilot jets which are on the inside between the two carbs have a cross head jet so I found them both were lose, so are they meant to be lose or tight if someone can put me right on that one, also checked that the jets are right I,E Main and Needle jets which are 230 mains with 106 Needle jets and someone told me I should be running 260 Mains which I have just ordered so hope they are right,

so if anyone can shed any more light on this subject I would be most Grateful of any comments.

Thanks Maurice

Maurice

simple check, you are putting the choke on and off correctly, easy to get mixed up, with the Amals it's a reverse of logical thinking. I've taken the chokes out of mine, they don't need them imho

gino

Hi Gino Yes I have been riding the bike for the last two years or more but yes when you pull on the cables it slides the chokes up inside the slides to the top which is off.....push it the other way and lower the choke slides that is on...but thanks for pointing that out...as yes some might get it wrong Lol

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Anal have recently changed the std jetting on premier's for 850 Commando's by changing the 17 pilots to 19 pilots due to weak running at tickover.

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Hi John well as I said there is a thread in there for a pilot jet but the new ones I got last year did not have any jets and I was told not to put any in. don`t know if that is right or wrong ?

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Previously maurice_cloud wrote:

Hi John well as I said there is a thread in there for a pilot jet but the new ones I got last year did not have any jets and I was told not to put any in. don`t know if that is right or wrong ?

Maurice, did you look at the exploded diagram of a Premier carburettor? Really it's an 'exploded photograph'. If not, I really think it answers that question. I'll post the link again here as a plain URL just in case, just scroll down a little on that page to see the image, and check the parts list to the left. HTH.

http://amalcarb.co.uk/generic-900-series-premier.html

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Thanks Colin I have just had a look at it and it is the oppsite side to the mixture screw which means there is not a pilot jet on the inside just need to take a look at the number on mine as someone said that Amalhave changed the premier jets on the pilot from 15 to 19 but I will check what is mine tomorrow.

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They went from 17 to 19, not 15 to 19. They are not stamped with a number, you have to count the rings on the jet and look up the matching number on the Anal site.

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Previously maurice_cloud wrote:

Hi everyonewell I have just done a engine rebuild and have just stated it up for the first time and the engine is sounding a treat, I had to strip it down and found that the Cam Lobes were Braking up...so on some advice was told to put in a PW3 cam in so I got that from A.N and all seems to have gone ok check all the things that I was also told by Norman White that it would go right in with No problems as the MK3 had all the bigger cutaways for the Tappet Blocks etc but I still checked them anyway, also the piston clearance on the Valves but all were fine other than when I started her Up she ran lovely and as soon as I tried to turn off the choke she would just cut out soon as I put the choke back on first press of the button she would start and again tried to turn off the choke she would stop. checked all the timing and put three more sets of spark Plugs in and still the same thing happen, Now she is fitted with near new Premier carbs and they were fine when I took her off the road in October and I have not done anything to them till Now, so I striped them down and cleaned everything including all the pilot jets outand as there are the Premier carbs they have the improved Idle circuit but the pilot jets which are on the inside between the two carbs have a cross head jet so I found them both were lose, so are they meant to be lose or tight if someone can put me right on that one, also checked that the jets are right I,E Main and Needle jets which are 230 mains with 106 Needle jets and someone told me I should be running 260 Mains which I have just ordered so hope they are right,

so if anyone can shed any more light on this subject I would be most Grateful of any comments.

Thanks Maurice

Hi Bro had a similar problem. Premium carbs changed pilots to 19, job done.

regards j

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Hi everyone 

Just an update on My Commando 850 MK3 well I stripped the carbs as I said again used new gasket and seals ordered two inlet Rubbers from AN and only one turned up so the other one came today so went right out fitted them both and she started first press of the button and running a treat with a little mess around with the mixtures she sat ticking over at 900 RPM no problem and after I rebuilt the whole engine with a PW3 Cam she sounds a treat if I say so myself just hope all the oil leak problems are all gone Now...meaning the ones from the cylinder head round near the push rod tubes so had the head skimmed by Scholar Engineering along with the 3 x 3/8" Helicoils which were on there way to pulling out.... so with that now done I hope she rides great she sounds it, so to everyone Have a happy Christmas and new year and let`s have some good riding next year too.

Cheers Maurice

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That's good news, happy holidays to you too!

 


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