Won't start from cold unless bump it.

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Muppet
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Main scooter: SX 150 running in

ya could check the spark with one of these https://www.motionpro.com/product/08-0122
C’est la vie
tippo88
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GTFOMWSC wrote:
tippo88 wrote: Sat Dec 02, 2017 5:27 pm
GTFOMWSC wrote:which plug are you using? b7,8 or 9 if its a 9 thats a cold running plug great for long distances but can be a pain when starting from cold sometimes.B8 if its a new set up first off
Thanks. It's an NGK BP7ES should I try an 8 do you think. Not sure if it makes a difference but average temp here in KL is 28c

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thats a hot running plug should only really use a 7 when you first start it up after the rebuild and the first 50 mile or so at running in speed.Try an 8 make sure you gap it right as well.One other thing to try if you can is,fuel on,no choke,put your hand over carb mouth for a couple of kicks,take your hand off,then try starting it.If it fires up could well be you need a bigger jet in it as you'll be basically sending fuel straight to the head that way.
Tried the hand over the carb trick and it started Image so making progress. Found some choke issues to (see below) so will fix those before changing pilot jet.
Thanks !

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tippo88
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a.lo.v2 wrote:I have been using these carbs for years and what I would say is can you definitely see the choke plunger moving? and when at rest I,e closed try and lift the outer out of the ferrule you will see how much slack is in the outer, they are too short for the inner on standard cable. you have a couple of options, 1) adjustable choke cable, the one I had still did not have the required length. they lengthen the inner not shorten it 2)shorten the inner not east with fixed ends, 3)find a longer adjuster(ferrule) I packed out the original with bits of pipe old cable for a while to test the theory and it worked but would not recommend for the long term (air leaks),4) in the end what you have to do is make a new outer from an old cable, clutch will do with a bit of trial and error you will work it out the outer will be about 1 to 2 cm longer than the standard cable
Thanks ! My choke cable had some play in it when in then on position which I assume is incorrect and would mean choke not fully on? I could adjust the play out with the adjuster on max but then my home made cable end came off. Will try shortening the inner cable a little.
I can't see any way of seeing how much the choke is moving?
As my issue is definitely mixture too weak at cold start I want to sort the choke properly before I mess with the jetting.

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tippo88
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Padge wrote:had same issue on someone's bike recently (pwk30), tried everything and no joy so ended up changing stator and fires up first kick hot or cold. try taking plug lead off and check spark while kicking it, a weak spark indicates LT coil on its way out, if you have a spare stator try it....aint got owt to lose
Thanks! Seems like my issue is weak mixture but wondering if ignition is also a contributing factor. I tried a Kytronic SB on it when first built and couldn't get a spark in pass through mode which Kytronic said could be related to stator problems. As I get a spark without the Kytronic I just took it off but not sure if the spark I have is good or weak.

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Chris in Margate
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With the choke OFF, if you lift the outer gently at the carb end, how much free play does it have? In other words how far can you lift it out of the adjuster before you feel it lift the choke?
Do this with the adjuster screwed half in thus allowing adjustment up or down.
You need a little free play to ensure the choke plunger seats but anything more than 1/8 inch is excessive.Measure this excess and then remove that much from the inner OR add that much to the outer with a different ferrule.
I take it you are then soldering a small end on for the lever end.
There are a number of adjusters from other carbs that you can add to your existing or replace but sometimes you have to retap the thread OR there are alloy tubes that your outer sits in.
Failing all this you can.lengthen the outer with the addition of some very small washers that will fit inside the top of your adjuster.
tippo88
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Chris in Margate wrote:With the choke OFF, if you lift the outer gently at the carb end, how much free play does it have? In other words how far can you lift it out of the adjuster before you feel it lift the choke?
Do this with the adjuster screwed half in thus allowing adjustment up or down.
You need a little free play to ensure the choke plunger seats but anything more than 1/8 inch is excessive.Measure this excess and then remove that much from the inner OR add that much to the outer with a different ferrule.
I take it you are then soldering a small end on for the lever end.
There are a number of adjusters from other carbs that you can add to your existing or replace but sometimes you have to retap the thread OR there are alloy tubes that your outer sits in.
Failing all this you can.lengthen the outer with the addition of some very small washers that will fit inside the top of your adjuster.
Thanks, had way more than 1/8" free play when choke off. Will shorten the cable next weekend and try and get the right length and a strong and on it .

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tippo88
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tippo88 wrote:
Chris in Margate wrote:With the choke OFF, if you lift the outer gently at the carb end, how much free play does it have? In other words how far can you lift it out of the adjuster before you feel it lift the choke?
Do this with the adjuster screwed half in thus allowing adjustment up or down.
You need a little free play to ensure the choke plunger seats but anything more than 1/8 inch is excessive.Measure this excess and then remove that much from the inner OR add that much to the outer with a different ferrule.
I take it you are then soldering a small end on for the lever end.
There are a number of adjusters from other carbs that you can add to your existing or replace but sometimes you have to retap the thread OR there are alloy tubes that your outer sits in.
Failing all this you can.lengthen the outer with the addition of some very small washers that will fit inside the top of your adjuster.
Thanks, had way more than 1/8" free play when choke off. Will shorten the cable next weekend and try and get the right length and a strong and on it .

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I fixed the choke and still wouldn't start without hand over the carb so put in a 38 pilot jet and a 8ES plug and started ok from cold, when hot and when warm Image Doesnt run quite as well as it did with 32 pilot jet but at least I can enjoy riding it now.
Thanks for all the !!

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tippo88
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tippo88 wrote:
tippo88 wrote:
Chris in Margate wrote:With the choke OFF, if you lift the outer gently at the carb end, how much free play does it have? In other words how far can you lift it out of the adjuster before you feel it lift the choke?
Do this with the adjuster screwed half in thus allowing adjustment up or down.
You need a little free play to ensure the choke plunger seats but anything more than 1/8 inch is excessive.Measure this excess and then remove that much from the inner OR add that much to the outer with a different ferrule.
I take it you are then soldering a small end on for the lever end.
There are a number of adjusters from other carbs that you can add to your existing or replace but sometimes you have to retap the thread OR there are alloy tubes that your outer sits in.
Failing all this you can.lengthen the outer with the addition of some very small washers that will fit inside the top of your adjuster.
Thanks, had way more than 1/8" free play when choke off. Will shorten the cable next weekend and try and get the right length and a strong and on it .

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I fixed the choke and still wouldn't start without hand over the carb so put in a 38 pilot jet and a 8ES plug and started ok from cold, when hot and when warm Image Doesnt run quite as well as it did with 32 pilot jet but at least I can enjoy riding it now.
Thanks for all the !!

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Thanks for all the help guys.

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