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mr_barbra
Joined: 02 Nov 2007
Posts: 42
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 Posted: Sat May 10, 2008 10:50 pm Post subject: bike is stuttering! |
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hello there, right it is hard to explain but today I did a 100mile round trip, and whenever I accelerated quicky or got the bike above 30m.p.h, the bike would 'stutter', like little jerks until I relax the throttle and then rev it again, and it would then eventually do it again and agian which made my journey slow and uncomfterable.
The drive belt looks good, and the engine and gear oil were both replaced 600k ago.
its a jmstar 50 qt-13 and its a 50cc
cheers
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joe_T
Joined: 19 Sep 2007
Posts: 2644
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Location: somerset uk bt49 qt-9
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autry024
Joined: 09 May 2008
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| Posted: Sun May 11, 2008 11:57 am Post subject: |
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| this sounds like the carb being too lean as you have feather the acceleration, but I had a similar instance and the ignition coil cap wasn't making full contact with the spark plug. Thats a even easier check as the plug will definitely tell you whats going on. you can replace the cap at any autoparts store
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joe_T
Joined: 19 Sep 2007
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Location: somerset uk bt49 qt-9
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mr_barbra
Joined: 02 Nov 2007
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| Posted: Tue May 13, 2008 3:14 pm Post subject: |
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| thruss91 wrote: | | well it's a fuel/ air problem. what air filter have you got, stock or k&n? is the filter dirty/come off the carb? |
I did have the old stock air filter pad that came with it, but I was recommended by a friend, to just take it out, and put in a very fine piece of allumium mesh instead, I asked if it would make too much air come in, but he said it would be fine. is this the problem?
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px166bajaj
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Joined: 09 Oct 2006
Posts: 6321
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Location: Sevenoaks Kent (Er, that's UK!)
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| Posted: Tue May 13, 2008 7:41 pm Post subject: |
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Sounds like a dodgy spark plug cap or losse leads to the coil to me. (losing contact due to engine movement)_________________ 
A dealer will say anything to get your money! |
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J€Di
Joined: 08 Nov 2006
Posts: 1306
Karma: +70
Location: Walsall, West Midlands - croooooooozin'!!!
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| Posted: Tue May 13, 2008 7:47 pm Post subject: |
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| mr_barbra wrote: | | thruss91 wrote: | | well it's a fuel/ air problem. what air filter have you got, stock or k&n? is the filter dirty/come off the carb? |
I did have the old stock air filter pad that came with it, but I was recommended by a friend, to just take it out, and put in a very fine piece of allumium mesh instead, I asked if it would make too much air come in, but he said it would be fine. is this the problem? |
YES. Unfortunately your friend is an idiot who knows nothing about how a carb fed bike works. More air needs more fuel, more fuel required a larger main jet in the carb. Put the original air filter back in and the problem will go away._________________ 
Midlands rider? Click HERE!!! |
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mr_barbra
Joined: 02 Nov 2007
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| Posted: Wed May 14, 2008 2:30 pm Post subject: |
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hmm thanks for the replies, when I get home, I shall try and check the spark plug, px166bajaj do you mean the cap that goes on the end of the spark plug? if so ill take it all off, clean the plug and put it back on.
Jedi, I (stupidly) through out the origional filter, is there a tempory replacement that I can use before I order a new one?
so by letting more air into the filter, it means the mixture is more air than fuel? is that how it works?
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Yellow Scooter
Joined: 20 Mar 2007
Posts: 3795
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Location: North Carolina USA
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| Posted: Wed May 14, 2008 4:13 pm Post subject: |
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| mr_barbra wrote: | hmm thanks for the replies, when I get home, I shall try and check the spark plug, px166bajaj do you mean the cap that goes on the end of the spark plug? if so ill take it all off, clean the plug and put it back on.
Jedi, I (stupidly) through out the origional filter, is there a tempory replacement that I can use before I order a new one?
so by letting more air into the filter, it means the mixture is more air than fuel? is that how it works? |
You have to upjet the carb anytime you put in a free flow or freeer flowing filter. I'd order a replacement air filter like the one you tossed out, and tell Mr Goodwrench to get bent, and to leave your scooter alone.
I don't know if there is any temporary stop-gap that can be done other than to upjet the carburettor, if it's gonna be a considerable amount of time before the replacment filter is in. It's a bit of hassle, but I'm afraid that is what it's gonna take to get the mix back in balance again.
_________________
Parents: DO NOT let your child chew on your scooter!
China still uses lead based paint!
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px166bajaj
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Joined: 09 Oct 2006
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Location: Sevenoaks Kent (Er, that's UK!)
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| Posted: Wed May 14, 2008 7:26 pm Post subject: |
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| mr_barbra wrote: | | hmm thanks for the replies, when I get home, I shall try and check the spark plug, px166bajaj do you mean the cap that goes on the end of the spark plug? if so ill take it all off, clean the plug and put it back on. |
By all means check the plug, but several people have had dodgy connections on the wire which goes to the plug cap. The thin wires to the coil can also have poor connections. The coil is at the other end of the fat wire coming out of the plug cap.
| mr_barbra wrote: | | Jedi, I (stupidly) through out the origional filter, is there a tempory replacement that I can use before I order a new one? |
Socks are your friend._________________
A dealer will say anything to get your money! |
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Aerostudent
Joined: 02 Mar 2008
Posts: 140
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Location: SoCal, USA
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| Posted: Thu May 15, 2008 5:50 am Post subject: |
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Yes, socks are your friend. Buy a 10 pack of 'em and put one or two over your intake (as needed) and the rest crammed into your friends mouth  Even if you want more air, I would not run with just a mesh screen, get a K&N, Uni, MRP, or other freeflow filter AND upjet to match! An upjet MIGHT not be needed, but will mostlikely.
I have been having a similar mid range problem, but not as bad as yours (it just boggs a little and sounds poppy and generally unhappy in the mid-range 38-45MPH). Originally I thought carb problem, but I adjusted it to reduce the bog, but haven't eliminate it. I am glad PX mentioned the plug cap, I have been having problems with that lately, so I may just get a new one to see if that fixes it. Thanks PX!
Aero
I need to buy stock in a good sock company 
_________________
Lance GS-R 150, Ir plug, MRP filter w/custom intake, drilled exhaust, tuned carb, MRP racing clutch, racing variator, +more. custom graphics. 64 MPH!
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px166bajaj
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Aerostudent
Joined: 02 Mar 2008
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Location: SoCal, USA
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| Posted: Thu May 15, 2008 6:08 am Post subject: |
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Thanks! +K back for the plug cap info. I will stop on the way home from school tomorrow and see about getting one. I'll post if it fixes, I was looking for a solution to my mid range puttering. Now I need to do some quick fine-tunning on my carb and get to sleep.
Aero
EDIT: Plus one to px166 when I can, I already gave one to Fox a bit ago. Is it once an hour or once a day?
_________________
Lance GS-R 150, Ir plug, MRP filter w/custom intake, drilled exhaust, tuned carb, MRP racing clutch, racing variator, +more. custom graphics. 64 MPH!
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px166bajaj
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Location: Sevenoaks Kent (Er, that's UK!)
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| Posted: Thu May 15, 2008 11:01 am Post subject: |
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| Aerostudent wrote: | | EDIT: Plus one to px166 when I can, I already gave one to Fox a bit ago. Is it once an hour or once a day? |
It all depends on your age......  _________________
A dealer will say anything to get your money! |
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Scootin
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