Engine Won't rev

[Ryley]

I've had 3 plugs in it now, plug makes no difference at all...

The coil sounds like it might be an option though

So where can I buy a coil for a chinese 50 in Perth ???

 

[dirttau]

where are u in perth

 

[Ryley]

I'm NOR in Warwick

 

[KTMKID]

coil,slide in carby is in the wrong way or blocked fuel lines???

 

[Ryley]

coil,slide in carby is in the wrong way or blocked fuel lines???

Slide in carby ??? Only goes one way mate.. Fuel supply not a problem at all, so it only leaves coil....

I'll try and get a coil for it today

 

[Ryley]

OK, it's not the coil. it made no difference at all...

So it's back to the carby. does anyone have any info on these Sheng carbies, or can anyone give a reason as to why it will only rev with the choke on ?

 

[Sidney]

thanks for telling me Sidney guy who knows everything about bikes.

Dude wtf? I'm just trying to help this guy out

 

[minidirt]

it sounds like jetting issue to me,
and the issue sounds like a main jet that is to small, as when you are putting some choke on you are increasing vacuum in the carby, which will draw more fuel through the jets, like a bigger main will alow.

the pilot is probably ok.

i'm sure you've tried it with the clip at the bottem, needle as high as it will go and taken the air/fuel screw in and out, thats where i would start before getting another main.
i wouldnt expect much though as the air/fuel screws effectiveness lessense at higher throttle openings.

oh and if you take the bottom off the carby the main jet may have it's size stamped into it, and i'd just try one a few (2?) sizes bigger, if you cant get another jet maybe you can find someone with jet drill's and just try a little the next size drill than what will fit in the jet.

 

[daniel40]

thats what i was trying to say before your main jet isn't the correct size china dont put the correct one in from the factory, for example people with the fake mikuni 25mm carby's put a 102.5 in when they come stock with a 95 to fix the problem, you may have to do something like this.

 

[Ryley]

it sounds like jetting issue to me,
and the issue sounds like a main jet that is to small, as when you are putting some choke on you are increasing vacuum in the carby, which will draw more fuel through the jets, like a bigger main will alow.

the pilot is probably ok.

i'm sure you've tried it with the clip at the bottem, needle as high as it will go and taken the air/fuel screw in and out, thats where i would start before getting another main.
i wouldnt expect much though as the air/fuel screws effectiveness lessense at higher throttle openings.

oh and if you take the bottom off the carby the main jet may have it's size stamped into it, and i'd just try one a few (2?) sizes bigger, if you cant get another jet maybe you can find someone with jet drill's and just try a little the next size drill than what will fit in the jet.

OK, I can see this getting ugly for me...Where can I get jets for a Sheng Wey Carby?? Most people haven't heard of them, so I'm assuming getting jets is gonna be a nightmare.

 

[KTMKID]

Buy a new carby.... Its a quick fix and it'd probably work out cheaper in the long run

 

[Bones]

hay mate. before you try all of this it sounds like a air/fuel mixture problem as the others have suggested, wrong size jets etc etc... its all in turn related to your fuel intake / air intake into the motor. personally i would say your oxygen to fuel ratio it out with a mix of bad jets could cause some serious problems like this....

my friend had a old school z50 which was having the same problems, to identify the issue what we did was get some thin cloth and suffocate your air filter. (if you have a airbox, take it off and put material directly over your air intake) if you have an air filter simply cover the air filter with more and more material till your about 10 sheets thick, (check how it runs between layer) this will show you if your air/fuel mixture's are dicky by controlling the amount of air which mixes with the fuel.... also when you do this adjust the idle point so then you can travel from idle to WOT and see the differences it makes....

before anyone judges this method let me say this, its a cheap effective way to check your mixtures, jets, intake etc etc.... and rather simple for those that arent so "tech head" minded about it all... and it worked perfectly for me on more than one occasion so it should work for you too..

good luck mate, let us know how you go

Cheers, Tony.

 

[Ryley]

OK all, thanks for your help, the problem is fixed...
Under a closer inspection (with me glasses on) I found a ever so slight blockage in the main jet...geez, doesn't take much does it?
But anyway, it purrs like a kitten, and the little fella is too scared to ride it now coz dad popped a wheelie on it...bugger.

 

[Ryley]

hay mate. before you try all of this it sounds like a air/fuel mixture problem as the others have suggested, wrong size jets etc etc... its all in turn related to your fuel intake / air intake into the motor. personally i would say your oxygen to fuel ratio it out with a mix of bad jets could cause some serious problems like this....

my friend had a old school z50 which was having the same problems, to identify the issue what we did was get some thin cloth and suffocate your air filter. (if you have a airbox, take it off and put material directly over your air intake) if you have an air filter simply cover the air filter with more and more material till your about 10 sheets thick, (check how it runs between layer) this will show you if your air/fuel mixture's are dicky by controlling the amount of air which mixes with the fuel.... also when you do this adjust the idle point so then you can travel from idle to WOT and see the differences it makes....

before anyone judges this method let me say this, its a cheap effective way to check your mixtures, jets, intake etc etc.... and rather simple for those that arent so "tech head" minded about it all... and it worked perfectly for me on more than one occasion so it should work for you too..

good luck mate, let us know how you go

Cheers, Tony.

You are dead right Tony, I did the cover the pod filter bit with various layers of cheese cloth, to prove a point, but as it pretty much does the same as running with the choke on, it was just to see how the plug looked after a run (as the choke winds itself off when the motor is running)

BUT, you are very right, as stupid as it seems to most, trial like that are a no cost test, and better than spending money to find it didn't fix it. Cheers for your help mate..

 

[Bones]

your welcome mate.. thats spot on to... its a cost effective way to identify or at least cut down your possibilities of what could potentially be causing the problem. its better than spending money on basically what is only speculation and 'guess work'.

glad to hear you got the issue sorted and your lad is happy again

Tony.