carby issues

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Kingers

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Location
Seville, Vic
ok well i think this is a carby related problem but im not 100% sure, basically when idiling the bike will just cut out with out warning it gives a cough then just dies, i have put the idel speed up a touch but still happens. Even when crusing around with the clutch out in 1st and 2nd it'll do the same, it also cuts out if a gear is selected and with the clutch held in all the way, only sometimes though, it seems to rev up all right it only has trouble at low revs. its also a bit of a pain to get started too.

I have adjusted my valvels to 003 and 004, also grinded out the intake pipe a bit to get rid out the crappy casting.

Have checked to see if fuel runs into carby and the flows good, cleanded the carby out, the is a good spark, but the spark plug is a touch black, and the clip on the carby needle is set to the bottom slot (the needle sits as hig as it can go) This was from factory.

have also had a bit of play with the air fuel screw but to no help, went full turns in both directions

any help appreciated, i have also had a bit of a search but still not to sure wat i should try
 
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update went out and raised the clip by 1 on the needle and couldnt start it so i put it back down and it started, also once started i raise the revs a bit by tightening the throttle cables and after about 30 secs or going it cuts out for no reason. is it starving of fuel and i need to do something with the floats in the carby?
 
have you checked all the wiring make sure no loose connections, that and the float level like you said is all i can think of. kinda sounds like its running off the fuel in the carby bowl when that runs dry it stops?????? maybe.
 
Maybe electrical and created by random vibrations. eg. Rust or loose fastener preventing proper earthing of the coil mount or the earth wire. Or maybe some loose wire connectors or spark plug cap. Maybe a dud coil/plug lead. Or just a dud spark plug. Slim chance it could also be a dud coil or CDI. If the problem really ***** you, it's not expensive to replace the plug+coil+CDI.

If it once ran fine with your current jetting, then don't change the jetting.

Next time your carb slide is out, check for excess slop and wear. Good idea to Inox oil the slide once in a blue moon.
 
ok well went for a ride over the weekend the bike did ok when its was going, lol. Its a pain in the arse to start and once started the revs need to be keep up other wise it will cut out. it seems to run fine all the way through the rev range.

i did check the spark and it did seem to be fine but i gota clean the bike 2moro so i'll go over the electrics and redo all the grounds and make em good.

does anyone know of somewhere that would be able to check the valve clearance and tune my carby for me? i did do the valvesw myself but i dont know how much friction should be on the feeler gauge though. Asked city motor bikes and they said 80 but i didnt want to pay that muchunder 50 would be good. I live in Seville, but will travel tolilydales, ringwood, ferntree gully, bayswater area (somewhere around those places would be good) in vic
 
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To check your valve clearances ... Remove the two valve covers and clutch cover ... Slowly rotate the flywheel counter clockwise and watch the inlet rocker (top one) go down then come back up ... Now slowly bring the "T" mark on the flywheel to line up with the index mark on the LHS centre case ... Both rockers should be on the base circle of the cam and that's where the clearances need to be adjusted at ... While holding the flywheel in that position see if you can feel or hear slight side to side movement in each rocker ... IF the clearances are OK you will feel some play ... IF not ... then readjust them until you do feel slight play ...

It definitely sounds like the inlet valve is not seating or sealing which causes a compression leak and blow back to the carb ... making for hard starting , hiccing and stalling at low revs ... then it comes good as the revs increase since there's less time for the compression pressure to escape ...

If a valve is bent it'll still leak even with the clearances set right ...
 
Ah changed your mind on the valve clearance situation :) Certainly worth getting them right. It's not too hard to do yourself. On the inlet for example, if the 003 fits, but the 004 does not, then that's good enough. Sometimes its a bit fiddly to get the feeler gauge in there. Be really careful to lock down the 9mm nut without the adjuster bolt moving its position, or else you end up with tight valves - again by accident. Just make sure the required feeler still fits under each rocker. Also if you've ridden around for too many hrs with tight valves, then you might have damaged your valve seats.

You checked your idle speed (not the air screw) on the carb??
 
ok thanks for the help guys checked the valves and the clearance seems to be set all good, so is there any easy way to check if the valve is bent or not seating properly? or is this gonna mean i have to take the head off? if so how big of a job is it to do and is it fairly easy?

Yeah i checked the idle screw on the carb, its set to idle pretty quick so it doesnt cut out, lol
thanks
 
The only way to test it with the head on is to screw an air fitting into the plug hole and pump the cylinder up while both valves are closed ... It's called a leak down test ... You watch a gauge on the pump to see how fast the cylinder loses pressure ...

Another good indicator will be lower than normal compression resistance on the kick starter lever ...
 
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hmm thinking about it there is still a fair whack of compression on the compression stroke when the bike is kicked around slowly, once the compression stoke is reaceched, its gota be given a bit of a boot to get it around, also is it normal on these bikes to sometimes have no compression when kicking it over? sometimes i can kick the kick starter around 6 times or so and have nothing stopping me, is there a decompression thing built into it or something
 
If it's a 120 or up it'll have a decompressor mech but what you're saying doesn't sound right ...
 
lol. it could be the way im explainin it i've never been good at explainin things, lol. its a 140
 
yay i finally fixed it, stupid f***ing intake manifold gasket, lol.

So the "ticking" sound was from airflow thru a loose or broken gasket?

About the 6 turns before feeling compression: That's EXACTLY why I dislike the stock anti-kick-back mechanism. It's not reliable. That POS mechanism had a lot to do with my case being cracked in my 140. A basic two lobe cam is reliable in terms of always finding TDC.

In any case, seriously consider an Akunar A1 cam - for much better low and mid rev torque. Assuming good jetting, carb, and airfilter, then I am talking night and day difference with the cam change. Approx prices: Cam is $55. Valve springs were about $20. New valves about $30. Postage about $20.

Easy to self install. Good fun in my opinion. See this post: http://www.miniriders.com.au/forum/tech-talk/18239-need-help.html#post172896
 

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