Monthly mikuni carby thread

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Found the rubber that's on the choke pin isn't secured over the hole correctly. Il lightly super glue that so it stays down.

Sort the lid where the cable goes in - to seal it propely.

Rub down the surfaces with emery paper and reseal.

Then I think it will actually be readable ... As it is at the minute it's random ... Sucking in unregulated air would do this !!

I'm going to stick with the 100 main jet, 20 pilot for now.

Thanks guys
 
There's also a hole at the side. Just about the petrol feed ... It comes off the carb horizontally and when I remove the carb I turn it on it's side to drain the fuel ....

I take it this should be always open?

Should I use 95 petrol instead of super , v power, ultimate wtc
 
lots of questions...

the carby should definately be set up with the choke off,
with the choke lever so it's making the plunger sit down into the carby.
all rubbers should make a decent seal, the throttle cable/carby rubber, the choke plunger to carby body etc
the breather vents should be open, allowing fuel to spill out if the bike is dropped etc.



the correct sized (26mm) plastic insulator with o'ring and gasket, can be bought off ebay for around $6-$8 delivered
or the one you match ported may still be able to be used, make up some paper gaskets using some 1.6mm thick gasket paper, one for each side of the insulator (incase the insulators' rubber o'ring is leaking)

i use 95 as a minimum octane, but usually BP 98, if i remember to buy it on the way.
i cant get 98 where i ride.



so clean the carby thoroughly with carby cleaner/throttle body cleaner, blow out all the orifices, passageways, jets, needle and seat etc etc with compressed air.
the fuel bowls sometimes warp on them too, see it you can face it off flat, with some 320 w&d paper on a hard block.

put the carby back together.
then set the carby fuel mix screw to 1.5 - 2 turns out.
set the idle speed screw so it opens the slide about 1.5mm above fully closed.
set the needle clip on the middle position.
start the bike and go from there.....

adjust mixture screw with bike warmish, slightly higher than normal idle, until best/smoothest rpm is found.
then drop the idle speed back until you have a decent idle.
then take the bike out and try it, the fuel mix screw may need a slight adjustment to get the best all over performance.
try adjusting the needle clip up and down, to find the best setting.


make sure you have a fuel filter, and a decent foam air filter fitted too.

let us know how you go, good luck
 
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Got all sealed up with some heavy silicone (it's holds up with brake fluid).

Renewed round o rings ... Sanded all surfaces and touch of silcone.

Made new grommets and secured where required.

Made paper gasket (from turbo return gasket paper, so good for taking heat)... For engine / manifold

Jets re cleaned.

Il fit up and see what she does ...

Start with 2 turns on the mixture ?

Thanks for the info on the idle !! Never knew where to start with that one !!

Thanks again !!!!!
 
sounds good,
yeah if you start at 2 turns out, you'll probably need to turn it in a touch when finding the sweet spot.

i didn't realise you had been trying to tune it with the choke on in your earlier posts.
thats probably why things were fluctuating a bit too.
 
Na I wasn't.

Well, I haven't been a proper run (only 1st-2nd round my house) ... but it fires first kick, revs nicely , sounds 100x better !! Used to sound like the choke was always on - crazy loud- horrible idle-

So, stripped the slide and found it heavy pitted where the idle screw would sit ... So I rubbed it as flat as possible.

Sealed the carb at the lid. The choke pin grommet, fuel bowl, @ inlet and head.

Set the idle as described.

Set the mixture to 1.5 turns out.

Set the tappets/valves and found inlet to be tight !! No clearance at all !!! Set to 0.10 and 0.152

Found the fuel filter flow arrow ... Backwards

Filled with 95 Ron premium fuel

Put new ngk plug

Started and purred 100% perfectly !! Although with no choke ... Was about 27/28*c ... This seem ok ? (choke raised idle even more)

Set the clutch as it was creeping forward ... Put a little to much and wouldn't kick ... Adjusted ever so slightly back ... Now kicks , can even do it by hand ? Sound ok ?

Hitting the track tomorrow. Anything need final attention ?!

Il plug chop and adjust needle as required ... Also set pilot screw to revs when I have a hand to hold throttle for me !!

Thanks for the help !! Really appreciate it - especially as it was so up and down and distraught not to have a pattern to work from !!!

Thanks again !!!!
 
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So 100 main. 20 pilot. Middle position on needle and sealed !
 
sounds good,
tight valve clearances wouldnt of helped.

when adjusting the fuel mixture, turn the idle speed screw in to raise the speed
then set the mixture, when you are done, drop the idle speed back down again.
 
Yea man, I'm happy

The clearances right? Ducar 125!

And do I need to raise idle much ? Or can I just do it from where it is now and adjust idle back down when rev's peak

Thanks one more time :)
 
sorry havent been near a computer today.

the bike will normally idle at around 1000 rpm, set mixture at around 1800 rpm
 
Got out today. Ran sweet for few laps. Then sweet for another couple laps.

Then all of a sudden, boggin at 1/4 throttle up to 1/2-3/4.
Tried needle clip in top and bottom. Think it got worse at bottom.

Mate had a spare Carby so swapped it and carried on

Tomorrow il strip down. Check for silicone contamination.
Order new gaskets and spacer, o rings and 97.

Then is still not working, il chuck it and get a new carb. Just not enjoyable it letting me down everytime now

Do you have the 26mm spacer ? You on 20. 97. 2 screws out. 1.5mm off bottom. Middle position?
125cc engine?

The carb I used today, the spacer didn't match to inlet/carb size. And needle middle. Prob 95, 15.

Went ok, didn't pull as hard down low. But good up top.
Will I get much more power using the matched 26mm spacer and next size up jet? over the std with unmatched spacer ?

Going to get a race cdi and coil
 
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And I can't find the $6-8 26mm spacers ! You got a link at all?
 
i can post a link tomorrow,
have you tried dhz link on the left of the page.
 
Only found the full inlet kit, incl manifold

Il have another look
 
Thanks man.

Think on this phone it doesn't show everything all the time on eBay.

I'm going to have to go on the laptop to try and find a fuel bowl o ring.
 
What carb you got? I got access to heaps of 2nd hand carbies.
 
Just looked, I think you got the 26mm mikuni copy?
 
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