DHZ 30mm mikuini carb tuning...??

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t.luisetto

t.luisetto

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hey all I recieved my new 30mm carb from DHZ's ebay store...

I bolted it on to the existing minifold and kicked it...

It sounded like a small harley and whenever i went to turn the throttle it would go to die...

So i pulled it apart and changed the needle position from at the bottom to the middle and i went thru all the slot on the pin to test it...

best response being in the middle... but it revved its tits off!!

How would i tune the carb to be just right, its on a 125cc engine.

and shold i ues the manifole that was supplied or is the old one good enough...???

HELP!!
 

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if it's a 30mm mikuni roundslide from DHZ ebay store, it will actually be a 26mm throat. I have two of these, one on a Ducar 125, the other on a genuine thumpy hunge ten... both worked great straight out of the box, although one suffered similar problems to what you experienced... dies in the arse as soon as you touch the throttle... easiest way to get around is to put the needle on the lowest clip, and if need be, put a small washer under the needle clip to richen it up a bit... if it's dying when you open the throttle, its starving of fuel.... Oddly enough, try the original inlet manifold... some of them do have different throat angles, and some mount the carby higher than others... for those who think this makes no difference, take a look at tunnel rams on cars... the higher the carby is mounted, with a longer vertical downdraught, the power will be spread higher in the rev range.. the lower the carby sits to the motor, the lower the power spread... ie: high carby, power up top, doughy down low, low carby, power down low, flat up top.. unfortunately, these are small motors, and can be touchy to adjustments to the air screw.... (bottom of the carby, bitch to get to... try one and a half turns out from screwed all the way in as a starting point and go from there...)
 
^^^^^^ .... Spot on info .... ^^^^^^^

Here's a pic of a horizontal engine showing the absolute best intake flow path for maximum power .....

Superhorizontalmotor.jpg


A bent manifold makes the engine take longer to rev out in gear and definitely runs out of breath up top ..... Pit bikes have a pitiful intake flow path .... the air basically has to do a complete "U" turn into the cylinder .......

Here's a link on carb tuning ...

Motorcycle Carburetor Theory 101

As to the high revving at idle ... make sure the slide has been put back into the carb in the right position ..... A pin sticking out of the inside of the slide bore has to go into the full length groove up the side of the slide ... if it's not lined up right , the slide will be held at partial throttle .......

You can also buy an easy adjust mixture screw to make tuning the "25" and "30" mm Mikunis less of a PITA ...

https://s.p6.hostingprod.com/@www.s...2_91&products_id=265&osCsid=f965790224a2a3b65
 
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hmmm...I want one of these heads on my Lifan...hahahaha...and the carb too!!
 
seems like an injection throttle body.. what kind / brand engine is it..?

I' m looking to put an injection system on my minimotard and this could be a good start..
 
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