mikuni carb

Re: mikuni carb

Bruno,
is that right that the idle screw is turned in to richen the mixture???

Fatboy
 
Re: mikuni carb

FatBoy said:
Bruno,
is that right that the idle screw is turned in to richen the mixture???

Fatboy
Click to expand...

no turn the mixture screw, the idle is the throttle stop
 
Re: mikuni carb

Umm, yeah sorry guys,:eek: i meant the pilot air screw, not the idle adjuster! :eek: :eek:
 
Re: mikuni carb

Thats me being dumb as well saying the idle screw, but is it right that the mixture screw is turned in to richen & out to weaken the mixture???

FatBoy
 
Re: mikuni carb

FatBoy said:
Thats me being dumb as well saying the idle screw, but is it right that the mixture screw is turned in to richen & out to weaken the mixture???

FatBoy
Click to expand...
Yes thats correct, it`s actually an air screw, so when you turn it in it lessens the air flow, thereby enriching the fuel mixture.
 
Re: mikuni carb

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BrunoKatz WW1FighterPilot said:
Hellon, as Simon says [No he`s not simple] don`t turn your RPM down lower that 1000 cos you will sod up your oil pump if you let it do a Shovelhead tickover. If you`re popping on the over run, could mean you`re running lean on the pilot jet. Try re-settting it, remember, on a mikuni you turn the idle screw in to richen it up. What colour are your plugs by the way?
Click to expand...

Hi I have finally got round to having a look at the plugs:

This is from the rear cylinder (lightened slightly by photo editor as it was underexposed):
attachment.php


This is front:
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(sorry i haven't quite got the hang of adding photos in here yet!)

I have been noting my overun, and I dont think it just backfires all by itself, but sometimes i blip the throttle before changing down and maybe once in three or four it causes a detonation somewhere, can't tell where though. Im beginning to think the Evo doesnt like throttle blipping, the stealership made of point of saying "roll the throttle on, this isnt a sports bike".
 
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Re: mikuni carb

frankly they all do that some worse than others but its diffcult to completly eliminate it
although it depends how bad it is.

if its in the pipes popping then its unburnt fuel,
required to cool and lubricate the upper cylinder, when the slide closes you are still on the idle circuit and this is controled by the mixture screw
if its spitting back through the carb this is due to it being too lean
 
Re: mikuni carb

I thought I was running too rich as there was quite a bit of carbon build up on the plates of my Supertrapp pipes, but looking at my plugs, all looks good; I will be leaving it as is (HSR 42 with factory settings) although I have some leaner jets just in case.......running sweat......;)
 
Re: mikuni carb

S.T.Chapman said:
if its spitting back through the carb this is due to it being too lean
Click to expand...

That is why i took the plugs out, I am by no means an expert on this stuff, :confused: do they look like the engine is running lean? look a bit sooty to me.
 
Re: mikuni carb

thats not how you do a plug chop

with a hot engine run at the rpm you want to look at then kill it and pull the clutch then look at your plugs.

your just looking at it at idle.
best way to set idle mixture/primary air
again hot engine, reduce tickover to lower than normal, turn air adjustment screw till you achieve fastest idle,
again reduce idle and repeat.
then turn screw other way till it starts to stutter, note positions and aim halfway between the two.
reset idle to 1000rpm.
 
Re: mikuni carb

oh just as a precautionary note
when performing a plug chop its allways better from a safety angle to stop and get off the bike first.
 
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