Front nearside carb only works when engine warms up !

[wirral_biker]

Sorry if mentioned before ( have you tried searching 20 years of carburettor posts ) but my front nearside carb is hesitant to fire up with the other five ( exhaust stays cold etc ) until engine warms up and then spits and farts a little before running well.  Plug is the correct colour and no oil residue etc.
Took carb top off in situ and sprayed a healthy quantity into the carb body and also drained the float bowl.
Seems better.  Only stopped ( got it all back together obviously ) due to poor light and managing to spray myself in the eye with carb cleaner 
Bike has only 3,500 miles on her and has done this since I acquired her late summer.
Is this a common problem or just a case to persevere  and maybe drain carb bowl and reverse fill with carb cleaner?    Have been running her with RED X each time to try to clear the carb.   Carbs don't look touched.
Cheers

[John Schmidt]

OK....front nearside? Both front carbs are about the same distance so which one are you referring to...the left front or right front; i.e., left side is 2, 4, 6 front to back. Right side is 1, 3, 5 front to back.

[wirral_biker]

Front left ( sorry we use 'nearside' over here in Blighty ! )

Just tried it again but same; missing until engine warms up then seems fine !

HT front lead on right side has been replaced already...wondering if it could be another faulty
HT lead.

Just strange that it starts to run sweetly after about 2 minutes ?

[Ricky-D]

I think a compression test is in order while the engine is cold, as you say.

***

[John Schmidt]

I think a compression test is in order while the engine is cold, as you say.

***

+1 

[wirral_biker]

It is just a tad slow to pick up, then runs fine.

I'll try to clean the carb again and then fit a temporary HT lead to see it that cures it.  Thanks  :-)

[CajunRider]

A few ideas from someone who definitely is NOT a carb guru... but I've opened and cleaned a few. 
No particular order... but these are cheap things to try that won't take hours of work. 

Run a tank of SeaFoam (or your favorite carb cleaner) mixed gas through it.  It MAY just be a partially clogged pilot or something of that nature.  make sure it sit overnight at least ONCE with the cleaner in there.

If that don't help, try giving the pilots a 1/2 turn open (or close) when you first crank up (on the carb in question).  Just don't lose track of current setting, so you can get back to where you are now if adjusting doesn't help.  Allow a few seconds between adjustments to let the engine "catch up".

Replace the spark plug on that cylinder (I've seen them do some WEIRD stuff, even when new).  Or, swap that plug with the known good one on the opposite side.

All that fails... spend some time with them to give them a GOOD cleaning then check the vacuum balance. 

[wirral_biker]

Thanks, just ordered some SeaFoam ( have been using RED-X for about 500 miles  without success) so we'll see how that goes.  Bike is on SORN ( i.e. off road ) at the moment.

Drained the float bowl today and injected carb cleaner directly into the float bowl.   Great spark and I actually changed the plugs over yesterday.  So electrics all OK.

Mixture screw looks really awkward to get to??   I'll try adjusting it over the next day or so.  ( Awful/cold weather here at the moment ).

After about a minute the engine warms up and the spitting and missing starts to disappear.

Thanks for the advice as I really don't want to take the carbs off.

[sixlow]

It is possible that your #2 carb is leaking the gas out slowly and you need new float needles, you may be in danger of hydrolock. Since that carb is at the end of the line for fuel delivery it may take a few minutes to get filled up and start running like the others. maybe a bowel drain test after it has been sitting for a day or 2 to see if it holds as much fuel as #6 might be an easy diagnosis.

http://www.amazon.com/gp/product/B001KOD732?psc=1&redirect=true&ref_=oh_aui_search_detailpage.

[wirral_biker]

OK..... little update.   Took out pilot screw out and flushed up with carb cleaner ( just a 'make sure' thing really ).   Jet was set at 2 1/4 turns out.     I have turned the jet in to 1 3/4 ( just a tad more ) as mine is a 1997 model and she seems to be running OK.  Having said that the engine is already warm so I will know tomorrow if enriching the carb works.
Fingers crossed.

[WintrSol]

OK..... little update.   Took out pilot screw out and flushed up with carb cleaner ( just a 'make sure' thing really ).   Jet was set at 2 1/4 turns out.     I have turned the jet in to 1 3/4 ( just a tad more ) as mine is a 1997 model and she seems to be running OK.  Having said that the engine is already warm so I will know tomorrow if enriching the carb works.
Fingers crossed.

Turning the pilot screw in (CW) will lean it out at idle. It doesn't set the balance between fuel and air flow in the pilot circuit, but the total volume of pre-mixed fuel and air to add to the air coming past the throttle (which contains almost no fuel); turning it CW reduces that volume.

[wirral_biker]

Edited:- 
Update today 16th December.....Just started up from cold and  old problem remains, she runs but still pops and spits on full choke....when reducing choke the engine settles down nicely.
I thought turning in the pilot screw would enrich the low running?

Manual says for my  May 1997 year only,  pilot screw is :-  1 3/4 turns out and as mentioned above, the 'faulty' one was 2 1/4 turns out.   Probably adjust all the other five to 1 3/4 turns out, at least I'll know that is correct !
All plugs are correct DPR7EA-9 with a good spark.

I think I'll remove the silencer on this side and fit new seals, just in case there is a slight air intake at the head until she warms up and expands etc.

Still raining.........

[wirral_biker]

OK..... removed and re-fitted silencer with three new exhaust gaskets.     Also yesterday I checked carbs 4 & 6  and they were set at 2 turns out.   So I have all three left hand carburettors on 2 turns out now.
Lot's better and only pops/spits quietly on full choke; moment choke is eased in halfway etc then all is well   
Cannot test ride her because she isn't road licensed ( SORN in our country )  so for a comparison I
am going to check the right hand side carbs to see what setting they are at.  I'm only wondering what the front right side number 1  is set at ( i.e. a little further out as per the left - number 2 carbs setting of 2 1/4 before all this started ).
Hope this is making sense.
Awaiting the seafoam which cannot do any harm over winter .