1980 project mikuni rs 34 tuning

Hello everyone ,  I have started to tune the bike I built some time ago. Motor is an 1197 , Head processed by the Late Larry C. , Head is as follows Stage 1  CRH Ported KZ head with 37/30 Stainless Steel Valves,  K410 Cam , Mikuni rs 34 with pod filters . When I started to adjust the carbs some time ago  I suspected the engine was running lean indicated by reading plugs so changed to the richest needle which got me closer. Last month I installed a wideband to verify and according to the wide band I was in a range of 14 to 14.5 afr heavy cruising speed  and plugs are still on the lean side as well as throttle response . Now I have Changed the  Needle jet to the next richer size and still has the richer needle (clip second grove from top ) plug color and throttle response and heavy cruise much better (wide band 13.2 to 13.5 . )  Its a hot summer were I live and I ride pretty aggressive so I'd like to stay on the richer side . pilot 20 with 135 main. The  Idle lumpy when rpm set at 1500 or below  and will clean up at 2000 . I have adjusted the mixture screw in between the 1/4 position  and the  1/2 position  with afr reading 12.8 to 13.0 . , Question  Are these carbs able to smoothly Idle at  lower rpm 1200 to 1500 ?  Maybe with stock Cams ?  I might fiddle with the air jets to see If I get any Improvement but my gut tells me with the 410 cams and head work idle is going to be  around 1900 to 2000 rpm for a smoother idle . Any thoughts would be appreciated, Thanks

If the needle clips are near the top (not the pointy end) then the mixture will be lean because that lets the needle drop further into the jet. Putting the clips closer to the pointy end will make the mixture richer. If Larry ported the head for those cams and carbs, then I think you should be able to get a smooth idle below 1500.

I have no clue regarding what you can expect for idle with a built engine like yours, but I do know that you have one wicked-cool looking machine there! 

For sure.

The "perfect "stoichiometric ratio" for a gas engine is 14.7:1 however most modern motors will run between 14.1 - 14.7 dependent on fuel quality. What you need to keep in mind is that to achieve this engine management ECU's are constantly measuring a range of pressure and temperature information and making continuous adjustments to the fuelling and ignition curve, also "water cooled" motors can safely run higher combustion temperatures. On an "air cooled" carburettor fuelled motor 12:1 - 13.5:1 is probably the best you can do safely.
IMHO with the engine work you have done without EFI and a full management package, a lumpy idle is something you will need to live with. Dialling the idle up to 2k to smooth it out will make the motor run very hot when stationary 
If you can get access to an exhaust gas analyser this will help with getting the idle right, CO should be around 4.0% and HC around 0.12% (1200ppm) If the HC is significantly higher when the CO is correct it would suggest an air leak which would also effect the idle. What ignition are you running (backing off the static timing a little may also help the idle)

Brother, your bike is stunning. Absolutely beautiful.   We don't hear/or see the Moriwaki name much over here, but it looks great on your "monster".

I'm looking for some dual flange air filters similar to yours and I'm not able to locate much info. Can you help me out? A vendor, or part number? Thank you Sir. 

My engine could be similar enough that the carbs as currently set up may help somehow.

KZ1100A2 with MTC-G1135-3 piston kit.  84' 1100 LTD bathtub head/stage 1 porting, ZX1100A cams (.375" lift).

RS34 has 130 mains, 35 pilots, and 1.1 +/- air jets with fuel screws 1/4 +/- turn out. Has the factory needle/jet w/clips in 3rd. slot.  Compression readings 165 psi. x 4
Accellerator pump set to operate from 1/2-3/4 throttle, with size 35 (TM36/43-A) leanest nozzles.  VM17/1002/60 leaner starter jets.

Dynatek 2000 ignition timing set to 38 degrees BTDC

Runs on regular E10 pump gasoline

What does yours idle at Dave?

Brief start up video:

photos.app.goo.gl/AQq3V6Bzv6m4CK9EA

Tach will hold 1000 rpms rock-steady at full operating temperature.



Denso 24ES-U plugs pulled this evening.  #1 looks a touch rich...will change that air jet from 1.0 to 1.1

Lumpy idle... Do you know where those cams are timed?

If set at 108/110 LC then yes they will be a bit lumpy, but not like a drag bike. Those are pretty tame cams, 266 duration. If you want it to idle like a stock 1100 set the cams a bit lower (106/107) and back off the ignition timing at idle.

Did you use ColorTune or AFR gauge to set the pilot size and fuel screw settings? (must be done on a hot engine)

Try to set the idle about 1500 max, lower is better. Carbs are a bit small for application, RS36 would have been better especially in hot humid weather.

Not sure why the lumpy idle is a issue, they are known for that feature when "worked" on.

 

Man, simply put: S E N S A T I O N A L ! ! !

I would, six ways to Sunday, rather have that "work of art", than ANY 21'st century motorcycle!

H.

You did not mention if the carbs have been vacuum syned or not, that could also cause lumpy rough idle that cleans up at higher revs.