Mikuni RS34 carbs

A good sync with Morgan Carbtune Pro was done shortly after assembly, and was great for several rides (400+ miles over several days) before Winter storage.
Most of those miles were ridden in mid 30-low 40 temps, so the engine was cold (cold) when first started each day. Not to say that has much to do with anything, because the starting routine didn't change much from before, when temps were better for tee-shirts and short-sleeves.

What follows is a pretty good description of my usual start-up ritual, which I've assumed until now to be typical for others with Mikuni RS carbs as well. Keep in-mind my bike has electric start, so there is no kicking involved.

With the choke plunger pulled out fully, the engine immediately starts and fumbles around for a few seconds until I close it about half way. At that position the engine revs like I think it should with the plunger pulled all the way out.
But it only likes that position for 15-20 seconds, and then needs to be closed all the way to stay running or it dies...
At that point with the engine idle 700+/- rpm, I then have to reach under the tank and adjust the idle screw slightly to bring the rpm up to 1000 where it seems to settle in and be happy. But after riding a mile or two, I then need to stop, (dismount) and reach under the tank again to adjust the rpm back down from 1400-1500.

After all that we're golden until the next cold start.

:S

That's normal behavior. I don't adjust the idle when cold I just use the throttle to keep the rpm's up until warm which is usually a minute or two then the idle is normal.

+1

Thanks, I am happy to hear that.

Actually, I'm ecstatic!!!

:woohoo:

You have to remember the carbs were dialed in with a warm engine. So when cold the A/F mixture is off until the engine warms up usually just a few minutes. All my carbed bikes and trucks do this . My KZ650 with OEM VM24 carbs do this also. I start the bike with choke after about 10 seconds choke goes off then it runs like shit for a few minutes until warm then runs perfect. These do not behave like FI which run perfect at any temp.

You had it dialed in when it was burning oil. Things have changed. I'll have to go through that when I install the new head and new rings.
Steve

Makes sense the engine would need a richer mix after installing new pistons and rings. One step with the Pilot Jets did it for the cooler weather, and no other changes were needed. I expect that will change in the Spring as things heat up.
Sure am glad I got the piston kit installed, and had a few good rides before the season ended.



I'm working on a method to make idle adjustment on RS carbs while sitting comfortably on the seat, and hope to have it fully-functional by Spring.

daveo wrote: I'm working on a method to make idle adjustment on RS carbs while sitting comfortably on the seat, and hope to have it fully-functional by Spring.

Have a functioning prototype, but must wait until Spring to test it out.

OK ya got me. MORE PICS :woohoo:
Steve

Well, OK...

Finally grew tired enough of reaching halfway under the gas tank for idle adjustments, and decided my flabby problem solving muscle was due for a long overdue workout.

Any feedback on this idea is welcome and appreciated in advance.

Did you make the parts?

SWest wrote: Did you make the parts?

It is a conglomeration of parts from several sources, except the support bracket which was fabricated from aluminum angle.

Installation is simple. The original idle adjustment screw is replaced with a new one, then the drive belt is fed around both pulleys as the bracket is positioned and snugly bolted down with the cap screw. Then simply start the engine and set idle.