Mikuni RS 36 setup items for 120 motor

[Paul LeClair]

Hi all

I am fiddling with the RS 36's from the RGS, trying to lean them out and still run well.

float height - no issues setting the height correctly and the same for all three, but, has anyone thought about what setting the float limiter tab should be set for? The float height tab obviously adjusts the height at which the float valves start to close. But, the other tiny little tab sets how far the floats are allowed to drop. Presently I have themm set so the floats can not drop all the way to the bottom of the bowl if the bowl empties, as I don't want the float needle valve to be able to come out so far that they could jam, but is there a specific setting recomended?

accelerator pump setting - at what perecentage of throttle opening is the beginning of accelerator pump actuation recomended to be set for? I have tried everything from just off idle to half throttle - the pump gives a pretty big shot of raw fuel - at the moment I have set it back to coming in at about half throttle

needle for a 120 - there are two basic needles available for the RS 36's, and I have tried both. The richer of the two needles seems too rich no matter what notch I set the clip on. The leaner of the two needles is still too rich my my RGS "1200" motor with the clip at the third notch, and I am about to try it witht eh clip at second notch from the top.

Who else out there is running RS 36's on a 120 motor? What settings are you using?

igntion timing - WITT on a 120 with high comp pistons - what curves are in regular use? I am back to the basic setting 2 which is most like the original Laverda setup, goes to a full advance of 32 degrees BTDC at around 2,750 or so, that's it. With todays fuels I am wondering if even 32 degrees may be too much advance and I am thinking about retarding the ignition back 3 or 4 degrees to maybe 29 or 28 degrees - thoughts, recomendations?

Paul LeClair

 

[laverdakeith]

Hi Paul. Ignition first, try curve 10 timed at 32 degrees at full advance (6000 rpm) you may well find the motor is then a lot more responsive to your carburation adjustments. I am running 9DZ5-50 needles on the middle notch and P4 needle jets (981 cc) Never fiddled with the float stops but I'm very carefull setting levels. Accelerator pump chimes in just before quarter throttle.
  Not sure how you are assesing your running conditions, I have recently started using a wide band air/fuel ratio meter connected to a probe in the collector, it is the bollocks... instant response to engine load and far far superior to the narrow band unit I had been using previously, look for around 13 - 13.5 on a steady throttle and 11-12 under hard acceleration, do not be tempted to run any leaner, they start to get hot and grumpy.


    Keith.

 

[Paul LeClair]

thanks, Keith

I am cringing a bit about setting timing at 6,000 rpm, but I wll get a couple of big fans out to blow on the front of the motor and give it a go at curve 10.

for the Laverda, I have become less than enthused about using the wide band sniffer at the dyno, I am going to have to spend the money for an LM2 wideband or similar and weld a bung into the collector of the RGS. Dialing in the carbs is a lot tougher than dialing in fuel injection.

on my ZX 14 I welded in a bung to the stainless steel collector just in front of the catalytic convertor in the header, and disabled the air injection into the exhaust, so I can get real world information under different street and track conditions. Amazing how much difference the ram air sytem into the air box makes. Anyway, on the ZX 14 I am running a Power Commander 5 with the AutoTuner module reading from the heated Bosch wide band sniffer, and I build my tuning map from a base map on which I have targeted between 13.0 and 13.4 depending on where in the rpm range and throttle opening the fuel injection is dealing with. Interestingly, the stock fuel injection map is really rich in the upper rpm/wide open throttle range, presumably to keep the motor from melting if some squid yanks out the air box and adds a four into 1 without dealing with the fuel injection, but dialing back the actual measured mixture near and at top end to around 13.0 adds almost twenty rear wheel horsepower on the dyno, really amazing.

so, on the RGS, I have been seeing soot on the plugs and in the heads exhaust ports, as well as in both tail pipes, while the dyno sniffer tells me my mixure settings are about spot on while the bike runs on the dyno... I think these DynoJet 250i dynos are a thing of the past, folks just haven't realized it yet, real time info from a wide band sensor, and something like an autotuner to build fueling maps, are a MUCH better way to go.

The 9DZ5-50's needles are the richer of the two choices, the RGS "1200" motor running those needles and P4 needle jets was stinky rich, I live at about 3,200 feet above sea level which may be relevant, my bike gets run between say 3,200 feet and 7,000 feet regularly, with occasional forays into the 10,000+ feet elevations. I am now running the leaner needle(still with P4's) which I just moved from middle notch to second from the top, but haven't got the bike back together yet to test ride, I am waiting on some bits from Wolfgang in the next day or so... The other variables include the 36 mm intake tracts, the near 40 mm exhaust ports, and the full larger diameter exhaust system supplied by Wolfgang, all of which I expected to make the bike run leaner as it should be flowing more air. I just checked valve clearances again, everything is spot on, between 0.13 and 0.16 on the intakes, between 0.25 and 0.30 on the exhausts, carb manifolds don't leak air, the carbs will be synchronized yet again on the vaccum sticks, and I will use the timing light on the igntion once I get teh bike up and running again. I was pleased to see that the ceramic coatin in the exhausts ports is holding up well, as is all the low friction coating on the cams/cam blocks/cam gears etc.

Paul LeClair