Anybody Running Mikuni Flatslide Carbs?

[dwyatt]

Looking to compare notes with others running Mikuni TM (flatslide) carbs. They offer some nice performance gains, but not many run them, so tuning information is difficult to come by.

 

[gruff54]

Grizld1 over at http://xs650temp.proboards.com is sorting out a set.

gruff

 

[grizld1]

No, sorry guys, mine are TM36/68 radial smoothbore pumpers--dedicated 4-stroke carbs. For some reason Mikuni hung the TM label on RS type carbs when they configured them for singles. I reconfigured for 2-cylinder use by having a machine shop tap the throttle shafts for 7X1.0 mm. studs (gotta be real straight to avoid excessive runout and resulting throttle shaft bind) and joining them with a coupling nut, lock nuts, and set screws through the nuts into the studs and through the shafts into the studs. A single bell crank hangs outboard on the left with a single AP actuator outboard on the right. I drilled and tapped into the AP chambers at the bottoms of the float bowls for 5 mm. barbs and fuel line to run a single AP (RS carbs feed a bank of 4 from a single pump). Anyhoo, the radial smoothbores are very different critters, and my baseline won't help at all on the cable-pull TM's. Jack has used TM34's for years; shoot him a PM if he doesn't jump in here.

 

[grizld1]

BTW, Dwyatt, your dyno runs show peak power at about the 70 hp limit the cases will hold in long-run racing events (i.e. road race, flat track, etc., as opposed top 1/4 mile blasts down the drag strip). Don't worry, be happy--congrats on a great job!

 

[dwyatt]

Thanks, those numbers aren't from my bike, pulled them from some info from Craig. My set-up is very similar, but running 700cc, which will drop the power a bit. In either case, I don't expect I'll be pushing that thing to redline often, tends to soil my leathers.......

I'll hook-up with Jack on settings. I got a decent baseline, but it isn't running very smooth at the bottom and those carbs are a pain in the arse to work on compared to the VM's.

ps Grizld, never mind on the PM I sent on the Garage site, you answered my question here.

 

[grizld1]

Too late, Dwyatt--already answered your PM but with a bit more detail, and it's probably stuff you already know. I wasn't sure whether you meant issues with lower throttle positions or issues in the lower rpm range, and was still under the impression that those were your dyno results (I should have recognized Craig's tables--that's what happens when ya get old). Anyway, Jack's an old hand with the flatslides and should have plenty of tips for you, particularly on NJ and needle selection.