Even with a top end of 13.5 (little bit lean), I bet that thing screams from 3.5k to redline..?

 

Back tire really likes to spin on the gravel roads now There's still more to get out of the top end though - feels a bit weak compared to previous set ups (that had an overly rich mid range), but that could just be the mid range being back up to par in comparison.

Might have to start playing with air jets to get it perfect. Maybe back to the P6 needle jet.

I don't mind having it a touch lean right now for fuel economy reason.

 

Logging some good miles commuting on the bike daily. Still happy with the TM, but needs a bit of "fine tuning". Did as much research as I could before I installed it, so my initial setup is still what I'm running today. I'm currently using:

• 130 Main Jet (can't remember what was stock, 127.5?)
• 9EBY01-51 Needle (Leaner than stock)
• First grove on needle (leanest)
• P8 Needle Jet (stock)
• 15 Pilot jet (stock was 12.5)
• Stock Pilot Air Jet (1.0)
• About two turns out on the fuel screw
• Stock accelerator pump settings (just off idle to 3/4ish)
• Airbox lid on, no snorkel. Stock header, FMF Q4 w/ quiet insert.

Just off idle is a nice little pop of power, assuming that's the accelerator pump. Never had that with the CVK. But then it feels kind of flat from about 2K-5K RPM. At 6K it starts to pull really well, and will pull all the way to redline. Not sure what I'm feeling down on the bottom end, I suspect it might be rich. Planning on trying one size leaner needle jet (P6) at some point and see what happens. Also, I might try a larger main as it feels like the top end power tapers off towards redline and I'd like to get some of that back if possible. I would love to have an air/fuel meter like some have installed. That would take a lot of guesswork out of jetting experimentation.

Some other benefits of the TM I've noticed:

• Better gas mileage. I've finished two tanks with the TM, and currently getting 55-60MPG. Was only getting about 50MPG with the CVK.
• The bike doesn't die when coasting to a stop anymore. I was in the habit of blipping the throttle with the CVK, but that seems unnecessary with the TM and I'm trying to break the habit.
• I don't really need the choke anymore. I just give the throttle a good twist (accelerator pump) before I start the bike, then hit the starter. She fires off quickly and just takes a few seconds of blipping the throttle before she'll idle on her own.

Some negatives:

• It's a physically larger carb and is kind of a tight fit. Filed some material off the large aluminum nut on the bottom of bowl and off the back side of the starter just to get a little more clearance.
• The throttle cables I'm using are just barely long enough. I had to get creative with the routing and it's less than ideal. I may order some custom longer cables in the future. Might not be an issue on a stock bike, but I've got taller bars and bar risers.

I'm following this thread and any others that mention TM jetting just to get a feel for what other users are running, and then trying to extrapolate for my setup. If I could have gotten the CVK running correctly, I probably would have just stuck with that. But now that I'm running the TM, I think it's a worthy upgrade.

 

The top end power felt exceptionally good past 6k rpm with the 568-P8 in (stock) and the 130 main jet (also stock with the TM).

You're definitely rich in the mid range when WOT with the P8. Mine ran really good despite this, but was flat in the mid as you point out. I never tried the 9EBY01-51 needle with the P8, so it's probably a little leaner than it was for me when I had the P8 in.

the 51 needle is quite lean at cruise. With the P6 and the P4 in, it was overly lean (p4 especially). Seeing 16 - 17 AFR at cruise when cold. So that likely explains your good fuel mileage. With a P8 I'd GUESS you're around stoich or high 14's.

Seems like the needle taper (51 vs 50) determines AFR's at the lower RPM's and part throttle, and the needle jet determines the AFR's under WOT and upper mid range RPM.

Agreed on the throttle cables. Would recommend longer ones even with stock bars so you can route them properly. Not necessary, but certainly advised.

When you say air jet, do you mean the slow air jet (pilot system) or the main air jet? Mine didn't come with a MAJ and from what I read that's pretty normal.

 

Yeah, should have specified. I meant the pilot air jet. Saw it mentioned in the Mikuni tuning manual and other tuning threads, so thought I'd include it as well. I think my issue lies more with the needle/needle jet, so I'll be leaving the pilot system as-is for now.

Filled up again this morning, 54.4 MPG. At this rate, the TM will *very slowly* pay for itself over the CVK

And for the TM setup information that you're posting here, are you running lidless?

 

I am running lidless yes.

 

The biggy issue has to be that with the TM you get immediate full main jet fueling every time you snap to WOT - add in the accel pump shot and a snap-and-hold from 3.5-4k would go waay rich ... Right?

 

It may be that the more refined slide and smoothbore design of the TM allows, maybe requires, this.

Just this evening I pulled the Acerbis tank to drop the needle to the 2nd notch from the 3rd notch to provide cleaner carburetion for some of the higher altitude I'll encounter in the La Sal and Abajo mountains of southern Utah. My 300 (292) still runs the 127.5 like it does at home. When I go to the Uncompahgre mountains around Silverton, CO, there is much higher and more extended riding at altitude requiring a drop to a 125 main.

Following Mustang's and Dan Moore's jetting numbers allowed me to get to a nicely workable setup quickly. A surprisingly big improvement was made going to that .9 air jet instead of messing with the pilot jet. This jet has a slightly different benefit than just doing the pilot jet.

 

That's sound in logic, but in practice it doesn't seem to be dumping as much fuel when mid range rpm under WOT.

I suspect this is due to the reduced air velocity of being WOT and a 36mm bore. With certain needle configurations I was able to run richer at part throttle than WOT.

 

Yes, that's right.. The reduced vacuum/air velocity of a low RPM snap would not draw biggy AF immediately - and the accel pump prevents what would otherwise be a huge bog - but as RPM's rise it would be able to draw, what would seem like, biggy AF directly outta the needle jet...?? Right ? And with the stock header+slipon, and MCM, I know the engine really starts "sucking" by about 4.5-5k... The point is: I wonder if CVK thinking (12.8 target over entire RPM range at WOT) is even realistic with the TM (obviously, discounting Accel pump affects).. It may be that top end AFR can be set, various "steady throttle" cruising AFR's can be set, but AFR's during a snap-and-hold WOT are not easily tuned without affecting everything else..? Any of this sound right?