Bonneville America Forums Forums Technical Forums The Vault Throttle Body Adjustment

Hi Folks. I thought I'd share my joy here. My 2010 Speedmaster was getting bit rough while negotiating steep inclines, and on my V-Star 650 that indicated unbalanced carbs. So, I figured I might do an adjustment on the throttle bodies and see what the difference would be.

I have 4600 km (2900 miles) on the bike now. My V-Star was happy when I balanced the carbs every 3500 km or so, and this would give me an opportunity to try out TuneECU. I have a Vag-Com cable that I purchased on eBay, and am running this on an Asus Netbook computer. I used TuneECU 1.67. A big THANK YOU to the developer(s) for making this software available!

Here's some screen shots:

Fast Idle while warming up


Engine Warm


Throttle Bodies BEFORE adjustment


Throttle Bodies AFTER adjustment


The tachometer readout doesn't update while in this mode on TuneECU so ignore that reading. It was barely a tweak on the adjustment screw to bring the throttle bodies into line. Both thottle bodies are now at 330 hPa as indicated on the two left dials on the dashboard.

Test ride. Did a 50 km loop which has various speeds, hills, and curves, but no LONG (8 km) hills at highway speeds. That'll be next week The engine does feel a bit smoother, even loafing along at 2800-3000 rpm. Of course, the real test is when I'm loaded up for those big hills.

Screwdriver. I used one of those right angle phillips screwdriver thingies. Not very good. I think I will be investing in a proper tool for this. You only adjust the balance screw every so sllightly, and I'd prefer a tool that will give small increments. The right angle tool was either too much to the right or the left in position.

So, it was worth doing, and I do recommend doing this very easy adjustment every so often.

H.

I bought a small ratcheting right angle bit holder from Home Depot, or maybe Lowes, that has a very fine toothed ratchet. Its the only tool that would work for me. I also use it to take the carb tops and bowls off.

Yes, I have one of those, too! Just never thought to use it as I usually use hex allen bits with it. I'll use that next time. That little ratchet tool is invaluable while working on the bikes.

Yup, the application is pretty good. It's limited on the Twins for now, but is fully functional for the triples, including the Rocket III. With the triples, you can upload maps, and create your own fuel maps. Hopefully that functionality will come for the twins as well. The developer has made this application available at no charge from here:

TuneECU

H.

Just to confirm that I did a 600 km loop the other day (Hwy 3 for those in BC) which has many challenging hills, and lots of curves

I did this trip 2-Up, and the bike was VERY smooth. So, even though TuneECU was reporting only a 10 hPa difference between cylinders, bringing the throttle bodies into balance made a huge difference in smoothness when the engine was working hard.

H.

Hi Folks. The TuneECU software has just been released with support for the Twins.

It is available from the developer here:
CLICKY

or here TuneECU Website

Version 1.7.1 has support for the Twins.

Please note that the developer has made this available free of charge for your use. Highly commendable of them!

Enjoy