Thursday, February 12, 2015

Replacing the Throttle Body Plates on Scarlett

Back when I had installed vacuum ports on Scarlett's EFI Throttle Bodies, we'd discovered a seemingly inability to balance the idle at lower than 1200 RPM.  It "appeared" that there was a small leak on the left side throttle body.

That was the theory anyways.  Some more examination in following days, I ended up shining a light through one end of the throttle body and sending the pictures to Randy, the dealer at UniqueRides in Fort Collins, CO.

He didn't like the distribution of light and ordered a replacement set of the plates that regulate how much air flow's through the throttle body.  There had been reports from other riders, that some of the initial run of plates on the early 2014 motorcycles had bent, since they were made of aluminum.  The new plates are still aluminum, but thicker, laser-cut and anodized, by Eletrojet...the company that designed the EFI throttle bodies.

I rode up to Fort Collins, today, arriving shortly before Noon and Randy got right to work on replacing the throttle plates.

 One of the original throttle plates, note the slight bend upwards on the right
Randy could get the old plates to wobble slightly!

 The new thicker, laser-cut plate, both sides were replaced by Randy.

The new plate in place, before being secured by provided screws.

Randy buttoned everything up and hooked up his laptop to Scarlett's EFI diagnostic port to check and balance the throttle bodies.

We encountered several issues.  

For quite a while, the laptop would intermittently lose connectivity with the ECUs on the motorcycle!  Very frustrating since you can't make adjustments while the tool keeps cutting out!  This caused some delays as the program had to be re-started, and at one point we ended up restarting the laptop.

We were getting inconsistent readings while trying to adjust/balance the idle to around 1000-1050 RPMs, and finally Randy ended up re-flashing the EFI mapping to "clear counters" as it were.  This seemed to help.

We found it very difficult, nigh impossible to balance the throttle bodies at an idle of 1000 (recommended by factory).  After many attempts and troubleshooting, Randy set it at 1100-1140 and things stabilized and the idle was balanced!  Weird.  Note: I probably should have taken the rig out for a warm up run, we just did the balancing by running the engine for a few minutes.   An email discussion with Jason of URAL indicated that by not doing the warmup run, the EFI was running in "open loop" mode probably.  Doh!

Then we checked things at 1800 RPM and some adjustments of both throttle cables were required.  So glad I decided to ride up and have Randy do this, I would have been thinking it was my experience and technique but Randy was having lots of trouble getting things balanced as well!

By the way, we also cross-checked by having my Harmonizer hooked up and the RPMs were very very close!

Finally, everything seemed balanced and I went out for a test ride.  All seemed well.  Interestingly, now the engine was idling at around 1060! 

 I got some more spare parts from Randy and shortly before 4PM left Fort Collins and right into the teeth of evening rush hour for the Metro Denver area!  It was a long slog of slow-n-go traffic once south of 104th Street but made it to Gun Club Road and Quincy Avenue just in time to capture the sunset's aftermath.

Randy and I both agreed that Scarlett seems to "like" running at 1100 RPM (indicated by dealer tool), 1080 indicated by my cheapo tachometer.  She sounds good at 1100!  We both also agreed that she was difficult to get balanced!  (Note to self, next time: warm up ride first!)

More riding to do, but she ran well all the way home.


Jason Ewert said...

What happens at the shop stays at the shop... 99.9% of the time. That "diagnostics" line item on your bill obscures a lot of hard work by smart people. That's why we think our modern cars are so reliable :) It sounds like you have a great relationship with your tech and you can't buy that with a stack of hundred dollar bills.

Richard M said...

That really was a lot of tech time to try and debug a nagging problem. Not really a drivability problem but something not quite working as it should. I guess they could've tried a different throttle body and if it worked, it still wouldn't have isolated the problem.

Charlie6 said...

Jason Ewert, thanks for the comments. I am lucky to have such a good dealer somewhat near me. It's a small shop, the owner is the mechanic...and I like it that way.

RichardM: Randy is the kind of dealer/mechanic who wants to do right by his customers. I could tell he was getting frustrated but he persevered! Heck, it was his initiative that got me the replacement plates, all based on my emails with him and pictures I took.