Bonneville T-120 First Impressions

atomsplitter

Top Fuel
Joined
Nov 29, 2007
Messages
1,787
Location
Keller, TX
Ride
2005 Rocket III
OK I've put a few hundred miles on my new (to me) 2017 Bonneville T-120 and thought I'd share some impressions of the experience. First I bought the bike to ride 'in-town' because it's a lighter easier handling option to the Rocket (in its current configuration). Stop light to stop light it pulls well, goes where you point it and overall gets the job done. I don't have aching hip joints after 30 minutes from having to kick my feet forward to footboards and I can stand flat footed at stops. Part of the appeal. What's not so appealing is the fork dive under braking and the poor suspenders in the back. Also less than ideal is the handlebar twist to left under hard braking (as though one disk is clamping harder than the other). After some research I found the reason for this behavior is Triumph saw fit to cheap out on the forks by damping only one of the fork legs. The other fork leg is simply sprung, no damper rod. It also explains why the forks do such a deep dive under standard loading because they fitted a short 'constant load' spring in both legs. While riding there's no real problem with handling, it isn't until you load the forks up it becomes noticeably deficient. To correct this poor behavior I've ordered progressive fork springs which included new end caps that have preload adjusters installed. Because I'm the same load solo as would be a normal rider with pillion (and no cracks about lead bars in the luggage too) I wanted to get the static load properly set so I have maximum fork travel. Because there's only one damping rod that is shared by both fork legs you must lock the fork legs together so it applies the forces equally. To that end I ordered a SuperBrace fork brace from New Bonneville. I have a fork brace on the XS 11 for the same reasons and that made a huge improvement on the XS for handling and braking. My hope is the brace will correct the same behavior the XS had of following road camber or rain grooves while riding. The brace on the XS eliminated that behavior completely.

Next I wanted to address the rear shock issues. When I rolled the bike out of my trailer I found the shocks were at the lowest (no preload) setting. Most people don't know what the preload collar is for apparently and don't adjust this collar for their riding and load requirements. I immediately clicked it up 2 notches before taking the first ride as a 'base' setting. After a hundred miles I clicked it up another notch. That was better, but any square edges I hit were telegraphed to the handlebars and my coccyx in a most unpleasant manner. The shocks are simply overwhelmed under impact and no amount of preload is going to fix that, so I ordered up some TEC remote reservoir replacements. They have the advantage of damping adjustment as well as preload (stock you can only fiddle the preload). Properly dialed in that should end the spinal shocks transmitted by most roads in Texas.

The latest thing I noticed is the left hand exhaust silencer is 'wiggly' where the right side is rock solid. I noticed this when I was deploying the side stand. Looking underneath the bike (I have a lift makes that job a snap) I found the exhaust joint at the catalytic converter is loose. I haven't gotten into the specifics of the problem yet as I have to research the brand of aftermarket silencer that was fitted to the bike. My guess would be the parts were installed by someone less than fully knowledgeable about engineering principles and has created a problem for the next owner (that would be me) to resolve. Hence the low price I got the bike for. Since I have to deal with this situation anyway I decided I might as well jettison the catalytic converter since its 4 lbs of backpressure inducing turbulence restricts the power the engine makes. I have a Motone cat-delete X-pipe on the way to address this problem and resolve the silencer issue at the same time. A two birds one stone approach. The ECU adaptability on this bike makes these mods a snap since you do a 12 minute tune and the ECM adapts the fuel maps based on the lambda sensor readings. There are additional maps available if I want to re-tweak it in but I'll see how the thing behaves before I contemplate fiddling the ECM.

I'll post up the results of these mods as to street worthiness after I get some run time on them. Haven't got the parts yet so will be a few weeks.. Here's a picture of the bike as I got it, I'll post a photo of the bike after the mods. (I've already replaced the fly screen with a proper unit).
 

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Michael_G

Road Therapy...
Joined
May 26, 2014
Messages
2,186
Location
Miami, FL
Ride
"Fiona" my '14 R3T & "Delilah" my '16 V-Rod Muscle
Sweet ride and glad you're getting her all sorted out. Standing by for the those MOD photos w/feedback... :thumbsup: :cool:
-MIG
 
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