Need Help R18 TC - weird resonance from engine guard / leg protection at 2700-2900 RPM - anyone else?

[Grether]

Hey guys,
Just picked up a used 2026 TC a few days ago, around 9k km on it. Love the bike but there's something bugging me I'd like to get to the bottom of.
In the 2700-2900 RPM range there's a pretty loud rumbling noise — deep and raspy, like something's resonating. Happens in all gears both on and off throttle, and also with the bike stationary in neutral revving through that range, so it's definitely not the drivetrain or the tyres.
I did a simple test with a friend: he held the throttle at around 2800 RPM while I pressed both hands on the engine protection bars. The noise dropped significantly. The engine guard and the lower leg wind protection panels mounted on it are clearly the source — both resonate together in that RPM range.
I partially disassembled the leg protection by removing the front snap-fit panel and checked that all the mounting screws on the engine guard were properly tightened — no change.
Has anyone else seen this on their TC? And more importantly — has anyone actually fixed it?
Thanks

 

[kate_brett]

Search ‘front wheel noise / resonance’ for possible reasons why.

 

[Grether]

Search ‘front wheel noise / resonance’ for possible reasons why.

Thanks for the tip — I went through the front wheel noise/resonance threads but couldn’t find anyone with the same issue.

This morning I did more testing and made some progress. First I removed both leg wind protection panels completely — the noise reduced slightly but didn’t go away, confirming the engine guard itself is the main source.

Looking more closely at the engine guard structure, I noticed it’s made of two separate components joined at the top center by a single through-bolt (one tube slides into the other). Both sides are fixed to the frame at the bottom, but only the right side has a welded flange connecting it to the frame at the top. The left side has no such connection — it’s only held by that central bolt linking it to the right component.

Result: the left side is structurally less constrained than the right, has more freedom to vibrate, and is clearly the loudest part of the assembly. This looks like an asymmetric design rather than a loose fitting issue — all bolts are properly torqued.

Still looking for a fix. Any ideas welcome.

 

[Cu Dubh]

Sorry, I don't have an answer as my TC has onlybthe typical fender resonance. BUT... I want to complement your superb description! Accurate and very descriptive. I've know professional technical writers who couldn't describe it that clearly!

 

[Phil-R18]

J'ai eu ce problème là sur un XV1900 et je l'ai résolu en mettant un morceau de caoutchouc entre le cadre et le pare-cylindre.

I had this problem on an XV1900 and I solved it by putting a piece of rubber between the frame and the cylinder guard.

 

[Grether]

J'ai eu ce problème là sur un XV1900 et je l'ai résolu en mettant un morceau de caoutchouc entre le cadre et le pare-cylindre.

I had this problem on an XV1900 and I solved it by putting a piece of rubber between the frame and the cylinder guard.

Thanks for the tip — that's exactly the kind of solution I'm considering.
Before trying any fix I want to confirm the diagnosis properly. My plan is to remove just the left side of the engine guard (the one without the upper mounting flange to the frame) and check whether the resonance disappears completely with only the right side in place. If that confirms the source, I'll look at inserting a silentbloc between the upper flange and the frame as a first attempt.
Will report back with results.

 

[Grether]

Sorry, I don't have an answer as my TC has onlybthe typical fender resonance. BUT... I want to complement your superb description! Accurate and very descriptive. I've know professional technical writers who couldn't describe it that clearly!

Thank you, much appreciated! Though I have to say, when something is annoying you enough, you become very motivated to describe it precisely! And that's exactly what a forum is for — helping each other. A well-described problem can be useful to others facing the same issue, not just the one asking.

 

[Petrus]

Thanks for the tip — that's exactly the kind of solution I'm considering.
Before trying any fix I want to confirm the diagnosis properly. My plan is to remove just the left side of the engine guard (the one without the upper mounting flange to the frame) and check whether the resonance disappears completely with only the right side in place. If that confirms the source, I'll look at inserting a silentbloc between the upper flange and the frame as a first attempt.
Will report back with results.

I get that a rubber silent block will most likely sort the vibration issue. Is also a one for the guard threads

 

[Grether]

Hey guys, update on the resonance issue.

I spent the day doing a systematic series of tests to isolate the source. Here’s what I found:

Removed left engine guard only:
Resonance almost gone during acceleration, still present during deceleration/throttle release. Interesting — the behavior changed but didn’t disappear.

Removed both engine guards:
Acceleration almost clean. Deceleration at ~2900 RPM still clearly there. So the guards are amplifiers, not the source.

Removed front fender (4 bolts, wheel stays on):
No change at all. Fender ruled out completely.

The leg protection panels obviously came off with the guards since they mount on them.

So after all this, I’m left with a resonance that shows up specifically during deceleration/throttle release at around 2900 RPM, with everything stripped off, and I still can’t pin down the exact source. The guards definitely make it worse but they’re not causing it.

Still investigating. Any ideas welcome

 

[LBV]

Is it possible that it's coming from the engine? Maybe check the valves to ensure they're in spec.

 

[CajunRider]

Maybe check various decorative engine covers???
- Outer valve cover
- Front chrome/polished engine cover and/or oil cooler/cover
- Top "engine case" pieces that cover the air intake & air filter

Perhaps you have a loose screw or two in one of those.