I sold my K7 Wee and bought an L4 Wee back in April. One major disappointment has been that the L4 Wee has been very viby, much more so than the K7. When I first got the bike it was viby right around 5200 RPM which turned out to be a loose lower throttle-body boot clamp. Once that was fixed it was still more viby than my K7 with a noticeable shudder right around 2-3K RPM and buzziness that starts around 7K and peaks around 8K RPM.
Anyway, one Rx for excessive vibes is to check the motor mounts and to reseat the thrust adjusters and re-torque everything to spec so I wanted to perform that procedure to rule it out as a cause. One catch is that the manual assumes you can lift the motor from the bottom which is not possible unless you remove the exhaust pipes (the cat is in the way). I developed this procedure to do a full realignment per the manual without removing the exhaust pipe and muffler.
Here are (roughly) the steps that I used;
- Loosen the rear axle and chain adjusters and move the tire forward to put slack in the chain.
- Remove the L/R foot pegs brackets and bungie everything out of the way
- Loosen the front & rear header clamps and muffler mount bolts (see notes)
- Remove the front upper motor mount through-bolt (you'll need two 17mm sockets, I had one and now have two)
- Remove the rear lower mount through-bolt (14mm socket + 14mm box wrench)
- Remove the front upper and rear lower thrust adjuster lock-nuts (you'll need a special castle socket tool).
- Loosen the rear lower thrust adjuster (19mm or 3/4" 6pt hex socket)
- Loosen the front upper thrust adjuster (see notes)
- Loosen the upper rear motor mount bolt and pinch bolt.
- Remove the upper V engine brackets and clean the mating surfaces. (optional)
- Install the V engine brackets and tighten bolts to spec (16.5 ft-lbs, see notes)
- Align the lower rear motor mount through-hole. (see notes)
- Install the lower rear motor mount through bolt and nut but leave it loose.
- Tighten the lower rear thrust adjuster to spec (8.5 ft-lbs)
- Install the lower rear thrust adjuster locknut and tighten to spec. (32.5 ft-lbs, castle socket)
- Align the front upper motor mount through-hole.
- Tighten the front upper motor mount thrust adjuster to spec. (8.5 ft-lbs)
- Install the thrust adjuster locknut and tighten to spec. (32.5 ft-lbs, castle socket)
- Install the front upper motor mount through bolt and nut but just snug tight.
- Tighten the lower rear motor mount through bolt to spec. (40 ft-lbs)
- Tighten the front upper motor mount through bolt to spec. (67.5 ft-lbs)
- Tighten the upper rear motor mount bolt to spec. (40 ft-lbs, see notes)
- Tighten the upper rear motor mount pinch bolt to spec. (18 ft-lbs)
- Reverse steps 1, 2 and 3 and go for a test ride.
Step2: If your bike has a lot of miles you may want to leave the header clamps alone. The bolt/nut tend weld together due to heat over time and if you have a lot of miles then when you try to loosen them they may just break off, something to avoid. My bike only has 7500 miles and the bolts came out but were screeching the whole way. I cleaned them up with a wire brush and reinstalled them with anti-seize compound. The down side is that some mechanics claim that loosening the pipes so they can realign with the new position of the motor is crucial to keeping them from transmitting vibrations. Your call.
Step6: The special castle socket is available much cheaper from sellers not named Suzuki. Its the same size as the GSXRs.
Step7/8: Both thrust adjusters need 6pt or hex sockets, a 12pt socket won't fit. The upper mount thrust adjuster is some odd-ball size like 23mm 6pt hex socket that is difficult to find. I was not even able to find or confirm that that size would work so I just ground down the thruster and used a 13/16" hex sparkplug socket. A 3/4" 6pt hex socket worked fine on the lower rear thrust adjuster.
Step10: The mating surfaces of my V-Brackets were a mess with old loctite, uneven paint and raised bosses around the bolt holes on the frame. I sanded everything down for a clean tight fit just to be sure a poor fit would not cause any vibration issues. If you don't clean them just make sure they are torqued to spec in the next step. I also lightly sanded the thrusters and engine mount points to remove old witness marks to give a clean surface for re-installation.
Step11: According to GW, the manual spec of 25.5 ft-lbs is wrong and too high for this size bolt. I went with his recommendation of 16.5 ft-lbs.
[Aside: At this point in the procedure the motor is only hanging from the upper rear motor mount bolt and rotates around that point]
Step12: Aligning the through-holes properly is really what this is all about. The witness marks on my upper and lower engine frame and thrust adjusters seemed to indicate that my motor was not square within the frame so I was hopeful this would fix my problem. Aligning is pretty easy if you look into each side of the bolt hole and adjust the motor position until everything is concentric. I also shone a line through the other way to confirm. Getting it spot-on was a bit tedious but doable with a little patience.
Step22: Be sure to check that the bushing that the upper rear motor mount bolts screws into is seated in its slot on the motor case. You can see it just behind the pinch bolt mechanism that traps it. One time I got everything set and had to redo this because the bushing was not in its slot.
I took some pics: First pic is the witness mark on the motor from the right side. Second pic is the witness mark on the motor from the left (circled in red). These are the tell-tales that the motor was not squarely in the frame. The lower thruster was even more out of alignment. Note the yellow circles in the second picture which highlight that the ignition coil was rubbing on my radiator hose, I'm guessing a few thousand more miles and I would be walking home. I am glad I caught that and rigged a rubber hose to give it more clearance. Pic three is the upper thrust adjuster that I ground down to fit in an 13/16" 6pt hex socket aka spark-plug socket. The last two pics are how I jimmied the motor around to align the motor mount through holes. There is hardly any pressure on the jack under the front cylinder and lightly tapping the wooden shims moved the alignment quite a bit but I got everything aligned and locked down.
So what was the result? After a fairly brief ride (just under an hour) I can say the bike is much smoother and less viby. On the freeway I especially notice how calm everything was right away. The mirrors were rock solid which wasn't the case before (but they weren't bad either). However, the 2-3K shudder and 7-8K buzziness remain but a little less noticeable so my search for a fix continues. One final comment, if you do this please verify my torque numbers, I could have them wrong and I don't want someone to break a bolt.