Transmission aligned... Belt still walks towards the inside edge...

[foundationapps]

Hi all, me again.

A 3rd new belt, and removing the spacer on the sprocket ... long story short, the chain is no longer touching the tire, 1/8" gap. Engine is aligned with the transmission, using a straight edge along the inside of the clutch hub, aligned to the outer plate on the front motor pulley. Looks parallel to me. Turning the motor over by hand with the plugs removed, belt remains perfectly centered.

With the engine running, it slowly walks left to right and runs slightly over the inside edges of both pulley wheels.

Any idea to run down this drift? Is it possible the motor is twisted slightly clockwise and / or the tranny slightly twisted clockwise enough to allow this walk?

Haven't ridden it yet as I don't want to loose the belt to drift to the inside and having the chain eat it's face off... lol Much appreciated. Taking this bike to a local garage built bike show tomorrow.

Respects to all, Summer CANNOT be ending already!!!!

[Bigincher]

Yes, it's common for there to be some slop in the transmission mounting plate allowing a certain amount of skew.
There is an aftermarket adjuster with a bolt on each side of the transmission to correct that malady. It's fairly normal with a belt drive.

[PanPal]

Also, Make sure the belt isnt too tight. They shrink when they warm up.

[foundationapps]

Posting this so others may learn...

I loosened up the engine mounts and tried to fix this "walking" issue by turning the motor. That didn't do anything but make it worse. So I loosened up the transmission bolts (remember to delink the chain this time, duh). Turns out my intuition that had me turning the transmission clockwise (looking from above) was wrong, I had to turn the transmission Counter Clock Wise (CCW). Belt was walking to the right, countered by turning the transmission opposite of the walk (or the skid like a car). Just like correcting for a skid in a car, opposite steering.

Belt could probably stand to loosen up a bit, but that's easy now that I know the solution to the walking issue.

[Buddhahoodvatoloco]

Kewl, figured it out.

[RUBONE]

The analogy I use is that it works like aligning a belt on a belt sander. The pully skews slightly to center the belt. On MC applications I always slightyle widen the trans mounting plate holes and skew it slightly back and forth until the belt runs true and then lock it down. The minimal misalignment does not affect the rear drive chain and it can stay in that position for the life of the belt.

[foundationapps]

Smudged with this issue a few times over the weekend. I always felt that the belt was just a bit too tight. Also, what was throwing me off was that with a steel heavy ruler aligned along the inside of the clutch basket, the edge of the ruler over the front pulley was a little more than 1/16" away from the plate / disc on the outside of the front pulley. That was throwing me off as I was trying to get the belt to just nearly touch that disc, the same as the belt just nearly touches the inside of the clutch basket. SO,,,,, insuring the belt was running 90 degrees to front and rear shafts, it is now perfect, with just about 7/8 of vertical play in the new BDL belt.

Rubone, that method of twisting the tranny while it was running helped a ton. To be on the safe side, I put just enough tension on the trans mounting bolts to make things stable, then basically used a huge wrench made of wood to twist the transmission around (maybe 3 degrees of movement) until the sweet spot was obtained. All in all, the front pulley seems about 3/32" out from the centerline of the bike more than the basket, belt is not rubbing, it's not over running the edges or touching the inside of the plate or clutch basket and it's slack enough not to bind the bearings and shifting.

Happy rider here.

[Bigincher]

Glad to hear you solved it, and glad you posted the results for future reference. Well done!