belt alignment problem - engine mounts

[ianwalton]

full story, bought this 450 about 3 months ago and from day 1 it has whined from 30 mph upwards, some times louder, sometime quieter, but always there.

read buckets of threads about this issue, specific to the 450, and buckets more on general bikes.

i read lots about the front pulley issues, so i went and bought a second hand unit, noise exactly the same.

i swapped out the read wheel and axle, including all hardware / spacers etc with my brother in laws 450. no change.

i laser aligned the rear wheel, no difference,

i checked tension, did it tight, did it slack, noise got louder, quieter, never went away.

took it to a garage, first 3 wouldnt even talk to me, last one said output shaft bearing, so i pulled the engine and swapped it

guess what ? NO DIFFERENCE. only thing it did was raise a half dozen different bloody oil leaks.

today, i played around with checking the alignement of the rear wheel, but instead of comparing it to the front wheel, i checked it with the front pulley and it is WAY out.

right now i cant decide how to proceed to fix it.

the only thing i can think of doing is to slacken off the engine mounts, start the engine, drop it in gear, get the wheel spinning to 30+ and use a crowbar etc to shift the engine around to see if the noise dissapears.

a permanent repair, shimming the mounts ?

anyone else got any ideas ?

[eaglerider]

No need to go thru all the things you listed, to align the front and rear sprockets, which is the problem. Loosen the rear wheel and align the sprockets by "centering" the belt in the rear sprocket "channel". You can do this best if yo have the bike jacked up where you can turn the rear wheel by hand, and watch the belt as you turn the rear wheel. Now, this will correct things, provided the bike has not been wrecked and the rear portion of the frame is not bent. your mistake apparently, was trying to align the rear wheel with the front one, instead of aligning the rear wheel/sprocket with the front sprocket on the engine.

[ianwalton]

i have done that, trying to align the rear sprocket to the front sprcket.

the rear wheel was at marker 4 on the left and 2.5 on the right. it became harder to move the right side axle because of the torque arm.

the belt was centred on the rear but, still whined.

i think this is because although the angular alignement was cured, it turned it into a parallel alignment issue, effectively narrowing the belts path. it would work if the belt was narrower.

it also brings up handling / wear issues if the rear wheel is left like that long term

i am sort of convinced that i need to somehow cure the front pulley alignment problem, not mask it by adjusting the rear

[eaglerider]

There is no engine mounting change......from the way you describe things, it sounds as if it is very possible that the frame is slightly bent at the rear part of the frame, preventing proper wheel/sprocket and front sprocket alignment........either that, or the engine mounts have been somehow been messed with. I don't know how they could have been messed with, as they are welded directly in place on the frame. Not being able to look at the bike in person, it makes things pretty hard to figure out what is causing the problem. Oh...one thing to check is the swing arm.....that is actually what governs the rear wheel position in relation to the rest of the frame. The belt should have just a little clearance on each side of the rear sprocket sides (the thin metal sides on the sprocket)
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