DIY Belt Change

[utopia]

I watched the "Brad the Bike Boy" video out of curiosity.
He uses the Gates app to check the belt tension by measuring vibration frequency but I notice that he makes no mention of which run of the belt to pluck in order to take the reading.
Presumably this would affect the result according to whether you plucked a longer or shorter belt run ....??

Personally, I like to use the allen key method on my 750 as I like the fact that you don't have to rely on an electronic "box of tricks" to give you an answer by some internal "magic".
It does however require the mechanic to have a decent mechanical "feel", which may not suit everyone.

As everyone has said, if you take your time and check your work before starting the motor, belt changes on 2v motors are pretty straightforward and you shouldn't have any trouble.
And I agree, once you're familiar with what to do, removing the belt covers is the trickiest bit.

[slob]

Originally Posted by utopia

...He uses the Gates app to check the belt tension by measuring vibration frequency but I notice that he makes no mention of which run of the belt to pluck in order to take the reading...

@22 ie the centre of the run between the drive pulley and static roller

Originally Posted by Luddite

As Dave G said, with the horizontal cylinder at TDC power, the cam on the vertical cylinder will try to rotate under the influence of the helper springs, which would, (in theory), affect the tension when you're checking the belt.

If you use the cam locking pins, then you can check both horizontal and vertical belt tensions with the motor at horizontal TDC. If you're not using the locking pins, then rotate the motor until the vertical cylinder is at TDC power.

Ah that's useful to know as I was going to get some of the Laser locking pins.

As for which method, I'll probably try both the allen key and the app to see how it works out

[Luddite]

You may be confused by the link posted by Darren as it shows four small locking pins (OEM 88713.2009) rather than the two larger ones described by slob at #2 (OEM 88713.2282).

As you've got the 800 motor, Darren's pins are the ones for your model; the larger pins are for the S2R 1000 and later models.

In case you're wondering where the pins go, they are shown in this service manual extract.



As has been mentioned previously, the pins aren't essential - if you do without them, just make sure you mark up the cam pulleys clearly and rotate the vertical cylinder to TDC power when checking that belt's tension.

Originally Posted by utopia

He uses the Gates app to check the belt tension by measuring vibration frequency but I notice that he makes no mention of which run of the belt to pluck in order to take the reading.
Presumably this would affect the result according to whether you plucked a longer or shorter belt run ....??

Utopia, you're correct in assuming that the belt frequency should be checked at specific points. Those "plucking points" are also shown on this page.

[slob]

Interesting. The later manual shows both points but the horizontal belt suggests the moveable/tensioner roller side, which I’d expect to be tighter. Does it give different frequencies for each belt? My manual suggests 140Hz for both, although I have a feeling that’s been updated since.

There is no need to spend money on the locking pins, all you need are a pair of 6mm drill bits.

You just slot them in as if you are putting them into your power tool, smooth end first. Has worked for me for years.

It's keeping the bottom pulley still that always causes me a problem, keep it in gear and hang a weight on the brake pedal.

Cheers Luddite, what page is that on so I can see if I can find it in my manual

[slob]

It's quite close to the beginning, near the end of the routine maintenance bit in mine

[Luddite]

Originally Posted by slob

Interesting. The later manual shows both points but the horizontal belt suggests the moveable/tensioner roller side, which I’d expect to be tighter. Does it give different frequencies for each belt? My manual suggests 140Hz for both, although I have a feeling that’s been updated since.

That extract's from the 620 manual, Rob, and it specifies 140Hz for the horizontal belt and a frightening 160Hz (!!!) for the vertical.

My Evo manual says 140Hz for both belts.

Exactfit recommend 99Hz and say they are safe to 110Hz.

[Luddite]

Originally Posted by rac3r

Cheers Luddite, what page is that on so I can see if I can find it in my manual

That's from a 620 manual so page numbers might be different. That extract was from section N4.2 page 342 of 546.

The section on checking the tension is section D5 page 108.

[Luddite]

Originally Posted by alickswud

There is no need to spend money on the locking pins, all you need are a pair of 6mm drill bits.

That won't work on the 800 as the cam end caps are different. (See post #19.)

Thanks all. I think I read somewhere there was an update and they changed it to around 100hz

Sort of related question but would the 60 or the 100 be more useful for bike stuff?

https://www.halfords.com/tools/hand-...rque-wrenches/

[utopia]

Originally Posted by slob

Interesting. The later manual shows both points but the horizontal belt suggests the moveable/tensioner roller side, which I’d expect to be tighter.

Just my opinion but I would guess that in each case the longest run of the belt is specified, whether that be on the "drive" side or the "slack" side.
Also that in each case the length of free belt between pulley and roller is the same, whether that roller is the tensioner or the idler.
Its the combination of length and tension which gives the frequency .. as any stringed instrument player will confirm.

At rest, I would expect the belt tension to be uniform throughout its entire length.
The vibrational frequency will vary though, depending on the free length of each section.

Whatever method is used, my personal opinion is that there is quite a wide tolerance on belt tension anyway ... though again that's just my personal opinion.
As long as the belt isn't ridiculously tight or so slack that it flaps around or risks jumping a tooth, I don't reckon it has much effect on either engine performance or belt life.
That said though, I always like mine to be as near to ideal as I can get them.

[Luddite]

Originally Posted by rac3r

Sort of related question but would the 60 or the 100 be more useful for bike stuff?

https://www.halfords.com/tools/hand-...rque-wrenches/

My most used wrench is a Halfords 8-60Nm 3/8" drive. And that does about 90% of the fasteners. I also have a chunky ½" drive for higher torque values, but its only regular use is for the rear wheel nut. The only other times it's been used is for the gearbox sprocket, flywheel nut and clutch nut - so hardly essential.

Just thinking if I decide to do the shock myself too then it would be good if it covered that