XJ600 History and Specifications

[CD]

I used BT45s in 2006 with 36/42 psi. Any less and I could feel the tyre moving about especially if the front was low.

The 600 clutch is only "wet" in the sense there is no seal to keep engine oil out. It effectively runs dry and the centre bearing almost never sees any oil. The first job with any D600 is to take off the clutch cover and grease those bearings. Also do the operating shaft because they also run dry.

[rowlf]

Mar 19, 2013 8:41:12 GMT CD said:

I used BT45s in 2006 with 36/42 psi. Any less and I could feel the tyre moving about especially if the front was low.

The 600 clutch is only "wet" in the sense there is no seal to keep engine oil out. It effectively runs dry and the centre bearing almost never sees any oil. The first job with any D600 is to take off the clutch cover and grease those bearings. Also do the operating shaft because they also run dry.

I noticed that the Bridgestones on my XJ900 were a bit "squirmy" when the pressures were low. I guess the sidewalls may be a bit softer than other tyres. The much higher recommended pressures over "standard" tyres would seem to bear this out.

You would think that they would be less suitable for a Diversion but they work very well. I shall still be trying the Michelin Pilot Activs on my 600 as they have excellent reviews and work at "Yamaha standard" pressures so on the face of it are a better choice. Cheaper too

That is good advice about greasing the clutch bearing and operating shaft. I will add that to my list of 'springtime' jobs. No rush then

[rowlf]

Still waiting for spring to grease those bearings. Doesn't summer (or BST) start this week?

[pol]

[rowlf]

small edit made

[CD]

BST = British Shiver Time

[pol]

looks like Michelin have the pressures for the Pilot Activ on their site now

Michelin

with the 2.0/2.3 as mentioned

[sleekitwan]

After reading psi in various places, I went with F33 R40 for the Battleax tyres front and rear on my Divvie 600. Or, as it has to be, F34.5 R41.5, to compensate for the rapid pressure loss as I detach the right-angle connector thing needed. Now, the thing is, the bike was run for ages with F29 R33, as unfortunately I only recently found out the proper BT45 pressures on the Divvie 600. So, the front is fine, but the rear, had cracked sidewalls and a flat ring around the middle you could land a Thunderbird on. It could stand up on it's own.

So, having rasp-planed the edges off the rear tyre to get one trip out of the bike, finally got a Michelin Pilot Activ for the rear. It seems stiffer than the BT45, but I got the bike expert nearby to fit them, so not much to go on.

Michelin are not half as helpful as Bridgestone re pressures. The BT45 pressures of F33 R40 seem absolutely spot-on, and the cracked sidewalls on the rear are not present on the front, indicating flex must have had a hand surely? Weather was the same on both, and cracks both sides, so it's not just grease etc from the chain. These are fatigue cracks.

Michelin gave no recommendation but check manufacturer's suggestions. Yamaha have not altered theirs so that's a dead end! Now, with the front BT45 having plenty of tread left (3 to 4mm) even in the MIDDLE, I am left guessing at the rear, the new Michelin Pilot Activ as recommended.

So, the way to guess for me is this: Lowest possible psi would be R33, that Yamaha give. The highest possible would be R50psi - but I put my bicycle at that, and it must be near the maximum rated pressure surely? I run my estate car at 45psi rear when it has half a tonne of tiles in it. The Battleax was good at 40psi. The tyre man - the professional mechanic - set the Michelin rear tyre to R44psi. That's what I was using for the BT45 Rear, when the bike was massively loaded on a trip to the lakes a while back. And hoping those cracks wouldn't widen...! My brother viewed them suspiciously on that trip, and I gave him a look that said 'some of us have mouths to feed...!' Ahem. BMW riders, with their 'proper ways of doing things' indeed.

Forget R33 - I wouldn't even entertain that nowadays. Forget also the R45 setting, that's only if ever, for massive loading of me and stuff galore, tools etc, all over the back tyre, AND a tank bag. I COULD just say why not hit the dead centre of these two - split the difference? That would be R39.

This would be lower than the recommended BT45 setting, and 3 psi higher than the recommended Yamaha pressure for fully laden, two up etc (ie 3psi above 36psi at the rear). All my vehicles, and motorcycles, act as if me and mine are heavy. All the tyres wear at the edges badly if we dare run at 'normal' pressures. That's 4-wheel or 2.

So, let's run the remaining front BT45 at the recommended 33psi (or F33+ as I always fumble some psi as the pump is extracted etc). As I reminded my brother who said his front suspension had gone soft - you harden up one end of a bike, the other is not independent of that change (he subsequently notched down the REAR spring a bit, and voila the front behaved better). I just wouldn't dream - at my apparently highish weight - of running any LESS than the fully laden rear psi of 36psi. This is narrowing down for me then, on this middleweight Divvie 600. Now, it seems to be F33+ and R36+ to R40+ (the BT45 rear tyre pressure) unladen. I can split that difference and get to F33+psi and R38+psi.

In fact then, this process has narrowed it down to within a couple of psi - hell, I ran the stoopid rear tyre at 33 psi when it was MEANT to be 40psi for ten years! SEVEN psi over! So, putting it in that context, how wrong can it be, to run this tyre anywhere between R36psi and R40psi?

That's it then, I settle for F33+ and R39+ in psi, for my front still-serviceable BT45 tyre, and my rear Michelin brand new Pilot Activ tyre with it's almost sport-bike looking tread pattern! As explained, the '+' sign allows extra psi for my fumbling as I disconnect the pump and right-angle adaptor, and the loss involved in using a decent standalone pressure gauge to re-check the value.

If you were a little less than my 190lbs (nearing 14 stone) allowing of course for leathers or whatever in addition, you might say the front is relatively unaffected, but maybe go as low as 31psi front, and the rear have at R36psi? The Divvie does seem to be a bike that is heavy on the rear weight distribution, although mine is a 'naked' version, and just a small bikini at the front, so it might be even more back-heavy.

[bobh]

It's possible the cracking of the rear tyre might have been due to age, not pressure, if it had been on for 10 years! If the front has been on for the same time, I'd seriously think about changing it, because the rubber will have hardened up and it will have lost a fair bit of grip. And you definitely don't want to run our of grip at the front.

I run the Diablos on my MT-03 at 30 front and 33 rear, with no obvious problems. Those are the recommended pressures, admittedly for the original supermoto-style tyres.

Personally, for your weight, on a D6 I'd go for 36 front and 40+ or so rear. It's better to be a little over than under.

If you're losing more than a fraction of a psi when checking the pressures with a gauge, you aren't doing it right!