i am going to replace the fluids on my m2 and xl1200s, both specify DOT 5. can i use DOT 5.1 or am i right to be a bit suspitious??

NO, dot 5 and 5.1 are incompatable.

_________________
Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

thought as much. thanks

DOT5.1 is a glycol-based (mineral) brake fluid and, confusingly, is an update for the DOT4 fluids.

DOT5 is a silicone-based fluid and the two are completely (as in throw-away and replace if you used the wrong one) incompatible.

DOT5 is (arguably) the better fluid anyway, because the silicone-based stuff doesn't absorb water so it's properties remain more stable over time. Glycol-based fluids should be replaced every few years.

Either way, the standards require the fluid to maintain a very low level of compressibility over the life of the product.

_________________
Good in straight lines
2001 X1 "The Tart's Handbag"
2001 FZS1000 "The Fridge"

_________________
Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

i hear you shouldn't mix the two fluids, but can you replace one with the other if you bleed the system out?

The two are completely different and components are designed for one or the other.

If you want to change, as a minimum, you'll need to change out all the hoses, seals, cylinders and possibly even the calipers.

Why would you take even the slightest risk in pissing around with your brakes.

_________________
Good in straight lines
2001 X1 "The Tart's Handbag"
2001 FZS1000 "The Fridge"

I wouldnt. thats why i asked first!

...........One lousy sheep, eh Maz?

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I started out with nothing and still got most of it left.

yeah, what he said!...

Ah ha, I see we have another ungrateful wretch.


But, unlike the other gentleman, you asked after I'd already said that you would need to replace everything.

_________________
Good in straight lines
2001 X1 "The Tart's Handbag"
2001 FZS1000 "The Fridge"

you didn't say what to throw away or replace, i was just trying to clarify!..

The whole lot, chuck the bike in the skip (but send me your postcode first... )

In my head, throw away and replace meant everything that might come in contact with the fluid. I can see that not everyone gets some of the stuff in my head, though. The bloody telepathy thing stopped working after I got that visit from the... hold on... tech forum...

_________________
Good in straight lines
2001 X1 "The Tart's Handbag"
2001 FZS1000 "The Fridge"

hmmm, so really everytime you buy a secondhand buell that has use DOT 5 on the reservoir cap you should repace all the seals and rubber hoses, just to be on the safe side if you get my drift, you never know what fluid past owners have topped up with.
calling a totally incompatible fluid 5.1 seems utter stupidity!....

Bet you can't guess which country's Department Of Transportation came up with that one then.

Gowan, have a guess, gowan gowan gowan

Oh, and brake fluid should never need to be topped up. If it does need topping, you may have a more serious issue which I'd recommend sorting PDQ. Alternatively, you may be just wearing the pads down, in which case, don't top up or it'll FUBAR your paintwork as soon as you change the pads.

_________________
Good in straight lines
2001 X1 "The Tart's Handbag"
2001 FZS1000 "The Fridge"