Yamaha Tmax DX

[MrGrumpy]

Well, the max power output is very similar, so top speed won't be much different. Maybe the Akra exhaust on your mk4 gave a bit more power - it maybe that manufacturers design better OE exhausts as they need every bit of efficiency to pass emissions restrictions and still give decent performance.
I'm always amazed at the mk6's overtaking acceleration especially from around 25mph or so. Can't comment about Autobahn performance!!

[MrGrumpy]

My Mk 4 indicated 100mph easier than this new Mk 6 ( when I rode it in Germany !! ) Or is it that the Mk 6 is smoother /Quieter / pipe more restricted ?

Had another thought on this....I used to feel that the speedo on my mk4 was outrageously optimistic - when the roadside speed warning signs said you were doing 30, the speedo read 36! And I seemed to be doing an indicated 70 on roads that I used to do 60 on, and not feeling any faster. So it seems quite possible that when the mk4 speedo said 100 you were only doing 90 at best, and possibly as low as 85! The mk6 speedo seems a bit more accurate, possibly halving the error (this is all very unscientific), so the reason why the mk6 may feel more reluctant to reach 100 on the speedo is that its actually going 5 or more mph faster!!

[abitmad]

The nav on my DX showing true speed reveals that the speedo is rather inaccurate by about 10% fast across the range. So 100 on the clock would in fact be only just over 90. As you say, I've also compared it with those electronic roadside speed displays which confirms the 10% or so fast reading.

But having had a large number of different bikes over a long period, I've noticed that reading fast is a very common situation, often with cars too. I've even heard it said that it's done deliberately by the manufacturers though have no idea if there's any truth to that. I can understand speedos reading a bit fast, because total accuracy is probably unachievable so better to err on the side of fast than slow, but 10% and over is rather too inaccurate I'd say.

[Mr Xmax]

I looked into this a little while back. Basically speedos are allowed to read fast (by a certain amount) but can never under read legally (at least in UK). That means manufacturers do deliberately make them over read so there's a margin of error.

[MrGrumpy]

Yes, to over-read is better than under- reading - for one thing, if it under-read, then you'd be exceeding speed limits when you thought you were sticking to them, which would produce all sorts of snags. So manufacturers err the other way, and anyway, its cheaper to tune the speedo rather than the engine....

Yes, I agree that the mk6 Tmax over-reads by by around 10% - but I think the mk4 was far worse than that, hence its apparently superior top end performance!

[tmaxrobbo]

Yes, to over-read is better than under- reading - for one thing, if it under-read, then you'd be exceeding speed limits when you thought you were sticking to them, which would produce all sorts of snags. So manufacturers err the other way, and anyway, its cheaper to tune the speedo rather than the engine....

Yes, I agree that the mk6 Tmax over-reads by by around 10% - but I think the mk4 was far worse than that, hence its apparently superior top end performance!

Agreed when my my 4 was indicating 100 it was 82 on the Tom Tom

[MrGrumpy]

Agreed when my my 4 was indicating 100 it was 82 on the Tom Tom

Blimey - even worse than I thought! I probably never exceeded a real 70 on mine in that case....all those years of being wild and crazy by exceeding speed limits and I now find that I was probably travelling slower than them!!!

[Stephen]

Tmax has had the 600 service done £99.00,took just over an hour,been out for a decent run today,does 5K rpm and 60 mph sound about right,to my un-mechanical ear it seemed a bit high,but remember i also run a x-adv and had 650 burgmans for years.

Steve