TMax DX on Dyno ?

[MrGrumpy]

Hi Guys

This is my 4th TMax, I have owned them since they first came out around 2002, and my latest one was bought new in March of this year and is the DX version. I have "tweaked" all my previous TMax's and the last 530 had a full Termi race system ( at great expense ! ) 16g DR Rollers in the standard variator, and a high flow air filter. I would say that this new DX was faster out of the box than any of my previous TMax's even after my "improvements" !

The 44hp figure is rear wheel as set up and measured on the PM Tuning dyno, and they are a very capable outfit well used to scooter set up.

I also have a Honda X-ADV and would say that "as delivered" the TMax was 99% as fast as the Honda on acceleration, so maybe Yamaha are being a bit coy with the HP figures, I dont know but all I can say is that the latest TMax is very very good.

Hope the above is of interest

Yes, very interesting thanks! I've always been intrigued that the mk6 Tmax seems so much faster than previous versions (and I've had all except the mk5!). It should be impossible to see 44bhp at the wheel if there is only 47 or whatever the official figure is at the crank, so I do think Yamaha are being, as you say, coy.

I've seen some test performance figures of the X-ADV, Tmax mk6 and Kymco AK550, and the Tmax was the same as the Kymco, despite allegedly have 6bhp (12%) less (albeit the Tmax is 20kg lighter). However, the X-ADV was significantly faster than both, despite being much heavier - though I noticed on my test ride that it doesn't feel it due to the way the power is delivered. It must be the extra torque of the NC engine and possibly the DCT.

Interesting!

[orange1290]

Well, the measurement by Yamaha of 47hp at the crank wasn't made on the dyno that recorded 44hp at the wheel, one was made in Japan and one somewhere in the UK. Dyno's (especially independent ones in so called 'tuning' shops) are notorious for giving different numbers (and being inaccurate), so unless all values were the output of the same measuring device, they are a meaningless comparison. Dynos are only useful when the SAME one is used for a before and after modification run is made.

[Ralph]

You loose about 30% of the power through a CVT transmission the X-max 300 is rated at 27 bhp at the crank and gives about 17/18 bhp at the wheel,
so 44 for the T-max seems dubious, though some Dynos make a calculation that measures this and gives a crankshaft output that would make more
sense.

[MrGrumpy]

Well, the measurement by Yamaha of 47hp at the crank wasn't made on the dyno that recorded 44hp at the wheel, one was made in Japan and one somewhere in the UK. Dyno's (especially independent ones in so called 'tuning' shops) are notorious for giving different numbers (and being inaccurate), so unless all values were the output of the same measuring device, they are a meaningless comparison.

Well, I agree that that is quite possible, though Tmaximus seems quite confident about the outfit he used. Its just that the suggestion that the stated 47bhp may be understated lines up other observations and tests that I've read. Its one of those lightbulb moments when the answer to a puzzle suddenly occurs. As you & I have both said, 44bhp at the wheel and 47bhp at the crank is impossible, so one figure is wrong! And Yamaha have an incentive to fib to make sure it still can be ridden on an A2 licence and can keep up with the Kymco AK550!

[bikerdezzie]

Got 46bhp on my mk3 at the back wheel on my old bike, had a power commander etc had been on dyno 3 times but i found 46 to be a bit hit n miss so knocked it to 43bhp and smoothed it out, not worth the hassle tbh i was quite happy with pipe, filter and jcosta variator.

[Tmaximus]

Just a short update to my last posting .... my TMax was dyno'd at PM Tuning before and after the work was carried out (same day ) so the 4hp gain up to 60 mph is true, and actually feels a lot more than that on the road, acceleration up to 60 is noticeably more rapid. It dyno'd at 44hp before and after the work, so peak HP did not increase, but curve shape is better. I accept that dyno's vary as do manufacturers claims, I have several bikes and scoots and most have ended up on a dyno to get the best from them, and next to my 690 KTM Duke R that has the KTM Power Parts 80HP cam and various other bits fitted that has 79hp at the rear wheel, this latest TMax probably feels the most impressive in terms of gains, so I consider the work worthwhile.

[EvilRacer329]

Let's not forget that Horsepower is a function of Torque x RPM; a Dyno measures power at the wheel, which itself is a function of the final drive ratio acting as a torque divider. I actually wish that manufacturers would stop quoting peak torque/power figures and would simply deliver a graph. As TMaximus has pointed out, the most interesting part of the improved performance he's documented is the increase in area under the curve, which translates to more thrust across a wide range of road speeds. A genuine real-world benefit.

Many tuned bikes only gain more power at the top-end, resulting in no noticeable difference at real-world speeds, while some even sacrifice mid-range torque/power in favour of higher figures at the very end of the rev range.

Nick

[Tmaximus]

Hi Nick .... your posting sums things up perfectly ! It's that "seat of the pants" feeling that is a combination of power, torque & gearing and probably hard to sum up with just peak HP figures, its the shape of the curve when properly understood means the most. It spun the rear wheel again today in the dry, and later on in the rain, for the first time in my life I used "rain mode" !!!!

[MrGrumpy]

. It spun the rear wheel again today in the dry, and later on in the rain, for the first time in my life I used "rain mode" !!!!

Isn't the traction control supposed to take care of that??

[Tmaximus]

Unlike an Aprilia, KTM or other sports bike the TMax TC is pretty basic and cuts the engine, not the seamless "electronic nanny" you get on sports bikes