What's a good way of assessing changes in performance?

[stinkwheel]

So an easily done, objective and preferrably quantitative test of how a bike is performing relative to how it did previously.

So if I start doing a few engine modifications on my restricted VFR, a way of checking to see if they have increased the power output or not.

A dyno run is all well and good but it's an expense and a hassle (and is in iteslf pretty subjective anyway). Seat of the pants has been proven to be nowhere near.

0-60 times seem obvious but it's difficult to be consistant and measuring it isn't as easy as it seems.

Standing 1/4 miles are similar and so much is down to the launch.

I was considering something like crossing a fixed point on a road nearby at, say, 4,000rpm in third gear then snapping the throttle open and seeing how far I travel by the time it hits 11,000?

Or a 40mph top gear roll-on between two fixed points and see what the speed is by the second point?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Islander]

[Pete.]

Datalog accelleration over a fixed time in a certain gear. I'd lend you the hardware but the last person who borrowed it fecked it up.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Kickstart]

Hi

Find a clear road and record the performance along there accurately (ie, half decent high frequency GPS), highish gear roll on from low speed to silly speed (lower gear means you get to the red line, higher gear means it takes longer so you will have a more accurate graph). Do your mods and do it again (same weather conditions, same amount of fuel in the tank, same clothing, etc).

In theory you could work out a dyno curve from the results, but practically I would just make everything as consistent as possible to get comparable results.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[G]

I think there may be phone apps that can do this?
Though may be just for OBDII vehicles.

I have a veypor which can do this - if I can work out where it is (unlikely in the next few weeks to be honest), you're welcome to borrow it and have a play.

Better yet, take work on one of the basic formulas along the lines of:
Pub power = Money spent + (brands names * shinyness of parts).

[Howling TerrorOutOfOffice]

Pardon the sidetrack gents...Just how much influence does atmospheric pressure play in this, if any? And air temperature? I ask as I get a noticeable power increase on cool days, mornings especially.
Not so much on the big twin, moreso the single 250.
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[G]

A good point - dyno places will have things worked in to their figures to account for this.
The 125/250cc 2 stroke GP bikes would be seen doing plugs chops in the morning to see if they need to change jetting for the current conditions!

[Islander]

[temeluchus]

Dear but cool:
https://www.veypor.com/vr2.html

there are a few datalogger and speedo apps for android which may do what you want.
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Some shite cruiser. Now with guns and FREEDOM!

[stinkwheel]

All good ideas.

I was thinking more along the lines of something I could do with either a stopwatch or (preferrably) measured points and/or the speedo.

I don't have any GPS compatable related electronic gizmos.

Thing is, with this new VFR being restricted, I DO have the CDI and carbs off the old one and I just got a set of UK market cams off ebay for much cheapness (there is no real second-hand market for VFR750 cams, they don't fail as a rule).

I'm concious that there is a real potential to make things worse by swapping parts off different models.

On a quick "seat of the pants" test last night (I put the old brakes back on, they are awful!), it appears to go like shit off a wet shovel compared to my old one. This might be because it was dark and I'm too used to riding the enfield but a dyno run might be in order to check some of this stuff hasn't already been done.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[garth]

Video the clocks and compare?

[G]

[Walloper]

Performance can easily be compared before and after by the methods listed.
The place you test must be the same.
Climatic conditions must be the same. i.e. Height of summer versus depths of winter when air densities are significant. (Dependant on how exacting your standards are.)

There is a simple performance test for Off Road equipment where each day the equipment has to freewheel down a known ramp (a bit of the quarry/mine measured out as a test site.) and apply full braking.
The equipment must stop within a measured distance or it must go to the shop for repair.

So your test area must be between McGinty's paper shop at the bottom of the hill and the bus stop outside Tesco at the top. 300-400 yds should be easy to time.
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[Kickstart]

Hi

Normal GPS might be a bit slow. Most are only 1Hz. Probably overall give you an idea, but might not give you any real idea of where it has gained / lost speed. You can get high performance GPS systems (10Hz ones are not that expensive).

Temperature will have quite an effect.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing