air fuel ratio on the dyno

[MattsDad]

There's too much to quote there Al and I won't give a biography as you did but in terms of what I've 'read', lets just say i have another 4 road goers as well as the one I race.
I'm not having a pop at you either, nor dyno's in general as I think they serve certain purposes. If someone has the inclination to go dyno, you might think they'd be able to pop the jet up or down depending on summer or winter and I don't think our climate gives the massive swings to overhaul completely.
My contention is that Lambda sensors don't work correctly on 2 strokes; I didn't read that on google today, I read it 2 years ago when I bought the sensor and from my own experience. Scooter dyno shops do not set up AFR correctly / optimum, they send you out rich so you don't come back and if that gets people to rallys etc its a happy compromise / margin for error, but how many punters understand that and your reply would be you ask them what its intended for. Equally if you want optimum for race, no chance, I've never seen someone take a dyno with them, you take the plug spanner out!

Tony, yes DAJ, been a while since I've looked at the blurb, I'll have a look tomorrow.

[tony]

No probs here mate.. all good chat
What do you race? Do we know each other?
I never take plug out for jetting btw... The bike is set before .. the air pressures are taken at the time.. humidity.. then you can cross reference that on a jetting chart... but with egt gauge you can see whats going on anyway.

[OzOAP]

Racing karts are a million miles away from road going scooters.

See ya Saturday Al :baddevil:

[tony]

Looking good Mr Hopkirk

[Speed Demon]

But I think you will be very surprised when you get a brake dyno to how much motors can be 'out'.

Al has pointed out three times already that he has a loading brake dyno - he had one before the inertia dyno! It does step testing etc. What part of that don't you understand?

[drunkmunkey6969]

At the end of the day the scooters leaving the workshop are set up for getting to rallys and back. The feedback I get from my customers is positive so something must be done right somewhere. They are set up using a combination of an inertia dyno, an AFR meter ,road testing and experience.

I dont think the average rally going scooterist can ask for muck more than that Al, good stuff.

What kind of scooters do you think we test here? I'd love you to come and tell a customer with a GT kitted TV running a 25mm through the airbox and a clubman all about adjustable jetting. He may well ask you if the kit comes in chrome I'll let you come and weld a boss on his downpipe for an EGT gauge.

LOL....funny, and i concur completely.

The fact is we test all kinds of scooter here. Most but not all have a remit of not squeezing every last hp from the bike but to jet it so it runs cleanly and gets them to where they want to go and back.

That is commonly the case, and the dyno is an ideal tool to facilitate those settings.

What others do I don't know but I don't think I'm on my own here.

You are not, i am in agreement with most (if not all) of what you say.

[drunkmunkey6969]

If someone has the inclination to go dyno, you might think they'd be able to pop the jet up or down depending on summer or winter.

Well you'd think wouldnt you......but sadly no. In fact if you spent a day at the dyno with me (which anyone is welcome to do) you'd be very surprised at the scooters we get through. One chap booked his scoot in for a dyno, but forgot to tell me that it had broken down last time he was out with it (therefore it didnt run at all on arrival as he pulled it out of the van) and asked if the dyno could tell him what the problem was?? WTF!!?? I had to explain what a dyno run was actually for.....not sure he understood. Occasionally i have to actually persued a customer that a dyno is in fact NOT what they need, its really bizzarre, you'd be quite surprised i think.

My contention is that Lambda sensors don't work correctly on 2 strokes;

Well I'd have to say that AFR meters attached to a dyno and callibrated for the software certainly DO work......?? Not sure why you think they dont? To use the word 'DONT' would imply that they have no use and no discernable function whatsoever? And that is not true. Maybe you mean that they are not perfect? (but what is?) That would perhaps be a more suitable phrase??

Scooter dyno shops do not set up AFR correctly / optimum, they send you out rich so you don't come back and if that gets people to rallys etc its a happy compromise / margin for error, but how many punters understand that and your reply would be you ask them what its intended for.

Well.....if it gets to and from the rally in all varying weather and load conditions and covers thousands of faultless miles, whats not set up correctly exactly? Are you suggesting that to remove the 'safety buffer' to cover varying load and weather conditions is a better idea? Im confused?

Equally if you want optimum for race, no chance, I've never seen someone take a dyno with them, you take the plug spanner out!

Is that to suggest that none of the racers at the race track own or use dynos.....lol? Or that their scooters have never been set up on a dyno? LOL. I think that probably 90+% use dynos for pre-race setups at some point, and quite a few own them (JB, Charlie Edmonds, Chiselspeed, myself and others?). I guess you just dont see them at the race track because its a big-ass piece of equipemt to lugg round and most racers have already set the machines up prior to race day, with a few varaiables to hand for fine jetting on the day. Cant imagine a big que for the dyno on race day with Charlie Edmonds at the front saying.....oops, forgot to sort me jetting!! lol


Anyway, at the end of the day, i can say this.......there are litterally thousands of scooterists out there, that have little or no technical understanding, have incredibly badly set up scooters....and they do need someone to help them to set their machines up, most of their mates are of the same ilk, and most do not know a local tuner or person they can ask to do the job for them (least not one they trust or that does it properly) and so they largly benefit from scooter garages re-jetting their carbs and fettling with their machines in whatever manner (dyno or by ear etc) to help get them dialled in. So to judge one method or another is perhaps not quite fair, each has its benefits under different circumstances and price brackets.

In my own (and somewhat unimportant) opinion, i always presumed that the people that slagged dynos off the most are those that liked to take the same amount of cash off their customers for setting them up, but didnt want to invest thousands of pounds in the equipment. Because lets be right about this, dynos are not a cheap bit of kit.....so its far far easier to say 'bollox' to them and the AFR meters etc, than it is to get your hand in your pocket for all the equipment costs!! lol. Dynos are a tool, some people choose to use them and adapt their methods accordingly, some do not.

And so there are thousands of scooterists that benefit from EITHER method (old school or dyno) by then getting to and from rallies more reliably than they would have otherwise (and that is all MOST want). AND......of course there are SOME scooter shops that are just plain robbers in my opinion, taking money off people for what is quite plainly shoddy service in the pursuit of cash gain, and again SOME of those shops have dynos, and some dont.........DONT balme the tools, blame the operator.

And as for the final tiny % of dyno users that are looking for the final tiny % of gains for top-level race set-ups.....well, who am i to criticise their methods whatever they are.......inertia dyno, loading dyno, old school no bollox tuning......at the end of the day if it gets them over the line in 1st place, then that is what is right for them and their customers etc. We just do what we do, it works for us, and it works for our customers and their specific requirements...........cant do much more than that can we?

[Speed Demon]

Well said Dan

On another note lets quash all this nonsense about there not being a load with an inertia dyno.

Think about it. If you put your scooter into fourth gear, lift the back wheel off the floor and accelerate how long will it take to rev out? A second perhaps.

There is a load on an inertia dyno and it is proportional to the mass of the drum, but it isn't adjustable.

@ Matts Dad - ironically of all the situations that an inertia dyno can't simulate - your situation of doing a 1/4-mile - is one where it replicates quite closely. If a run through all the gears takes 16 seconds on the track then you'll probably find that it's pretty similar on the dyno too. The more power you have, the shorter a run through all the gears will take.

Whether you believe that the AFR has any relevance to 2-strokes is up to you. Are you trying to say that anyone who uses one is a charlatan just on the basis of something you've read on the internet? That's classic keyboard warrior behaviour. Clearly they do work because you can manipulate the graphs by changing jets and the results remain largely repeatable on different days. What you do with that information is then a subject for interpretation.

Just because you've never found a dyno operator that you trust doesn't mean that none of them know what they are doing.

[tony]

Well Sticky, ....If you run an inertia dyno as its supposed to be used from a standing start it has load.. of course... but how to you hold it in midrange and replicate load it has in the real world without a load device?
All I am saying is that this is the way to go for tuning in the scooter world.. you know this is true already.
I've seen how little load is on a motor on an inertia dyno once the drum is spinning and how little effect it has when mapping ignitions.
I was only trying to be constructive and give out some of my findings and things I've learnt over the years.

[drunkmunkey6969]

Both Sticky AND Tony are quite right: an inertia dyno DOES have load, getting a 200kg, 400kg or whatever weight roller to accelerate takes work from an engine and does provide load, but no it isnt adjustable and cant be HELD at a specific RPM unit for an extended duration.

And I personally think the consitency in results from our inertia dyno (and linked AFR system) are brilliant. The abilty to track increases/decreases in BHP and performance, along with the detailed and repeatable AFR information, that shows amazing consistency when altering the jetting is outstanding.

When on the dyno and watching the power curves, matching them to the AFR curves, knowing which runs you held what throttle positions, knowing which parts of the curves relate to which RPM range/throttle poistions and specific jet ranges takes some doing and is very rewarding once you establish a repeatable and consitant pattern of data/adjustmenst/results.

Of course nothing is perfect, and everything can be improved, but to what end? And where do you draw the line? Cost vs need/benefit ratios have to be considered at some point by both the operator (set up costs) and customer (incereasd cost for never ending tests/equipment etc).

I would think (and i could be wrong of course) that if a dyno operator is setting up a scooter for a rally going scootersist to cover various loads and weather conditions, the end result on the jetting wouldnt be VASTLY different between either an inertia dyno or a loaded device......in my opinion the customers scooter set up, and the actual carb adjustments that can be made (carb adjustability and jetting size jumps) are usually the limiting factor for what can be achieved, NOT the testing device used!