TPS/Carb jetting/Cans!!

[leevtr]

Well I don't think the seasons make enough of a difference, otherwise manufacturers wouldn't be able to find an across the board setting to sell their bikes. My old storm I had for 4 years, had it dynojetted, never touched it again. I do know that the heat did affect the top end, my I could only tell by my top speed at the end of a lap of the ring, couldn't feel it day to day.

I looked at the dynojet settings this morning on the fitting guide. Admittedly this is with their needles, and might not work with FPJ, but I have used 180 jets, and AF screw 2 turns out. The result below. The red line is my old storm, which, at the time of the dyno run, had 30-odd thousand miles.The blue is my current bike, about 12000 at the time. Both were standard DJ settings, no dyno time ( other than these power runs where no adjustments were made. ) These runs were on the same dyno, by the same operator, about 7 years apart. Looking at Griffs output of 110bhp, and bearing in mind he isnt quite happy with the way the bike runs, mine doesn't look that optimistic after all.

Ones running lean, and ones running rich? You must have felt that surley?

Sent from my GT-I9300 using Tapatalk 2

Well whatever the mixture lines are showing, look at the power curves. They are both very smooth, so theres nothing there to feel.

[seb421]

Well I don't think the seasons make enough of a difference, otherwise manufacturers wouldn't be able to find an across the board setting to sell their bikes. My old storm I had for 4 years, had it dynojetted, never touched it again. I do know that the heat did affect the top end, my I could only tell by my top speed at the end of a lap of the ring, couldn't feel it day to day.

I looked at the dynojet settings this morning on the fitting guide. Admittedly this is with their needles, and might not work with FPJ, but I have used 180 jets, and AF screw 2 turns out. The result below. The red line is my old storm, which, at the time of the dyno run, had 30-odd thousand miles.The blue is my current bike, about 12000 at the time. Both were standard DJ settings, no dyno time ( other than these power runs where no adjustments were made. ) These runs were on the same dyno, by the same operator, about 7 years apart. Looking at Griffs output of 110bhp, and bearing in mind he isnt quite happy with the way the bike runs, mine doesn't look that optimistic after all.

Ones running lean, and ones running rich? You must have felt that surley?

Sent from my GT-I9300 using Tapatalk 2

Well whatever the mixture lines are showing, look at the power curves. They are both very smooth, so theres nothing there to feel.

baldrocks mate looking at those AFR curves there would be dead spots all over the place and hesitation on the throttle

Your engine is essentially an air pump, Ideal and theoretical numbers are derived for your bike for it to run its best for smooth power it should be a consistent air to fuel ratio ideally 14:1 through out the rev range

http://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio

[leevtr]

I cant even be bothered to respond to that now. Obviously you are a complete expert, and I know nothing. And this is how you spell ' Surely '.

[seb421]

I cant even be bothered to respond to that now. Obviously you are a complete expert, and I know nothing. And this is how you spell ' Surely '.

I don't claim to be an expert mate or to put across that you know nothing but either his dyno unit is buggered or there are other forces at work because there should be no way such a varied mixture should give a sickly smooth power curve

I don't intend to piss you off or anything it just doesn't make sense scientifically as the burn will be all over the place

Thanks for the grammar

[VTRDark]

I were that good/brave/stupid...delete as applicable

Mmm which one to choose only teasing

It is interesting to compare different peoples dyno print outs, but they are not be all and end all of everything, see post http://www.vtr1000.org/phpBB3/viewtopic ... 14#p238575
a real world road test and the way a bike feels/runs and fuels will tell you how a bike is running. If it feels sluggish or is hiccuping using excess fuel etc it tells one that something is not quite right. You could have a perfect read out and the bike does not perform as well as it could out on the road/track. The dyno machine is just a tool to help you determine what needs adjusting.

If it wasn't for not having a long straight where one could safely go flat out in top gear to determine the right size main jet for performance, then one could near enough tune their own carbs spot on with a bit of seat of the pants judgement. How to tune a CV carb http://www.vtr1000.org/phpBB3/viewtopic ... 14#p111182 A track bike will be tuned for different conditions on that particular day just before the race. Obviously on a road bike it is not as vital but it does show how different conditions effects things.

I don't confess to know everything about carbs or dyno's and still have a lot to learn. Mostly it will come from experience as tuning carbs is a bit of a Black art. As for the dyno print outs I really don't understand a lot of it, but the A/F is easy to work out. It's pretty much imposable to have a dead straight line along the dotted line, but that is what one is aiming for as that line is there as a guide for a reason. Yet again the torque curve is easy to understand and one is aiming for a smooth transition from the bottom all the way through to the top. If you get both of them spot on then your laughing or is that grinning or does it, the bike may not quite feel right in real world tests and may need further tweaking.

This is why I take such an interest in carb tunning, I love the mystery behind it all. The theory is easy to understand but real world practise is something else. A black art.

If we had fuel injection then all this would not be such a problem as electronics would take care of the A/F ratio for us according to the map that is installed. In the case of racing they would change or alter maps accordingly to different conditions and setups, but for a road bike this is not really necessary.

(:-})

[leevtr]

I cant even be bothered to respond to that now. Obviously you are a complete expert, and I know nothing. And this is how you spell ' Surely '.

I don't claim to be an expert mate or to put across that you know nothing but either his dyno unit is buggered or there are other forces at work because there should be no way such a varied mixture should give a sickly smooth power curve

I don't intend to piss you off or anything it just doesn't make sense scientifically as the burn will be all over the place

Thanks for the grammar

Well like I said, the power curves dont show any dips, which would explain why the bike feels good. Is that not logical ??
Secondly, one of those lines AF is pretty damn close to spot on, and lets be honest, no one will probably ever achieve perfection , especially on a carbed bike. The other is 7 years old, so its hard to remember, but I dont recall any issues. Wierd thing is, the line that shows more fluctuation, is actually mated to the higher power curve, go figure. The other thing I think is worth pointing out, is both same set up, 7 year gap, and the power curves are almost identical, which cant be a coincidence.That must also mean his dyno was buggered twice. Plus the fact that after the first run, being pleasantly surprised at the outcome, I did ask about the accuracy, and the dyno had been calibrated with the last month.
He did call me a lucky b'stard though, with regards to the results !

No hard feelings, but I dont talk baldrocks. I can only tell you what I know from experience, which is what I'm doing in this instance.

[leevtr]

[quoteI were that good/brave/stupid...delete as applicable][/quote]

Now we both know what you want to say Carl

[seb421]

I cant even be bothered to respond to that now. Obviously you are a complete expert, and I know nothing. And this is how you spell ' Surely '.

I don't claim to be an expert mate or to put across that you know nothing but either his dyno unit is buggered or there are other forces at work because there should be no way such a varied mixture should give a sickly smooth power curve

I don't intend to piss you off or anything it just doesn't make sense scientifically as the burn will be all over the place

Thanks for the grammar

Well like I said, the power curves dont show any dips, which would explain why the bike feels good. Is that not logical ??
Secondly, one of those lines AF is pretty damn close to spot on, and lets be honest, no one will probably ever achieve perfection , especially on a carbed bike. The other is 7 years old, so its hard to remember, but I dont recall any issues. Wierd thing is, the line that shows more fluctuation, is actually mated to the higher power curve, go figure. The other thing I think is worth pointing out, is both same set up, 7 year gap, and the power curves are almost identical, which cant be a coincidence.That must also mean his dyno was buggered twice. Plus the fact that after the first run, being pleasantly surprised at the outcome, I did ask about the accuracy, and the dyno had been calibrated with the last month.
He did call me a lucky b'stard though, with regards to the results !

No hard feelings, but I dont talk baldrocks. I can only tell you what I know from experience, which is what I'm doing in this instance.

fair deuce mate, but I would ask that if its an identical set up then why such a difference with the fuelling across the range between the two?

[leevtr]

No idea. Like you said, there are many variants. I dont know what time of year the first run was done, temperature, nor the state of the air filter at the time, ( although I never let them get filthy ) and one bike had 20,000 more on than the other. Put 2 untouched bikes of the same year on the same dyno back to back and they still wont be identical.

[VTRDark]

but I would ask that if its an identical set up then why such a difference with the fuelling across the range between the two?

Two totally different bikes, different amounts of wear and tear on carbs, pistons, carbon build up etc. Different cans, maybe TPS being slightly different settings makes a difference, there are so many factors. This is why every bike is slightly different. Then you have to take into consideration that they are not back to back dyno runs on the same day under the same conditions with the same dyno tech doing the run. If it was that simple we would all have the same setups on our bikes.

I'm not sure it's possible to get a straight torque curve versus the A/F ratio though this would be ideal. Some say that these bikes should be tuned to torque which would give you a consistent pull of power throughout. But what about the fuelling this has to come into play as well. I guess it's a case of getting an even balance between the two. Like everything there is going to be a compromise somewhere. Is one aiming for maximum HP or is one aiming for perfect fuelling. Is the dyno tech setting the machine up to give you max HP (bragging rights) or is he setting it up for perfect fuelling. Then how do the different gears affect things. Why is Griff's dyno print out in 4th gear and not 6th.

Well one things for sure this has triggered my feel to learn more on the dyno side of things. I would love to understand how to interpret all the readouts and what's what. I would never rely on a dyno tech to do my tuning under normal circumstances, just as I would never take my bike to a garage for repairs and servicing. But I would use them for a power run so I can then decide what I need to change with my jetting myself. But for optimum results this would have to be done on the same day with the same dyno machine and dyno tech running the show

It would be nice just be able to determine which is the best size mains for highest speed and good pull above 7500 rpm, then once that's done the rest can pretty much be done on the road, but one may as well move onto the needles and then the pilot circuit while there. I just wish dyno runs did not cost so much money. It's not as if they are using a lot of electric or taking a lot of time to do a run. I suppose it's how they pay for such expensive equipment.

(:-})

[leevtr]

Two totally different bikes, different amounts of wear and tear on carbs, pistons, carbon build up etc. Different cans, maybe TPS being slightly different settings makes a difference, there are so many factors. This is why every bike is slightly different. Then you have to take into consideration that they are not back to back dyno runs on the same day under the same conditions with the same dyno tech doing the run. If it was that simple we would all have the same setups on our bikes.

I just said that

[tony.mon]

Seems to me that dyno runs are for two real purposes.
One is to get the bike, with it's current fitments (filter, cans, system, advancer, tps setting etc) set up to fuel at its best, and the second reason is to take a baseline reading, change something then take another reading. This gives you direct and real comparisons on a like-for-like basis, so that you can see what difference each small change makes.
An example might be raising needle heights, or fitting different cams.

But comparison runs weeks , months or years apart aren't really of any use, as the variables- ambient temp, air pressure, tyres fitted, pressures, wear, chain and sprocket conditions etc- will all play their part, and skew the figures. Even fuel temperature, which is why top race teams chill the fuel before a race.
All interesting, but fundamentally as useful as saying an orange tastes better than an apple.

Mines booked on for some development work on Monday 24th March, looking forward to that, as long as I can get a dry day or two to try some things first.
It's lean at the top end, 7-9,000, but strong low down, so the stacks I fabricated a while back may be inefficient at higher revs.
I'll swap them out for two std ones, long ones, and see if that gets it revving out cleanly again.
But I've changed so much in the airbox I really need to try to isolate what particular thing I've done it is that causes this issue, and then decide if it can simply be jetted to maximise the current setup or whether I need to undo one of the modifications.

Still want to move on to variable stacks and ram air, though, but I need to get this done first. That'll be my new baseline setting for the further work.
Small steps, perhaps, but you don't fall over as often that way.

[lloydie]

Monday the 25th tony the 24th is a Sunday !

[VTRDark]

And I think Bananas are better.

(:-})

[seb421]

Carl can you remember the size of the screws used in the bowl of the carb?

Want to replace mine with some socket headed ones, been a while since i made any changes cant cant remember what state they are in n