Should I do it?
#41
11-05-2006, 01:56 AM
RE: Should I do it?
Those figures are not rear wheel HP. They are measured at the counter shaft...big difference. A dyno measures rear wheel HP.
ORIGINAL: Iowaguy
I hope his advice helps you. Just fyi- I was in a Honda shop yesterday looking for a couple links for my oem chain since I put on a 45 rear sprocket and the chain won't go around it now. Anyways, I was looking at the new CR's and CRF's. They had a bunch of new '07's on the floor already. I asked them if they had any idea how much horsepower the CRF 250 and CR 125 put out. They got out their printouts from Honda- 38 horse for the 125 2-stroke, 36 for the 250 4-stroke. The 450 I can't remember exactly, but I think it was around 46. I thought this was pretty eye opening because really, you're probably not far off from a full on MX bike's horsepower. But that 125 is a real power monger imo. They couldn't tell me about the X models, you know the enduro CRF's with lights. Man, those are nice bikes, wonder if one could dual sport one of them. Looks like all it would need is turn signals. Can anyone tell me if that would be possible in IA?
I hope his advice helps you. Just fyi- I was in a Honda shop yesterday looking for a couple links for my oem chain since I put on a 45 rear sprocket and the chain won't go around it now. Anyways, I was looking at the new CR's and CRF's. They had a bunch of new '07's on the floor already. I asked them if they had any idea how much horsepower the CRF 250 and CR 125 put out. They got out their printouts from Honda- 38 horse for the 125 2-stroke, 36 for the 250 4-stroke. The 450 I can't remember exactly, but I think it was around 46. I thought this was pretty eye opening because really, you're probably not far off from a full on MX bike's horsepower. But that 125 is a real power monger imo. They couldn't tell me about the X models, you know the enduro CRF's with lights. Man, those are nice bikes, wonder if one could dual sport one of them. Looks like all it would need is turn signals. Can anyone tell me if that would be possible in IA?
#42
11-05-2006, 02:04 AM
RE: Should I do it?
ORIGINAL: Nobrakes
What is new is that this same test in 2nd gear now brings the front up strong also - and again, I gotta be careful about looping backwards.
And yes, as you've probably surmized about me needing to watch out about looping backwards, I am a beginner at wheelies - basically I can pull them up, ride a short distance and drop back down, but I haven't yet mastered finding the balance point and keeping it up longer.
But suffice to say that 2nd gear, no clutch, stock gearing wheelies are entirely possible now with this setup - just whack the throttle open and give an ever so slight tug on the bar. I was actually pretty surpised by this. In fact, I think it's a bit easier to do it in 2nd than in 1st because there seems to be a little greater control and RPMs left after the wheel is up in order to balance it out.
I haven't tried 3rd yet.
What is new is that this same test in 2nd gear now brings the front up strong also - and again, I gotta be careful about looping backwards.
And yes, as you've probably surmized about me needing to watch out about looping backwards, I am a beginner at wheelies - basically I can pull them up, ride a short distance and drop back down, but I haven't yet mastered finding the balance point and keeping it up longer.
But suffice to say that 2nd gear, no clutch, stock gearing wheelies are entirely possible now with this setup - just whack the throttle open and give an ever so slight tug on the bar. I was actually pretty surpised by this. In fact, I think it's a bit easier to do it in 2nd than in 1st because there seems to be a little greater control and RPMs left after the wheel is up in order to balance it out.
I haven't tried 3rd yet.
great news your getting close with the tuning. If your interested in learning to wheelie this thread may interest you http://www.advrider.com/forums/showthread.php?t=173274
#43
11-05-2006, 02:10 AM
RE: Should I do it?
ORIGINAL: tremor38
Those figure are not rear wheel HP. They are measured at the counter shaft...big difference. A dyno measures rear wheel HP.
Those figure are not rear wheel HP. They are measured at the counter shaft...big difference. A dyno measures rear wheel HP.
Also, I think the answer to this next question is "NO", but if one were to put on a different sized rear wheel OR change the final drive gear ratio, would that change the dyno's HP reading? I think the answer is no, since changing the gear ratio does not change power, but it's possible it could have some affect depending on how the machine is set up. I don't know much about dyno's and how they load the rear wheel.
I will say that my knobbies on my K760 were noticably worn down a little after the test and when I picked up my bike.
Also, another question, when they do these dyno runs, do they shift through the gears or stay in one gear throughout the test? Again, I'm just curious.
#44
11-05-2006, 02:10 AM
RE: Should I do it?
Awesome! I'm sure the futher tweeking/different jets you have planned will get that midrange totally dialed in. I never would have guessed about the knobbies not working so well on a dyno. I supposed that's where an experienced guy like Eddie aka 'Burned' comes-in.
Glad to hear you've made such quick improvement.
Glad to hear you've made such quick improvement.
ORIGINAL: Nobrakes
It most definitely did. My next step was to basically just lower the needle a bit (lean it out) by moving the clip from the 4th position to the 3rd. But instead, I followed Eddie's advice as closely as I could within the contraints of the jet sizes I had available to me. I reduced the main jet and the pilot jet to 152 and 52 respectively from 155 and 55. I didn't have the 145 and 45 sizes that Eddie recommended. Neither do I have that needle he mentioned, but I did move the clip to the 3rd position.
Well, it's a WHOLE lot better right now, but there still might be a hint of a stutter in the low mid-range, so I'm going to order the jets and needle he recommended and give that a try.
And by better, I mean that it is pulling VERY strong now in the mid-range, similar to what my CVK was doing in that range before I swapped. So now I have both a very strong pull right off the start when I whack the throttle that the FCR provides as well as a good solid strong pull in that mid-range. Before it was stuttering and sputtering there and noticably weaker than what the CVK was delivering. So right now, I'm close to having the best of both carbs.
As I've mentioned before, my baseline grunt test is to whack the throttle open at low RPM in 1st gear. All the times before w/the 300cc and CVK, the front would come up with a little tug. But now I have to be careful of looping the bike backwards - it comes up strong and fast. Remember, this is with no clutch, stock gearing, and a size 120 tire, all of which pessimize wheelying capability.
What is new is that this same test in 2nd gear now brings the front up strong also - and again, I gotta be careful about looping backwards.
And yes, as you've probably surmized about me needing to watch out about looping backwards, I am a beginner at wheelies - basically I can pull them up, ride a short distance and drop back down, but I haven't yet mastered finding the balance point and keeping it up longer.
But suffice to say that 2nd gear, no clutch, stock gearing wheelies are entirely possible now with this setup - just whack the throttle open and give an ever so slight tug on the bar. I was actually pretty surpised by this. In fact, I think it's a bit easier to do it in 2nd than in 1st because there seems to be a little greater control and RPMs left after the wheel is up in order to balance it out.
I haven't tried 3rd yet.
IMO, even with this level of mods, I'm not so sure. Maybe with the higher performance cams and maybe a more aggressive CDI we might get close. But those MX bikes are purpose built for full-time WOT and power delivery. Not only that, but the suspension on those bikes are 100% better for their purpose than ours would be on the MX track - I think ours is just way too soft for that. But all that performance comes at huge maintenance overhead with VERY frequent top end rebuilds and the works.
But honestly, the KLX "331" + FCR is perfect for me right now. Good solid torque where I want it - down low. Snappy throttle when you want it, but very controllable for the slow technical trails that I like. Perfect for popping the front up over logs and streams, yet not so agressive that it is hard to control in the tight stuff. And when you want to, you can wind it out fast to your heart's content.
Compared to stock, or even what I had a few months back w/the 300cc & CVK, it has a totally new character with the larger displacement and the pumper. I wound out the gears a little bit ago on a short straight and before I knew it I was up to 75 MPH with room to spare in very short order. What a blast! I wish I could have tried the pumper on the 300cc to see how that was, but the very long delivery time from FSW just didn't allow for that. While the combination I have was not cheap to do, about $1800 counting the pipe, it has really made this bike the ultra-fun street legal trail and off-road bike that I wanted. I am 100% happy. It's been a fairly long time in getting here and I'm not sure I'd want to go through it all again, but the end result is totally worth it to me.
I really like those, too. Also check out the new 2007 WR's - those look pretty sweet also and shouldn't be too hard to make street legal in states that allow that.
ORIGINAL: Iowaguy
I hope his advice helps you.
I hope his advice helps you.
Well, it's a WHOLE lot better right now, but there still might be a hint of a stutter in the low mid-range, so I'm going to order the jets and needle he recommended and give that a try.
And by better, I mean that it is pulling VERY strong now in the mid-range, similar to what my CVK was doing in that range before I swapped. So now I have both a very strong pull right off the start when I whack the throttle that the FCR provides as well as a good solid strong pull in that mid-range. Before it was stuttering and sputtering there and noticably weaker than what the CVK was delivering. So right now, I'm close to having the best of both carbs.
As I've mentioned before, my baseline grunt test is to whack the throttle open at low RPM in 1st gear. All the times before w/the 300cc and CVK, the front would come up with a little tug. But now I have to be careful of looping the bike backwards - it comes up strong and fast. Remember, this is with no clutch, stock gearing, and a size 120 tire, all of which pessimize wheelying capability.
What is new is that this same test in 2nd gear now brings the front up strong also - and again, I gotta be careful about looping backwards.
And yes, as you've probably surmized about me needing to watch out about looping backwards, I am a beginner at wheelies - basically I can pull them up, ride a short distance and drop back down, but I haven't yet mastered finding the balance point and keeping it up longer.
But suffice to say that 2nd gear, no clutch, stock gearing wheelies are entirely possible now with this setup - just whack the throttle open and give an ever so slight tug on the bar. I was actually pretty surpised by this. In fact, I think it's a bit easier to do it in 2nd than in 1st because there seems to be a little greater control and RPMs left after the wheel is up in order to balance it out.
I haven't tried 3rd yet.
Just fyi- I was in a Honda shop yesterday looking for a couple links for my oem chain since I put on a 45 rear sprocket and the chain won't go around it now. Anyways, I was looking at the new CR's and CRF's. They had a bunch of new '07's on the floor already. I asked them if they had any idea how much horsepower the CRF 250 and CR 125 put out. They got out their printouts from Honda- 38 horse for the 125 2-stroke, 36 for the 250 4-stroke. The 450 I can't remember exactly, but I think it was around 46. I thought this was pretty eye opening because really, you're probably not far off from a full on MX bike's horsepower.
But honestly, the KLX "331" + FCR is perfect for me right now. Good solid torque where I want it - down low. Snappy throttle when you want it, but very controllable for the slow technical trails that I like. Perfect for popping the front up over logs and streams, yet not so agressive that it is hard to control in the tight stuff. And when you want to, you can wind it out fast to your heart's content.
Compared to stock, or even what I had a few months back w/the 300cc & CVK, it has a totally new character with the larger displacement and the pumper. I wound out the gears a little bit ago on a short straight and before I knew it I was up to 75 MPH with room to spare in very short order. What a blast! I wish I could have tried the pumper on the 300cc to see how that was, but the very long delivery time from FSW just didn't allow for that. While the combination I have was not cheap to do, about $1800 counting the pipe, it has really made this bike the ultra-fun street legal trail and off-road bike that I wanted. I am 100% happy. It's been a fairly long time in getting here and I'm not sure I'd want to go through it all again, but the end result is totally worth it to me.
They couldn't tell me about the X models, you know the enduro CRF's with lights. Man, those are nice bikes
#45
11-05-2006, 02:13 AM
RE: Should I do it?
ORIGINAL: MaverickAus
great news your getting close with the tuning. If your interested in learning to wheelie this thread may interest you http://www.advrider.com/forums/showthread.php?t=173274
great news your getting close with the tuning. If your interested in learning to wheelie this thread may interest you http://www.advrider.com/forums/showthread.php?t=173274
That Losiu dude is quite the wheelie master.
#46
11-05-2006, 02:02 PM
RE: Should I do it?
That's were things get a bit screwy with a dyno. If you're talking about an inertia dyno, inertia X Acceleration=Torque, so if a drum with the same inertia is accelerated faster you should get a higher torque result. Inertia of the vehicle's drive train is also taken into account, but, yes the reading is taken at the rear wheel. Horspower=Touque X RPM, so if you accelerated to the same RPM or higher, your horsepower should be more. It doesn't seem right, I know. Maybe someone with more dyno experence than myself can contribute. Of all the dynos, the inertia drum type is the least expensive and yields horsepower results that are 10-15% higher than brake or eddy current dynos. It would be interesting to know which type of dyno your 'Tuner' used.
ORIGINAL: Nobrakes
I'm curious about this also - the torque measurement - is that also at the rear wheel? I think the answer is yes, but I want to make sure. Doesn't seem like it could be anything else without punching in the gear ratios and back-calculating to the crank.
Also, I think the answer to this next question is "NO", but if one were to put on a different sized rear wheel OR change the final drive gear ratio, would that change the dyno's HP reading? I think the answer is no, since changing the gear ratio does not change power, but it's possible it could have some affect depending on how the machine is set up. I don't know much about dyno's and how they load the rear wheel.
I will say that my knobbies on my K760 were noticably worn down a little after the test and when I picked up my bike.
Also, another question, when they do these dyno runs, do they shift through the gears or stay in one gear throughout the test? Again, I'm just curious.
ORIGINAL: tremor38
Those figure are not rear wheel HP. They are measured at the counter shaft...big difference. A dyno measures rear wheel HP.
Those figure are not rear wheel HP. They are measured at the counter shaft...big difference. A dyno measures rear wheel HP.
Also, I think the answer to this next question is "NO", but if one were to put on a different sized rear wheel OR change the final drive gear ratio, would that change the dyno's HP reading? I think the answer is no, since changing the gear ratio does not change power, but it's possible it could have some affect depending on how the machine is set up. I don't know much about dyno's and how they load the rear wheel.
I will say that my knobbies on my K760 were noticably worn down a little after the test and when I picked up my bike.
Also, another question, when they do these dyno runs, do they shift through the gears or stay in one gear throughout the test? Again, I'm just curious.
#47
11-05-2006, 05:42 PM
RE: Should I do it?
I think he said is was a Dynojet 250.
It really depends on how well the machine can put a load on the rear wheel and how well it can determine what that load was. The load on the rear wheel and how fast it is spinning determines the power. And as Eddie said, if the rear wheel is slipping due to the knobbie tread, then the full power of the bike will not be delivered to the machine and you'll get a low reading.
If one hooked the rear wheel up to a generator and powered an electrical load - that would be one way of precisely measuring the output, i.e., just measure the voltage being produced and the current being pulled through the generator - power = current * voltage. But you'd also need to know what the efficiency of the generator was. For example, my pesimized 22 hp turns out to be 16 Kilowatts if you do the conversion. But the generator itself may only be 50% efficient, so the real output might be 32 KW - that's where it would get squirrely I think since generator efficiency is probably not a constant with its RPMs. Either way, that's a pretty big electrical load and would require a fairly hefty generator and some good sized heating elements to load it. But it would be one way of doing it.
But you should get the same reading for output power regardless of the drive train, rear wheel size, etc. Rear wheel torque is an entirely different matter and that does depend entirely on the drive train. Power is essentially a measure of how fast that torque can be delivered.
While I'm familiar with the physics of power and so forth, dynometer implementations are new to me so a lot depends on how they are actually implemented. Hence my questions. I'm sure Google has the answers.
It really depends on how well the machine can put a load on the rear wheel and how well it can determine what that load was. The load on the rear wheel and how fast it is spinning determines the power. And as Eddie said, if the rear wheel is slipping due to the knobbie tread, then the full power of the bike will not be delivered to the machine and you'll get a low reading.
If one hooked the rear wheel up to a generator and powered an electrical load - that would be one way of precisely measuring the output, i.e., just measure the voltage being produced and the current being pulled through the generator - power = current * voltage. But you'd also need to know what the efficiency of the generator was. For example, my pesimized 22 hp turns out to be 16 Kilowatts if you do the conversion. But the generator itself may only be 50% efficient, so the real output might be 32 KW - that's where it would get squirrely I think since generator efficiency is probably not a constant with its RPMs. Either way, that's a pretty big electrical load and would require a fairly hefty generator and some good sized heating elements to load it. But it would be one way of doing it.
But you should get the same reading for output power regardless of the drive train, rear wheel size, etc. Rear wheel torque is an entirely different matter and that does depend entirely on the drive train. Power is essentially a measure of how fast that torque can be delivered.
While I'm familiar with the physics of power and so forth, dynometer implementations are new to me so a lot depends on how they are actually implemented. Hence my questions. I'm sure Google has the answers.
#48
11-05-2006, 07:40 PM
Join Date: Feb 2006
Location: Roswell, NM
Posts: 5,432
RE: Should I do it?
ALl right Brian, since you are a tech number guy, this should help.... There are 2 types of Dynos. Inertia and loading. I do not have experience with loading type, but I know a little of Inertia type, Dynojet uses inertia type. 1 horsepower = applying a 550 lb force thru a distance of 1 foot in 1 second. So to measure HP you need to measure force in lbs and velocity in feet per second. Inertia dynos measure the time it takes to rotate the steel drums one turn. So, if you change to a smaller tire, or change to lower gearing, it will show an increase in hp and torque numbers, by as much as 25% !!
The correction factor represents the "loss" from crank thru drivetrain to the rear wheels. When they do correction numbers they assume a mechanical efficiency of only 85% ...... barometric pressure, humidity, temp, etc..... That translates usually around a 7% difference. I can't remeber the conversion they do. summin summin square root etc....lol..... It is SAE conversion that Dynijet uses. Another thing about Dynojet, is the machine assumes, in corrected hp, that all engines are using the same rotating engine mass. So, the corrected hp numbers would assume the same rotating mass to a 250cc than it would to a 330 cc.... there is a lot I still don't understand either, or even remeber!! dang old age. lol lol
But, if you used a lighter wheel, a non-knobby tire, a tighter strectched chain, etc...you would have less rotaing mass, and you would "fool" the dyno into thinking more hp and torque. So, really to do a dyno with knobbys, you are robbing yourself of at least 8-9 horsepower. If you get the chance, etc, change to a street tire and re dyno, and I would bet you would be around the low 30's range.
Anyway, that's why a dyno is not a good test to determine actual hp, or compare your hp to others, it is only a good test with a starting point, and to help you tune. That's it. But , it is the best standardized test that is available in a mass market. There is a dyno that measures actual true hp at the rear wheel, but the thing runs in the millions and I have never seen one. Only read about it.
Even better, there is a method, I can't remeber what it is, to take your displacement, bore x stroke, cubic centimeter volume, intake volume, etc, that would give you exact engine HP. I can't for the life of me remeber what the conversion chart is, but I will go thru some old books, and see if I can find it again. It will give you really close numbers to what the engine would put out hp and torque. Measure that and compare it to the numbers you have at the rear wheel, and it will roughly give you how much powertrain loss you have also.
I'l see if I can find all the conversion charts for you. And I will see if I can find the SAE chart that dynojet uses so you can see how they calculate their numbers.
You said hook a gen to rear wheel and calculate power...that high dollar dyno, is how they do that. So, I read anyway! lol
The correction factor represents the "loss" from crank thru drivetrain to the rear wheels. When they do correction numbers they assume a mechanical efficiency of only 85% ...... barometric pressure, humidity, temp, etc..... That translates usually around a 7% difference. I can't remeber the conversion they do. summin summin square root etc....lol..... It is SAE conversion that Dynijet uses. Another thing about Dynojet, is the machine assumes, in corrected hp, that all engines are using the same rotating engine mass. So, the corrected hp numbers would assume the same rotating mass to a 250cc than it would to a 330 cc.... there is a lot I still don't understand either, or even remeber!! dang old age. lol lol
But, if you used a lighter wheel, a non-knobby tire, a tighter strectched chain, etc...you would have less rotaing mass, and you would "fool" the dyno into thinking more hp and torque. So, really to do a dyno with knobbys, you are robbing yourself of at least 8-9 horsepower. If you get the chance, etc, change to a street tire and re dyno, and I would bet you would be around the low 30's range.
Anyway, that's why a dyno is not a good test to determine actual hp, or compare your hp to others, it is only a good test with a starting point, and to help you tune. That's it. But , it is the best standardized test that is available in a mass market. There is a dyno that measures actual true hp at the rear wheel, but the thing runs in the millions and I have never seen one. Only read about it.
Even better, there is a method, I can't remeber what it is, to take your displacement, bore x stroke, cubic centimeter volume, intake volume, etc, that would give you exact engine HP. I can't for the life of me remeber what the conversion chart is, but I will go thru some old books, and see if I can find it again. It will give you really close numbers to what the engine would put out hp and torque. Measure that and compare it to the numbers you have at the rear wheel, and it will roughly give you how much powertrain loss you have also.
I'l see if I can find all the conversion charts for you. And I will see if I can find the SAE chart that dynojet uses so you can see how they calculate their numbers.
You said hook a gen to rear wheel and calculate power...that high dollar dyno, is how they do that. So, I read anyway! lol
#49
11-05-2006, 08:42 PM
RE: Should I do it?
Thanks BigRig - that's good information. I think that dyno result is even worse than I thought as far as absolute accuracy and is pretty meaningless if it is not put into context with a reading before all the mods, decent tires, etc. It sounds as if even a gearing change will produce a different HP number on the Dynojet so by running stock gearing that's probably affecting it too. If I'd known I'd have been this interested in this stuff way back when, I'd have gotten a basline run when my bike was in stock form. Oh well, too late now - I am NOT putting the '250 sleeve back on.
Oh well, it was a $75 learning experience but on the up side the air/fuel information was useful. I've placed an order for the jets and needle the TT jetting expert recommended based in part on that information. Even the small change I've made with the jets I have available have made a world of difference so I can't wait to try the "recommended" setup.
I would be interested in that power calculation based on engine parameters if you can dig it up. I'll do some Googling also.
Oh well, it was a $75 learning experience but on the up side the air/fuel information was useful. I've placed an order for the jets and needle the TT jetting expert recommended based in part on that information. Even the small change I've made with the jets I have available have made a world of difference so I can't wait to try the "recommended" setup.
I would be interested in that power calculation based on engine parameters if you can dig it up. I'll do some Googling also.
#50
11-05-2006, 09:16 PM
Join Date: Feb 2006
Location: Roswell, NM
Posts: 5,432
RE: Should I do it?
ORIGINAL: Nobrakes
I would be interested in that power calculation based on engine parameters if you can dig it up. I'll do some Googling also.
I would be interested in that power calculation based on engine parameters if you can dig it up. I'll do some Googling also.
I am not sure if the KLX is capable of doing it, but on the newer street bikes, and on cars, there is a program you can buy for your laptop, that plugs into the aldl port, and will give you fuel mapping and etc...So that way you could do it yourslef everytime and not have to keep taking it to the dyno people.