D
dja981
Guest
Laverdalothar said:
And c) If Lothar agrees
Dave
Mikuni RS question this time
- Thread starter Spondonrider
- Start date
And c) If Lothar agrees
Dave
Laverdalothar
Hero member
- Location
- Germany
If only you knew me, Dave... I am absolutely happy to agree not to agree - or disagree to agree - or what ever... 
I have no experience with the Mikunis personally, just with Keihins and they worked way better than the Dell'Ortos for me. That said, that was a personal and very subjective experience, too, so...
But the differences between the 3 systems and the results depend on so many factors that it is hard to compare two bikes; they will barely have the same setup...
I had the chance to ride a 1000 SFC with standard setup after almost 8 years now having improved mine. It was so much lacking of power in ALL circumstances, it really scared me (and the Dell'Orto were freshly overhauled with all new stuff in them, ignition timing was checked, compression superb etc. - all running as it should, just lacking of torque and power all over the rev-range; maybe less so much above 6.000, but below... :-[ )
I have no experience with the Mikunis personally, just with Keihins and they worked way better than the Dell'Ortos for me. That said, that was a personal and very subjective experience, too, so...
But the differences between the 3 systems and the results depend on so many factors that it is hard to compare two bikes; they will barely have the same setup...
I had the chance to ride a 1000 SFC with standard setup after almost 8 years now having improved mine. It was so much lacking of power in ALL circumstances, it really scared me (and the Dell'Orto were freshly overhauled with all new stuff in them, ignition timing was checked, compression superb etc. - all running as it should, just lacking of torque and power all over the rev-range; maybe less so much above 6.000, but below... :-[ )
Laverdalothar said:
Not hard at all, Lothar.
A dyno does not measure power, it measures torque and calculates power from that (the modern, electronically controlled ones at least. Old systems would show torque and rpm, it was up to the operator to calculate from there. He would also need to work in the effects of air temperature and pressure, modern dyno programs and sensors make that superfluous these days.). Power is the product of torque and rpm, that should still be a left-over from school physics, no matter how long ago that was.
If the dyno you're using cannot show torque, there's something wrong with it... or its' operator! :
piet
Well done, Cam.
Same results as mine... only I've got a few more ponies, but still the same as with the Dellortos before the swap.
Work out the idle glitch and you'll turn out happy.
You will find though, that "ridability" is enhanced, be it only by the smoother mid-range transitions due to the preciser fuel metering which in turn results in better mileage, and the lighter throttle action! You can lighten that even further by removing one of the 2 return springs. Did that shortly after fitting my mickies, no issues at all, neither during road nor track use.
piet
Same results as mine... only I've got a few more ponies, but still the same as with the Dellortos before the swap.
Work out the idle glitch and you'll turn out happy.
You will find though, that "ridability" is enhanced, be it only by the smoother mid-range transitions due to the preciser fuel metering which in turn results in better mileage, and the lighter throttle action! You can lighten that even further by removing one of the 2 return springs. Did that shortly after fitting my mickies, no issues at all, neither during road nor track use.
piet
Laverdalothar
Hero member
- Location
- Germany
Piet,
if you use an acceleration type dyno (which most people use...), you start to measure somewhere above 2.500 Revs with the measurement, right? Some operators even start above 3.000. Throttle response and low end torque is almost impossible to measure on these dynos, as you simply pull the throttle fully open (or almost) and measure how the bike deals with this.
Flat-slides carbs need a little more sensitive operating. Flipping them open can even make the bike stall (if you do that from idle). Try it.
Next thing is the exhaust system used. I got the carbs set before I changed to SR-Racing exhaust. When I finally had that exhaust installed, we found the bike to be way to rich and I had to drop the needle two notches (keep in mind, the Keihins have 5 notches, not 3 as the Dell'Ortos) and had to adjust idle. Consumption dropped again and power and torque in midrange (around 4.000) went up. sign of a good exhaust, I agree (we had that discussion before, right? ).
So - maybe investment in a proper exhaust is a better one than into carbs? :
if you use an acceleration type dyno (which most people use...), you start to measure somewhere above 2.500 Revs with the measurement, right? Some operators even start above 3.000. Throttle response and low end torque is almost impossible to measure on these dynos, as you simply pull the throttle fully open (or almost) and measure how the bike deals with this.
Flat-slides carbs need a little more sensitive operating. Flipping them open can even make the bike stall (if you do that from idle). Try it.
Next thing is the exhaust system used. I got the carbs set before I changed to SR-Racing exhaust. When I finally had that exhaust installed, we found the bike to be way to rich and I had to drop the needle two notches (keep in mind, the Keihins have 5 notches, not 3 as the Dell'Ortos) and had to adjust idle. Consumption dropped again and power and torque in midrange (around 4.000) went up. sign of a good exhaust, I agree (we had that discussion before, right?
).So - maybe investment in a proper exhaust is a better one than into carbs? :
Lothar,
A dyno does NOT measure power, no matter which system is used! All it actually measures is the torque applied by the driving wheel and the associated revs. What turns up at the display is a calculated figure from the individual measurements.
That these acceleration type dynos don't/cannot show decent torque values just shows howcrap useless they actually are for serious tuning work...
I have yet to see a device capable of actually measuring (mechanical) power.
piet
A dyno does NOT measure power, no matter which system is used! All it actually measures is the torque applied by the driving wheel and the associated revs. What turns up at the display is a calculated figure from the individual measurements.
That these acceleration type dynos don't/cannot show decent torque values just shows how
I have yet to see a device capable of actually measuring (mechanical) power.
piet
Cam,
One of the best features of the Mikuni Flatslides is their ability to let the engine idle, even the big bore high comp engines we build will happily idle below 500 rpm if we wish to drop the adjustment down. My 2nd Jota, 1175cc with the works will idle at < 400 rpm (digital tacho). There must be something amiss if you are experiencing issues at idle.
Power figures are no surprise, carbs by themselves cannot really make an engine produce more power but the carbs can and will change how the engine performs through the rev range and that is what Piet refers to with the rideability comment, totally agree.
Lothar, our Dyno has a built in weather station, it constantly measure air temperature and humidity and from those measurements the Stuska software calculates a correction factor. As the engine runs the HP is calculated by the software using this correction factor, engine speed and the readings being sent from the strain gauge on the Water Brake itself which is basically measuring deflection.
To do the initial set up on the Water Brake you bolt on an arm of a known length and then add "x" lbs to the end of the arm which causes the strain gauge to measure a deflection, you then set a calibration point in the software, add higher weights, calibrate, etc.
Any computer controlled Dyno would be operating in a very similar manner.
Red
One of the best features of the Mikuni Flatslides is their ability to let the engine idle, even the big bore high comp engines we build will happily idle below 500 rpm if we wish to drop the adjustment down. My 2nd Jota, 1175cc with the works will idle at < 400 rpm (digital tacho). There must be something amiss if you are experiencing issues at idle.
Power figures are no surprise, carbs by themselves cannot really make an engine produce more power but the carbs can and will change how the engine performs through the rev range and that is what Piet refers to with the rideability comment, totally agree.
Lothar, our Dyno has a built in weather station, it constantly measure air temperature and humidity and from those measurements the Stuska software calculates a correction factor. As the engine runs the HP is calculated by the software using this correction factor, engine speed and the readings being sent from the strain gauge on the Water Brake itself which is basically measuring deflection.
To do the initial set up on the Water Brake you bolt on an arm of a known length and then add "x" lbs to the end of the arm which causes the strain gauge to measure a deflection, you then set a calibration point in the software, add higher weights, calibrate, etc.
Any computer controlled Dyno would be operating in a very similar manner.
Red
D
Davo
Guest
If that well known Italiophile and master of the Guzzi, Mario at Thunderbikes, recommends ripping off the Dels on a goose and replacing them with flat slide Miks, throwing in the comment "Chalk and cheese", there must be something to it
Dellortoman
Hero member
- Location
- Tasmania, Australia
I just put some 17.5 pilot jets in the carbs (had 15's in it) and it makes a big difference. Bike starts easier and idles nicely now. It even starts without choke on a cold engine (wouldn't do that before either) and settles into a slow idle straight away. I set the mixture screws at 1.5 turns as a starting point, but it's idling so nicely now I don't think I need to fiddle with them.
With the $15 pilot jets the idle was all lumpy with an occasional backfire. I tried winding the idle mixture screws in and out but couldn't tame it. I can't believe the difference it's made by going up a size in pilot jets. I haven't taken it for a ride to see how it's affected the transition from idle to slightly cracked open throttle, but I expect it'll be a bit smoother. I'll go for a blast tomorrow. Hopefully the roads will be drier then.
Cheers,
Cam
With the $15 pilot jets the idle was all lumpy with an occasional backfire. I tried winding the idle mixture screws in and out but couldn't tame it. I can't believe the difference it's made by going up a size in pilot jets. I haven't taken it for a ride to see how it's affected the transition from idle to slightly cracked open throttle, but I expect it'll be a bit smoother. I'll go for a blast tomorrow. Hopefully the roads will be drier then.
Cheers,
Cam
Dellortoman
Hero member
- Location
- Tasmania, Australia
PS: while the bike was idling, it was making a bit of a rattle. I thought it was the Mikuni flat slides flapping around in the breeze until I leaned on the seat and the rattle stopped. It was the bloody duck tail rattling. A closer look revealed that the centre bolt had fallen out. That's the one that goes through the bottom of the duck tail tray, bolting it to the tail light fitting.
It's almost impossible for human fingers to get in under the tail light bracket to get a nut on the bottom end of the bolt. Then more cursing and swearing trying to get a spanner on the nut to tighten it. I'd finished messing about with the carbs and was psyching myself up to do battle with that ductail bolt (been there before).
Then I thought fuck it, I'll take the duck tail off, un-bolt the tail light bracket from the mudguard and weld a nut on the underside of the steel bracket. That'll make the installation of that bastard ductail centre bolt a whole lot easier. I got it apart only to find I'd already welded a nut on there on some previous occasion when it pissed me off! Good thing I'm not a CLQ member.
Cam
Dickhead
It's almost impossible for human fingers to get in under the tail light bracket to get a nut on the bottom end of the bolt. Then more cursing and swearing trying to get a spanner on the nut to tighten it. I'd finished messing about with the carbs and was psyching myself up to do battle with that ductail bolt (been there before).
Then I thought fuck it, I'll take the duck tail off, un-bolt the tail light bracket from the mudguard and weld a nut on the underside of the steel bracket. That'll make the installation of that bastard ductail centre bolt a whole lot easier. I got it apart only to find I'd already welded a nut on there on some previous occasion when it pissed me off! Good thing I'm not a CLQ member.
Cam
Dickhead
D
Davo
Guest
While you have it apart fitting that nut why not paint the frame
motoddrob
Hero member
- Location
- S/W Australia
Hi Cam, I went from 15s to 17.5 pilots and it made a huge difference. Prior to the change there was alot of coughing and spitting. Now with the new rebuilt/upgraded motor hopefully the carbs will be sorted.
D
Davo
Guest
Cosi
Hero member
- Location
- Kingscliff
Hmm, i should go up to 20's then
1 turn and on 17.5s
1 turn and on 17.5s
Dellortoman
Hero member
- Location
- Tasmania, Australia
OK, I'll screw them in a bit and see what happens.
D
dja981
Guest
sfcpiet said:
I'll send you a photograph of my arse.
Dave