Dyno numbers

[L J VFR]

Hello everyone.  Just wondering if anyone has ever had their 3rd gen on a dyno.  I've heard numbers ranging from 68 to 100 HP.   Just curios to see if a MOOT member has ever put their bike on one and seen REAL numbers.  If so what mods have been made to the bike as well, please..   Again,  Thanks,  Lance

[Sledge Hammer]

I was just told about a weekly gathering of riders around here that usually includes somebody with a dynamometer. It's only $20, so I'm planning on doing that before I tinker with the engine or the exhaust. It would be nice to have a baseline for comparison of before-and-after performance. If I can get those numbers I'll post them if you don't get a chance to run yours before then. First, though, I have to get mine back on the road. Either it got hold of some bad gas or it's allergic to pollen, because it can barely get out of its own way in first gear until 4000 RPM.

[trapper]

Either it got hold of some bad gas or it's allergic to pollen, because it can barely get out of its own way in first gear until 4000 RPM.

Bad gas?  Dirty fuel filter?  Clogged jets?  Fuel pump? (I think 3rd gens have these, right?)  Just throwing darts....

[Greg Cothern]

I hear #'s raning from 76-83 for stock to lite mods.  Heard #'s from 83-90 for heavier mods.

Give Dave Dodge a call he has most of the #'s on most of the mods.

[Sledge Hammer]

Bad gas?  Dirty fuel filter?  Clogged jets?  Fuel pump? (I think 3rd gens have these, right?)  Just throwing darts....[/quote]

Nope, no fuel pumps on 3G Magnas and I have been too lazy to put a real fuel filter in it. But the other two darts you tossed out could yet strike the bull's-eye. Since it is quite recent behavior, I am hoping it is only bad gas. I would really hate to go into the carbs on it. But I also noticed a huge accumulation of chainwax slingoff on rubber hose near the front sprocket. If the manual is correct, one of two hoses that come down to that point is the breather hose for the fuel tank. The other is the overflow line in case the radiator belches. If that slingoff has clogged the entrance to the breather tube, that should be a relatively easy fix. In any event, I have to wonder what possesed Honda's engineer to bring a fluid over flow line out right next to the chain.

[Sledge Hammer]

I hear #'s raning from 76-83 for stock to lite mods.  Heard #'s from 83-90 for heavier mods.

Give Dave Dodge a call he has most of the #'s on most of the mods.

Are those numbers at the rear wheel or are they extrapolated back to the engine? In any event, I think it is still more horsepower than a Piper Cub develops, even if the "wings" are only decals on the Magna!

[Greg Cothern]

Mike has the bike sat for a couple weeks without starting?  If so the slow speed jets can clog rather quickly.  Since you can ride it, put some Seafoam in the tank and take her for an aggressive tank full ride.  Keeping the RPM's up over 6K as much as possible.  
This should clear things up quite a bit, if not at least you got to burn a tank of gas and have fun while doing it!!!

[lragan]

In any event, I think it is still more horsepower than a Piper Cub develops, even if the "wings" are only decals on the Magna!

Oranges and apples comparison.  The 65 hp Continental in the Cub will crank out 65 hp, continuously, at varying altitudes, and with reliability that you can quite literally bet your life on, for 1000 to 1200 hours between overhauls.  The same horsepower in a continuous duty water cooled engine will weigh about a ton and pump an irrigation well for even longer periods.

The Honda V4 is an awesome engine, but the horsepower ratings are really not comparable between automobile and motorcycle engines and those designed for constant speed, continuous duty.

[Magnum Magna]

To expand on what I think Lawrence is saying.  You can pull 80 hp to get to 60 miles and hour but when you hit 60 and stop accelerating you could be doing only 10 hp to maintain 60 miles an hour.  In an airplane a fall back of hp like that you will be going down.  I believe 60 or 65 % of full power  will keep the same speed not 13 % of full power.

[Sledge Hammer]

To expand on what I think Lawrence is saying.  You can pull 80 hp to get to 60 miles and hour but when you hit 60 and stop accelerating you could be doing only 10 hp to maintain 60 miles an hour.  In an airplane a fall back of hp like that you will be going down.  I believe 60 or 65 % of full power  will keep the same speed not 13 % of full power.

Oh, doubtless, and in fact the reason it was even in my thoughts was because a co-worker and I were discussing the homebuilt aircraft he had heard about in which the powerplant was a Suzuki GSX-R1000 to avoid the cost of buying a Lycoming, Continental or Rotax aircraft engine. Our discussion centered around the very point you and Lawrence are making that horsepower ratings have to be considered in the context of how the engine is used. That Suzuki engine which is so great on the track is definitely not what I'd want to depend on keeping an airplane flying. Conversely, 60-65 horsepower doesn't sound like much, but I'd like to see somebody who can make continuous, undiminished use of it on the street hour after hour without killing himself along the way. I am a frustrated would-be pilot, but if motorcycles were designed, built, and maintained to the same specifications as aircraft, I probably couldn't afford to fly a Magna, either.

[Sledge Hammer]

Mike has the bike sat for a couple weeks without starting?  If so the slow speed jets can clog rather quickly.  Since you can ride it, put some Seafoam in the tank and take her for an aggressive tank full ride.  Keeping the RPM's up over 6K as much as possible.  
This should clear things up quite a bit, if not at least you got to burn a tank of gas and have fun while doing it!!!

I like the way you think, Greg, I like the way you think.

[Greg Cothern]

Ahh we see this also in our radio controlled airplane engines as well.  We have one particular engine manufactuer that has a SUPER reliable engine, but its a bit heavy and down on power for our aerobatic airframes. 
Now if you can find something that has a very broad flat torque band and is reliable then you are good to go!

[dgc67]

A couple of things people often overlook, or just don't know yet perhaps, is the difference between horsepower and torque as well as the importance of powerbands.  Torque is just as important a number to consider when looking at pure acceleration.

As has already been eloquently stated here, horsepower is what gives you that constant top end power/speed.  Horsepower is all about acheiving and then maintaining that top speed.  Torque is what helps get you to that speed quickly.  An engine with high horsepower and low torque may go 200 mph, but it will take awhile to get to that speed.  Conversely, an engine with less horsepower but good torque is going to pull really hard off the line, but won't have anything in the way of top speed.

A good combination of hp/torque and knowing where your powerbands for these 2 factors start and end is the key to putting all that power to good use.  Most powerbands end before the redline of the engine and i nmost case shifting should occur at the end or just after that powerband, not at redline, for maximum acceleration.

[L J VFR]

Good point DG on torque and horsepower curves.  I do love my 383 stroker engine for this particular reason.   Thanks everyone for their input on my question.  I did talk to Dave Dodge and on my particular bike with a K&N with no modded; stock exhaust and shims, will probably do 78 to 80 HP.  .....  Lance

[TLRam1]

DG,

That is one of the better explanations I have seen for the layman to understand.