niko
TY 4 Stroke Junkie
Just wondering if the hp from a 800r 2stroke is measured the same as a 1000c yamaha 4 stroke.
In other words are both 150hp the same from both motors?
niko.
In other words are both 150hp the same from both motors?
niko.
Typically hp is measured from a brake dyno mounted to the primary clutch shaft. I am sure both engines are measured the same and the fact that they both make the same peak hp just shows the benefit of a 2-stroke.
If you were to look at the hp/torque graphs, you would see that the 4-stroke has a much wider and flatter power band which leads to more power across the rpm range. The real difference is when you calculate the area under the power curve, that will show just how much more power you get from a 4-stroke. Peak hp is just for bragging rights.
If you were to look at the hp/torque graphs, you would see that the 4-stroke has a much wider and flatter power band which leads to more power across the rpm range. The real difference is when you calculate the area under the power curve, that will show just how much more power you get from a 4-stroke. Peak hp is just for bragging rights.
niko
TY 4 Stroke Junkie
thanks Derek, great to know when mates are trying to tell you other wise.
niko.
niko.
Deadman
Expert
Well said. Peak #'s aren't that important for trail riders. Peak power is great for racing, the challenge is to keep that power level high at lower rpm's. 2 strokes just can't do that like a 4 stroke can.
Canadian Lad
Extreme
Another important point for a trail rider is to be able to maintain that power/speed for long periods of time without blowing up. This is a place wheree the 4 stroke excels over the 2 stroke. Long lakes or old railroads for example.
I found a couple of dyno graphs of some 2-stroke and 4-stroke sleds on the net.
As you can see, the Summit 800 has a peak of 117hp at 8100rpms and it just climbs the entire time, never really leveling off.
The RX-1 hp curve jumps to over 100hp by 7000 rpms and stays pretty level slowly climbing to 137.5hp by 9800rpms
Click the thumbnails for larger images.
As you can see, the Summit 800 has a peak of 117hp at 8100rpms and it just climbs the entire time, never really leveling off.
The RX-1 hp curve jumps to over 100hp by 7000 rpms and stays pretty level slowly climbing to 137.5hp by 9800rpms
Click the thumbnails for larger images.
wigman1
Pro
All I know is that I have been riding high powered sleds for over 35 years, and these 4 strokes are simply amazing for the power they put out at all rpm ranges. 2 strokes put out lots of power per cc, but you have to clutch them to stay within a very narrow power band in order to make them really run up to their potential. The chart on the RX1 tells it all - the flatter the powerband over the rpm range, the easier it is to clutch and the better the sled will be in the trail torque department, which is the most important for the average rider. I think the more that the 4 strokes get refined, the more logical of a choice they will be. Wig
Eagle1
Expert
Even the difference between a triple and a twin 2-stoke is very different. Having rode my ultra triple for 10 years and then riding my budies 600 xc, I thought are you kidding,almost boring. Thats why I'am going 4 stroke 
Can't wait to ride my first Yamaha
Can't wait to ride my first Yamaha
rxrider
Jan-Ove Pedersen
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Good question, I will also add that 4strokes Yamaha's does NOT loose power if you overshoot peak HP by 500 rmps, only a few HP lost. Do it to a 2smoker and it stops pulling as the HP drops off sharply.
Add a turbo or supercharger to your Yamaha and have tremendous torque building as boost kicks in just above engagement speed, now the comparison ends - the 4stroke is in another galaxy when it comes to torque down low
I won't even start talking about peak HP hahaha LOL.
Add a turbo or supercharger to your Yamaha and have tremendous torque building as boost kicks in just above engagement speed, now the comparison ends - the 4stroke is in another galaxy when it comes to torque down low
I won't even start talking about peak HP hahaha LOL.
niko
TY 4 Stroke Junkie
interesting stuff! now my clutch ingagement is at aprox 3600rpm is there a way to bring it back to 3000? it seems like im reving the hell out of it just to get it moving?
420ATTAK
Pro
eagle one you are right twins and triples are a different league you will find the 4 stroke is alot like a triple lots of pull where ever you want it!!! only better!!! welcome to YAMAHA you will love it! not trying to steal the post but what did you get?
rxrider
Jan-Ove Pedersen
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niko - Your engagement speed are perfectly normal.
At 3600 rpms your clutch only spins at approx 2900 rpms. To get clutch rpms; calculate (engine_rpms x 30 / 37) crankshaft has 30 teeths and the secondary shaft has 37 teeths.
You can lower engagement and midrange cruise rpms by going with a Green-Pink-Green 30/121 with a preload of 30 and a total force of 121 as a replacement for the Yellow-Silver-Yellow at 35/118. This will reduce engagement speed while giving you slightly more prms at speed running it WOT.
At 3600 rpms your clutch only spins at approx 2900 rpms. To get clutch rpms; calculate (engine_rpms x 30 / 37) crankshaft has 30 teeths and the secondary shaft has 37 teeths.
You can lower engagement and midrange cruise rpms by going with a Green-Pink-Green 30/121 with a preload of 30 and a total force of 121 as a replacement for the Yellow-Silver-Yellow at 35/118. This will reduce engagement speed while giving you slightly more prms at speed running it WOT.
Eagle1
Expert
spring ordered white xtx
cant't wait Similar threads
