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A few minutes with the L on the dyno

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Yesterday I had a few minutes to throw my L up on the dyno at the shop.  

 

This is the first time I've put it on there since I rebuilt/restored it.  It is a stock bore, stroke, and compression engine with the stock carb (Dave's mods with 55/158), de-snorked with a UNI, and a full XR's only exhaust.  

 

Unfortunately, the battery was dead on my oxygen sensor interface box so I didn't get the AFR but I want to get that referenced as well.  

 

I've heard power numbers all over the place since I've owned it and been interested in knowing for myself.  I wanted to get my own baseline.  It produced about what I was expecting.  I was very pleased to see where the all the torque is in the RPM range and how long it stays there.  It is where it belongs.

 

As I have time and money to do it and will be interested in watching the power change to see what works and what doesn't.

Dyno Runs.jpg

Edited by hollerhead
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I was very pleased to see where the all the torque is in the RPM range and how long it stays there.

It would be nice if we could see at what RPMs it had the power and torque.

 

Any chance of scanning that dyno sheet again and including the RPM scale which I'm assuming is along the bottom.

 

 

I hope to stick my bike on a dyno in about a month.  I'm looking for a little more than 35 hp.

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It would be nice if we could see at what RPMs it had the power and torque.

 

Any chance of scanning that dyno sheet again and including the RPM scale which I'm assuming is along the bottom.

 

 

I hope to stick my bike on a dyno in about a month.  I'm looking for a little more than 35 hp.

 

It's along the "0" axis, it's faint but it's there. If your display still can't show you the first dotted vertical line on the left is 2000RPM and the last on the right is 8000.

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It's along the "0" axis, it's faint but it's there. If your display still can't show you the first dotted vertical line on the left is 2000RPM and the last on the right is 8000.

Faint is right!  Thanks.  Yes, I can see it if I look real close.

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It would be nice if we could see at what RPMs it had the power and torque.

 

Any chance of scanning that dyno sheet again and including the RPM scale which I'm assuming is along the bottom.

 

 

I hope to stick my bike on a dyno in about a month.  I'm looking for a little more than 35 hp.

 

Below is the data table scan.  

 

I like the graph for tuning as it makes the "bad spots" easy to see ,and to watch the tune improve, but the table is much easier to see the actual numbers.  I keep the smoothing option turned off in the software in order to magnify potential problem areas.  It makes for an uglier graph but I like the honesty of it.  Mine sure is ugly.  I can feel just about all of those bad spots.  I really don't see many ways to get those spots out with the stock carb and non-adjustable ignition.  I guess a carburetor swap is next on my list.  

 

I honestly don't pay much attention to HP as I never (rarely ever) see those peak HP RPM's while riding but HP numbers and bragging rights are what keeps customers coming in and pays the bills.  I've found that by tuning with the torque curve I end up with a better overall tune but it will actually feel (and may actually be) slower.  I suppose its because you don't get those small bursts of power on the way up.  I always ask my customers whether they want max HP or the best tune and most of the time they want HP.  The hardcore touring guys usually understand how a smooth and strong torque curve makes for a better riding bike regardless of HP numbers. 

 

Even though it is tough to compare two different dyno machines I'd like to see your runs too when you get around to it.  What types of power mods do you have to your L?

 

 

 

 

PJ Dyno Table.jpg

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Even though it is tough to compare two different dyno machines I'd like to see your runs too when you get around to it.  What types of power mods do you have to your L?

102.41 mm piston (675 ccs), 10.5:1 compression.  Nothing else at all other than the usual pipe, rejet, airbox, uni-filter stuff.  I'll definitely post when I get dyno information.

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102.41 mm piston (675 ccs), 10.5:1 compression.  Nothing else at all other than the usual pipe, rejet, airbox, uni-filter stuff.  I'll definitely post when I get dyno information.

Cool, can't wait to see it.  That piston in on my list as well...

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Good lord... it's as bad as I thought! 350 pounds of bike and it doesn't make as much power as a modern 250F! Why do I keep dumping cash into the turd?! LOL... cuz it's my turd and i love it.

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Good lord... it's as bad as I thought! 350 pounds of bike and it doesn't make as much power as a modern 250F! Why do I keep dumping cash into the turd?! LOL... cuz it's my turd and i love it.

Ah, but none of the little guys can make that torque down low. HP is for kids.

Those bikes are a lot of fun too, just a different kind of fun.

Edited by hollerhead

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Ah, but none of the little guys can make that torque down low. HP is for kids.

Those bikes are a lot of fun too, just a different kind of fun.

The torque is nice, no doubt. Tractoring around stalled out 250F race bikes on steep, nasty sections of trail is its own kind of fun. Of course they blow past you like you are sitting still down the trail, but it feels good in the moment. I had almost half of my XRL's flywheel shaved off and it's still a tractor! 

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Good lord... it's as bad as I thought! 350 pounds of bike and it doesn't make as much power as a modern 250F! Why do I keep dumping cash into the turd?! LOL... cuz it's my turd and i love it.

 

I often stare at my bike and ask the same question and come up with the same answer.

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I got my dyno sheet.  This was a "free" dyno run, so they didn't bother connecting up anything to determine RPMs of the engine, so no torque numbers, but the horsepower numbers seem reasonably solid.  A nitrous Kawasaki hit 204 hp a bit earlier.

 

On my run, I was consistently at 41.6.  I've never seen such a flat horsepower curve.

 

Another 2001 XR650L with similar carb, air cleaner, and pipe but stock piston hit around 35.6 immediately after my run.

 

Here are the two charts:

DynoCharts_zpsjumjy6px.jpg

 

Oh, and the top speed shown on the dyno pretty much matched what I saw when crossing the San Mateo Bridge, on the flat part:

XR_TopSpeed_zpskf4yvw7d.jpg

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Great numbers.

Odd that they didn't show the torque though. The software already has the data in there.

All the data is derived from the dyno wheel acceleration not the bike.

They just need to change the display choices and print out for you.

Edited by hollerhead

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