dyno run and safe jetting for 2001 SRX

Stephfg

Stephfg

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Joined
Jan 20, 2009
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335
Location
Timmins Ontario
hi guys,

I put my sled on the dyno on Friday. First, my tach is right on. Second, the peak power and torque on my 01 (all stock) is at 8,369 rpm. Third and I don't want to share this one, but peak torque was 53 and peak HP was 84.6 (warm engine). I knew my sled was jetted rich but not that much!

My sled was jetted at 150 and 148.8 mains with #40 pilots, needle at 3
Current jetting is 147.5 and 146.3 mains with #42.5 pilots, needle at 3 (that's what's highlighted in my manual)
Altitude is about 900 ft here. According to the manual, I'm jetted for between -7C (20F) and -18 (0F). It was -10C for the run. But looking at my plugs, they are black and wet. It looks like like I'm several sizes to rich. The guy with the dyno thinks it could probably be brought down 4 sizes.

For those of you who have rejetted, how far off was the factory setting from where you are now? I know I'll have to try a few times with different sizes but I'm looking for a baseline.

thanks
 
first something doesnt run ok if u did only 84.6 hp on dyno check power valve ect
 
it was off the crankshaft, using Land and Sea's Dyno-mite. Re-ringed this summer, carbs are clean, power valves are fine. I chose not to do a second run because even though I thought it might increase with fresher air (my sled was warm but was still smoking), I knew it wouldn't come anywhere near what it should without rejetting.

my brother-in-law's 99 TCat went from 160 to 180 (heat soaked) just by jetting down a few sizes (still at a safe level). It's ported and piped. On our ride last week, he burned about 2/3 the gas that I did, and that's before he jetted down.
 
IMO:

There is something seriously wrong with either the dyno or your sled!
If its your sled, a few jet sizes is not going to effect your hp numbers enough to correct that low of power output your sled is making.
I think you should be checking power valve operation and installation[upside down?]reeds, choke circuit stuck open, compression, your stator output, crank phaze, CDI ect.
 
Steph , the t-cat pulled 160 hp and your srx pulled 84ish...? check what the others suggested , does it pull ok on the trail vs your buddys t-cat / ? did the dynomite screw up when you pulled your # ?


no point jetting untill you sort that out
 
his t-cat pulled 180 once it was jetted right. On the trail mine seems fine, but I don't usually try running with him. He always wants to ride faster than I do. He has fairly aggressive porting. Maybe I should have done a second run. There's no doubt I'm running too rich though. When I took it apart this summer, my pistons were clean all around.
 
JM.02c

Like harness racer indicates, this just doesn't make sense.

At 84.6 hp your sled would run very weak + slow.

An interesting possibility:

-if someone confused the numbers here, and you actually had 84.6 ft lbs of TORQUE at 8369 RPM that woul equate to 134.8 hp...hmmm?
 
sideshowBob said:
-if someone confused the numbers here, and you actually had 84.6 ft lbs of TORQUE at 8369 RPM that woul equate to 134.8 hp...hmmm?
Click to expand...
I have the dyno print out (120 readings in 12 seconds) and it has the column headings. It's 84.6 HP. My main reason for putting it on the dyno was to see where it made power and if my tach was accurate. At least that information is useful.
 
if the motor pulls 8400 rpm & runs fine in the field than it's probably dyno/operator error. listen to ssbob. '01 jetting is safe for that motor if you use fresh 93 octane pump gas. i have had numerous yamaha's on the dyno. w/ every one the tach was spot on!
bob
 
Untill your making 140-ish hp, I wouldnt clutch to 8300 rpm's. I am very interested in your max-peak HP rpm once its running right though. I was turning 86-8700 (tach) Sunday night on a hard ice road and it was pulling hard and wrapping the needle around the dial...
 
update. rode the sled yesterday and it wasn't pulling. maxing out at 8100. this morning I checked the powervalves. I had a broken cable on #3. Looks like it got worn from the powervalve coming through the piece it is seated in (thin piece with the slot in it). I have a spare one that I'll be able to replace it with. the other 2 cables still look fine. It probably broke during the last ride before the dyno run since I was still overrevving at that point.

I cleaned the valves 600 km ago but hadn't look at the cables. Disappointed it's broken but kind of relieved at the same time! That probably explains most of the low dyno results.
 
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