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[TLC]

Is it hard on the motor when you do the dyno tune? Just watching it the other day and seeing the speedo get pegged out at 150mph plus on my FXSTSSE3 got me wondering.

[willyB]

As long as your tuner does not raise the RPM Limiter you'll be okay for a tune. Now having said that, I would not recommend dynoing your scoot all day every day. Keep in mind, your motor is designed to handle RPM's below the redline. Otherwise the factory would have set the RPM Limiter well below the max redline.

Seeing a 150 MPH+ on the speedo indicates that the tuner was making a 6th gear run.

Don't worry.

[Heatwave]

Is it hard on the motor when you do the dyno tune? Just watching it the other day and seeing the speedo get pegged out at 150mph plus on my FXSTSSE3 got me wondering.

uhhhh, the speedo only goes to 120. It would be somewhat difficult to get "pegged out at 150mph".

[cvobiker]

uhhhh, the speedo only goes to 120. It would be somewhat difficult to get "pegged out at 150mph".

he is referring to the speed indicator on the Dyno screen. And I'm firm believer that a lot of scissored cranks we hear about these days are born on the dyno table.   I say this because I had the last 6 Harley's I've owned dyno tuned. The first three were per-2006 bikes, the last three were 2007, 2008, 2008.  The 2007 suffered twisted crank syndrome twice, both after the tune, the 2008 Ultra stock motor did after tune and the same bike with a 131 did as well. My 2008 Fat Bob also has crank problems and will be torn into within next moth or two.. For those that think its me,  nope I guarantee I don't run my bikes as hard as done on the dyno table... I've since resigned from anymore dyno tunes and will see how the Revolution Performance EMS does...Oh,, the first three, pree 2006 bikes, never had any motor issues and put over 60K trouble free miles on a 2001 Road King...Harley defiantly don't make em like they use to. 

[Heatwave]

he is referring to the speed indicator on the Dyno screen. And I'm firm believer that a lot of scissored cranks we hear about these days are born on the dyno table.   I say this because I had the last 6 Harley's I've owned dyno tuned. The first three were per-2006 bikes, the last three were 2007, 2008, 2008.  The 2007 suffered twisted crank syndrome twice, both after the tune, the 2008 Ultra stock motor did after tune and the same bike with a 131 did as well. My 2008 Fat Bob also has crank problems and will be torn into within next moth or two.. For those that think its me,  nope I guarantee I don't run my bikes as hard as done on the dyno table... I've since resigned from anymore dyno tunes and will see how the Revolution Performance EMS does...

Still hard to believe the dyno's speedo said 150 since the final gear ratio would not deliver 150mph without exceeding the redline of the engine.

[cvobiker]

Still hard to believe the dyno's speedo said 150 since the final gear ratio would not deliver 150mph without exceeding the redline of the engine.

I would say he was at 6,000 RPM...    Not sure what his bike specs are,   Check out the calculator and see if you can pin down his RPM/speed ratio

http://www.nightrider.com/biketech/calc_speed_rpm.htm

[Heatwave]

I would say he was at 6,000 RPM...    Not sure what his bike specs are,   Check out the calculator and see if you can pin down his RPM/speed ratio

http://www.nightrider.com/biketech/calc_speed_rpm.htm

Max speed for his bike is going to be around 135mph at 6000 rpms on a dyno. On the road he'll never get to 6000rpms with stock HP due to wind resistance and would top out at something less than 120mph.

[grc]

If you have the actual final drive ratio and the tire diameter, it's pretty easy to calculate road speed versus rpm.  I don't happen to have the specs for a Softail Springer, so I haven't done the calculations.  But I did do a similar set of calculations for the older model Touring bikes a few years back in response to a question about theoretical max top speed, and I can tell you that the 2003-2006 five speed Touring models with stock gearing and tires were good for exactly 150 mph at 6200 rpm in top gear.  Of course while it would be possible to pull those numbers on a drum, it would be impossible to come close on the road due to aerodynamic drag, tire drag, etc.

Anyhow, what does this have to do with the OP's question?

TLC, if the guy doing the dyno testing is a real pro he can do a full dyno tune without causing undue stress to your engine and drivetrain.  The trick is finding someone who is fully competent.  It seems that every podunk Harley shop jumped on the "performance" bandwagon over the past decade or so, and many went out and bought a DynoJet.  There is no shortage of hardware, but there is a real shortage of fully qualified and knowledgeable folks to use that equipment.

The biggest danger to your engine is excessive heat and excessive load at low rpms.  A good dyno room will have controlled conditions and high volume airflow over the engine, and a good dyno operator won't hammer the bike in upper gears from low rpms.  If you see a WOT run in top gear that starts out below 2500 rpm or so, I'd submit that the operator doesn't understand the current state of Harley crankshaft quality. 

Anyhow, the short answer IMHO is that when done properly, an occasional dyno test is no worse on your engine than those occasional wide open throttle blasts that most of us perform out on some country highway every once in awhile.   


Jerry

[TLC]

Thanks for all the replies,the room it was done in was only in the 40s and he would only go to 3 or 4 throttle positions and then let it cool down for 10 minutes or so.He said the rev limiter was set at 6200rpms.All in all it only took only over an hour,some new software I was told that you did not have to put the numbers in manually or something.Will ride it home tomorrow about a 50 mile ride in the upper 30s with no fairing.BRRR.

[HILLSIDECYCLE.COM]

Thanks for all the replies,the room it was done in was only in the 40s and he would only go to 3 or 4 throttle positions and then let it cool down for 10 minutes or so.He said the rev limiter was set at 6200rpms.All in all it only took only over an hour,some new software I was told that you did not have to put the numbers in manually or something.Will ride it home tomorrow about a 50 mile ride in the upper 30s with no fairing.BRRR.

40 degree temps in the dyno room is not what you want.
Scott

[TLC]

Well maybe it was closer to around 55-60 cause it had the heat from inside the service area.He was saying it helped not to be hot like in the 80s or higher.