I know some motors need to be rev up good .. and have them blown out once in a while..

Just curious to how often you guys do yours? Mine 12 SG starts red lining around 5500 RPMS.. but goes to 8000 on the tach.

do you guya get on it every once and a while and go to 7000 RPMS or even more?

just curious.. on how far in the red I should go... when I have a flat piece of highway...

Thanks

Mo

 

I am going to read what the more experienced HD owners will say.
I am new to this bike but I see no reason to redline the engine.
Cruising along I am 2500 3000 RPMs but getting on the highway or taking off at the front of a red light I let the engine have some high reves but never red lining it.
In the 70 I had a street bike that would foul plugs two times a year. Later found out I did not run the engine high enough. It was a two stroke engine.

 

the reason the rev limiters is set at 5500 rpms is because at motor speeds much higher than 6000 the momentum of the valvetrain becomes stronger than the springs- and the valves will whack the piston - ouch$$$ ( this was sometimes called "valve-float" and is why overhead cams motors will rev up higher)

in days of old ( think pre 1986) when cars all had carbs and maybe even points ignition...and pre '75 there were no cats ( so leaded fuel- and points ignitions and no EPA mandated detergents in the fuel..and no synthetic oils...

back then carbon build up in the heads could be a concern, and carbon could act as a glow plug and cause pinging.

high school kids would take dad's car out to "blow out the carbon"...

a more professional approach was to use water injection to remove the carbon- high pressure water was sprayed into the carb throat on a running motor at WOT.

the water would clean the combustion chamber.

modern motors, EFI, electronic ignitions and mandated detergent fuels and oils have made that a thing of the past ( unless you ride and drive old junk like me)

I regularly run my V twins at 4k cruising...on my evo bagger, 70 mph was reached at 3300 rpms- so not unusual to be running 4 or 4300 rpms. I'd hit rev limit ( 5800 on that one) once in a while when getting going quick.

On the 09, 80 MPH is reached at 3100 rpms in 6th gear. I use my gears so that I am rarely under 2700 rpms unless on flat ground with no headwind- which is 70 MPH in 6th on this bike- under that speed I am in a lower gear

If you are in 6th gear you will be limited by wind resistance long before the redline- you'd probably poop out about 4300 rpms--5th gear might get you close to 120 which would be right at the rev limiter- depending on the road, wind, your weight how much crap is on the bike and whether the fairing has unloaded the front tire to the point where you crashed at 110.- our fairings unload the front starting at about 85 mph wind speed

Mike

 

I think that bit about "blowing out the carbon" is just a lot of poppycock!
I think it's just an excuse for people to "get on it".

I am VERY easy on my motors; I shift around 3 grand, & I never have fouling or carbon problems.

 

Rev limiter will stop you way before you get to 7000 rpm's unless you have a tuner and have made adjustments to your redline. If I am not mistaken the ThunderMax takes the redline out to about 6145 rpms. I am always surprised when I hit the rev limiter. It usually happens when I haven't been on the bike for a week or so, due to travel for work.

 

Dickey knows what he is talking ‘bout.

 

I've seen a carbon(Italy tune-up)blow-out many times in the old day's. Not much these days. I've hit the rev limit many a time, set @ 6200.

Only reason to do this is if your running high compression and exp. knock or ping! But as noted by Mike water spray can work.

That spray didn't work on my 11 to 1 S&S engine, had to up the octane. Racing fuel....too much $$$.

Went to a 50% E85 to E10 mix after upping my jets on my S&S. Sure limited my range but I knew where in the Midwest had E85... at least we have it!!!

But if I wanted to ride I needed a bike like in my sig, can run on 87 octane if needed. Mike said pre 1986? My 1986 is spot on! hehe

 

Interesting observation. I ran my last SG up over the ton a couple of times and one of the reasons I backed off (quickly) was how twitchy it felt. I was just thinking cross winds, didn't consider the aerodynamics as a source.

 

Dad would push the old family Oldsmobile up to a hundred MPH back in the late 1950s to blow out the carbon. It was baloney then and it's baloney now. Especially with Harleys which aren't, by any means, high revving engines.

Unlike the below which is a 193HP BMW right at its 14K rev limit. If you watch really close you can see the "carbon" flying off the valves!

 

Funny story
I was 17 had a new 1980 Z28. I was safe but used the HP it had.
I worked with a lady that her husband had a 911. They got a ticket doing 99 and if you live in Texas you know what that means (you were doing over 100). She told me they where blowing out the carbon. I said: If that is true next time keep it in 3rd gear and not 5. Her reply was that would not be as fun. I said I agree with that.