Revving question

[jc55]

Today I started my bike for the first time with fuel after a 6 year lay up. All new lines, filters, fuel pump, plugs, tried muffler on AND off. Bike wasn't warmed up and partially choked, but...


Idled PERFECT. No hesitation whatsoever. I didn't ride it.
A couple of quick revs and it went to 3000rpm.


This bike doesn't seem like a 'revver'. Meaning, a quick blip doesn't take you to 5k. Does that sound correct?


Just wondering if I should have the injectors rebuilt while I rewire and paint.


Thanks in advance!

[kennybobby]

Are the throttle butterfly valves closing after you blip it, stuck throttle cable or choke holding butterfly valves open?

Press the throttle linkage at the manifold down by hand toward closed position to see if idle returns.

[jc55]

You know, they slightly drag on closing, but after exceeding them a few times, they close quick now.


I did start it up and rev to 5k. It went smoothly, but doesn't have that sport bike feel, more of a torquey feel.

[The Mighty Gryphon]

My K75's with Jetronic don't rev like my 16V K100 with the Motronic.  The Motronic responds instantly while the Jetronic bikes sort of build rpm's. 

I attribute the difference to the lag that comes from the MAF sensor in the Jetronic system.  You snap the throttle open, but then you have to wait for the engine vacuum to pull the flapper in the MAF sensor open.  The response is fine for something like a passenger sedan, but it is not the same as the Motronic that works off the throttle position. 

What you are experiencing is old technology from the dawn of mass produced fuel injection.

[jc55]

Perfect, perfect, perfect. Exactly what I thought. It builds rpms as you stated. No real lag, just doesn't snap like a CBR.


Thank you guys. On a side note, the thing sounds like a tiger at 5k :2thumbup:

[The Mighty Gryphon]

There are times in the garage with my bikes when I daydream about replacing the MAF sensor with the throttle position sensor off the Motronic. 

Has anyone upgraded their bike with a Motronic ECU?

[Chaos]

I'm just glad mine runs :riding:

[The Mighty Gryphon]

I'm very glad mine run, too, but the crisp response of my 16v Motronic bike is spoiling me a bit.

[Nine80seven]

'84KRS, after warm, throttle responds just like Dels with pumps on airhead.  Twist, vroom!  Better because of light flywheel.  Of course every piece of the fuel system was gone through, completely meticulously cleaned, synchronized, new cable, etc.,  also installed the later 180 degree cradled throttle bodies instead of the 90 degree cradle.  Dumped a ton of new parts into old bike.  Way more than the bike cost.  And still dumping in more this winter.  It's fun, hobby, keeps you on yer game.  Moved the ground yesterday, upgraded to 4 gauge.  Off topic but, I can't quantify the gift of working on something in the garage to the happiness/gratitude of living good. IMHO

[D.Bachtel]

My  K75C doesn't roll up as quick as a two stroke might or even a British Twin.
It has never failed to start once I sorted it out. Idles like a little kitty. Mine was also a 6 year dry storage resurrection.

Once you're onboard and rolling it will continue to roll on up very smoothly without hesitation.
Incredible delivery, pulls hard on the uphill runs. Just generally kicks ass. With the stock exhaust I have pleasant turbine whine, all the time.
Very soothing.

No sure what top end will be, haven't approached 8k in 5th just yet.


This is the most modern machine I've ever owned, and my first button start. Even the suspension seems plush to me.
Disc brakes? Never had that before either.


Don in Nipomo

[jc55]

Thanks. With no point of reference, that gives me more clarity. I bench tested and cleaned the injectors today under pressure, so I'm thinking I'll be okay

[K1300S]

it doesn't rev like a sport bike because, well, it isn't a sport bike.  it weighs over 500lbs.  skinny tires.  redline is only 8k.  it is a old sport TOURING bike.


my K75s revs....nicely.


my K1300s revs...insanely.