Hello Everyone,

I hope you all are having a great start at the week and is doing well. Some background information, V&H FuelPak, V&H High Flow Intake and 2-2 Kinetic Sidewinder Exhaust. (This issue was going on regardless of exhausts, Kinetic is my third set). Bike runs Shell V-Power 91 (out here in CA). Motorcycle is about 4 months old, never dropped, no crashed or accidents. I have done all installs myself, serviced it myself; not my first rodeo but I sure as heck don't know it all and I have a ton to learn in general - which is what leads me to this forum asking for some advice.

Regardless of gear (I never do this from gears 2 to 1 though) when I downshift either coming to a stop or to be at a lower gear / higher rpm for some added power; the bike feels as if the engine completely loses power and a 'puff' or hissing noise momentarily appears in substitute of the (awesome) 'BRAP'. This happens about 1 out of every 15 downshifts or so. As soon as I pull in the clutch then blip the throttle to match revs of the lower gears is when this loss of power / hissing noise phenomena happens - as I'm twisting the throttle.

I just came out of my local HD dealership and the service fella there told me he never downshifts for more power because he has a bigger motor lol.. He couldn't get past why I rev match downshift the damn thing. So I am hoping the world out there can help me with my issue. Thank you all in advance for taking the time to contribute here. If I left anything out or can't seem to explain it as well as I should then I apologize in advance. Just let me know what it is and I will try to be more clear about it.

 

I want to add that this appears to happen in the higher RPM range as well. Typically (if not always) over 3k. Stock Clutch and 1.5'' tank lift. I know when I used to run the 3'' tank lift the bike would stutter when low on fuel but this is happening even when I top it off on the fuel as well.

Now I also feel it may be me with my riding style. I am used to riding sport bikes, rev matching happens fast when on one of those. Is the sportster platform with the evo motors not intended for sudden downshifts (provided with the right amount of [quick] throttle blip)? I ask because I notice the bike doesn't exactly enjoy quicker yanks at the throttle. New to Harley's and all so I figure I would throw that out there. Hell, I am a new rider in general, been only riding for about 5 years now. lol

 

Rev match?
Been riding 40+ years and never heard of reving to down shift and I don't understand your reason for doing it.
Am I missing something?

 

Some motorcycles benefit from throttle blipping more than others. A big V-twin or single cylinder engine with a lot of engine braking can more easily lock the rear tire if the clutch isn’t released carefully, so blipping makes sense.

 

Been riding Harleys since 1960, big twins and Sportsters and haven't found the need to do this to shift. All my bikes have shifted just fine. I think its BS.

 

I have rode some older bikes in the past that seemed to shift into gear smoother if you blipped the throttle while shifting.
That was back in the 70's. Never experianced it on a Harley, or any newer bikes.

 

I must be explaining it wrong because I thought it was a very common concept performed in both manual cars and motorcycles in general. Please let me re-explain what I mean by rev matching while downshifting in a scenario.

Lets say you are riding the bike at 65mph on 5th gear on the highway. You want to accelerate forward as fast as you can and you have two options; you either apply full throttle on the bike on 5th gear or you downshift it to a lower gear (lets use only 4th in this example even if we can maybe put it in third but don't want to put that much stress on anything). Now you choose to downshift. How would you downshift from 5th to 4th while you're cruising at 65mph? I would pull the clutch in while simultaneously kicking the gear down to 4th and blipping the throttle to match the (higher) revs that the bike would cruse on at 4th gear while traveling 65mph. Otherwise if you just pull the clutch and kick the gear down and let go without matching the revs by blipping the throttle (hence rev matching) the rear tire will most likely lock up because of it.

Now me and my buddies call it rev matching and the talk at the track is known for it to be 'rev matching' from either car guys, road racers or plain old regular Harley dudes. I am sure other folks call it a different thing but this is what I mean by rev matching. I hope this helps though, honestly. Thanks.

 

No, I didn't mean to say that I blip the throttle in attempt to have the gear shift smoother. I was referring to blipping the throttle to increase the revs, therefore matching the revs of the lower gear because it will be at a higher RPM if traveling at the same speed. Say downshifting from 5th to 4th while traveling at 65mpg. My sportster shifts smooth for my own taste lol.

 

I have Forty Eight with stage 1 etc and I always blip the throttle on downshifts; always done this on all bikes and in fact instructed to do this as a young lad on trials bikes back in the 70s. It’s does make mechanical sense and by matching crankshaft speed to the new gearbox speed the clutch gets an easier life. I’ve ridden sports bikes around tracks such as the Nurburgring too and before slipper clutches came on the scene, blipping to match engine speed with new gear box speed was fully recommended to prevent rear wheel lock up. Slipper clutches are essentially performing this engine-clutch-gearbox speed matching for you.
Moving on - my Forty Eight performs this procedure perfectly - so I suspect it’s in the throttle adjustment or FP3 tune you have selected or even clutch adjustment. I have learned too that these bikes are sensitive to service adjustments and lubing such as this. Get them right and you’re ride is sweet, get one or two of them slightly off and you can get off behaviour that you describe.

 

Rev matching is not only safer, but causes less mechanical strain on gear boxes, clutches, and transmissions, as well as less wear on the rear tire. Plus it makes the ride so much smoother.

Back to your original question, it sounds like you are either running a bit too rich at that time or your timing is a bit out in low load situations such as that.