RPM's increase when clutch is engaged

[dcarver]

Since oil seems to be the main apparent culprit, this test was running Syn Napa 10-40..

 

[rocketdoc]

And we need to know the ambient temperature in Degrees C if this is to be meaningful. My money is the temp/viscosity issue, have seen it on my own but would have not have thought to make a video, or report it to you lot. But I'm one of those shy Canadians. Oh, by the way, Happy Thanksgiving to all our US friends.

 

[painman]

Don I believe the answer is not pursuing this problem while the bike is on the center stand. I do suggest however you do this experiment "off" the center stand "on" a smooth road on level ground of course with little or no traffic around. Too many variables IMO with the rear wheel off the ground could cause the symptoms you describe. But what matters is when you are riding and then if there is still a problem go from there. Good luck with this.

Annnd happy Thanksgiving to you rocketdoc and you Don and all our fjr forum friends! Take care, PM. <><

 

[BobbyBlue]

I have a little to add DC...i rarely use the center stand cuz i's a pussy and the sidestand works jes fine, but i've mostly lived in apt complex's and these have all required feathering the clutch to a more or lesser degree, and that final 1cm of lever travel always results in a 300 or so RPM increase...i trail brake and compensate with my right foot but i am careful in drizzle et al due to this normal anomaly...one adjusts...its our species hallmark...not that i'm a member or anything !

Happy Turkeyday !

Bobby

(my condolences to any turkeys who might read this !)

 

[Fred W]

OK... By now you should all know that I am an inquisitive type of guy. You know the saying: "Curiosity killed the cat?" Yeah, that was my cat.

So naturally I had to try and play Mythbuster on this recently perpetrated FJR urban legend. And I am here to report:

I had just added some Techron to my fuel tank and wanted to get some fed into the fuel lines and injectors for a nice soaking over the Turkey Holiday. It was rainy and crappy ouit so I decided to just idle it on the center stand. Which was when the idea to bust that DCarver YouTube video myth popped in my (often EtOH addled) brain.

Well, I didn't make any (lame ass?) video, but it did work exactly the way Donnie's video showed: Hold the rpms steady (I don't have a throttle lock so just used my hand on the throttle rocker) at any steady rpm (I tried several different ones) and as you let out the clutch and engage the drive line the rpms climb up by about 25%. Pull the clutch lever back in and they immediately drop by that amount. Put it into neutral and repeat the experiemnt exactly and there is no change in rpm. All of this is on my first gen. Why is it doing this? Sure beats the hell out of me... :huh:

 

[ionbeam]

[speculation]

The idle speed has a design specification of 800-1,200 (Gen dependent). This is the rate the engine needs to turn to idle smoothly and reliably. Factors include induction/exhaust flow characteristics, reciprocating mass and flywheel weight. When in neutral or with the clutch pulled in this rpm range works just fine.

Most shaft drive motorcycles have 12%-17% energy loss. When the engine is coupled to the rear drive this loss has to be accounted for as well as the rotational mass of the rear wheel. If not compensated for the engine probably would stall at lower rpms. Some fart smeller at Yamaha probably realized that in heavy traffic riders would be rolling at or near idle speed, in gear, and the engine would stall like that. That same Yamaha engineer may have realized that some dufus would put his FJR on the center stand, put it in gear and let the clutch out thereby loading up the engine with all the shaft drive stuff and the rear wheel. So, he added a fuel trim that would be sufficient to keep the engine idling smoothly, without stalling.

[/speculation]

 

[carlson_mn]

 

[dcarver]

OK... By now you should all know that I am an inquisitive type of guy. You know the saying: "Curiosity killed the cat?" Yeah, that was my cat.

So naturally I had to try and play Mythbuster on this recently perpetrated FJR urban legend. And I am here to report:

Hah! Take that all you naysayers and non-believers! :lol: Thanks Fred, and I'll send the 50 spot I promised for this post..

That same Yamaha engineer may have realized that some dufus would put his FJR on the center stand, put it in gear and let the clutch out thereby loading up the engine with all the shaft drive stuff and the rear wheel. So, he added a fuel trim that would be sufficient to keep the engine idling smoothly, without stalling.

Ahhh, you do wub me! :wub: Me thinks ionbeam is on the right track.

 

[HotRodZilla]

I'm just curious...Why do we care? Does this have some meaning regarding performance or longevity, or is this just a "Hey, look at that" kind of deal.

 

[FJRBluesman]

I'm just curious...Why do we care? Does this have some meaning regarding performance or longevity, or is this just a "Hey, look at that" kind of deal.

Gunny! But, it is goofy and no one else noticed this phenomena, so DC is on the cutting edge of FeeJ science! h34r:

I found a similar but different issue with internal combustion engines in general.... immersed in water they don't run at all. H2O has oxygen, and we mostly have nitrogen in our atmosphere, soooo.... Any ideas? :blink:

 

[ionbeam]

I'm just curious...Why do we care? Does this have some meaning regarding performance or longevity, or is this just a "Hey, look at that" kind of deal.

Yamaha has been trying to hide a number of serious design flaws from us just like the one that D found. Another past Forum member discovered that when the motorcycle is on the center stand and you repeatedly rev the engine from idle to red line that it will start to make hard mechanical noises. Another uncovered a major flaw when they discovered that if you put the bike on the center stand and run it up to 5,000 rpm and hold it there for an extended length of time the engine speed would start would waver.

Hmmm, it's beginning to sound like the root cause of the problem is the motorcycle being on the center stand and not out on the road being ridden.

 

[RossKean]

Hmmm, it's beginning to sound like the root cause of the problem is the motorcycle being on the center stand and not out on the road being ridden.

I guess maybe we should petition Yamaha for a center stand recall. It's clearly a defective design that will cause untold injury and death if it's multiple failings are not corrected.

 

[HotRodZilla]

Fuckin' centerstands!

 

[ionbeam]

Yup, seems to be yet another center stand failure.

 

[beemerdons]

Mr. Carver, what you really should've been thankful for yesterday is that FJRay and Chuy don't live within 100 miles of you, because Ray and Papa would've put our Size 12 brogans right up your butt for starting this stupid ass thread! jes' sayin' and nuff' said!

What is really amazing to me is how you managed to suck in "The Smart Guys" Fred W and ionbeam to this ridiculous cluster ****! Not surprised at all HotRodZilla and FJRBluesman arrived here, those two clowns are drawn like moths to "The Stupid Flame"!

 

[FJRay]

Mr. Carver, what you really should've been thankful for yesterday is that FJRay and Chuy don't live within 100 miles of you, because Ray and Papa would've put our Size 12 brogans right up your butt for starting this stupid ass thread! jes' sayin' and nuff' said!

What is really amazing to me is how you managed to suck in "The Smart Guys" Fred W and ionbeam to this ridiculous cluster ****! Not surprised at all HotRodZilla and FJRBluesman arrived here, those two clowns are drawn like moths to "The Stupid Flame"!

Excuse me !! Size 13 and why are you looking at my feet??

 

[HotRodZilla]

Mr. Carver, what you really should've been thankful for yesterday is that FJRay and Chuy don't live within 100 miles of you, because Ray and Papa would've put our Size 12 brogans right up your butt for starting this stupid ass thread.

Excuse me !! Size 13 and why are you looking at my feet??

Cuz' Papa Chuy knows what they say about guys with big feet.

 

[FJRBluesman]

Mr. Carver, what you really should've been thankful for yesterday is that FJRay and Chuy don't live within 100 miles of you, because Ray and Papa would've put our Size 12 brogans right up your butt for starting this stupid ass thread.

Excuse me !! Size 13 and why are you looking at my feet??

Cuz' Papa Chuy knows what they say about guys with big feet.

Funny, that's Papa Chuy's arse size too.