Stall / low RPM performance issue resolution......

14115 Views 7 Replies 5 Participants Last post by Erik Sher, May 18, 2015

luvbnabubba

Discussion Starter · May 15, 2015

After 2,000 miles of poor performance, dealers telling me I "don't know how to ride a sport bike", and other such nonsense, I finally found a repair shop that listened and was knowledgeable enough to fix the problem!

Problem: After installing an Akrapovik exhaust and DynoJet Commander V controller - at a dealership where I bought the bike, by the way - the bike stalled randomly when throttle was applied and the engine flooded at below 6000 RPMs (e.g., riding in town).

Background: Yamaha Corp. wouldn't do anything about it and two dealerships said it performed that way because I was an inexperienced rider (despite the fact I've been riding for about 40 years). No, I'm never going back to those dealerships unless forced to do so because of a warranty repair.

Solution: Factory setting for the Commander V was too lean on the low end of throttle application and low RPM cruising speed. The 13.8% air /gas ratio mix ("ideal") was off by a lot at the beginning of throttle application (stalled when throttle applied) and at below 6000 RPMs (too much gas, not enough air).

Manually adjusting the DynoJet air / gas ratio to the desired 13.8% from the factory settings completely resolved the problem. I did everything I could to cause it to happen this afternoon - 3000 RPMs in fourth gear, repeated super slow application of the throttle, etc. - and I couldn't get it to stall or flood.

Hope this helps anyone experiencing similar problems. Good luck and ride safe!

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Bob H

· #2 · May 15, 2015

Sorry you had those problems...but it all went wrong when you added a fuel controller you didn't need. The Akrapovic Titanium with the Cat and the supplied baffle was designed to work on the stock fuel map. I ran the same setup since last July and it fueled extremely close to being ideal. Yes it was a hair lean at idle but that was solved by everyone by disconnecting the 02 sensor. Doing that made the CPU go into safe mode with a constant 13.5 a/f on the entire closed loop portion.
If you bought the Akra carbon race system....then disregard the above. With that you need a fuel controller of some kind for sure. Even then...the stall and lean condition during closed loop is solved by disconnecting the 02 sensor. If it isn't disconnected....the stock 02 keeps taking fuel from the new fuel controller you had installed and never finds the a/r ratio it is looking for.

My question is....which Akrapovic system are you running? And....no matter which system you have...the 02 sensor must be disconnected.

Hope you don't mind the assumptions I made. I'm responding to all the members here who read this and get confused about fuel controllers.

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YamaHappy

· #3 · May 15, 2015

Actually, I appreciate this information. I was looking at getting the Akrapovic Carbon over the Ti. I figured I would need an EFI remap but I didn't realize I won't with the Ti. I wonder what the cost difference offset is...

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Bob H

· #4 · May 16, 2015

YamaHappy said:
Actually, I appreciate this information. I was looking at getting the Akrapovic Carbon over the Ti. I figured I would need an EFI remap but I didn't realize I won't with the Ti. I wonder what the cost difference offset is...

If you go with the Akra Titanium system...make sure you buy the Cat Converter and have the baffle installed. No fuel controller is needed. If you remove the baffle....all bets are off and a fuel controller is required.

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YamaHappy

· #5 · May 16, 2015

Hmmm, more to consider then. I actually would want the baffle installed as without it I feel the bike sounds too much like a dirt bike. Besides, I only just sold my Triumph Striple because the noise was killing my hearing. This bike stock is a little too quiet though so I will be upgrading the exhaust.

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YZEtc

· #6 · May 16, 2015

I have the Akrapovic titanium exhaust with the Dobeck EJK.
The bike runs great, and has a sweet tone to the exhaust, sounding very much like a 700cc version of an RC51 or other V-Twin sport bike with an aftermarket exhaust.
To achieve this tone is the main reason I switched exhausts.

Mine has the baffle in, and I DO NOT plan on removing it as I do believe it will then be loud enough to wake the dead.
With it in, it is louder than stock, but not too loud.
Actually, it sounds very good, both in tone and volume.

Personally, I believe it a good idea to use a fuel programmer with an aftermarket exhaust.
Sure, the bike will run without one, but it will run better with one.

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Bob H

· #7 · May 16, 2015

YZEtc said:
Personally, I believe it a good idea to use a fuel programmer with an aftermarket exhaust.
Sure, the bike will run without one, but it will run better with one.

I agree...but in this case with the FZ07 ...the AKRA TI exhaust was designed to run on the stock fueling. No other motorcycle I ever heard of is like that. Yamaha OFFICIALLY says that with the AKRA TI...the warranty will not be voided if the CAT is used and the baffle is installed.
I also just added the EJK controller and it does run smoother and is a bit more civilized to ride. In the past I have used fuel controllers and jet kits on 100% stock bikes....and they all ran smoother and better with one.

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Erik Sher

· #8 · May 18, 2015

i had Acra Tit DB Killer OUT for 1000 km and no problems with fueling, only problem was after 2 hours of highway that i had terrible headache and bells inside my head.
Put DB Killer IN and momentarily had stall issue as the idle dropped or idle is very poor mixture?

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