Surging at Full Throttle

Foxrider64 · May 16th, 2016, 05:40 AM

I performed a search and came up empty handed

More often than not, the surging issue is at lower RPMS. Yesterday at Palm Beach International Raceway I was having surging issues at full throttle in 6th gear running about 90mph.

It didn't feel like the gear was jumping and my first thought was the clutch plates slipping. After pitting back in and getting past my frustration of having two mechanical failures in one day I remembered that I had put gas in the tank before that last session.

This is the first time this bike has ever experienced this in 4 years of racing/track days. It has 4300 miles, K&N air filter, stock air box w/ snorkel, full Leo Vince exhaust, block off plate, stock jets with no shims.

What are your opinions of it being the clutch vs. bad gas vs. something else?

RacinNinja · May 16th, 2016, 06:19 AM

Stock jets, no shims with full exhaust and and air filter???

I'm surprised you didn't have issues before this!! I would bet you're a little lean up top and have been for a while. This could have affected the valves....might be worth checking them to see if they need adjusting.

Of course, start with the easy thing: gas. Drain it and try another batch.

Foxrider64 · May 16th, 2016, 06:24 AM

Quote:

Originally Posted by RacinNinja

Stock jets, no shims with full exhaust and and air filter???

I'm surprised you didn't have issues before this!! I would bet you're a little lean up top and have been for a while. This could have affected the valves....might be worth checking them to see if they need adjusting.

Of course, start with the easy thing: gas. Drain it and try another batch.

Every time I have checked the plugs they looked fine, a little lean, but not terrible. I have been trying to find a shop that will actually dyno tune my bike but if it doesn't have a power commander my local shops won't touch it.

Good points though.

RacinNinja · May 16th, 2016, 06:26 AM

Quote:

Originally Posted by Foxrider64

Every time I have checked the plugs they looked fine, a little lean, but not terrible. I have been trying to find a shop that will actually dyno tune my bike but if it doesn't have a power commander my local shops won't touch it.

Good points though.

There is a jetting database here with TONS of entries. It's a good place to start and should get you in the ball park, or at least a little richer.

Also, for what it's worth, reading plugs in the age of non-leaded fuels is a bit pointless. After reading plugs and reading plugs, then going to the dyno, we were always about 3-4 jet sizes too large to get the plug the color we thought was good. The dyno told the whole story and it's a shame yours won't do carbed bikes!

Motofool · May 16th, 2016, 07:40 AM

Clutch is slipping.

ULW · May 16th, 2016, 08:56 AM

Clutch behavior is different than fueling issues behavior...

With the clutch you will see the engine revs go up without much change in speed... let's say 8,000RPM at WOT and then it surges up to 9,500 and back down to 8,000 without the accompanying rise in motorcycle acceleration performance... that's a slipping clutch under a high load, and it's fairly smooth. A certain RPM in a certain gear equals a certain speed EXCEPT if the clutch is slipping, then the engine speed will rise without the MPH, and it's not a subtle steady situation but a dynamic depending on how the clucth disks are generating heat and friction, etc.

With a fueling issue, AFR is either borderline (jetting or FI mapping) or intermittently changing (fuel filter, fuel pump, fuel quantity, fuel quality)... in this case a lean issue will cause it, and the bike performance follows the surging, it's not as smooth.

So please tell us in more detail what you're experiencing based on that?

Foxrider64 · May 16th, 2016, 12:37 PM

Quote:

Originally Posted by ULW

Clutch behavior is different than fueling issues behavior...

Agreed- and it doesn't feel like a slipping clutch to me based on previous experiences with it.

Quote:

Originally Posted by ULW

With the clutch you will see the engine revs go up without much change in speed... let's say 8,000RPM at WOT and then it surges up to 9,500 and back down to 8,000 without the accompanying rise in motorcycle acceleration performance... that's a slipping clutch under a high load, and it's fairly smooth. A certain RPM in a certain gear equals a certain speed EXCEPT if the clutch is slipping, then the engine speed will rise without the MPH, and it's not a subtle steady situation but a dynamic depending on how the clucth disks are generating heat and friction, etc.

At full throttle in a full tuck I am not watching my tach at all. When it first happened I pitted in and came to a full stop and then ran through every gear under acceleration (practice start). The surging did not happen again until I hit a long straight where I was in 6th at full throttle again.

Quote:

Originally Posted by ULW

With a fueling issue, AFR is either borderline (jetting or FI mapping) or intermittently changing (fuel filter, fuel pump, fuel quantity, fuel quality)... in this case a lean issue will cause it, and the bike performance follows the surging, it's not as smooth.

As mentioned, I had recently fueled up- the fuel had been purchased that day and is just pump fuel. I ran the same fuel in my truck which actually was performing like a turd on the drive home. The bike gave no indication in the 4 previous sessions of running excessively lean and nothing was changed besides the fuel.

If my kids allow it, I will drain the tank this evening but I have no where I can test a race bike at full throttle in my area.

RacinNinja · May 16th, 2016, 12:44 PM

Quote:

Originally Posted by Foxrider64

Agreed- and it doesn't feel like a slipping clutch to me based on previous experiences with it.

At full throttle in a full tuck I am not watching my tach at all. When it first happened I pitted in and came to a full stop and then ran through every gear under acceleration (practice start). The surging did not happen again until I hit a long straight where I was in 6th at full throttle again.

As mentioned, I had recently fueled up- the fuel had been purchased that day and is just pump fuel. I ran the same fuel in my truck which actually was performing like a turd on the drive home. The bike gave no indication in the 4 previous sessions of running excessively lean and nothing was changed besides the fuel.

If my kids allow it, I will drain the tank this evening but I have no where I can test a race bike at full throttle in my area.

While you're in there, check the fuel filter if you have one and be sure there are no kinks in your fuel line.

For grins and giggles you can also check the vent in your fuel cap. Is it aftermarket by chance?

Foxrider64 · May 16th, 2016, 12:54 PM

Quote:

Originally Posted by RacinNinja

While you're in there, check the fuel filter if you have one and be sure there are no kinks in your fuel line.

For grins and giggles you can also check the vent in your fuel cap. Is it aftermarket by chance?

No filter beyond the screen on the petcock, stock fuel cap, and good ideas. Thanks

RacinNinja · May 16th, 2016, 12:59 PM

Quote:

Originally Posted by Foxrider64

No filter beyond the screen on the petcock, stock fuel cap, and good ideas. Thanks

Welcome!

jkv45 · May 16th, 2016, 03:34 PM

Quote:

Originally Posted by Foxrider64

At full throttle in a full tuck I am not watching my tach at all. When it first happened I pitted in and came to a full stop and then ran through every gear under acceleration (practice start). The surging did not happen again until I hit a long straight where I was in 6th at full throttle again.

That would suggest a fuel flow or vent issue to me.

Foxrider64 · June 6th, 2016, 10:10 AM

Was able to make it back out to the track for some testing-

It was bad gas.

The fuel I had the issue with came from a Sunoco station. Even though it was probably a fluke- I will not be buying from a Sunoco station again.

csmith12 · June 6th, 2016, 10:56 AM

Quote:

Originally Posted by Foxrider64

Was able to make it back out to the track for some testing-

It was bad gas.

The fuel I had the issue with came from a Sunoco station. Even though it was probably a fluke- I will not be buying from a Sunoco station again.

The one near Jennings? NEVER buy your gas from there again. It's not the first time bas gas has been purchased there. Left @Sirref out on the track on the exit of turn 1 on my bike. :\

Sirref · June 6th, 2016, 11:01 AM

^ that was from the marathon, I wasn't the only one who had that issue that day as well

csmith12 · June 6th, 2016, 11:06 AM

Oh snap, sorry then... my bad. Carry on.

Glad you got it figgered out Alex and it was a simple problem.

Sirref · June 6th, 2016, 11:10 AM

It's not a good sign that there's been more than one place selling bad gas near Jennings. I've got to remember in the future to pick up all I need on the way

Foxrider64 · June 7th, 2016, 06:43 AM

It was actually in Okeechobee in South/central Florida by Palm Beach International.

Alex · July 1st, 2016, 08:45 PM

What do we think the bad gas really means? Water in the tank? Other impurities? Mis-rated octane? (selling regular as premium)

May 16th, 2016, 05:40 AM	#1
Foxrider64 Hello Moto Name: Alex Location: Ft. Myers Join Date: Mar 2013 Motorcycle(s): 1975 RD350; 2001 KX125; 2003 Z1000; 2003 KDX50; 2009 ZX6R; 2011 Ninja 250R; 2014 KX250F Posts: 352	Surging at Full Throttle I performed a search and came up empty handed More often than not, the surging issue is at lower RPMS. Yesterday at Palm Beach International Raceway I was having surging issues at full throttle in 6th gear running about 90mph. It didn't feel like the gear was jumping and my first thought was the clutch plates slipping. After pitting back in and getting past my frustration of having two mechanical failures in one day I remembered that I had put gas in the tank before that last session. This is the first time this bike has ever experienced this in 4 years of racing/track days. It has 4300 miles, K&N air filter, stock air box w/ snorkel, full Leo Vince exhaust, block off plate, stock jets with no shims. What are your opinions of it being the clutch vs. bad gas vs. something else?

May 16th, 2016, 06:19 AM	#2
RacinNinja Vintage Screwball Name: B Location: Washington Join Date: Feb 2016 Motorcycle(s): 2011 Ninja 250, 2008 Ninja 250, 2019 KTM 1290SDR, 2017 FZ10 Posts: A lot. MOTM - Mar '16	Stock jets, no shims with full exhaust and and air filter??? I'm surprised you didn't have issues before this!! I would bet you're a little lean up top and have been for a while. This could have affected the valves....might be worth checking them to see if they need adjusting. Of course, start with the easy thing: gas. Drain it and try another batch. __________________________________________________ Goin' fast on slow bikes!
	1 out of 1 members found this post helpful.

May 16th, 2016, 07:40 AM	#5
Motofool Daily Ninjette rider Name: Hernan Location: Florida Join Date: Mar 2011 Motorcycle(s): 2007 Ninja 250 Posts: A lot. MOTY - 2016, MOTM - Dec '12, Jan '14, Jan '15, May '16	Clutch is slipping. __________________________________________________ *Motofool* *.................................Never ride faster than your guardian angel can fly* "Mankind is composed of two sorts of men — those who love and create, and those who hate and destroy. Love is the bond between men, the way to teach and the center of the world." - José Martí

May 16th, 2016, 08:56 AM	#6
ULW ninjette.org member Name: David Location: Arizona Join Date: Mar 2016 Motorcycle(s): 2015 Ninja 300 X 2 Posts: 24	Clutch behavior is different than fueling issues behavior... With the clutch you will see the engine revs go up without much change in speed... let's say 8,000RPM at WOT and then it surges up to 9,500 and back down to 8,000 without the accompanying rise in motorcycle acceleration performance... that's a slipping clutch under a high load, and it's fairly smooth. A certain RPM in a certain gear equals a certain speed EXCEPT if the clutch is slipping, then the engine speed will rise without the MPH, and it's not a subtle steady situation but a dynamic depending on how the clucth disks are generating heat and friction, etc. With a fueling issue, AFR is either borderline (jetting or FI mapping) or intermittently changing (fuel filter, fuel pump, fuel quantity, fuel quality)... in this case a lean issue will cause it, and the bike performance follows the surging, it's not as smooth. So please tell us in more detail what you're experiencing based on that?
	1 out of 1 members found this post helpful.

June 6th, 2016, 11:01 AM	#14
Sirref Private Joker Name: Ben Location: Towson, MD Join Date: Nov 2012 Motorcycle(s): '99/'01 Ninja 250 "sketchy", '13 Ninja 300 "yoshi", '03 GSXR 600 "merlin" Posts: A lot. MOTM - Mar '14	^ that was from the marathon, I wasn't the only one who had that issue that day as well __________________________________________________ I see you over there seeing me, do you see the me I think you see?

June 6th, 2016, 10:10 AM	#12
Foxrider64 Hello Moto Name: Alex Location: Ft. Myers Join Date: Mar 2013 Motorcycle(s): 1975 RD350; 2001 KX125; 2003 Z1000; 2003 KDX50; 2009 ZX6R; 2011 Ninja 250R; 2014 KX250F Posts: 352	Was able to make it back out to the track for some testing- It was bad gas. The fuel I had the issue with came from a Sunoco station. Even though it was probably a fluke- I will not be buying from a Sunoco station again.

June 6th, 2016, 11:06 AM	#15
csmith12 The Corner Whisperer Name: Chris (aka Reactor) Location: Northern KY Join Date: May 2011 Motorcycle(s): 2010 250 (track), 1992 250, 2006 R6 (street/track), 2008 R6 (track) Posts: Too much. MOTY 2015, MOTM - Nov '12, Nov '13	Oh snap, sorry then... my bad. Carry on. Glad you got it figgered out Alex and it was a simple problem. __________________________________________________ Goal: Shake A Million Hands \| Look through the corners \| Track Day Prep \| Closest track? \| The Mid-Ohio School

June 6th, 2016, 11:10 AM	#16
Sirref Private Joker Name: Ben Location: Towson, MD Join Date: Nov 2012 Motorcycle(s): '99/'01 Ninja 250 "sketchy", '13 Ninja 300 "yoshi", '03 GSXR 600 "merlin" Posts: A lot. MOTM - Mar '14	It's not a good sign that there's been more than one place selling bad gas near Jennings. I've got to remember in the future to pick up all I need on the way __________________________________________________ I see you over there seeing me, do you see the me I think you see?

June 7th, 2016, 06:43 AM	#17
Foxrider64 Hello Moto Name: Alex Location: Ft. Myers Join Date: Mar 2013 Motorcycle(s): 1975 RD350; 2001 KX125; 2003 Z1000; 2003 KDX50; 2009 ZX6R; 2011 Ninja 250R; 2014 KX250F Posts: 352	It was actually in Okeechobee in South/central Florida by Palm Beach International.

July 1st, 2016, 08:45 PM	#18
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	What do we think the bad gas really means? Water in the tank? Other impurities? Mis-rated octane? (selling regular as premium) __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)

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