General stalling question...



20 replies to this topic
  • motoxjeff

Posted January 19, 2014 - 05:21 PM

#1

Hey guys,

 

Quick background.  2014 YZ 450F, I ran VP U4.4 (no other engine mods, etc) at a race today.  C class rider.

 

The bike has just been a pain in the a$$ to start, but the bigger problem is stalling coming into the corners.  My idle is set at around 1000-1040 rpms (according to my hour meter).

 

The problem is this.

 

FULL throttle into the corner, hard brakes, then immediate stall (Yes I pulled in the clutch).  Could this be the U4.4 making my bike run differently than pump gas?

 

Any HELPFUL advice or thoughts appreciated.

 

Thanks.



  • gimped up

Posted January 19, 2014 - 05:24 PM

#2

Improperly jetted.

  • motoxjeff

Posted January 19, 2014 - 05:45 PM

#3

Improperly jetted.

Uhh….on a 4-stroke?



  • ktmrider125sx

Posted January 19, 2014 - 05:46 PM

#4

Jetting and or valves out of adjustment

  • Monk

Posted January 19, 2014 - 05:47 PM

#5

Race fuel for a C rider?

  • motoxjeff

Posted January 19, 2014 - 05:59 PM

#6

Race fuel for a C rider?

Yes, and please don't tell me how I don't need it.  It makes me feel good inside, and I can afford it.  If you have something positive to say, then I would love to hear it.  Next.



  • Krannie McKranface

Posted January 19, 2014 - 06:10 PM

#7

Improperly jetted.

 

Yeah, no jets in a 2014; it's FI.

 

You need to get the Yamaha Re-mapping tool, and start some reading in the Yz450 forum about what mapping changes to use.



  • JTucker

Posted January 19, 2014 - 06:11 PM

#8

Idle too low??? Plus there's no need for race gas. It does smell good though.......



  • gimped up

Posted January 19, 2014 - 08:54 PM

#9

Uhh….on a 4-stroke?

You haven't learned sarcasm yet! Lmbo

  • Bturner

Posted January 19, 2014 - 10:12 PM

#10

Hey guys,

Quick background. 2014 YZ 450F, I ran VP U4.4 (no other engine mods, etc) at a race today. C class rider.

The bike has just been a pain in the a$$ to start, but the bigger problem is stalling coming into the corners. My idle is set at around 1000-1040 rpms (according to my hour meter).

The problem is this.

FULL throttle into the corner, hard brakes, then immediate stall (Yes I pulled in the clutch). Could this be the U4.4 making my bike run differently than pump gas?

Any HELPFUL advice or thoughts appreciated.

Thanks.


That's your problem right there. Race fuel in a stock bike. You need pump fuel, 93 at the most. Unless you have a HC piston & a motor built for race fuel, your just making the bike run worst. Try pump fuel. It'll run like it's supposed to.

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  • uuhhhh

Posted January 19, 2014 - 11:42 PM

#11

IIRC U4.4 is oxygenated. You're probably running lean on the stock tune. Either have the fuel map tuned or switch to pump gas.



  • motoxjeff

Posted January 20, 2014 - 04:11 AM

#12

IIRC U4.4 is oxygenated. You're probably running lean on the stock tune. Either have the fuel map tuned or switch to pump gas.


I remapped the bike when I got the FMF pipe so it should be good there. I'll play with the idle ...

  • slammedmind

Posted January 20, 2014 - 04:16 AM

#13

I remapped the bike when I got the FMF pipe so it should be good there. I'll play with the idle ...

as above you need to map it for the fuel youre using



  • grayracer513

Posted January 20, 2014 - 03:45 PM

#14

In answer to your original question, yes, the gas could be the direct cause.  And in spite of your apparent rejection of the idea, you'll probably need to remap for the fuel because of the very high oxygen content, as has been suggested. 

 

The fact the you already did that for the pipe means nothing because no matter what setup you had before, or how dialed in it was, U4.4 will require remapping/rejetting in pretty much every case, with no other change being made.  It could turn out to be an even bigger matter if the idle mix has to be tweaked, because the GYT-R tuner can't do that.  The dealership will have that capability, but you either need to go to them, or buy the much more expensive ECU scanner the dealers use.

 

Overall, it might be a whole lot simpler to use one of VP's non-oxygenated race fuels instead.  Also as mentioned, the idle speed is a bit low at 1200 rpm.



  • motomike137

Posted January 21, 2014 - 05:08 AM

#15

What a bunch of jagoffs... dude comes in here and asks a simple question and gets told how he should or shouldn't spend his money. The only person who even comes close to giving him a decent answer is grayracer.



  • motoxjeff

Posted January 21, 2014 - 11:01 AM

#16

What a bunch of jagoffs... dude comes in here and asks a simple question and gets told how he should or shouldn't spend his money. The only person who even comes close to giving him a decent answer is grayracer.

I know right?  I'm an &%$#@! for running race fuel in my bike, during a race.  



  • grayracer513

Posted January 21, 2014 - 01:28 PM

#17

That's enough, now.



  • motoxjeff

Posted January 22, 2014 - 02:21 PM

#18

In answer to your original question, yes, the gas could be the direct cause.  And in spite of your apparent rejection of the idea, you'll probably need to remap for the fuel because of the very high oxygen content, as has been suggested. 

 

The fact the you already did that for the pipe means nothing because no matter what setup you had before, or how dialed in it was, U4.4 will require remapping/rejetting in pretty much every case, with no other change being made.  It could turn out to be an even bigger matter if the idle mix has to be tweaked, because the GYT-R tuner can't do that.  The dealership will have that capability, but you either need to go to them, or buy the much more expensive ECU scanner the dealers use.

 

Overall, it might be a whole lot simpler to use one of VP's non-oxygenated race fuels instead.  Also as mentioned, the idle speed is a bit low at 1200 rpm.

Gray,

 

I bought a jug of T4.  I'll test it next week in California.  I think that will be better, without screwing around with too much re-mapping.  I turned the idle up to around 1,500.  

 

http://www.vpracingf.../motocross.html

 

T4™
T4 is designed for stock or slightly modified 4-stroke bikes, quads, UTVs, SXSs and other off-road vehicles used in competition.  Unleaded and ethanol-free, T4 is a direct pour-in replacement for premium pump gas, which has a short storage life and has caused a heightened need for repairs in the powersports industry due to its ethanol content.  While riders facing extreme conditions are forced to add octane boosters or race fuel to increase the octane of pump gas, T4’s 100 octane rating (R+M/2) provides greater protection against detonation.  Compared with more expensive performance parts that increase power along only a small slice of the power curve, T4 offers 2-3% more power and better throttle response across the entire RPM range.

 

 


TYPICAL VALUES
•    Color: Yellow
•    R+M/2: 100

•    Motor Octane: 93
•    Specific Gravity: .745 at 60° F


  • YZPaGuy

Posted January 23, 2014 - 03:42 PM

#19

Just a quick question. How many races/practices have you used the 4.4? Did this just start happening after several tanks full or is this the first time you are using 4.4?

 

Only reason I'm asking is if you have been using the fuel for a while it may be a motor/clutch problem rather then the fuel. Just seemed to be the only question no one has asked.



  • motoxjeff

Posted January 25, 2014 - 06:06 AM

#20

Just a quick question. How many races/practices have you used the 4.4? Did this just start happening after several tanks full or is this the first time you are using 4.4?

Only reason I'm asking is if you have been using the fuel for a while it may be a motor/clutch problem rather then the fuel. Just seemed to be the only question no one has asked.


It was the first time using it. Just had my valves checked and they are in spec. Turned my idle up to around 1500 and it seems to be running fine now. I'm going to try the T4 instead of the U4.4. Talked to a VP rep and he said it would run better in my bike. I'm also going to get the throttle body mod from injectioneering. Should run like a champ





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