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How did the carb look?
The bike still runs fine but has developed a bit of a lean bog and of late. Ill get into the carb tonight and see how it looks, i ran out of time last night
This.
The EFI systems in our motocross bikes are incredibly basic. Full time open loop speed density = "I'm just gonna do some quick math on what air flow/density/charge I'm getting, throw some fuel in, hopefully its right!"
Someone should ask the factory mechanics if they are running closed loop when we see the O2 sensors in the headers. Assuming they are widebands, are they using them to trim the fuel in closed loop? Or just for monitoring and making adjustments to fueling manually.
You're right but I think the main point he was trying to make is running high octane fuel in a bike that doesn't have increased compression is just a waste of money as you won't make any more power.
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O2 sensors are only used for reading AFR so they can make the appropriate adjustment. When its race time, the sensors come out and the plugs go back in the bung.
My first time going into the 4 stroke space. I went to a Vortex and started using T4+. First can posted seemed good but the second can had a few moments with hesitation and some lean deceleration tendencies. I didn’t think too much about it but I’m wondering if the batch numbers match up with others.
Get that crap out of there. This is how the fuel wrecked everyone's engines a few years back. It's probably getting lean because the carb is getting plugged up. Seems you caught it just in time.
For sure with race fuel you don't want to store it in the bike. It tears up everything. Honestly the stuff these days is far easier on the fuel system than the stuff I was running 20 years ago. But that stuff made way more power lol.
…I purchased a new can of VP T-4 from Temecula Motorsports in July 2025.
Before I took it to the register to pay, I checked the batch number on the can against the bad batches listed by VP
The T-4 that I was buying was not listed as having an issue.
I used the T4 for the first time in a new stock 2025 KTM 350 SXF with about six hours on the motor, and there was no other fuel in the bike.
The bike ran fine for about 20 minutes, but unfortunately it decided to cut out over one of the larger jumps at Fox Raceway.
obviously I knew that there were past issues with this fuel, but I thought that it had been resolved, boy was I wrong.
I drained the fuel from the bike immediately, and tried to return the unused portion of the can for an exchange or refund with Temecula motorsports, they told me to take it up with the VP as they would not be issuing any refunds or exchanges.
I normally use ETS fuel exclusively, as I have never had a problem with their product, unfortunately, I had to buy VP because ETS was out of stock.
the bike in question has never had any more problems running ETS or pump fuel.
I was listening to Keefers show yesterday, and he claims that the VP fuel causes the O-rings in the fuel pump to expand, potentially cutting off the fuel supply to the engine.
So, no more VP fuel for me. If anybody wants a free can of T4 with about a half a gallon missing, hit me up😀🤣
I was running T4+ in my CRF450L dual sport. Bike was running fine but when I got to the low fuel light which means around 0.5 gal left and after about 0.1 gal, the bike started cutting out briefly and then after another 0.1 gal the bike was sputtering nearly to a stop. I shut the bike off and checked the fuel hut there was still plenty in the tank. When I restarted I was able to get back home with minimal stuttering. I had just read this thread so I drained the rest of the T4 and filled it with premium gas. But I wonder if the T4 got my fuel pump or if this was just due to low fuel.
VP wont cover your fuel pump. 😉
I've run U4.4 exclusively for about two years with zero issues, but have since moved to av gas. Much more consistent and it's only $5.00 a gallon. Win/win.
Any tips on how to locate a place to buy av gas? A quick google search was less than helpful. I think it’s time for my relationship with vp to end… after hearing about all these problems I don’t know if I’ll ever be able to trust them, and certainly not at the price they sell it.
I currently have been running C9 and haven’t had any issues, that being said I would like to try ETS or Renegade and not quite sure where to purchase it here in the las vegas area… i’ll crack another post ride beer and start doing some google searches i suppose!
100ll self serve
Search that
Renegade is even more expensive than vp. They use to have free shipping which was cool but last time I checked they were no longer doing that.
My buddy bought a low hour (30) ish Honda 450 and the pump went out. Was purchased from original owner and close friend that only ran this fuel. Crazy. We thought it was a Honda thing because another friend put multiple in his crf450 but also ran same VP fuel exclusively.
All of this points to one thing.....stop using VP fuel. This is now the 2nd major issue, so pick another Brand
Pit Row
At this point i’ll go run probably not so fresh 91 ethanol free that’s sold at a flyin J truck stop for RVs but it’s about 80 miles from the house! I’ve tried getting 100LL from the two municipal aero puertos close to me and they said they wouldn’t sell to me into a plastic fuel can only to aircraft… i don’t get that so if anyone knows a trick let me know!
Pump gas for the win!
Yea man, fuck that. I would rather die than use the gas my bike is designed to run on.
Seems this VP fuel has left lingering effects and hearing it damages O rings makes sense. I replaced injector, reset TPS too many times, replaced fuel filter in tank and in line cone. Dumped the VP but still once in awhile get a hesitation when cracking the throttle. Fuel pump next to replace.
As far as AV gas my experience our airport has it and it is leaded we ran in 2 bikes for several months, both ran fine no weird occurrences like the VP crap. I then tore them down both 4 stroke bikes, the pistons had large amount of grey residue on them and the valve stems too. I assume this was the lead in the AV gas? didn't make them run bad but seemed a lot of residue I didn't want in my engine. 91 pump gas is best we can do and bikes have been just fine with the exception of the one damaged by VP fuel.
Go to self serve small air strips and go late at night is what I did. Avoid people entirely.
Ahhhahhahahahha.....🤣
You can go to a regular gas station anytime, no one's ever stopped me from filling my utility jugs.
Where are you getting av?
Man, I've done alot of riding for 25 years and have never had an issues with 93 premium from the pump. Bike will sit for a couple weeks go ride with no issues. The insistence on people to spend more money than needed then scream about track prices increasing by $10 is blowing my mind right now.
I only had trouble in NJ one time with filling plastic gas cans. Nj pumps your gas and is a ridiculous state.
But yeah of course you can go to a regular gas station anytime. These guys were asking about avgas so I made the recommendation based on that…
If you have a old two stroke , set up for c12 or whatever , 100ll is a great alternative.
I’ve know race car builders to set the engines up for it too, just a cheaper alternative to the insane race gas prices.
Driving my RV from West Virginia to Connecticut we were in NJ late in the day. I pulled into a gas station, hopped out, swiped my card, and started fueling. A couple minutes later a guy comes around and is like what are you doing!? 😅 I'm just an ignorant Kansan...
Try grenading a motor due to crappy pump gas and get back to me.
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