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Only $10 for all 2026 SX, MX, and SMX series.
100LL from any municipal airport. You will never, ever, have another problem.
we dont need to see anything, id bet a paycheck the talk doesnt do the walk. The yellow seat cover and rolled forward ape hangers tell me all i need to know
Keefer confirmed on his podcast that bikes other than the Yamaha are having issues with T4. I’m hoping VP covers a new fuel pump if I need one.
My buddy with a 24 KX450 has been having issues for awhile. Bike doesn't want to idle, hard starting, and trouble codes blinking on the map switch. It's funny because I've been telling him to try pump gas. I'm going to show him this thread.
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I run 91 ethanol free pump gas in all my bikes, no issues.
This.
Realize T4 is oxygenated. If you are getting popping on decel, you are too lean and need to rejet / remap for the "air" coming in with the fuel.
If you've jetted a 2t for oxygenated vs. non-oxygenated, you'll find that there is a bit of a jump between the 2.
Properly calibrated engines using oxygenated fuel will generally make more power but still needs a slightly richer than stochiometric A/F ratio.
Best way to know / tune is using a lambda sensor and a dyno.
Best fuel for weekend warrior = 91 non-oxy or the av gas mentioned above due to also being non-oxy for the same reasons. Find a gas station that has a lot of recreational traffic: boats, atv's sxs's. They will generally have the freshest / stable 91 non-oxy.
I seem to remember Vp being hard on 1/8 scale crank bearings from day 1.
Four different Honda's and four fuel pumps replaced.
One thing in common on all bikes, VPT4+.
Hmmm. I have two bikes at home full of T4+ that I have ran a couple tanks through but now I am thinking of dumping. Figures
There is an engine masters episode where they completely debunk the 'higher octane = more power' myth. If your engine can tolerate 87 octane, then there will be no power gained all the way through 116 octane race fuel. Just run the 87. The only uptick they saw in power was when they ran oxygenated fuels (for obvious reasons). The fact that these guys are saying they just switched back to pump gas to fix the problem definitely makes you wonder why they would ever run race gas. If it is consistency you are after, fill up at the same gas station and run it. People are funny.
If you run lower octane than the engine requires, then you will see a drop in power because the bike will pull timing to keep the thing from knocking.
P.S. Obviously run premium fuel as that is what the engine package requires in modern mx bikes.
Same. Shitty to pay extra for quality/consistency then receive neither.
I have been using Sunoco Std 110 for the last 39 yrs. with no issues 2 or 4 stroke modern & vintage bike.
There isnt a single dirt bike on the planet that has the ability to detect knock and pull timing......
Just pointing out....I mentioned earlier in the thread that I run Q16 in my drag car. That stuff is 10% oxygenated and is corrosive.
If I'm not going to run that car for more than two weeks, I drain the fuel out of the entire system and put a little 2t fuel through it. This is a well known an accepted practice in the auto racing world when using that fuel. It will eat seals, gaskets and even the cast aluminum of carbs/heads/intakes.
Sounds like you guys need to start draining your T4+ between rides.
Way to take a great looking bike and make it UGLY.
Someone get some footy of pro riding please..
There is no knock sensor in a dirt bike engine. It won’t pull timing. It also won’t richen up the mixture to make extra power from oxygenated fuel since there is no O2 sensor. The base mapping should be tuned by the oem to not blow up on e10. T4 has a little more oxygen than e10.
Make that 5 possibly. I usually run VPR but bought a couple pails of T4+ because that was all I could get at the time. Bike started bogging on me this summer after riding for a while, mostly after landing and getting on the throttle. 2022 crf450 with only 40 hours.
Bought some T+4 a couple months ago, hopefully not part of the bad batch. No problems so far
Pit Row
I stay far away from VP now since Spring 2024. It’s not just T4 or T4+, they had issues with C50, VPR, MRX02, ect. They introduced the + fuels to replace the bad batches but people are still have issues with them. Little bikes, 50, 65 and 85 are having cracks replaced left and right. It leaving a black slime looking film all over the bottom end but it’s hard and flakes off. VP is complete trash going on almost 2 years now, stay far away.
I mean, it says to drain it, right on the can...
Did you have any other issues? Did you get the two amber light flashes on the map switch that indicates a MAP performance issue?
I’ve been having the same issue with my 2019 KX450. I replaced the fuel pump but didn’t think that the fuel was the problem so I continued to run T4+. The issue persisted and I’m just now hearing about people having similar problems.
Not sure if my new fuel pump is done now. How do you test if a fuel pump is still good?
I havent had it happen on any landings. Noticing it coming out of a corner hard in 3rd it will cut out for a second. Not all the time. Very intermittent.
Gonna try just running pump gas when im out again saturday and see if that solves it.
Most auto parts stores have tool loaners where you can get a fuel pressure tester. (you put it on your card and they refund when returned) But in the past when road racing with the original U4 it melted the plastic screens in our ZX636s, and the plastic wound up in the pumps.
Did the new fuel pump fix the issue?
I haven’t put one in it yet, I’m done riding for the year so I’ll do it over the winter.
I made a thread here about the issues I was having, someone recommended checking for bubbles in the tank coming from the fuel pump with it running, which I definitely had. I’m not 100% sure that’s an indication of an issue but I gotta try something, hate the idea of going out there on a track risking my life because I never know if my bike is going to cut out or not.
been using avgas for 30 years.......very crisp and easy to jet and smells factory......
For any one wondering, last night I pulled apart one of our YZ125's that has been running on T2+ for a few weeks. Sure enough, black shit in the crankcase. Not much, not enough to cause an issue in my opinion but it obviously shouldnt be there. Im not sure what VP's problem is, or maybe im doing something wrong?
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