Posts
741
Joined
12/1/2018
Location
@sundaymotos, NJ, USA
Edited Date/Time
9/10/2019 6:38am
I bought a 2018 350 SX-F new in December. The motor is completely stock and I've run VP T4 since the first tank. Bike has 17 hours on it and has run great until recently.
The bike rode great during my last ride (normal practice day at the track). Got home, pulled the air filter, put the air filter cover on, washed the bike, and put it in the garage. It then sat for 3 weeks because life got hectic moving into a new home. When I finally settled in, I cleaned the air filter, installed, and tried to start. The bike turned and turned and turned but would not start.
I checked the fuel line, the fuel pump, the fuses and the rest of the electrical connections. Essentially drained the battery troubleshooting. Took it to my new local shop (long standing and reputable). They checked: the compression, the ignition, and connected to the computer with no codes. Eventually, they determined that the fuel was the issue. They completely flushed the tank, the pump, the lines, the rail and injector.
They filled it with 93 pump gas and fuel conditioner. Got it started and said it was good to go. They said the fuel that was in the bike was really bad... that it didn't smell like gas or race fuel. However, I pour it right from the metal T4 jug into the tank - not sure how it could be bad. Fuel is only 2 months old, stays in the metal container, and in a temp controlled environment. Shop guys told me to run 93 instead, but I can't see how fuel with ethanol could be better for this engine than T4, which is designed for 4 stroke stock motors.
Anyway, I picked up the bike yesterday, and started it again tonight. It struggled to start more than before this issue began, but it did start. However, when I cracked the throttle the first few times once warm, it kept stalling... maybe 3 or 4 times. Keep in mind, normal pump gas is in it now.
So what do you guys think? Do I need to rip this thing wide open at the track and blow out whatever could be causing these issues? Or could that further exacerbate the issue? Should I stop running T4? I was thinking maybe the valves are off, but since the bike only has 17 hours on it, everyone said that wouldn't be it. Please help...
Thanks,
Austin
The bike rode great during my last ride (normal practice day at the track). Got home, pulled the air filter, put the air filter cover on, washed the bike, and put it in the garage. It then sat for 3 weeks because life got hectic moving into a new home. When I finally settled in, I cleaned the air filter, installed, and tried to start. The bike turned and turned and turned but would not start.
I checked the fuel line, the fuel pump, the fuses and the rest of the electrical connections. Essentially drained the battery troubleshooting. Took it to my new local shop (long standing and reputable). They checked: the compression, the ignition, and connected to the computer with no codes. Eventually, they determined that the fuel was the issue. They completely flushed the tank, the pump, the lines, the rail and injector.
They filled it with 93 pump gas and fuel conditioner. Got it started and said it was good to go. They said the fuel that was in the bike was really bad... that it didn't smell like gas or race fuel. However, I pour it right from the metal T4 jug into the tank - not sure how it could be bad. Fuel is only 2 months old, stays in the metal container, and in a temp controlled environment. Shop guys told me to run 93 instead, but I can't see how fuel with ethanol could be better for this engine than T4, which is designed for 4 stroke stock motors.
Anyway, I picked up the bike yesterday, and started it again tonight. It struggled to start more than before this issue began, but it did start. However, when I cracked the throttle the first few times once warm, it kept stalling... maybe 3 or 4 times. Keep in mind, normal pump gas is in it now.
So what do you guys think? Do I need to rip this thing wide open at the track and blow out whatever could be causing these issues? Or could that further exacerbate the issue? Should I stop running T4? I was thinking maybe the valves are off, but since the bike only has 17 hours on it, everyone said that wouldn't be it. Please help...
Thanks,
Austin
Because the bike killed the original battery, that could be your issue due to it labouring to start. I would replace the battery, check grounds and go from there. I would also suggest a hard reset too.
My bike would start so bad on stock Ecu. Now with the remap and Vortex. + battery. It will instintly start.
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50/50 T4/91 pump on Vortex Ecu. I’ll use straight T4 when racing.I normally drain my tank if I’m not going to ride within 7 days.
The stock mapping is really bad, I’d put my money on it that your bike would start better with a new map. My 16 250sxf would drain the battery all the time with stock ecu. The new map will also compensate for the TPS.
Have you tried setting your throttle position reset?
1) Leave throttle closed/don’t touch it, hold the kill switch and press the starter for 3 seconds
2) turn throttle wide open, hold the kill switch and press the starter for 3 seconds
This is said to reset and set the throttle position. Doesn’t work magic but maybe worth a shot.
I also always just ran the stock mapping with t4, because VP says its a pour in replacement. Its really not a pour in replacement and their banking on the stock mapping being rich. I never had any decel popping or anything but the bike felt a little jerky (I had a buddy alter the delivery down low to clean this up). Ultimately I now have a map with +4% and another with +8% fuel across the board to compensate for the fact that T4 is about 7-8% lower Stoich than pump, and the bike rides SO much better.
3 weeks for an oxy fuel to sit in a vented tank on the bike is a long time. Would you trust it if you left it in the 5 gallon pale with the cap off for 3 weeks?
Not to discredit the advice, but it could also be that whatever “alleged” bad fuel was in the bike has now fully burned off. I’m heading to the track on Sunday. I still have the same metal jug of T4 that the shop blamed, and I’m going to chance it and try it. If the bike continues to run well on it, I think we might be able to credit the TPS reset as the solution. I’ll keep you guys posted.
So it wasn't the fuel. I burned through that tank for T4 just fine.
Here's the issue now: The bike will start, but only if I apply 1/8 throttle and hold it until warm. If I don't apply throttle, the starter will just keep turning. If I let off the throttle while still cold, it will stall. Pushing the cold start button doesn't help, so I assume the idle isn't the issue. Once the bike is warm, it starts fine without throttle application. Starting is especially difficult after washing. I lay the bike on its side when washing, so I'm wondering if the tip over sensor could be part of the problem (just learned that this was a thing). Because it runs fine when warm, could it be the valves? Bike only has about 20 hrs.
I still haven't bought a new battery or remapped it. Trying to avoid troubleshooting through spending unnecessary money. The good news is that I can get the bike to start, but for a new bike, my OCD would prefer it to start without a hiccup.
Thoughts?
I'm on a Honda CRF250 now and its the same. Struggles with stock mapping, instant on a Vortex.
So far I’ve ruled out the fuel, tps, and battery. Again, the bike runs great once it’s warm, just having some trouble starting. I’m not in a position to spend a bunch of money on a remap. Any other ideas?
Also, does anyone know the torque spec for the engine mount? I had to remove it to access the tps and I can’t find the ft lbs in the manual.
I've prepped the battery as you've described - hitting the start button and letting the battery warm and fuel pump kick on. I wait about 10 seconds and then try to start (holding down the start button).
I want to stress that it only starts once I apply just the slightest bit of throttle while holding the start button. I'll maintain this throttle for about 10 or 15 seconds, then I can back off and it will idle normally.
If not use it.
If yes, then up your idle speed.
Also remember that the TPS setting is to be done with throttle completely closed. If that was not done and you only have a .52 v reading, then you are way lean. Try resetting it to .58-.62 v at closed throttle. Then reset the idle up after started to see what change it made.
Paw Paw
Pit Row
So my bike was brand new this summer the problem started just right after I bought this twin air filter cover... After I broke my collarbone it was kinda hard with 1 arm to change my filter so I just washed my bike without the filter cover and guess what my bike fired up immediatly... So i'm guessing this filter cover might be the reason why our bikes take several crank before starting up. The reason behind it? I have no idea but you should try to wash your bike without that air filter cover and see if the problems still occurs. I know this might sounds crazy but maybe theres a reason behind it!
So, my bike is also starting now, without issue. I've run a few tanks of 93 pump gas and turned up the idle. Coming full circle on this thread, but I think that the VP T4 may be too lean for this bike without a remap. Additionally, the weather has cooled down quite a bit, so that may be something to consider. Also, I typically wash my bike on its side (triple clamp on the stand) with the air filter side facing down. However, I when I washed it the other day, I inadvertently went air filter facing up. When I finished and put it upright on the stand, it started right up - even without the cold start pushed in.
So it could be anyone of these adjustments. I guess time will tell lol
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