Added reply in a thread VP U4.4 Question 11/12/2021 3:30 PM

Depends on how old the fuel is that you are leaving in your bike. Fresh fuel straight out of a can should be ok to leave in your tank for a week or so. But if the fuel has been previously opened and has been sitting around exposed to air then you are ... more »

Added reply in a thread Will VP t4 make my bike run leaner ? 6/26/2021 7:55 AM

If your pump gas has 10% ethanol, then it has roughly 7% oxygen content. Specific gravity, T4 is 0.75 while 93-octane pump fuel ranges from 0.72-0.77 depending on the summer or winter blend and local regulations. The advantages of T4 is consistency and ... more »

Added reply in a thread Switching fuels to VPR -storage? 6/26/2021 7:43 AM

Yep. UV also is an energy contributor to aid in kicking off those dimerization gum forming reactions. Like mxb2 said, keep it stored in a dark cool place, preferably in the original container.

Added reply in a thread Switching fuels to VPR -storage? 6/25/2021 9:52 AM

It's not the oxygenates that cause the storage problems in these fuels (VPR/MRXo2/U4), it's the presence of Isoprene and other olefin compounds that will turn into gum eventually. VP and other fuel manufactures use inhibitors to slow that reaction rate ... more »

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 12/14/2020 6:08 AM

Our pipe turned this color with the stock jetting with sea level and 85F conditions. Plug looked ok when pulled so we continued running the bike.

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 10/20/2020 11:02 AM

That could be a long thread so to sum it up quickly... - Consistency (Pump fuel has summer and winter blends) - Resistance to detonation - Octane number - Flame speed - BTU content - Oxygenated without Ethanol - Cleaner burning Yes...for competitive ... more »

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 10/20/2020 10:37 AM

I hear ya! The T2/T4 is not an eye popping difference but for race days I feel its a hassle free fuel. On practice days, I blend it 50:50 with 93-pump.

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 10/20/2020 10:01 AM

I haven't touched the bike since it's running so well! Very happy. I'm pretty sure I miss-read the manual when I mentioned my bike came stock with a s-4 but I have not checked physically. I do have the 42-73 needle to try and since the temps are finally ... more »

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 10/17/2020 8:20 AM

I thought digger was referring to non-Mikuni jets flowing different than original Mikuni jets. So an aftermarket 520 may not flow the same as a Mikuni 520.

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 10/16/2020 7:19 AM

How did the Bill's pipe and silencer perform? Did you need to change jetting once the pipe/silencer was installed? Good idea on the throttle housing swap...I'll look into that as well.

Added reply in a thread Anyone running VP T2 in their KTM 250sx? 10/16/2020 7:13 AM

Pretty damn close explanation Bruce! Alcohols and ethers are both oxygenates and add oxygen content to your fuel. And since normally aspirated gasoline engines operate at an air/fuel ratio in the range of 12:1-14:1, the more oxygen the fuel can bring ... more »

Added reply in a thread 2019/2020 KTM 125/150 SX Repair Manual 9/17/2020 8:34 AM

I could use a copy as well.

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 9/16/2020 9:11 AM

I have no idea...mine came with the closed air box and my buddies came with the vented but we bought them at different dealerships. The other issue is we plan to race the limited class (250 limited) and I do not think the vented cover is legal for that ... more »

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 9/15/2020 10:00 AM

Weekend Track Update: The bike ran pretty good. Only slight bogging when not in proper gear or if momentum was lost during cornering. Sea level track with temps in the lower 90's but the track is sandy so I'm curious of how it will run on a tacky track ... more »

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 9/10/2020 4:03 PM

We'll be at 3-palms Saturday and Sunday for the race. #88 KTM. Swing by and say hello.

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 9/10/2020 12:54 PM

Thanks FGR, AJ and digger...good info. I learned a little more about jetting.

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 9/10/2020 7:25 AM

You are correct. AvGas has a specific gravity in the range of 0.68-0.74 and most pump fuels are in the range of 0.72-0.77 along with most racing fuels. So you would need to increase the jetting to make up for the difference in fuel weight given the carb ... more »

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 9/9/2020 5:08 PM

Another satisfied customer of diggers jetting specs...cleared up the 1/3 throttle stumble in my 2021 KTM 125. JD jet block gasket installed S4 needle jet (factory) 42-74 needle in #2 #5 slide 35 pilot 520 main 1.5 AS VP T4 32:1 Motul 800 90F @ sea level ... more »

Added reply in a thread 125/150/250/300 KTM/HUS/GG jetting thread 9/9/2020 10:54 AM

Did your 2021 TC125 come from the factory with a S4 needle jet? The S4 is listed in the manual as being factory installed, so should I believe them or pull it out to check? "In the past on other bikes I've generally had to go a few sizes bigger on the ... more »

Added reply in a thread Keeps blowing pistons 8/12/2019 10:02 AM

The radiator is bent in a moon shape from top to bottom? Obviously, you can't check the radiator flow now but you can take it off the bike and place your house water hose in the fill neck and make sure you get a good flow out of the radiator outlets. ... more »