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Found 6 results

  1. Regarding: 2015 / 2016 250FX Looking for input from current owners who ride at elevation (5000 feet up to 10,000 in less-often occasions). Quick stats: I'm a *long* time KTM 2-stroke owner (200, 250 and 300), but I want to change things up entirely and get back into riding more often (the mountain bike has taken over, but I'd like to mix it back up more evenly, and getting a new bike, something totally different, might put the spark back in me). 175 pounds / Ability is A / Expert in technical skill; need to get my intensity and speed back. That's also where the idea of a 250F comes in - I love small-displacement bikes. I live in Northern Utah, and ride tight, technical off-road mountain single track, desert, and Colorado once or twice a year, with a few races thrown in. My concern is the power at high elevations - my typical scenario is 5,000 - 8,000 feet. Weight is 175/180 pounds geared up. 5'9". Who is riding this bike at elevation - any feeling of being underpowered? I'm guessing not but would love to hear from guys riding this bike high in the mountains. I would be buying this bike without having even ridden a 250F in a long time, but again, looking for a major change, love small-displacement bikes and feel like this bike "may have it all" as far as the 18" wheel, great suspension, e-button, etc.
  2. Hello Everyone! I just purchased a 2015 CRF150RB for my girlfriend to learn on. I had the same bike some 10 years ago and it suited me well so I figured it would probably be a good learner for her with some extra room once she wants to go a little faster. I picked the bike up with supposedly 50Hrs on it, although I'd guess it's higher. The bike is completely stock (to my knowledge) with the exception of an R&D Flex-Jet. Problem is.. I bought it down in Phoenix, and I live and ride in Sedona/Flagstaff area so we have a pretty significant difference in altitude. Typically riding between 4,000-6,000ASL, and 65-90F temps. I have no idea what jets are in it currently (PO says stock), but the bike just doesn't want to start! Probably take 20-30 kicks to get it running, and it runs pretty well once it's going but a real PITA to kick back up again once the girlfriend stalls it. The bike probably needs a valve adjustment, but I don't want a half torn apart bike in the garage over the holidays so I figure it would be best to make sure I have all the parts to put it back together all at once. I think I've read every single thread on this site about jetting and thoroughly boggled my mind with different opinions, trying to compare setups to other people's setups at similar temps/altitude. So where should I go from here? Pilot jet? Main jet? Needle position? JD jetting kit? What's your experience, and where should I be looking to make this thing run nicely for her so she can start it in a couple kicks instead of a couple hundred kicks. Not too worried about spending some cash, but I prefer to do the work myself. Thanks for the input everyone!
  3. Okay im not sure if this is a problem or not but it kinda bothers me. I have a 2004 yz250. I had jetting problems with it but I believe I have fixed it (in a way) the stock main jet was 178 and pilot was a 50. Stock needle at 2 clip position. That jetting ran fine for 2 years at 500ft elevation. Earlier this month it seems to sputter and bog at high rpms ans not hit the powerband and it would bog just riding bumpy trails too and hitting hills it would bog BAD! I checked reeds ans they are fine. I repacked the silencer and I checked power valves for carbon build up ans they seemed fine and it all moved good ans smooth. So I bought a JD jetting kit and the pilot jet i have in now is a 45 and it called for the main jet to be 172 and red needle at 3rd position for my elevation. I took it to the trails and it still was bogging at high rpms and riding bumpy trails. So I changed the main jet to a 168 it had in the kit and the top end power was fine after that it hit the powerband and stuff but low end it wasn't great so I moved the clip position from the 3rd to the first at the top to lean it out and it seemed to help. It doesn't bog low end or anything but it seems the first 1/4 throttle it tends to bog just a tad. So my question is how can I fix that little bog and is my jetting okay for what elevation im at? Is it too lean?? It seems to me some other people run their main jet at 172 for 500 ft elevation. Thank you for reading and your responses! I'll be sure to check here every now and then to get the problem fixed.
  4. Due to the large amount of phone calls regarding this topic, it is prob a good idea to post up some "information" regarding this. highly debatable, subject(s). Not going to get real indepth but touch on a few basics that constitute what is required in order to have true elevation and temperature control with ANY carburetor. A few "concepts" on carb function:Again, not 100% encompassing, just basics. 1) ALL carburetors function on a pressure differential (Delta P) between the Carb Float Bowl and Engine. 2) This Delta P is what will,largely,determine how much "signal" is present to "pull" fuel up the needle jet into the engine. 3) Larger Delta P will equal more fuel flow and vice versa. 4) The engine will always be the low pressure side and the carb will always be the high pressure side. 5)We can consider the engine side a constant vacuum in terms of pressure (even though it varies) 6) The Carb float bowl pressure will vary with elevation. As you raise in elevation, the atmospheric pressure will lessen (usually) and the pressure of the float bowl will lessen as well. 7) Lesser ATM Pressure will equal lesser Delta P and equate to less fuel flow. 😎 IF your carb float bowl vent lines are vented ANYWHERE but into their own dedicated pressure chamber, your float bowl pressure WILL be at atmospheric pressure (or very close to it) 9) ANY and all Carbs will lessen flow as you raise in elevation. Meaning... ALL carbs have a built in elevation control simply as a result of its design and function. __________________________________________________ ___ OK.. Now that the "Basics" have been touched upon.. let's dive into what it truely takes to have control over elevation and temperature: 1) VERY SIMPLE--> Control Delta P and you can control the fuel flow! How do we control Delta P? You can control Delta P via altering engine side pressure or carb side pressure. Simple as that. It is possible to control either but controlling the carb side is WAY easier than controlling the engine side. How does one control the float bowl pressure? The only sure fire method to control the float bowl pressure is to have it vented into it own dedicated pressure chamber. This method has been used in the snowmobile world (huge elevation and temp changes) for many decades! They would connect ALL the float vent lines together and connect them to a dedicated pressure chamber that is controlled via the ECU and an Atmospheric Baro Sensor. Basically, they would sense the ATM pressure (baro sensor) and adjust this chamber volume based on this sensor. They also had a temp sensor that would add to the mix and adjust even further using the temp sensor's input. NOTE: this was a "programmed" function based on sensor inputs and the mechanical circuitry to implement it. It required dedicated electronic and mechanical circuitry. If ANY of these circuits failed (and they would occasionally) the jetting got "incorrect" in a hurry. Worked pretty well. We could run the SAME jets at 10,000ft that the sleds at sea level were running. Pretty impressive! So... How do you know if you have elevation and temperature control with your carb? Simple--> does it have a temp and baro sensor and a dedicated float bowl pressure chamber? IF it does NOT, then you do NOT have compensation outside of the built in mechanical compensation present with ANY carb.
  5. Hey guys so I've recently been looking at a yz125x and its going to be my first 2 stroke dirt bike. I've read a lot about 2 stroke jetting and I still don't know if I should keep the stock jetting. I live at around 330 feet in elevation but where I ride the elevation is around 3,000 feet. I don't know if it will make that much of a difference so I'm just looking for some insight. I would ask the dealer but I don't know if whatever that guy says is true. If anyone has any insight or has a similar situation please let me know, thanks.
  6. I just purchased an 02 xr400 it came from a beach city and I live in the mountains around 6500 ft just curious what jetting and float clip position I should be running the bike still fires up and runs good once warmed up a little stutter in throttle though.
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