Jump to content
Sign in to follow this  

Removing the lurch from a YZ250FX ?

Recommended Posts

I bought a YZ250FX that suffers from lurching.  At small throttle openings it wants to accelerate somewhat hard.  Yet closing the throttle even a bit causes it to decelerate.  It is somewhat hard to modulate the power delivery at small throttle openings.

What can I do to smoothen out the power delivery at low throttle openings ?

Share this post


Link to post
Share on other sites

I have the Yamaha programmer.   I'd love to see some of the maps people are running as a starting point.

 

The previous owner installed a G2 throttle and slow turn cam.  I'm not sure which one.

 

What RPM should I set the idle to ?

Share this post


Link to post
Share on other sites

Practice makes perfect, get used to it.

I don't think anyone needs a different throttle cam myself.

I can send a couple maps that make it feel better. It honestly does not bother me, just got used to it.

Share this post


Link to post
Share on other sites

I have the Yamaha programmer.   I'd love to see some of the maps people are running as a starting point.

 

The previous owner installed a G2 throttle and slow turn cam.  I'm not sure which one.

 

What RPM should I set the idle to ?

Here's what I have loaded in my tuner. I tried #2 which is halfway to the GYTR recommended "smooth" and thought it was too mellow. Been happily running #3 and haven't played with any others yet.

 

maps_zpspfotxlt1.jpg

  • Like 1

Share this post


Link to post
Share on other sites

I use the MXA map on mine with the butt plug taken out of the muffler.

 

Bike runs so good that I'm done tinkering and am just going to ride it.

Share this post


Link to post
Share on other sites

Thanks for the maps.  How does one remove the butt plug from the muffler ?

 

I presently ride a WR450F, so its no problem for me to adjust to the FX lunging.  However, I feel the bike would be better all round if the lunging was tamed down. 

 

Has anyone played with the TPS to mellow the lunging action ?

Share this post


Link to post
Share on other sites

Thanks for the maps.  How does one remove the butt plug from the muffler ?

 

I presently ride a WR450F, so its no problem for me to adjust to the FX lunging.  However, I feel the bike would be better all round if the lunging was tamed down. 

 

Has anyone played with the TPS to mellow the lunging action ?

 

I knew I shouldn't have posted on this thread.

Share this post


Link to post
Share on other sites

I have a 15 250fx. The lurching is a real pain. I have tried all the tricks with exhaust and mapping. A while back I found a video of a man who specializes in an improved fuel line for the FX. What I can recall is he is a KTM performance pro. The video showed a digital gauge hooked up before and after the fuel rail. The fx has a double 90° angle on the fuel line prior to entering the injector. At low speeds the fx has issues with flow. The part was about 70 bucks. For the life of me I cant find the guy or the site online!! Acording to this man he has completely solved the issue with low speed throttle off on type of feel. 

If anyone knows anything about the guy I would love help tracking the part down to buy it asap. 

Share this post


Link to post
Share on other sites

I bought the bike (2017 YZ250FX) from KTMandHusky.com in the video outlining the difference with and without the fuel rail modification.  I have not ridden a stock YZ250FX so I don't have a comparison, however I do not notice any lurching when off  or low throttle.  My previous two bikes were a 2006 and 2011 KTM 300 and I have to admit to a difficult time adapting to a four stroke.

I have learned to ride the slow technical terrain with a liberal use of the clutch, however it seemed to physically wear me out on the longer rides.  I installed the G2 throttle tamer and this helped my endurance significantly.   The downside for me is it is more difficult to get the front wheel off the ground as the snappy throttle response is not there.  Just one more riding technique to work on.

  • Helpful 1

Share this post


Link to post
Share on other sites
9 hours ago, chama said:

I bought the bike (2017 YZ250FX) from KTMandHusky.com in the video outlining the difference with and without the fuel rail modification.  I have not ridden a stock YZ250FX so I don't have a comparison, however I do not notice any lurching when off  or low throttle.  My previous two bikes were a 2006 and 2011 KTM 300 and I have to admit to a difficult time adapting to a four stroke.

I have learned to ride the slow technical terrain with a liberal use of the clutch, however it seemed to physically wear me out on the longer rides.  I installed the G2 throttle tamer and this helped my endurance significantly.   The downside for me is it is more difficult to get the front wheel off the ground as the snappy throttle response is not there.  Just one more riding technique to work on.

Yeah the G2 throttle looks cool. But loosing the snap when I need it sounds opposite to what I'm looking for. My bike definitely has a significant feel of "on off" when it comes to low speed. I ride a lot of tight technical stuff and I have to use my clutch in excess. My bro rode my bike the other day and had a stall out during slow speed. He spent the next 30 mins complaining about the touchy throttle at slow speed haha.

Share this post


Link to post
Share on other sites
On 10/24/2018 at 8:20 PM, Honeybagder said:

The trick is to not use 1st gear ever and use second gear sparingly...

You don't have partial throttle issues if you keep it wide open. Lol.  In all seriousness though, I had issues at first that went away pretty quickly. At first I thought the engine breaking was going to throw me over the bars.

Share this post


Link to post
Share on other sites
On 10/24/2018 at 5:20 PM, Honeybagder said:

The trick is to not use 1st gear ever and use second gear sparingly...

Yeah I ride at a quick pace nearly every moment I ride. But when I put around with my kid on the tank, it gets pretty jerky. 

Share this post


Link to post
Share on other sites
25 minutes ago, joemc04 said:

You don't have partial throttle issues if you keep it wide open. Lol.  In all seriousness though, I had issues at first that went away pretty quickly. At first I thought the engine breaking was going to throw me over the bars.

Lol yeah it can be intense at times. If a $70 fuel line improvement can fix it I'm all in. Still waiting on the site to get back to me because the site no longer lists the part for yamaha.

Share this post


Link to post
Share on other sites
1 hour ago, revindevin said:

Lol yeah it can be intense at times. If a $70 fuel line improvement can fix it I'm all in. Still waiting on the site to get back to me because the site no longer lists the part for yamaha.

IMO you would be better off burning $70 worth of gas through the bike vs this "fix".

  • Like 2

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...