Jump to content
Sign in to follow this  

drz400sm 2008 terrible mpg!

Recommended Posts

I just completed the 3x3 mod, JD jet kit (red needle, #155, clip on 3rd, stock pilot, TT extended fuel mixture screw) and it already had a two brothers muffler with spark arrestor removed. I am at about 4400-4600 elevation. The bike as of right now has a 15/41 (15/38 next weekend). before the 3x3 and jet kit i got 55mpg and wasn't easy on the throttle. Now riding easy I get 30 mpg. I played with the fuel mixture screw and noticed no change in how it runs or idles. Any idea of what can be causing the -25mpg? wrong jet? wrong needle? Some post say if they turn the fuel screw just 1/4 turn the bike dies… i turned mine all the way in and it still ran and i was able to rev it out with the throttle.

Edited by james7607

Share this post


Link to post
Share on other sites

What pilot did you put in?

I'm waiting for Craigo the Jet King to chime in......

Edited by Motor7
  • Like 1

Share this post


Link to post
Share on other sites

I just completed the 3x3 mod, JD jet kit (red needle, #155, clip on 3rd, stock pilot, TT extended fuel mixture screw) and it already had a two brothers muffler with spark arrestor removed. I am at about 4400-4600 elevation. The bike as of right now has a 15/41 (15/38 next weekend). before the 3x3 and jet kit i got 55mpg and wasn't easy on the throttle. Now riding easy I get 30 mpg. I played with the fuel mixture screw and noticed no change in how it runs or idles. Any idea of what can be causing the -25mpg? wrong jet? wrong needle? Some post say if they turn the fuel screw just 1/4 turn the bike dies… i turned mine all the way in and it still ran and i was able to rev it out with the throttle.

No reaction to fuel screw...so use pilot jet next size smaller..

The needle setting you are using is leaner than what I would have suggested, so the bad news is fuel economy wise, it won't get better... :(

I would use blue needle clip 3 and 155 main jet

Clip 3 on the red needle is really too lean....thats recommended for over 9K feet....

Share this post


Link to post
Share on other sites

No reaction to fuel screw...so use pilot jet next size smaller..

The needle setting you are using is leaner than what I would have suggested, so the bad news is fuel economy wise, it won't get better... :(

I would use blue needle clip 3 and 155 main jet

Clip 3 on the red needle is really too lean....thats recommended for over 9K feet....

It has the stock pilot jet in it, are you saying to put the JD #25? everything runs fine the way its setup and has a nice amount of power but I'm concerned about the fuel/mixture screw and of course the MPG. I really appreciate all you help! This weekend ill change out the needles.

Share this post


Link to post
Share on other sites

See that, just mention his name and ......{{{poof}}}

superman.gif

  • Like 2

Share this post


Link to post
Share on other sites

Lol yeah .. It should be SuperJET .. with the FCR logo instead of the S on the front of the shirt .

You see, even SUPERMAN is rocking the ''S'' for the REAL S as his logo 😏

  • Like 1

Share this post


Link to post
Share on other sites

Wow 30mpg....I get 47mpg with Stock carb JD jet kit 160 main, blue needle clip on 3rd, #25 pilot jet w/stock screw 2.9 turns out. Airbox 3x3.25 mod, S-1 Hotcams , CW440BB, MRD-SSW.

Share this post


Link to post
Share on other sites

Wow 30mpg....I get 47mpg with Stock carb JD jet kit 160 main, blue needle clip on 3rd, #25 pilot jet w/stock screw 2.9 turns out. Airbox 3x3.25 mod, S-1 Hotcams , CW440BB, MRD-SSW.

What elevation are you at? I'm right at 4600 and 4800ft

Edited by james7607

Share this post


Link to post
Share on other sites

I emailed JD and this is there reply

James,

I would use the recommended pilot which is a 25. the blue needle is richer so I would think the millage would be worse.

Share this post


Link to post
Share on other sites

I emailed JD and this is there reply

James,

I would use the recommended pilot which is a 25. the blue needle is richer so I would think the millage would be worse.

If you have no reaction to rpm when turning the fuel screw all the way in , you need to go to a smaller pilot jet.....

I said that your mileage wouldn't get any better with a richer needle in my first post,

if you're not getting any surging and mileage is a priority over performance just stay with the red needle....

The drop in fuel economy is most likely user related, ....sorry there is no magic to improve your economy figures....

If it had poor economy from new, I would say you may have had head flow issues....

Share this post


Link to post
Share on other sites

This weekend I'm going to install the blue on three, I just ordered the #20 jet and the 38t sprocket. I'm optimistic ill get the power everyone speaks of with craigo's settings. I've herd power wheelies are easy to achieve with these mods, right now there impossible without popping the clutch.

Share this post


Link to post
Share on other sites

This weekend I'm going to install the blue on three, I just ordered the #20 jet and the 38t sprocket. I'm optimistic ill get the power everyone speaks of with craigo's settings. I've herd power wheelies are easy to achieve with these mods, right now there impossible without popping the clutch.

I wouldn't get too excited about a huge jump in performance with a jet kit .....It's more about obtaining the optimum fuel curve than performance....

If you want some bolt on power the keihin 39mm Fcrmx is the way to go.....

Share this post


Link to post
Share on other sites

What elevation are you at? I'm right at 4600 and 4800ft

Near sea level.

Share this post


Link to post
Share on other sites

I have a DRZ 440 with 39mm FCR Carb, MRD/SSW pipe. I run 15/39rear sprocket and there is no such thing as a power wheelie with this gearing and I have a 50hp bike. Maybe if I hammered the bike off a dead stop in 1st, but F that.

Share this post


Link to post
Share on other sites

Last message from JD when I responded with the fuel/screw not adjusting at all. I haven't changed anything yet, still with the wife waiting for the little one in labor and delivery, he's a bit comfortable in there lol.

James,

Move the needle clip position 1 step higher to have improved mileage.

Start with the fuel screw near 2 1/2 turns out from closed as an estimate.

Sometimes the rpm change is very slight when adjusting the fuel screw, so you might not hear the increase or decrease of rpms within the screw adjustment.

--You can also take note of how long the choke is needed on cold mornings, when warming up, as an indication of running lean or not.

Share this post


Link to post
Share on other sites

would anyone recommend getting the kientech fuel mixture screw or keep the Thumper talk screw and get a smaller pilot jet? I've heard bad things about the Thumper talk screw falling out.

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...