'03 DRZ with FCR-39MX jetting issues.

Hey guys,

 

I've been trying various settings with my newly acquired FCR39MX and I've had some interesting tuning issues...

 

Here's my current bike set up:

2003 DRZ400S model

stock header with FMF midpipe & silencer (kinda loose bushing connection)

3x3 modded airbox

K&N Filter (clean)

75°F ~300ft elevation, not humid

 

first attempt:

using the pod air filter that came with the carb and no airbox

165 main jet, #42 pilot, 2 turns out fuel screw, red needle on 4th notch from the top, 

>Results: very difficult to start, engine warm idle set at 1300rpm or so engine wants to die, opening throttle leads to a 10 to 15 second high idle 2500 rpm or so..  engine feels very hot

 

Second attempt:

using the stock air box with side cover on, seat off.

165 main jet, #42 pilot, 1 1/2 turns out fuel screw, red needle on 4th notch from the top, o-ring mod applied.

>Results:  very difficult to start, engine warm idle set at 1300rpm or so engine wants to die, opening throttle leads to a 4-5 second high idle 2500 rpm or so...  engine noticeably cooler running than before.  backfiring often

 

Third attempt:

using the stock air box with side cover on, seat off.

165 main jet, #42 pilot, 2 1/2 turns out fuel screw, red needle on 4th notch from the top, o-ring mod applied.

>Results:  no difference from the second attempt.  rode around a little, engine pulled ok, backfire on decell, bike wants to quit on idle, no hesitation through the range.

 

I've checked squirt duration, looks like it misses the slide and runs for 1.5 to 2 seconds.  seems ok.

Hooked up the tps sensor, the sensor mounting bolt hole allows a swing of a few degrees, not sure how to adjust this play of 15° or so...

Installed the thin o-ring mod according to the JD Jet Kit instructions.  this eliminated the accelerator pump hover of 1 to 2 seconds.

 

I'm planning on installing the MRD zpro in a week or two but I want a proper baseline to start with first.

carb came from: http://www.oemdirtbikeparts.com/DRZ400SM-DRZ400S-DRZ400-FCR-39-CARB-UPGRADE-KIT-p/drz400_carburetor_fcr39_carb.htm

I read the foam pod filter allows more air than a drz engine will ever be able to make use of so it's going in the random parts bin..

 

Let me know what baseline settings I should try to get this bike back to a purr, there doesnt seem to be much agreement in the spreadsheet i found on here.  see attached along with pictures of the carb.

 

Thanks!

FCR39 mx.JPG

FCR39 mx 1.JPG

FCR39 mx 2.JPG

DRZ FCR SSW Jetting.jpg

Edited by braaapopopop

I would use the stock air box like you did in attempt 2 and 3 (remove the snorkel and do the 3x3 mod if you haven't already), because very few people have gone the pod filter route so it would be extremely dificult to recommend jetting over the internet for that.

 

I would also drop the main jet to a 160, bump the pilot jet to a 45, and set the idle to 1800rpm.

I don't why you just didn't get it from the TT store, price wise there is not that much in it....anyway that's your choice..

So before going on , will you be staying with the stock air box?....They are absolutely no benefits in using the pod.......

Edited by Craigo 485sm

Thanks Wisconsonite, I will see if i have that size pilot jet and swap it in along with the 160 jet.  are you suggesting that will fix my current situation or would that work better for when I get my SSW?  

 

Craigo, I honestly didn't realize there was a TT kit prior to buying the one off oemdirtbikeparts, knowing now that these can be tricky to set up properly I would've just purchased the TT kit and moved on.

 

I am sticking with the stock air box after all.  I had read the same, no benefits for using the pod filter, more airflow than the engine could ever use... I was tempted by the notion given that I can remove the airbox and save some weight.  but i've read enough bad things about the pod filter now that I'm sticking with the stock air box with the 3x3 mod and K&N air filter.

 

some of the things I haven't checked are my pilot air jet size, main air jet size or attempted to remove the TPS sensor.  

Ok then , I would jet it to suit your new MRD pipe that's coming..run without the air box door with existing pipe set up

 

200 main air jet

100 pilot air jet

160 main jet

JD Blue Needle, Clip 4

45 pilot jet

2 turns fuel screw ( fine tune with this procedure http://www.thumperta...ad.php?t=327405)

Do the o ring mod

 as mentioned above set your idle to 1800rpm -/+ 50

Just going over the carb.

Slow jet was clogged, cleaned it, reinstalled it.

Main jet swapped for the 160

42 pilot jet seemed clogged as well so I swapped this for a 40, I don't have the 45 and the 40 seems to flow better than the 42...

Installed the blue JD needle on clip 4

Turns on fuel screw set to 2.

I looked and it appears as though my main air jet and pilot air jets are both missing... See attached. How important is it that I have these two items installed?

Here is where the air jets should have been..

IMG_20140507_215149.jpg

Well hey nevermind, I found the 100 pilot air jet and installed it. Not sure where the 200 main air jet goes but I'm pretty sure I don't have it.

Just going over the carb.

Slow jet was clogged, cleaned it, reinstalled it.

Main jet swapped for the 160

42 pilot jet seemed clogged as well so I swapped this for a 40, I don't have the 45 and the 40 seems to flow better than the 42...

Installed the blue JD needle on clip 4

Turns on fuel screw set to 2.

I looked and it appears as though my main air jet and pilot air jets are both missing... See attached. How important is it that I have these two items installed?

 

Well hey nevermind, I found the 100 pilot air jet and installed it. Not sure where the 200 main air jet goes but I'm pretty sure I don't have it.

 

Get a 45 pilot jet and 200 main air jet...The MAJ goes next to the PAJ

OK, thanks will do.

 

Quick question, my last attachment shows the carb is now fitted with a 100 air pilot jet, which i've confirmed.  right next to it is the MAJ, an un-threaded opening, should I just buy the 200 MAJ and tap the bare hole accordingly?  maybe this hole is already tapered for 200?  I dunno, when I see no threads i just assume nothing needs to go there.

 

Thanks again.

OK, thanks will do.

 

Quick question, my last attachment shows the carb is now fitted with a 100 air pilot jet, which i've confirmed.  right next to it is the MAJ, an un-threaded opening, should I just buy the 200 MAJ and tap the bare hole accordingly?  maybe this hole is already tapered for 200?  I dunno, when I see no threads i just assume nothing needs to go there.

 

Thanks again.

 

Ok so no threads,,just leave the hole as is and get the 45 pilot jet ....

Edited by Craigo 485sm

Ok

IMG_20140507_221758.jpg

Edited by braaapopopop

Thanks Craigo, I've ordered everything and I'll post the results once they all get installed.

 

Just to be sure of a few things, #1 should I assume the unthreaded and open MAJ port is set up to run the correct amount of air?  #2  should I make any adjustments to the TPS sensor that I have installed, and is it doing anything either way?  

 

Thanks a lot for your help so far.

Thanks Craigo, I've ordered everything and I'll post the results once they all get installed.

 

Just to be sure of a few things, #1 should I assume the unthreaded and open MAJ port is set up to run the correct amount of air?  #2  should I make any adjustments to the TPS sensor that I have installed, and is it doing anything either way?  

 

Thanks a lot for your help so far.

 

#1....Yes

#2....Leave it disconnected

#1....Yes

#2....Leave it disconnected

 

For #2... Any advantages/disadvantages to leaving it plugged in? I'm thinking if it plugs in fine to the stock connector then why not leave it? 

wondering the same thing, what harm does it do plugged in?  is it providing an incorrect or unusable signal?  I suppose I could throw an ohm meter across the legs of each TPS and find out how the two differ between the stock mikuni and the fcr.

For #2... Any advantages/disadvantages to leaving it plugged in? I'm thinking if it plugs in fine to the stock connector then why not leave it? 

 

 

The TPS only controls the amount of advance at partial throttle openings and the CDI is the only control over the amount of retard at high rpm.

With the TPS unplugged the CDI uses a default map that adjusts the timing curve by rpm only.

On the dyno there is no difference plugged in or unplugged.

keeping the TPS connected will soften the throttle response...

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