Jetting thread number 5 million here we go!
I have a 2006 DRZ SM. Stock pipe, stock filter, 3x3, JD Jet kit with 155 main, stock pilot, kientech at (i believe) 2.5 turns out, red needle on 3rd clip. I live in Milwaukee, so my elevation is about 600-650 feet. Temperatures swing pretty wildly from 50's to 80's.
While cruising at steady throttle, the bike surges. It doesnt buck, and its not violent, but you can feel it surging. I was cruising at 35 in 3rd today and it surged as long as I held the throttle steady. Once you move the throttle, it goes away, go back to steady throttle and it returns.
Thoughts?
Troubleshooting a surging issue
Started by
Mattydiah
, Jun 05 2012 06:18 PM
20 replies to this topic
Posted 05 June 2012 - 06:51 PM
Thumpertalk wisdom says use the stock pilot with the kientech. Should I be running the biger pilot?
Posted 05 June 2012 - 08:09 PM
Matty - Has it always done this? Was it windy when it was surging? I have given this advise before but nobody ever says if it works or not. Simply remove the vent hose from the carb as a test and see if the surge goes away.
If no joy, go to the blue needle.
If no joy, go to the blue needle.
Posted 05 June 2012 - 11:00 PM
Your lean on the needle ..use blue needle clip 3
One would use red needle clip 3 at around 9,000ft...plus
One would use red needle clip 3 at around 9,000ft...plus
Edited by CraigoDRZ485sm, 05 June 2012 - 11:42 PM.
Posted 08 June 2012 - 04:41 PM
Mattydiah, on 08 June 2012 - 04:19 PM, said:
I mis-spoke in my original post. The blue needle is in there on the 3rd clip.
Ok thanks for the clarification......Surging is a tell tale sign of being lean..
Cover the 3x3 hole by 1/3 with tape....If better , go for clip #4...
Did you test Noble's theory??
Edited by CraigoDRZ485sm, 08 June 2012 - 04:42 PM.
Posted 10 June 2012 - 05:23 PM
OK, so, the tape over the 3x3 seemed to help, but made the top end worse, meaning my main jet is probably OK and I could go down a clip on the needle.
BUT, removal of the carb vent hose also seemed to help.
So which is it? Is there somewhere I can reroute the carb vent hose so it works, or do I just have to leave it off altogether?
BUT, removal of the carb vent hose also seemed to help.
So which is it? Is there somewhere I can reroute the carb vent hose so it works, or do I just have to leave it off altogether?
Posted 10 June 2012 - 06:35 PM
Mattydiah, on 10 June 2012 - 05:23 PM, said:
OK, so, the tape over the 3x3 seemed to help, but made the top end worse, meaning my main jet is probably OK and I could go down a clip on the needle.
BUT, removal of the carb vent hose also seemed to help.
So which is it? Is there somewhere I can reroute the carb vent hose so it works, or do I just have to leave it off altogether?
BUT, removal of the carb vent hose also seemed to help.
So which is it? Is there somewhere I can reroute the carb vent hose so it works, or do I just have to leave it off altogether?
If you make changes you do them one at a time to gauge differences....
re route the vent hose to above the air box..
Posted 10 June 2012 - 06:45 PM
707drz, on 05 June 2012 - 07:15 PM, said:
i guess i didnt process the entire post......long day sorry. yes stock pilot is recommended with extended fuel screw
Are you sure of this? I used the extended fuel screw and 25 pilot that the JD kit came with. I don't remember the instructions suggesting otherwise.
Edited by 2WheelsGood, 10 June 2012 - 06:45 PM.
Posted 10 June 2012 - 06:53 PM
2WheelsGood, on 10 June 2012 - 06:45 PM, said:
Are you sure of this? I used the extended fuel screw and 25 pilot that the JD kit came with. I don't remember the instructions suggesting otherwise.
You will often get jetting variations to the common settings, depending on such factors as altitude and climate...
Colder areas usually call for richer settings
Posted 10 June 2012 - 07:19 PM
Route the vent hose any place except in the air box or near the opening to the air box. You are looking for sill air at undisturbed atmospheric pressure. The correct place is where it makes no difference. Any place that affects running to the negative is the wrong place. Personally I think the single vent to the carb is a mistake by Mikuni and makes the location more sensitive. And I think this is a much over looked factor. It took me about 3 years to discover the carb vent was causing my surging.
Posted 10 June 2012 - 07:21 PM
CraigoDRZ485sm, on 10 June 2012 - 06:53 PM, said:
You will often get jetting variations to the common settings, depending on such factors as altitude and climate...
Colder areas usually call for richer settings
Colder areas usually call for richer settings
Well of course, but that's not the question. All other things being equal, why would you want the stock pilot for the extended fuel screw and the 25 (or whatever) for the stock fuel screw? Other than being extended for ease of adjustment, what's the difference between the two screws that would cause you to use two different jets?
Posted 10 June 2012 - 07:42 PM
2WheelsGood, on 10 June 2012 - 07:21 PM, said:
Well of course, but that's not the question. All other things being equal, why would you want the stock pilot for the extended fuel screw and the 25 (or whatever) for the stock fuel screw? Other than being extended for ease of adjustment, what's the difference between the two screws that would cause you to use two different jets?
The extended screw has a richer profile.....I see you live in Michigan...I presume that's a reasonably cold climate you have there..??
Edited by CraigoDRZ485sm, 10 June 2012 - 09:35 PM.
Posted 10 June 2012 - 08:01 PM
Man I have the same exact problem but I have full exhaust. I need to check that hose vent line, I've just been riding the bike as is but I think its time to fix it.
Posted 10 June 2012 - 08:03 PM
Man I have the same exact problem but I have full exhaust. I need to check that hose vent line, I've just been riding the bike as is but I think its time to fix it.
Posted 11 June 2012 - 10:38 AM
Noble, on 10 June 2012 - 07:19 PM, said:
Route the vent hose any place except in the air box or near the opening to the air box. You are looking for sill air at undisturbed atmospheric pressure. The correct place is where it makes no difference. Any place that affects running to the negative is the wrong place. Personally I think the single vent to the carb is a mistake by Mikuni and makes the location more sensitive. And I think this is a much over looked factor. It took me about 3 years to discover the carb vent was causing my surging.
is it unhealthy to pull the vent hose all together? Seems like my 05 is running really well without the vent hose attached. I
Posted 11 June 2012 - 11:03 AM
notraps, on 11 June 2012 - 10:38 AM, said:
is it unhealthy to pull the vent hose all together? Seems like my 05 is running really well without the vent hose attached. I
Without the hose the vent is more likely to get blocked by dirt/debris or submerged when going through a water crossing. Route the vent up high.
Posted 11 June 2012 - 12:25 PM
No vent hose is not unhealthy at all to the motor but yes with no hose, debris is more likely to enter. I figured out how to add a second vent to the right side. Probably over kill but something I wanted to do. Still not sure of the best place to route the hose. Right now I have it under the gas tank and that seems to be OK.
