Jump to content
Sign in to follow this  

25 pilot jet

Recommended Posts

What does a 25 pilot jet actually do?

Share this post


Link to post
Share on other sites

Provides a richer mixture to the pilot circuit (during idle and just off idle), the stock pilot jet is a 22.5 so the 25 is larger.

 

When you do the 3x3 mod and re-jet the 25 pilot jet is recommended for use with the stock fuel screw. If you use an extended fuel screw the 22.5 pilot jet is recommended because the extended fuel screw has a richer taper.

Share this post


Link to post
Share on other sites

Provides a richer mixture to the pilot circuit (during idle and just off idle), the stock pilot jet is a 22.5 so the 25 is larger.

 

When you do the 3x3 mod and re-jet the 25 pilot jet is recommended for use with the stock fuel screw. If you use an extended fuel screw the 22.5 pilot jet is recommended because the extended fuel screw has a richer taper.

 

I had  22.5/160 extended fuel screw (2.75Turns)  with DynoJet kit and open RS2 in warm calif 0 ft from PO.  It would hesitate at idle/neutral when i blipped throttle hard. it popped a bunch on decel as well, but i wouldn't say it worried me. 

 

taking advice reading from Drzforums (some highly recommend 25pj for either fuel screws) I changed out to Mikuni 25PJ (still 2.75Turns) and it made it made it much better. and id say solved hesitation by 90%. also popping decreased noticeably to now when only quickly closing throttle or hard engine braking.

 

i had tried throughly cleaned all jets before changing over to 25 PJ also and didn't solve. however I haven't touched needle clip and perhaps that might have solved it also. 

Edited by accuracy

Share this post


Link to post
Share on other sites

Should I just move the clip on the needle first and if that dosent get rid of a tiny flat spot then put the needle back to original and put in the 25 pilot jet and see what happens?

Edited by berjo

Share this post


Link to post
Share on other sites

The 25 pilot does not work well with the TT extended fuel screw,  i tried errthing,  had to go back ot the 22.5 with the TT extended fuel screw and all was good. 

  • Like 1

Share this post


Link to post
Share on other sites

I had  22.5/160 extended fuel screw (2.75Turns)  with DynoJet kit and open RS2 in warm calif 0 ft from PO.  It would hesitate at idle/neutral when i blipped throttle hard. it popped a bunch on decel as well, but i wouldn't say it worried me. 

 

taking advice reading from Drzforums (some highly recommend 25pj for either fuel screws) I changed out to Mikuni 25PJ (still 2.75Turns) and it made it made it much better. and id say solved hesitation by 90%. also popping decreased noticeably to now when only quickly closing throttle or hard engine braking.

 

i had tried throughly cleaned all jets before changing over to 25 PJ also and didn't solve. however I haven't touched needle clip and perhaps that might have solved it also. 

 

The recommended jetting is just that……..a recommendation. It is what works for most people and because of this it is a great starting point. Not every component is EXACTLY the same, and not every set up (even if it is set up the same as someone else) is EXACTLY the same. Because of this there is some fine tuning that must be done by the rider to verify that their jetting is correct.

 

I myself had to make a deviation from the recommended jetting because my DRZ would surge while cruising.

  • Like 1

Share this post


Link to post
Share on other sites

Should I just move the clip on the needle first and if that dosent get rid of a tiny flat spot then put the needle back to original and put in the 25 pilot jet and see what happens?

 

Generally I would say no, unless the current needle position is incorrect.......You don't mess with one fuel circuit to fix another, and should be tuned separately

What's your current needle setting.?

List any mods?..+ riding altitude 

 

 

 

What does a 25 pilot jet actually do?

 

The larger the number the higher the fuel flow......

In 99% of cases a 22.5 pilot jet with extended fuel screw will be used....

Use this procedure to determine pilot jet size is correct -------> http://www.thumpertalk.com/topic/271735-how-to-confirm-your-pilot-circuit-setting/

Share this post


Link to post
Share on other sites

The recommended jetting is just that……..a recommendation. It is what works for most people and because of this it is a great starting point. Not every component is EXACTLY the same, and not every set up (even if it is set up the same as someone else) is EXACTLY the same. Because of this there is some fine tuning that must be done by the rider to verify that their jetting is correct.

 

I myself had to make a deviation from the recommended jetting because my DRZ would surge while cruising.

 

Yes I completely agree. I didn't mean to make it sound as if my way to fix was only way. Just trying to help out others as they have helped me from advice i've read on the boards. I must disclaim that, myself, am new to drz's.

 

I also had surging on my bike at steady throttle at about 65-70 mph (15-43 gearing, so probably just over half throttle), but i changed my fuel screw from 2.5 to 2.75 turns. I think i made it mostly go away but not confident.

May I ask what solution made your surge go away? From what I've read, it may be incorrect clip position, but im trying to avoid messing with that.  (sorry to go offTopic)

Edited by accuracy

Share this post


Link to post
Share on other sites

Surging at 1/2 throttle has nothing to do with your pilot jet..You are on the needle circuit...

If you list your current carb settings, pipe, engine mods and riding altitude we can evaluate ...

Share this post


Link to post
Share on other sites

Surging at 1/2 throttle has nothing to do with your pilot jet..You are on the needle circuit...

If you list your current carb settings, pipe, engine mods and riding altitude we can evaluate ...

Cause i am getting a surge at 1/2 throttle, would a 25 pilot fix this or just moove the needle down one clip?

Share this post


Link to post
Share on other sites

Cause i am getting a surge at 1/2 throttle, would a 25 pilot fix this or just moove the needle down one clip?

 

Surging does indicate a lean condition .......at 1/2 throttle surging the needle would be the one to look at, not pilot jet..

What needle is installed.? and what mods ?(pipe BB etc)

Share this post


Link to post
Share on other sites

Dynojet kit with 155 main jet, 22.5 pilot, needle 2nd clip from top, 3x3 mod, k&n air filter, MRD SSW, needle is at 3.5 turns out. Apart from the surge it runs perfect. The surging on my bike is at a slow increase in throttle up to about 65-70 kph, only a little flatspot.

Edited by berjo

Share this post


Link to post
Share on other sites

You have a typo and possibly a couple issues. The PAJ would be 22.5 not 2.25. The "needle" should most likely be at the 3rd or 4th position from the top (blunt end) down. The air/fuel screw (not needle even though it is needle like) would probably do better at 2.5 to 2.75 turns out from full bottom position. Be careful to not screw the a/f screw in all the way to hard. It can damage the tip.

 

Have you adjusted your a/f screw and idle screw for maximum vacuum? That is always important once you settle on your needle position and jetting choices.

Share this post


Link to post
Share on other sites

Yes I completely agree. I didn't mean to make it sound as if my way to fix was only way. Just trying to help out others as they have helped me from advice i've read on the boards. I must disclaim that, myself, am new to drz's.

 

I also had surging on my bike at steady throttle at about 65-70 mph (15-43 gearing, so probably just over half throttle), but i changed my fuel screw from 2.5 to 2.75 turns. I think i made it mostly go away but not confident.

May I ask what solution made your surge go away? From what I've read, it may be incorrect clip position, but im trying to avoid messing with that.  (sorry to go offTopic)

 

I changed the clip position (from clip 3 to clip 4) and that cured my surging problem. I changed the clip position because like craigo said, I am at mid throttle and that means I am on the needle circuit. And surging indicates a lean condition so I moved it to a richer position.

 

Clip 3 worked fine for me in the summer with the warm temps but, when it got cooler in the fall it started to surge so I switched it to clip 4. I could probably go back to clip 3 because it is summer again but my MRD/Z-Pro should be here in a couple weeks and I would just have to go back to clip 4 when I installed that. So I am just going to leave it on clip 4 for the time being.

 

 

My previous post wasn't meant for you directly, it was more of a general statement, it just seemed appropriate to quote your post. I was trying to make the point that while the recommended jetting works just fine for most, some may need to adjust their jetting slightly.

Share this post


Link to post
Share on other sites

Dynojet kit with 155 main jet, 2.25 pilot, needle 2nd clip from top, 3x3 mod, k&n air filter, MRD SSW, needle is at 3.5 turns out. Apart from the surge it runs perfect. The surging on my bike is at a slow increase in throttle up to about 65-70 kph, only a little flatspot.

 

Which Dynojet jet kit, stage 1 or 2 ..? (DJ3109 or DJ3110)

Share this post


Link to post
Share on other sites

The 25 pilot does not work well with the TT extended fuel screw,  i tried errthing,  had to go back ot the 22.5 with the TT extended fuel screw and all was good. 

Hmmm...the PO jetted this bike but for higher elevation and didn't keep any of the stock/spare parts :facepalm: so, I don't have the stock 22.5 PJ. I guess I'll see how it works out with the 25 and go from there.

  • Like 1

Share this post


Link to post
Share on other sites

Which Dynojet jet kit, stage 1 or 2 ..? (DJ3109 or DJ3110)

Stage 2 DJ3110 Edited by berjo

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  

×