Jump to content

Anyone running 5th from the top jd?


Recommended Posts

Hello all,

I know this is a jetting forum related question, but I think it is more specific to the drz forum...

Ok here's what I got 2008 drz400s sea level, Muzzy exhaust, and 4x4 intake hole.

Stock Fuel screw 2.75 out

Pilot 25

Main 160

JD blue 4th clip (correct spacers)

Symptoms; bike starts fine, idles fine but when the throttle is cracked there is a loud bang out the tail pipe. The bike does not stall, but pops out the pipe bad(very loud like Harley). It does not stutter or hesitate just a loud bang when the throttle is blipped. It seems to run well when pulling through the gears, and has some backfiring between shifts and slight popping on decel.

Tonight I moved the JD clip to the 5th clip setting to richen it up a tad to counter the poping, and opened the fuel screw to 3 out. It still bangs real loud when cracking the throttle off idle. I plan on doing a test ride in the am with the new setting but figured id see if anyone else has encountered the loud pop off idle. Is it normal to have a loud pop off idle or is this a lean symptom?

Thanks!

Edited by gtlegacy
Link to comment
Share on other sites

Ive considered that as a tuning tool, but do not want tape to be a perminent addition to the bike if you know what i mean. The loud pipe bang when the throttle is cracked may be normal...no silencer or spark arrestor. I just dont know since this is my first 4 stroke build.

Link to comment
Share on other sites

Ok so I rode the bike this morning and it ran much better on the mid. No popping between shifts. I think that im still a tad lean on the pilot circuit. Im gunna play around with the intake hole size next.

Link to comment
Share on other sites

I gutted all sides of my airbox. The box is opened up so much that it's function with intake air flow is almost completely redundant. Before I went to the FCR, my jetting was:

- 165 or 170 main (depending on ambient air temp and humidity)

- 5th clip down

- 3 turns out

- 1100ft

I had the needle set on the 4th clip with 2.75 turns out before September of last season. As the cold started to set in, popping and back firing started to become a real issue. I went with the settings posted and it was fine. I had to get the 165 and 170 jets from my local shop. You should really go to a richer pilot before you start going past 3 turns out on the screw. Everyone runs into things like this once in a while. Just dink around with it and it'll work out.

Link to comment
Share on other sites

I understand you want a bigger hole than 3x3 but when you do that you are going to be on your own when it comes to figuring out the jetting. Pretty much all the advice on jetting in this forum assumes you have the hole at 3x3.

Yeah, that's right, most of the time. It's just because a lot of people like doing the tried and tested route. That's cool. If it works why screw with it, right? I got no problem with that. There are just some nut jobs (i.e. me) that try to think outside the airbox. Jetting isn't rocket science it's just time consuming without a dyno. A lot of people are nervous about experimenting because they're not confident enough in their own abilities to dive head first into the deep end. But that's fine, everybody can't be good at everything.

Link to comment
Share on other sites

Yeah, that's right, most of the time. It's just because a lot of people like doing the tried and tested route. That's cool. If it works why screw with it, right? I got no problem with that. There are just some nut jobs (i.e. me) that try to think outside the airbox. Jetting isn't rocket science it's just time consuming without a dyno. A lot of people are nervous about experimenting because they're not confident enough in their own abilities to dive head first into the deep end. But that's fine, everybody can't be good at everything.

Its also a matter of diminishing returns. Unless your running a 470 or something there isn't much to gain with a bigger hole than 3"x3" in the air box. You end up going through all that work and gain nothing.

Link to comment
Share on other sites

I gutted all sides of my airbox. The box is opened up so much that it's function with intake air flow is almost completely redundant. Before I went to the FCR, my jetting was:

- 165 or 170 main (depending on ambient air temp and humidity)

- 5th clip down

- 3 turns out

- 1100ft

I had the needle set on the 4th clip with 2.75 turns out before September of last season. As the cold started to set in, popping and back firing started to become a real issue. I went with the settings posted and it was fine. I had to get the 165 and 170 jets from my local shop. You should really go to a richer pilot before you start going past 3 turns out on the screw. Everyone runs into things like this once in a while. Just dink around with it and it'll work out.

I think ill be dialed perfectly with a slightly bigger pilot. Its almost there, just a tad lean. Thanks for your help and input.

Link to comment
Share on other sites

if it requires a larger jetting than surely it must create a tiny bit more...?

Kinda what i was thinking to. If its getting more air with larger than 3x3 than it will need more fuel and in turn more hp...The only thing I can think of for only needing a 3x3 is air velocity. Also maybe to big of a hole will affect the lower end?

Link to comment
Share on other sites

if it requires a larger jetting than surely it must create a tiny bit more...?

who worked out 3x3 in the 1st place? 3x3 isnt really that exact...

nope,doesnt make even a tiny bit more.

the 3x3 mod is just left over deal from the dr350 days.

its shearly kept as exactly 3x3 to have some sort of constant for jetting set ups.

you can make the intake hole what ever size you want as long as you dont want to use standard jetting set ups.

a stock displacement drz doesnt even need a hole as big as 3x3.

Link to comment
Share on other sites

nope,doesnt make even a tiny bit more.

the 3x3 mod is just left over deal from the dr350 days.

its shearly kept as exactly 3x3 to have some sort of constant for jetting set ups.

you can make the intake hole what ever size you want as long as you dont want to use standard jetting set ups.

a stock displacement drz doesnt even need a hole as big as 3x3.

Eddie,

What about the back-fire screen? Removing it on my old 450X made a ton of difference.

Link to comment
Share on other sites

the honda screens are much more restrictive.

i remove the screens on mod motor drz's but its not restricting a stock displacement drz.

if you remove the screen make sure you have the air boot off when you do it and make sure to remove all of the straggler wires from the air box mold.

Link to comment
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:

×
×
  • Create New...