DRZ Jetting after Big Bore and Hot Cams

I tried posting this question on the DRZ forum with no results so sorry if it's not news to anyone. I have a 2002 DRZ400 and am trying to figure out what carb I have on it. I know that it is an FCR and I believe that it was stock. Is there a number on it somewhere that will tell me what model it is? I bought the bike from someone that had started modding it. They did a yoshi pipe and header and he took out the snorkel. I have since gone down on the front sprocket and up on the rear (can't remember right this minute what the gearing is). It ran great for 2 years and then it wouldn't start one day and they found it had a compression problem so while I was at it I did the Athena Big Bore kit and Hot Cams Stage 1 (intake and exhaust). They told me at the shop that the main jet was a 170 and the pilot was a 38. They did not change the jetting. Before the compression problem and subsequent upgrade it ran perfect with those jets. I haven't got out on the trails with it yet but around the house it seems to have a tremendous amount of low end torque. The problem is the bike will not idle well now and will quit if I don't roll a tiny bit of throttle in. Also it wants to sputter and backfire a while rolling the throttle on and off. The Athena website is no help and I can't call them since they are in Italy. My questions are:

1. How can I tell what model of FCR carb I have?

2. How can I tell what model of Yoshi pipe I have? It just says offroad.

3. What would be the proper jetting with the big bore kit and hot cams?

4. Is my idle problem related to the jetting?

5. I've read that the airbox mod should be 3X3 and mine has only had the snorkle removed. Should I make it 3X3, keeping in mind that it ran great on it's current configuration with the pipe?

Thanks for any help....

1. How can I tell what model of FCR carb I have?

A pic is one of the best ways to get help on that.

If the carb has the digits 29F written on it near the float bowl gasket area, it would be an FCR from a DR-Z400 kickstart or DR-Z400E.

2. How can I tell what model of Yoshi pipe I have? It just says offroad.

Easiest way is with another pic.

Is the muffler can round/oval or more like a triangle?

Is the head pipe a gold color or a rainbow of colors with a big diameter and springs holding it together?

3. What would be the proper jetting with the big bore kit and hot cams?

I think knowing exactly what version of the carb is on your bike must be known, first.

4. Is my idle problem related to the jetting?

Could be.

A 170 main jet sounds unusually large, for starters.

5. I've read that the airbox mod should be 3X3 and mine has only had the snorkle removed. Should I make it 3X3, keeping in mind that it ran great on it's current configuration with the pipe?

If you want to be able to use the jetting advice and data from most members, then you'll need the 3X3 hole cut where the snorkel is.

Besides, what a waste of putting on the FCR and exhaust system while keeping the teeny-tiny air inlet.

You want some power, don't you? :p

I am assuming you have a DR-Z400S model, by the way.

1. The carb has the words Flat CR inscribed on the top. Without removing it I can't see any other identifying marks on it. I hope these pictures come through. Is that enough to tell me what jets it needs?

http://i663.photobucket.com/albums/uu360/imflying/FCR1.jpg

http://i663.photobucket.com/albums/uu360/imflying/FCR6.jpg

2. The Yoshi pipe is oval and it doesn't look like a slip-on. The header looks much bigger in diameter than most others I've seen and it looks to be copper or gold in color.

http://i663.photobucket.com/albums/uu360/imflying/yoshi1.jpg

http://i663.photobucket.com/albums/uu360/imflying/yoshi2.jpg

http://i663.photobucket.com/albums/uu360/imflying/yoshi3.jpg

5. My bad on the 3X3 mod being left undone. It is actually a 3X3.5 hole. What fooled me was it didn't look like it had been cut. It still had a raised lip around it.

Thanks once again. Hope this gives you enough info to steer me towards the correct jets. I have to go outside now and put it back together ...again.

1) E model slant

2) Full Yosh stainless steel RS2

3) Sort of confirms bike model is a E

No doubt, the pilot jet is clogged. I would replace it and check the fuel screw setting.

i'm in agreement with Wil except i think the pipe is a Yoshi Stainless RS-3.

Sounds like a pilot circuit problem, and if i'm not mistaken, the slantbody FCR still has the coast enrichener circuit on it. i've read that that item should go away. Hopefully, will or Eddie will chime in and either confirm my guesses/observations or tell me to shut up and quit giving misinformation.

Good luck!

tom

Thanks for all of the help so far. I think I'm getting closer to my answers. So to recap. I have:

2002 DRZ 400e

Yoshimura stainless RS3 pipe and header

3X3 airbox mod

Athena Big Bore kit

Hot Cams Stage 1 (intake and exhaust)

Slant body FCR carb ( Is that the same as a FCR 39?)

I think the main jet is 170 and the pilot is 38

With that info what jets should I be running now?

Thanks again..

Thanks for all of the help so far. I think I'm getting closer to my answers. So to recap. I have:

2002 DRZ 400e

Yoshimura stainless RS3 pipe and header

3X3 airbox mod

Athena Big Bore kit

Hot Cams Stage 1 (intake and exhaust)

Slant body FCR carb ( Is that the same as a FCR 39?)

I think the main jet is 170 and the pilot is 38

With that info what jets should I be running now?

Thanks again..

The E model comes stock with a 45 pilot.

170 main is very large as well. I think the shop might have given you the wrong numbers, I would pull it and check myself. 1 hour job

I bought the bike with the pipe, header, and airbox mod already done so I'm pretty sure that the stock jets weren't being used. Had way too much power for stock.

yes, i believe the slantbody FCR is 39mm

I took the carb apart. Apparently the shop did the big bore kit and hot cams and never took the carb apart. Seems the problem all along was that the mixture screw was all the way in. The main jet was a 170 and the pilot was a 45. I opened the mixture 1.5 turns and replaced the 170 main with a 172, cleaned everything up a little bit and put it all back together. It cranked on the first bump of the starter. I pushed the choke in and it went to idle and stayed there. No quitting. It was great. It's a bit rich now but I will leave it like that for a little bit especially with the new big bore and cams. So the final settings are as follows

2002 DRZ400e

FCR 39mm carb

172 main

45 pilot

needle on the 4th clip

Atena Big Bore

Hot Cams intake and exhaust

Yoshimura RS3 header and pipe

The questions that I have now are:

How do I get it leaned properly?

Go down on the main jet?

Lean the mixture?

Change the clip position?

I was wrong about the carb ID mark being 39F.

I should have written 29F.

I have the following parts on my SM:

3X3 airbox hole

FCR39 carb from a DR-Z400E (has the 29F ID on it)

Hotcams

94mm big bore

FMF full exhaust system with a Q2 muffler

The bellmouth on my carb is the one from Sudco that lets you keep the stock SM airboot (rubber manifold connecting airbox to the carb).

I used the jetting specs listed in these forums that came recommended by Eddie, and the bike runs perfectly with awesome throttle response - I'm still amazed to this day (1,500 miles later) how much better the bike runs with this setup:

160 main jet

EMN needle on the 3rd (from the top) clip groove

45 pilot jet

100 pilot air jet

2.5 turns out on the fuel screw (I started with 2 turns out)

Coasting enrichener removed and nipple on side of carb body plugged

I sometime wonder, due to the muffler I'm using, if dropping my main jet down a size would be even better, but the bike runs so well, I haven't been motivated enough to try it. :p

Maybe when it gets hot and muggy.

Finally got the bike out today for it's first ride since the rebuild. Absolutely wicked. I thought that it was going to be rich but it ran perfect. Here's how it's outfitted now:

2002 DRZ400e

FCR 39mm carb

172 main

45 pilot

needle on the 4th clip

Atena Big Bore

Hot Cams intake and exhaust

Yoshimura RS3 header and pipe

This bike rips. I was pulling really steep hills in 2nd and 3rd gear. I could bog it down in second to almost a stop and then stomp on it and it would pull right on up the hill. What a great day. I do have one problem now!!! I noticed that it would pour fuel out of the overflow in the bowl if the bike was the least bit tilted to the side or up a hill. I noticed it an hour or so into the ride. It dumped so much fuel out that I had to refill the tank within three hours of start and stop riding. Anyone have any ideas? I can't believe that dirt could have gotten in there already. I changed the oil and air filter prior to this ride. I also had the carb off and cleaned the jets, needle, and float bowl prior to this ride.

I still think the 172 is too large a main. I have a full yoshi ti and a 165 was perfect, now that i've raised elevation its rich and i'm gonna have to drop down to a 162 or even a 160

I still think the 172 is too large a main. I have a full yoshi ti and a 165 was perfect, now that i've raised elevation its rich and i'm gonna have to drop down to a 162 or even a 160

Would that cause the fuel overflow problem? When the bike is tllted at all, fuel pours from the overflow.

Problem solved (I think). Took the carb apart again. The float was sticking in the open position. Fixed it and now no leaking. Also went back to the 170 main needle. Will see how it performs if it ever stops raining. Thanks for all the help.

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