I'm a new XR400 2002 owner.I've added a Uni filter,removed snorkel,and installed a new Pro Circuit T4 Muffler.I've installed a 62 pilot,162 main.The bike runs really good now all through the power band but I still get a small amount of backfiring when I chop throttle.My next move is to go up again on the pilot to a 65.What jetting have you all ended up with on your XR400's.:confused: :think
XR 400 jetting
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ThumpinTahoe
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- Jan 19, 2002
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I have the exact same set up as you. T4, uni, snorkel. I live in tahoe (6000')and run a 158/58. I think you are running a bit rich. I think that is why you get the backfire. I have heard that around sea level 160/60 is the way to go. Since I have done my mods, my bike is running great and can climb hills with any bike out there. I hope that you love your xr4 as much as I do.
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- #3
Our bikes are almost exact.Mine also has a Baja kit.I tried going up to a 65 pilot and that only made it run a bit fatter but did not not stop the small amount of popping I get.I'm in the SoCal desert so my jetting may be a bit different from yours.I'll try a few more smaller sizes and tweek the air mixture screw.I know I'm close.I also put the 1.5'' end cap on my T4 and that makes it bit quieter but I couldn't notice any power loss at all.I also went to a 14T counter shaft.For the hills out here I needed more grunt.The answer is yes,I do love this bike as much as you!I traded in a 2001 KLX300 for it and I'm a much happier person.:)
snaggleXR4
Member
- Aug 5, 2001
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Hey,
I'm not familiar with your T4, but I had a similar setup on my '96 XR4 with UNI, no snorkel and XR's Only pipe. I'm in NW Florida, basically right at sea level. Xr's Only set me up with the 160/60 combo when I bought the pipe. It was a hair on the leaner side, but fattening up the fuel screw helped. The bike ran really well, very crisp throttle response etc, clean revs. At 162/62 you should be plenty fat, make sure to adjust your fuel screw, and fatten up your needle setting before you go for a 65 pilot. Keep in mind, I've never had an aftermarket pipe that didn't backfire a little. Backfiring can be a sign that you are lean, but it can also backfire when you are too rich. However, the lack of backpressure on aftermarket pipes has a big effect too. Play around with what you have now, fuel screw, needle position, check your plug, before you go getting to fat, that's not good for your bike either. Good luck, and don't jet your bike by whether it backfires or not.
I'm not familiar with your T4, but I had a similar setup on my '96 XR4 with UNI, no snorkel and XR's Only pipe. I'm in NW Florida, basically right at sea level. Xr's Only set me up with the 160/60 combo when I bought the pipe. It was a hair on the leaner side, but fattening up the fuel screw helped. The bike ran really well, very crisp throttle response etc, clean revs. At 162/62 you should be plenty fat, make sure to adjust your fuel screw, and fatten up your needle setting before you go for a 65 pilot. Keep in mind, I've never had an aftermarket pipe that didn't backfire a little. Backfiring can be a sign that you are lean, but it can also backfire when you are too rich. However, the lack of backpressure on aftermarket pipes has a big effect too. Play around with what you have now, fuel screw, needle position, check your plug, before you go getting to fat, that's not good for your bike either. Good luck, and don't jet your bike by whether it backfires or not.
ThumpinTahoe
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- Jan 19, 2002
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cali bike
My Calif bike came with 138-55. After installing the t4 I had no backfire. I'm not sure that they backfire much running lean. Fattening it up did help a ton. The best mod I made was the uni air filter.
My Calif bike came with 138-55. After installing the t4 I had no backfire. I'm not sure that they backfire much running lean. Fattening it up did help a ton. The best mod I made was the uni air filter.
A16 needle
No, the CA bikes don't come with the A16 needle. I have the exact same set up, T-4, UNI, Pulled Snorkle, and rejet to 58/158-160. I am in Sacramento, but ride in elevations up to 6000-7000 feet. I have also changed the needle to the A16.
At Higher elevations I get a small amount of poping, but you can go down on the Main jet and usually solve this pretty easily.
No, the CA bikes don't come with the A16 needle. I have the exact same set up, T-4, UNI, Pulled Snorkle, and rejet to 58/158-160. I am in Sacramento, but ride in elevations up to 6000-7000 feet. I have also changed the needle to the A16.
At Higher elevations I get a small amount of poping, but you can go down on the Main jet and usually solve this pretty easily.
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- #8
My Ca.XR400 2002 came with an A116A needle.Is this the one you guys are refering to?
I tried the 65 pilot and tweeked the mixture screw but the popping was no better or worse but I did lose a liittle snap on the bottom so I put the 62 back in.After a bit more tweeking on the mixture screw i got the bike running really good with a small pop now and then durring the first 15 minutes of riding.After that she runs pop free.
I tried the 65 pilot and tweeked the mixture screw but the popping was no better or worse but I did lose a liittle snap on the bottom so I put the 62 back in.After a bit more tweeking on the mixture screw i got the bike running really good with a small pop now and then durring the first 15 minutes of riding.After that she runs pop free.
A16 Needle
My stock CA 2000 XR400 needle says A2E on it. You may want to double check with the shop at the local dealer to see if they changed the specs on the newer model.
I went with the recommendations of other riders and XR's Only on their website. I have been very happy with the jetting at 58/158-160 and the new A16 needle. You may be a little high on the pilot jet, thus causing your popping.
My stock CA 2000 XR400 needle says A2E on it. You may want to double check with the shop at the local dealer to see if they changed the specs on the newer model.
I went with the recommendations of other riders and XR's Only on their website. I have been very happy with the jetting at 58/158-160 and the new A16 needle. You may be a little high on the pilot jet, thus causing your popping.
mtngoat
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- Jun 12, 2000
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What altitude are you riding? I think you're fat on jetting even at sea level and cooler temps (more air density). A little off-throttle popping is not a problem; both my XR4s do it.
I'm also skeptical that new CA models come with the A16 needle, since my shop mechanic told me the alternate needle is needed to clear CARB. Last one I changed was on a 2001 and I've done a 2000. Maybe the 2002 is different?
I'm also skeptical that new CA models come with the A16 needle, since my shop mechanic told me the alternate needle is needed to clear CARB. Last one I changed was on a 2001 and I've done a 2000. Maybe the 2002 is different?
