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Shred Jesse

Installed JD Jet kit... now my WR400 spits flames...

32 posts in this topic




So... my WR400 now spits flames.

I installed the JD jet kit, which consists of next to nothing. I installed the blue needle as recommended on the third clip, and went to install the 170 jet, and it friggen BROKE just lightly putting it in. It wasn't cross threaded or anything.. A reverse drill bit took it out without any metal shavings or anything! It was barely in there...

Anyways, went with the 168 instead, as I figured a bike meant to go from 3k-6kfeet would just be a smidge lean at sea level.


Welp, apparantly a WR400 meant to operate at 3k-6k feet is a FLAME THROWING MONSTER at sea level, because my bike is spitting MAD flames!


I'm dyno tuning my bike this weekend. Not quite sure what results to expect from my flame shooting monster. Something is awry that's for sure...

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Wow that is a cool show you got going there! Probably not good for your buddies behind you though haha

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Hah. I should keep it like this and try a hare scramble. Go ahead and try and pass me, I got a flame thrower!

Also... my exhaust is spark arrested somewhat ironically.

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oh... and some more information:

Ran the bike up the street and bike, ran great. Popped a wheelie, zipped around a bit, had to stop as I knew my neighbors were going to whine.

Bike ran fine, felt great, everything worked as it should... while spitting flames.

Double checked bike for any air leaks just know. Carb mounts were all on fine, but could have seated a mm or two more. Made sure they're prefectly snug and the clamps were as tight as feasible.

So I've got no idea what's going on, but whoooieeee do I like cool shooting flames. I bet the rangers will love seeing my bike!

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Per eddies "what I need to know" thread:

99 WR400

Full FMF powercore exhaust with powerbomb header

168 main jet, blue needle from JD jet kit on third clip (per instructions). Stock pilot jet (70?). Airbox cover removed. Greywire mod performed (YZ ignition timing)

So... my WR400 now spits flames.

I installed the JD jet kit, which consists of next to nothing. I installed the blue needle as recommended on the third clip, and went to install the 170 jet, and it friggen BROKE just lightly putting it in. It wasn't cross threaded or anything.. A reverse drill bit took it out without any metal shavings or anything! It was barely in there...

Anyways, went with the 168 instead, as I figured a bike meant to go from 3k-6kfeet would just be a smidge lean at sea level.

Welp, apparantly a WR400 meant to operate at 3k-6k feet is a FLAME THROWING MONSTER at sea level, because my bike is spitting MAD flames!

I'm dyno tuning my bike this weekend. Not quite sure what results to expect from my flame shooting monster. Something is awry that's for sure...

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It spits only whn you close the throttle so my bet is pilot circuit, or decel enricher circuit.

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When do the flames occur? Acceleration? Deceleration? Steady Throttle? When?

What did you change just before this started?

Even a 168 is a very large jet, I would think you'd be running a 155 on that bike at that altitude. However, the main jet is not your problem.

Was this the same bike that had bad bogging? You did not have this flame issue then, correct?

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Please do not make the same post in multiple forums. It makes the searching of answers more difficult for tothers and forces people to write the same response twice. I have merged the post you made in the jetting forum into this one.

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You are too lean. Richen the low end, not the main.

You probably have significant popping on decel too.

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Please do not make the same post in multiple forums. It makes the searching of answers more difficult for tothers and forces people to write the same response twice. I have merged the post you made in the jetting forum into this one.

Sorry. I sometimes get lower responses in a model specific forum, but get great responses in the general forum for jetting or suspension. Since I'm getting responses here I'll leave it as is.

The flame occurs on decel. Thought you could hear it in the video. My bad for not explaining that a bit more. I'll play with the low end, and also purchase some additional pilot jets.

The main jet choice is UNDER the recommendation of JD jetting. They recommend a 170. My bike already had a 170 main jet, and I went to install the 170 from JD and it broke almost instantly. Manufacturing defect? Anyways, are the JD jetting 170 and a 170 from the manufacturer any different?

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Welp, in preperation for any fine tuning I may need to do... I purchased pilot jets one size up and one size down, along with pilot jets two sizes up from 170. I've now get a pretty wide range of jet sizes to run with! This bike will murderate trails when I'm done!

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something is definitely not right with that bike! lol! Forget the main jet, 168 or 170 should be fine. Re-check the needle to make sure it's seated correctly inside the carb and moves freely. Then check your pilot jet, make sure it's not clogged up, change it out to one size larger if you can. Might also have to remove the carb and use some air to blow the ducts and make sure there's no debris stuck anywhere.

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I've cleaned the carbs all the way out recently so I know it's all clean and legit. I removed all the jets and hit it all with an air compressor, carb cleaner, etc etc.

Wouldn't the bike run all kinds of suqirrley if the needle wasn't seated? It slid in fine and everything is there, so I'm inclined to believe there isn't a problem there. It may just be excessively lean on the bottom end...

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I've cleaned the carbs all the way out recently so I know it's all clean and legit. I removed all the jets and hit it all with an air compressor, carb cleaner, etc etc.

Wouldn't the bike run all kinds of suqirrley if the needle wasn't seated? It slid in fine and everything is there, so I'm inclined to believe there isn't a problem there. It may just be excessively lean on the bottom end...

Did you take the slide out when you had it cleaned? If so, is the slide plate in the right way?

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One size up on the pilot jet and set the fuel screw out to 1.75 turns out for a starting point. An aftermarket adjustable fuel screw would be a good addition if you don't have on.

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Like SXP said, Did you remove the slide when you did the carb cleaning? It's possible to re-install backwards, and this will cause the problems your having. Maniac

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I did not remove the slide. I focused on the jets and doing the carb modifications.

I will try going up a size on the pilot jet. I also ordered an adjustable fuel screw from zip-ty racing for my carb.

I'm dyno tuning the bike Sunday. Hopefully a size up on the pilot and the fuel screw adjustment sorts everything out for me.

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Dude - good video thats gnar-

Question with the FMF addition was the previous or stock jetting running lean too? pop on decel?

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