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Kehein FCR emulsion tube* (07 WR450f)

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Do I need to replace it?

 

Should I stick with stock (no perforations) or get an aftermarket one like the Factory Pro emulsion tube?

 

I read the WR250 had a perforated emulsion tube. Has anyone ran one in their WR450 and compared to the stock one?

 

 

*emulsion tube aka needle jet. 

 

Edit: if you prefer this be in the WR subforum I can move it. I just figured the FCR was in many models so there might be a better turnout of people with experience.

Edited by Nixinus
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Depends. Are you an "A" class or semi pro racer that never lets the RPMs drop below 8,000? Then the solid tube provides better performance. A 'B or C' racer or trail plonker? Then the WR perf tube works better.

BTW, after market or OEM perf tubes work the same. Just one comes with stickers.

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Thank you, that's a helpful comparison. I would want to try out a perf tube then, if I don't already have one. I've only tore down and rebuilt the carb once since I've owned the bike and can't remember if it was perforated or not. 

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Swapping the tube is super easy. If you do not know, all you do is drain the carb, pop off the 17mm cap, remove the main, unscrew the tube, put in the replacement, then the main and the cap. Takes five minutes at most.

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I've read that the late model carburated WR's did not have the perforated emulsion tube. Either intentional (MAJ hole is closed) or accidental, do you know a parts number for the perforated needle jet? I was going to get one from a WR250, I think 2002.

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5TJ-14947-00-00

I've NEVER seen a main air jet closed. Every bike I have seen has a jet, almost always a #200. Fuel is still 'bubbled up', just the perforations better atomize the fuel for improved smaller throttle operation.

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2 hours ago, William1 said:

5TJ-14947-00-00

I've NEVER seen a main air jet closed. Every bike I have seen has a jet, almost always a #200. Fuel is still 'bubbled up', just the perforations better atomize the fuel for improved smaller throttle operation.

That's what has me confused. I need to get my carb out and see for myself.

 

The thread below has info on this subject. Some say the MAJ is not "drilled through". Some others say the part number you listed is supposed to have emulsion holes but is a solid tube instead. I'm unsure what part number to order, newer WR450 5JG 14264 (supposedly w/out holes) or the older 5TJ 14947 (w/holes). 

 

 

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On 8/14/2017 at 6:16 AM, William1 said:

5TJ-14947-00-00

I've NEVER seen a main air jet closed. Every bike I have seen has a jet, almost always a #200. Fuel is still 'bubbled up', just the perforations better atomize the fuel for improved smaller throttle operation.

 

I ordered both these part numbers below. Both of them are SOLID tubes...anyone know for certain what part number isfor.perforated tube??

5JG-14947-00-00 = solid tube

5TJ-14947-00-00 = solid tube

__________?? = perforated tube

What is the correct part number?

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5 hours ago, Sasha Rudolfski said:

 

I ordered both these part numbers below. Both of them are SOLID tubes...anyone know for certain what part number isfor.perforated tube??

5JG-14947-00-00 = solid tube

5TJ-14947-00-00 = solid tube

__________?? = perforated tube

What is the correct part number?

I believe the 5TJ is a perf tube. I am not familiar with the other number.

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6 hours ago, William1 said:

I believe the 5TJ is a perf tube. I am not familiar with the other number.

I ordered both, both of the tubes are solid tubes....sorry about the multiple posts...

Edited by Sasha Rudolfski
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