Ninja JX21 Driving me NUTZ

Old 12-16-2010, 03:08 PM
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Default Ninja JX21 Driving me NUTZ

I have a JX21 that will not idle unless I have the idle gap at around 3 to 4 mm. Every time a go back to 1.5 mm gap it will not run loads up and dies. I have replaced the fuel line and tank high speed and low speed O rings front and rear bearings. Still have the same issue, no matter how lean it is on the low speed needle still doesn't idle correct. This is on an MBX6 and the motor has 5 gallons on it. Anyone else seen this problem before?
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Old 12-16-2010, 03:09 PM
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The low speed needle (LSN) can easily affect the idle. Sounds like that could be your issue.
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Old 12-16-2010, 03:10 PM
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OOPS

Last edited by robbieg; 12-16-2010 at 03:23 PM.
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Old 12-16-2010, 03:15 PM
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Sounds like a bad air leak to me, like a cracked case. That's the only thing that would explain it running good for 5 gallons and then having idle issues.
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Old 12-16-2010, 03:22 PM
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id say worn p/s. no compression= no idle
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Old 12-16-2010, 03:47 PM
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mine was at flush on lsn and i just had to tune hsn, may be too loose to hold compression and needs a squeeze.
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Old 12-16-2010, 04:54 PM
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+1 at 5 gallons it may just be worn out and compression is to weak. Thats is a symtom for weak compression. Check that since it sounds like you have everything else covered.

Thanks,
Lance
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Old 12-16-2010, 06:46 PM
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How is your clutch? What glow plug are you using?
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Old 12-16-2010, 07:48 PM
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check the case and if its good get a new p/s. check that the rod isnt worn. I had one pinched and it didnt work for me.
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Old 12-16-2010, 08:35 PM
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Originally Posted by Jamie2 View Post
I have a JX21 that will not idle unless I have the idle gap at around 3 to 4 mm. Every time a go back to 1.5 mm gap it will not run loads up and dies. I have replaced the fuel line and tank high speed and low speed O rings front and rear bearings. Still have the same issue, no matter how lean it is on the low speed needle still doesn't idle correct. This is on an MBX6 and the motor has 5 gallons on it. Anyone else seen this problem before?
set ur needles to factory settings and tune from there, lets not jump the gun here.
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Old 12-16-2010, 09:13 PM
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Originally Posted by Jusleanit View Post
set ur needles to factory settings and tune from there, lets not jump the gun here.
Yeah, I have tried everything I can think of. I took it back to the fatory settings to run in the new front and rear bearings. I have not been able to find any indication of the case being the problem. The motor is seald up so I don't see it being an air leak. I have never had a pinch done on a P/S since I normaly get around 8 to 10 gallons out of my motors with no issues.
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Old 12-16-2010, 09:28 PM
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To run in the new bearings?? Did the problem arise immediately after the new bearings were installed? If so, I would look for an improperly seated bearing or a bad bearing. It could also be an air leak that occurred during the process of installing new bearings, but an air leak usually doesn't make an engine load up in the way you described. Cracked block is very unlikely with the Ninja block. If you cracked one of those, you deserve a medal or something. It is also possible that it doesn't have enough compression to idle. I would go back to base settings and try again before you do anything else.
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Old 12-16-2010, 09:44 PM
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You have a pm.

Rex
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Old 12-16-2010, 10:12 PM
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Try this: originaly posted by Joe Alessi: if you get lost i always start here with my OS's
2060 pipe w/p4 plug

Idle: 1-1/4 (turns in from JUST closed)
HSN: 2-1/2 (turns out from bottomed)
LSN: 4 (turns out from bottomed)
MRN: 3-1/4 (turn from bottomed)
hold the carb slide WOT while bottoming LSN or MRN to prevent damage.

i usually end up around here when done tuning. just remember to get the hsn dialed in first, then tune the lsn, and adjust the idle if need be.

Idle: 1-1/8 (turns in from JUST closed)
HSN: 2-1/8 (turns out from bottomed)
LSN: 3-1/2 (turns out from bottomed)
MRN: 3-1/4 (turn from bottomed) So i would try to retune it after i check the compression and conrod ect..Non of the engines r same and lot of thing could efect your tune and engine but you can start from there ....Good luck!
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Old 12-16-2010, 11:05 PM
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Originally Posted by JAMMINKRAZY View Post
To run in the new bearings?? Did the problem arise immediately after the new bearings were installed? If so, I would look for an improperly seated bearing or a bad bearing. It could also be an air leak that occurred during the process of installing new bearings, but an air leak usually doesn't make an engine load up in the way you described. Cracked block is very unlikely with the Ninja block. If you cracked one of those, you deserve a medal or something. It is also possible that it doesn't have enough compression to idle. I would go back to base settings and try again before you do anything else.
No, I put in new bearings to try and fix the problem. I didn't think it was the issue but I figured since the motor has 5 gallons on the motor it was worth a try.
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