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Old March 6th, 2018, 09:17 AM   #1
skip
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bike won't go past 55mph

09 ninja valve job done carb cleaned now bike won't go past 55mph any ideas what could be wrong
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Old March 6th, 2018, 09:29 AM   #2
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Well, with that information, all I can suggest is that either the valves are set wrong, or the carbs are not truly clean.
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Old March 6th, 2018, 09:37 AM   #3
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Quote:
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09 ninja valve job done carb cleaned now bike won't go past 55mph any ideas what could be wrong
When 2 things are done at once it complicates the troubleshooting process.

Check that there isn't any blockage of the intake. Confirm that the slides rise and fall freely. Damaged or incorrectly installed diaphragms might do it as well.

Any chance the cam timing could be off? It is a bit more involved than the Pre Gen engine.

Here's a link with some photos and info - https://www.ninjette.org/forums/showthread.php?t=9924
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Old March 6th, 2018, 09:49 AM   #4
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Quote:
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Well, with that information, all I can suggest is that either the valves are set wrong, or the carbs are not truly clean.
Carb cleaned 3xs
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Old March 6th, 2018, 09:51 AM   #5
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Quote:
Originally Posted by jkv45 View Post
When 2 things are done at once it complicates the troubleshooting process.

Check that there isn't any blockage of the intake. Confirm that the slides rise and fall freely. Damaged or incorrectly installed diaphragms might do it as well.

Any chance the cam timing could be off? It is a bit more involved than the Pre Gen engine. Took filter out nothing blocking the slides sliding well diaphragms in good shape

Here's a link with some photos and info - https://www.ninjette.org/forums/showthread.php?t=9924
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Old March 6th, 2018, 09:52 AM   #6
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Quote:
Originally Posted by jkv45 View Post
When 2 things are done at once it complicates the troubleshooting process.

Check that there isn't any blockage of the intake. Confirm that the slides rise and fall freely. Damaged or incorrectly installed diaphragms might do it as well.

Any chance the cam timing could be off? It is a bit more involved than the Pre Gen engine. Syncd carbs as well

Here's a link with some photos and info - https://www.ninjette.org/forums/showthread.php?t=9924
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Old March 6th, 2018, 09:53 AM   #7
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Carb cleaned 3xs and sync
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Old March 6th, 2018, 10:43 AM   #8
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Forgive us, but we've seen multiple cases of someone cleaning the carbs several times, and still missing some small passage or some other hidden problem.
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Old March 6th, 2018, 11:24 AM   #9
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Did you reinstall the air box? All carb boots properly installed and no air leaks?
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Old March 6th, 2018, 11:28 AM   #10
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vacuum lines? cam phasing correct?
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Old March 6th, 2018, 11:47 AM   #11
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Boots installed sir box installed no air leaks
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Old March 6th, 2018, 12:04 PM   #12
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Quote:
Originally Posted by skip View Post
Carb cleaned 3xs and sync
And the rest of it?

Trying to help, but limited feedback isn't helping.

EDIT: I see you did add comments at the end of each of my sentences. Hard to follow when added in the quote box.

Last futzed with by jkv45; March 6th, 2018 at 03:12 PM.
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Old March 6th, 2018, 02:10 PM   #13
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Are both cylinders firing? What does it sound like? Capped at 55 mph means it is *way* down on power, approaching only 1 cylinder's worth.
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Old March 6th, 2018, 03:08 PM   #14
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Due to exponential increase in wind-resistance, it's not linear. Aero-drag increases to square-power of velocity. Going 55mph requires about 9bhp, less than 1-cylinder. Because going from 55 to 100mph would require:

[(100mph/55mph)^2]*9bhp = 29.8bhp (crank)

Or over 3x the power to go 1.8x faster. So it's actually down by -70% of peak-power.
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Old March 6th, 2018, 03:13 PM   #15
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Not sure if both cylinders are firing
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Old March 6th, 2018, 03:29 PM   #16
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It's easy enough to (carefully) feel the exhaust pipes to find out.
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Old March 6th, 2018, 04:20 PM   #17
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Yep, or use an infrared pyrometer to measure amount of imbalance: https://www.amazon.com/dp/B013Z8NHCG

Quote:
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Not sure if both cylinders are firing
Pull the plugs and make sure you have strong white/blue spark on both. It's not uncommon to have wiring or coil issues that results in weak spark on one side or both.

When was last time you changed plugs? In good shape with correct gap?
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Old March 6th, 2018, 04:21 PM   #18
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First up is it American ? Or is it scared ? ������

Just kidding. Sounds like it’s running on one cylinder check both exhaust headers are hot where it connects to the engine, a few seconds after start up.

If OK, check carbs ar3 corr3ctly assembled & that the slides lift all the way.
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Old March 6th, 2018, 04:51 PM   #19
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Plugs changed 2 months ago
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Old March 6th, 2018, 04:52 PM   #20
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Also the exhaust sounds muffled
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Old March 6th, 2018, 06:22 PM   #21
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Cam timing.
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Old March 6th, 2018, 07:26 PM   #22
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Make sure the gas line and petcock are flowing cleanly... I just had this situation where the bike had the screen break off in the tank and rusted crud had blocked flow going to the carbs.
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Old March 6th, 2018, 07:30 PM   #23
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Will drain tank and see
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Old March 6th, 2018, 09:15 PM   #24
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Quote:
Originally Posted by skip View Post
09 ninja valve job done carb cleaned now bike won't go past 55mph any ideas what could be wrong
Assuming it was running properly before stated work was done, I would start by double and triple checking if stated work was performed properly. Making sure any wiring unhooked is hooked up properly also.
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Old March 6th, 2018, 11:03 PM   #25
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Bike was bogging backfiring then did valve job cleaned carbs now no bogging or backfiring just not going past 55mph at a complete loss
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Old March 8th, 2018, 04:56 AM   #26
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valves clearance not to spec? cam timing ?
maybe carb clean 4xs is require? winter blend gasoline caused me extra intermittent stumbles
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