Instant loss of power - Wrist Twisters
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post #1 of 8 Old 05-22-2017, 08:59 PM Thread Starter
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Instant loss of power

Haven't been around much or posted in the last year+, but now I gots problems, so here I is...

Riding home from work today, about 5 minutes in, I shift down through the gears to 2nd, slowing down from 60 to around 20 to turn onto the freeway on ramp.

About halfway into the corner just as I was beginning to accelerate out of the turn, there is an immediate change in the exhaust note with an accompanying loss in power.
It wasn't a complete loss of power as the bike didn't die, more like a complete downward shift of the power band.

With the change in the exhaust note, my brain leapt to the speculation that some baffling broke free in the muffler, and was partially choking off the exhaust flow.

I chose to power through and limp home, cause the bike was still running, and I didn't know if it would continue running if I stopped.
The fact my brain was working on the "broken baffle" theory, both tires were still inflated, and the bike wasn't currently on fire weighed in on the decision also...

A couple minutes later I came to my senses realizing my single Two Brothers can doesn't really have baffles to break loose...
Worrying that it could be a wheel problem that might cause me to get bucked off the bike @ 60 mph, i chose to pull over.

I pulled in the clutch, eased the throttle back to a level higher than normal idle speed, pulled over, stopped, put it in neutral, and let go of the throttle.
The bike idled smoothly at a slightly lower than normal speed.

Look thinks over, and not seeing anything obviously catastrophically or structurally wrong, hopped back on to start for home.

I had to slip the clutch in while holding the throttle way higher than normal to keep the bike from dying.
Accelerating through the gears I had the throttle close to wide open, and built speed very slowly through each gear.

Hit 60 again and shifted into 6th.
maintained speed fine, but when the throttle was opened up from this point it really didn't offer up much more.
It felt like I would have needed to downshift to build anymore speed, but being in limp home mode I didn't try.

Got home, pulled in in to the garage.
Still idles smooth, starts ride up, but very different exhaust note.
Revs to high RPMs without issue in nuetral.

Used to drive muscle cars and it feels exactly like a car with a locked up distributor advance.

Mods from stock:
Single Two Brothers can
PC3
Flapper mod
Pairs plates
all years old
no recent work other than rear caliper.


There's my story. A bit long winded, but there it is.

Any ideas what direction to start looking in?



If I don't reply immediately it is due to my 12-14 hr. workdays (also the reason I haven't been around much), but I will, and will update if I find the reason.

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post #2 of 8 Old 05-22-2017, 09:08 PM Thread Starter
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Just under 16k miles

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post #3 of 8 Old 05-23-2017, 03:16 AM
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First thoughts are PCIII ground or FPR.

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post #4 of 8 Old 05-23-2017, 04:07 AM
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I'm also thinking failed fuel pressure regulator. Could also be a coil failing under load. Are all your header pipes heating up evenly? Maybe pull your spark plugs and check their condition, are any wet, fouled? Also check the ground to the frame under the tank.
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post #5 of 8 Old 05-23-2017, 12:50 PM
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Easy test. Unplug PC3. Test ride. Report back.

"Towards the end of the vid, it looks like she may have had a bafflectomy." - MarylandMike
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post #6 of 8 Old 05-23-2017, 07:24 PM Thread Starter
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Quote:
Originally Posted by Islandboy View Post
Are all your header pipes heating up evenly?
Bingo!

Center 2 weren't heating up at all.

Coil wire popped off.

Turned out to be the easiest thing to check, thanks for the extra brain cells Islandboy.

Thanks all for the input.
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post #7 of 8 Old 05-23-2017, 07:27 PM Thread Starter
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bada bing bada boom.

Problem solved!
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post #8 of 8 Old 05-23-2017, 08:57 PM
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Easy fix.That sneaky little bugger! Well done on finding that. Handy little tip that feeling up your header pipes. It's not my original idea. I had the same thing happen to an old bike years ago. Would start, idle, run for a bit then crap out. Some old fella said "feel your headers". I did and two were cooler. Turned out one of the coils was on its way out.

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