220 run away

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220 run away

Postby chriswelfare » 11:29 pm Jan 23 2018

Bike sat for a year or so. When I cranked it up it went straight to high rpms. I cleaned the carb. Figured my idle circuit was lean. Didn’t fix it. Cleaned the carb again. Same issue. Just did a pressure test, Put 7 psi on the motor. It held the pressure. So I don’t have an air leak. Getting desperate here guys. Any suggestions would be greatly appreciated.
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Re: 220 run away

Postby Jason » 01:07 am Jan 24 2018

timing off somehow??

Have you tried a different plug??
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: 220 run away

Postby Jim B » 01:42 am Jan 24 2018

I had the same problem on an old '84 CR250 I used to own. The weird thing was, the kill switch would not shut off the bike when the RPMs went way up. Turned out the base gasket was installed incorrectly (not by me :naughty: ) and there was a vacuum leak. I'd check for vacuum/air leaks.
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Re: 220 run away

Postby Jason » 01:48 am Jan 24 2018

Yes. That is true. In addition to a pressure test, do a vacuum test.

Jim B, awesome finger wag, HECK YEAH! :supz:
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: 220 run away

Postby Jim B » 02:03 am Jan 24 2018

Jason wrote:Jim B, awesome finger wag, HECK YEAH! :supz:

I bought that old CR to part out and decided to fix it up and ride it. (I bought the CR not long before I bought the KDX. Once I bought the KDX I lost interest in the Honda and did wind up parting it.) It was a bit ratty, but it was REALLY fast. It was ported and had no low end to speak of (pre-power valve) but, boy, did it have a mid- and top-end hit. :supz:
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Re: 220 run away

Postby Jason » 04:12 am Jan 24 2018

HA HA :partyman:

Power valves are nice!
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: 220 run away

Postby chriswelfare » 08:08 am Jan 24 2018

OK, I'll try a vacuum test tonight and post the results. Thanks Guys.
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Re: 220 run away

Postby Jim B » 12:05 pm Jan 24 2018

chriswelfare wrote:OK, I'll try a vacuum test tonight and post the results. Thanks Guys.

Have you tried spraying carb cleaner to check for vacuum leaks? Be careful if you do it. (I'd only try it on a cold engine.)
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Re: 220 run away

Postby chriswelfare » 12:30 pm Jan 24 2018

Jim B I have tried the ol carb cleaner trick. Tried it with starter fluid too. No results. I've got a spare carb I'm gonna try on the bike tonight off my donor bike. I've sprayed cleaner through all the jets and disassembled everything but i guess there is a chance that a passage :please: way is plugged somewhere. viewtopic.php?f=77&t=22279#
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Re: 220 run away

Postby Jim B » 12:45 pm Jan 24 2018

chriswelfare wrote:I've sprayed cleaner through all the jets and disassembled everything but i guess there is a chance that a passage :please: way is plugged somewhere. viewtopic.php?f=77&t=22279#

I meant to spray it on the outside of the engine (say, around the base gasket) to see if it affects the RPMs while the engine is running.
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Re: 220 run away

Postby chriswelfare » 12:54 pm Jan 24 2018

Exactly. I got the bike started and sprayed carb cleaner all over the motor, carb boot and carb. No results so I tried the same trick with ether. Still no results. All signs point to a leak but I just cant find one. Gonna put vacuum on it tonight.
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Re: 220 run away

Postby Jim B » 12:57 pm Jan 24 2018

chriswelfare wrote:I got the bike started and sprayed carb cleaner all over the motor, carb boot and carb. No result...

Weird. :doh: :hmm:
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Re: 220 run away

Postby chriswelfare » 01:09 pm Jan 24 2018

I know. I'm gonna try vacuum tonight to completely rule out a leak. Then I'll try the spare carb. I didn't run it for nearly a year. I think there is something in a passage in the carb somewhere. I cleaned the jets and tried to blow out all the passages. I've got both carbs soaking right now. I'm gonna beat this tonight.
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Re: 220 run away

Postby Jim B » 01:14 pm Jan 24 2018

chriswelfare wrote:I've got both carbs soaking right now.

Be careful not to ruin the jet block gaskets.
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Re: 220 run away

Postby chriswelfare » 01:16 pm Jan 24 2018

Ummm, what are "Jet Blocks"?
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Re: 220 run away

Postby chriswelfare » 01:20 pm Jan 24 2018

Ok, a little googling and I answered my own question. I haven't dissembled the jet block so i'm not sure how I would damage the gasket. Am I missing something here.
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Re: 220 run away

Postby Jim B » 01:21 pm Jan 24 2018

Try the search. It's a very common problem with the PWK. The jet block is the part where the main jet mounts. It's sealed to the carb body with a gasket that tends to go bad over time. Especially if the carb body has been soaked in carb dip.
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Re: 220 run away

Postby Jim B » 01:23 pm Jan 24 2018

chriswelfare wrote:I haven't dissembled the jet block so i'm not sure how I would damage the gasket. Am I missing something here.

They deteriorate over time and carb dip is pretty bad for them.
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Re: 220 run away

Postby chriswelfare » 01:46 pm Jan 24 2018

Ahhh, Ok, thanks for the info. Good to know.
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Re: 220 run away

Postby Jason » 08:28 pm Jan 24 2018

One really should not dip a PWK carb.

Sudco or jets r us for a new gasket, Security Torx 10 or 20?? to get the jet block out and replace the gasket.

If it sets up for a year, then the carb needs to be cleaned, lawn mower, motorcycle, leaf blower, weed trimmer, whatever.

Try not to use ethanol in any of those and try not to let them set up.
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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