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Author Topic: Breaking up is hard to do.  (Read 1420 times)

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Offline DV Red Herring

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Breaking up is hard to do.
« on: February 03, 2018, 08:59:07 AM »
This morning I pulled my carbs off to clean a stuck needle valve and check float heights. The bike was running well previous to this. Now, it breaks up after 4k rpm and/or heavy throttle. This is new. I only took it for about a 30 minute ride out because I really don't like pushing it home. I'm lost as to why it's doing this now. Its a 750K4. Any thoughts?
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Offline seanbarney41

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Re: Breaking up is hard to do.
« Reply #1 on: February 03, 2018, 09:21:26 AM »
Condenser
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Offline TwoTired

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Re: Breaking up is hard to do.
« Reply #2 on: February 03, 2018, 12:30:10 PM »
Look at spark plug deposits.  Review/revisit your 3000 mile tuneup check list to isolate that only the carbs have an issue.  Air filter clean/clear/new?

Cheers,
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline DV Red Herring

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Re: Breaking up is hard to do.
« Reply #3 on: February 05, 2018, 02:51:54 PM »
Of course TT was right. Checking the brand new plugs revealed 3 very nice tan plugs and 1 very sooty plug. I swapped on one of my known good condensor sets. No luck. Now on my third pull of the carb rack. All of the floats measured correctly. I pulled the needle and seat from number 3 (the offending cylinder) and found a little Itty bitty speck of dirt that I all but had to pick out. On a good note, I can now pull the carbs and have them on the bench in about 10 minutes.
« Last Edit: February 05, 2018, 02:59:56 PM by DV 750 »
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Offline jgger

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Re: Breaking up is hard to do.
« Reply #4 on: February 05, 2018, 08:40:53 PM »
If the float levels are all good, then check the Jets in the offending cylinder. I have seen jets come loose or out in other carbs.........makes for a very rich carb.
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Offline Don R

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Re: Breaking up is hard to do.
« Reply #5 on: February 05, 2018, 09:46:21 PM »
 I found a jet laying in the bowl once. That'll make your plug wet.
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Offline DV Red Herring

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Re: Breaking up is hard to do.
« Reply #6 on: February 06, 2018, 06:14:22 AM »
Great idea. I will go back in and check each of them.
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Offline dave500

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Re: Breaking up is hard to do.
« Reply #7 on: February 06, 2018, 01:05:39 PM »
check the numbers on the jets,one might be oddball?
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Offline TwoTired

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Re: Breaking up is hard to do.
« Reply #8 on: February 06, 2018, 01:39:10 PM »
Quote from: dave500 on February 06, 2018, 01:05:39 PM
check the numbers on the jets,one might be oddball?
If it's a used bike, the jets may have been drilled, too, making the numbers misleading.

Cheers,
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline ofreen

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Re: Breaking up is hard to do.
« Reply #9 on: February 06, 2018, 02:55:41 PM »
Quote from: Don R on February 05, 2018, 09:46:21 PM
That'll make your plug wet.

Talk dirty some more.
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Offline BobbyR

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Re: Breaking up is hard to do.
« Reply #10 on: February 06, 2018, 03:03:44 PM »
 :) :) :) :) :) :) :)
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Offline DV Red Herring

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Re: Breaking up is hard to do.
« Reply #11 on: February 11, 2018, 05:12:25 PM »
So, this is what I did. Returned the air screws back to 1 turn out. That definitely helped. Still broke up around 5k rpm. Took the bottom of the airbox off and ran it with no filter (to see if it was an overly rich issue). All but cleared it up. Pulled the carbs again and dropped the needle to second from top. With the whole airbox and filter on, it sometimes breaks up, and sometimes not. I'm starting to realize that HiFlo filters aren't too good. When I buy my K&N I will have to undo some of this leaning of fuel that has happened...
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