More carb problems

  • ewolpert
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More carb problems

31 Jan 2015 19:03
#660264
Hey guys,
A little history:
When I rebuilt my carbs, one of the pilot screws broke off in the pilot hole and I was unable to get it out, as were several mechanics. I had to drill out the hole and now it is about 1/16". I have adjusted all valve clearances and as well as made sure my timing advancer is in good working order. I have no airbox and instead have pods on the carbs.
Here is what is going on today:
I bench synched the carbs using this method: I pulled the carbs from the bike, tightened all adjustment screws all the way down and loosened the throttle screw until it was just touching the pulley. I then used a 0.8mm wire and adjusted the carbs so the wire moved freely and at the same level in all the carbs. I adjusted the pilot screw so that it was seated and then backed it off by 3/4 of a turn. Now the bike will run with the choke off, but it is very prone to runaway idle, which will eventually return to normal if the choke is let off. The bike will run at about half choke but if I try to open the throttle the bike dies. Also, at half choke I have to adjust the throttle open in order to keep the bike running. At full choke the bike will run at a lower throttle, but either way I am not getting close enough to get readings on the gauges. If there is anything I missed you can think of let me know.
Eddie
78 KZ650 b2a

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  • spdygon
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Re: More carb problems

31 Jan 2015 19:35
#660270
Runaway idle means there is a vacuum leak somewhere . Did u get the broken pilot jet out ....if so did u install a new one ...same size?
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  • ewolpert
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Re: More carb problems

31 Jan 2015 21:04
#660275
Well, the vacuum leak isn't on the boots as carb cleaner does nothing when sprayed on any of the boots. I did get the screw out and put that back in the carb. It does not have a tip. I am not sure where I might have a vacuum leak at. I have sprayed carb cleaner all over and the only place that affects idle is the air intake. I think I might need new screws as well as new jets. I currently have 10.2 or 102 main jets. I dont know what I should be running with pods.
Eddie
78 KZ650 b2a

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  • SWest
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Re: More carb problems

31 Jan 2015 21:29
#660280
You need the bleed screw with the tip.
Steve

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  • Nessism
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Re: More carb problems

01 Feb 2015 07:49
#660291
The stock carb jetting won't work with pods.

Hanging idle means lean. Might be vacuum leak as mentioned, poor idle mixture related to the pilot screw setting, or carb sync can affect that as well.

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  • JR
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Re: More carb problems

01 Feb 2015 09:07
#660300
ewolpert wrote:
When I rebuilt my carbs, one of the pilot screws broke off in the pilot hole and I was unable to get it out, as were several mechanics. I had to drill out the hole and now it is about 1/16".

Do you mean that the tiny hole into which the tip of the pilot screw fits was drilled out to 1/16 inch ?
I know next to nothing about Mikuni carbs but am pretty sure that if similar happened on one of my Keinhin CV34 carbs I would have scrap that carb.
If indeed the hole is now 1/16 inchs then I would think that could well be the reason for the problems.
Others with more experience and knowledge please jump in

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