260z kohler surging/backfire

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Dragonslayr

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• Jun 12, 2018 / 260z kohler surging/backfire

• #1

Gravely 260z model 992047 serial 001595
Kohler cv740s Spec CV740S-PS-0011

I've a surging issue with my mower I'd like some help with. I am not well versed in small engines, though I seem to be in a really steep learning curve as I've been fighting this for awhile now..

I've read and searched, but the issue evades me. To date:

Removed gas tank and cleaned
Replaced lines to filter, carb and even the vacumn line to the fuel pump.
Replaced fuel pump.
Replaced carburator with this one
Took off air breather - Did not help

Am getting great gas flow to the carb.

I do not mind replacing the parts I did as it is an older mower and was due some TLC. However, it still surges/backfires.
I seem to have gotten it to mostly stop backfiring by turning the idle speed screw way up and at least I can mow now, though it is still not right.

I do absolutely love this mower and humbly as for assistance please.

 

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Dragonslayr

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• Jun 13, 2018 / 260z kohler surging/backfire

• #2

I forgot to add, I sprayed wd40 and then starter fluid around the intake and saw no difference.

 

EngineMan

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• Jun 13, 2018 / 260z kohler surging/backfire

• #3

surging issue is almost down to carb, when you said you replaced it, was it with a new one or used one, if used did you clean it, you haven't said that you have check the valves.

 

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Dragonslayr

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• Jun 13, 2018 / 260z kohler surging/backfire

• #4

EngineMan said:

surging issue is almost down to carb, when you said you replaced it, was it with a new one or used one, if used did you clean it, you haven't said that you have check the valves.

Click to expand...

I replaced it with a new after market carb from amazon for 50.00

Unfortunatly, my significant other thru the original away when I left it laying around. My bad, because at this point, I'd have liked to try rebuilding it.

I have not tried checking and adjusting the valves. I will try that (after I watch a video)

 

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Dragonslayr

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• Jun 13, 2018 / 260z kohler surging/backfire

• #5

I see how to adjust the valves, however, I've a question, I see no mention of adjusting valves in the manual. Nor do I see mention of clearance from the rocker to the stem. Obviously I'm missing the wording in the "clearance" section. Could you guys help me out finding the clearance or at least what terms I need use to find it?

 

EngineMan

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• Jun 14, 2018 / 260z kohler surging/backfire

• #6

The Kohler CV740 is Hydraulic so no need to adjust.

 

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Dragonslayr

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• Jun 14, 2018 / 260z kohler surging/backfire

• #7

Hmm, so what was I supposed to check on the valves?

I'm also wondering if I should not assume I got dirt in the new carb during installation and try to clean it. Then, if that does not work, fork out the 270.00 or so and order the oem Kohler carb?

 

EngineMan

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• Jun 14, 2018 / 260z kohler surging/backfire

• #8

Dragonslayr said:

Hmm, so what was I supposed to check on the valves?

I'm also wondering if I should not assume I got dirt in the new carb during installation and try to clean it. Then, if that does not work, fork out the 270.00 or so and order the oem Kohler carb?

Click to expand...

I hadn't got a file on the Kohler CV740 out of all that I do have, so I had to check it up, it was then that I realized is was Hydraulic, remember we all make mistakes... you should be able to repair the old carb....I would have thought....check that the new one is bad before you pay out yet again.

 

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Dragonslayr

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• Jun 14, 2018 / 260z kohler surging/backfire

• #9

Great! I will try cleaning this one up and see how it goes first! Thank You

 

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Dragonslayr

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• Jun 15, 2018 / 260z kohler surging/backfire

• #10

Ha, I cleaned the snot out of the carb and reinstalled it. My surging issue has gone away!!!

However, My backfire at low idle has not gone away.
I adjusted the idle speed screw back up quite a way and I may get some pops, but no loud backfire thru exhaust.

I also have an issue when I hit a good bump of losing power. I've disabled the seat switch, and took off the break switch tested and cleaned perhaps I should take the wire off the coils to test all safety switches at the same time??

Getting great solid spark solid orange on both plugs and have installed new plugs.