Kubota 400 ci backfire issue

Rollo

Member

Equipment
Kubota RTV400ci
Mar 18, 2023
31
3
8
Michigan
Looks like it's .11 to .16 mm (.0044 to .0063 in) for both. Screenshot attached.

Also, here is a link to the workshop (service) manual: https://www.kubota.cz/data/soubor/WSM_RTV400_EN.pdf

I'm having the same issue here. So far I've done engine oil change, transmission/differential oil change, new spark plug, new fuel injector, both air filters, added inline fuel filter, and a new 300CCA battery. The issue persists.

Would be great to hear if the valve clearance adjustment fixes this. Please send updates!
A friend was over and wanted to adjust the valves by seeing if they were open or closed. It definitely made a big difference in the amount of times it backfires and also less impactful or power loss during backfires. This weekend I am going to go strictly by the book and adjust the valves. Looks like I am on the correct path.
 

Rollo

Member

Equipment
Kubota RTV400ci
Mar 18, 2023
31
3
8
Michigan
I readjusted the valves to .005 and it seems to be what the issue was. It might have a slight backfire once in a while, so I will bring it down a little more one day. But it is greatly improved. Thank you everyone for your advice.
 
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CiscoRanger

Active member
Lifetime Member

Equipment
L4150DT / BF900
Oct 3, 2022
240
124
43
Texas
Great news Rolio! Great job fixing it, and glad you are back in business!
 
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