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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 13023
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I've worked on a couple GX Honda engines now and today i had

Customer Question

Hello my name is***** worked on a couple GX Honda engines now and today i had a GX390 which didnt run properly installed a new carb still nothing, i took off head checked valves and they were all pretty good. I checked the tank and it was loaded with rust put on a new tank and it works again but now it vibrates really bad yet before it didn't. what would this cause from just taking off the head?
Submitted: 1 year ago.
Category: Small Engine
Expert:  Donald replied 1 year ago.

Hello Dan, and thank you for choosing Just Answer. My name is***** will be happy to assist you. I will need to ask you some troubleshooting questions as we go.

Expert:  Donald replied 1 year ago.

What is your engine being used for?

Expert:  Donald replied 1 year ago.

We can continue from here. Thanks!

Customer: replied 1 year ago.
Its used on a small manure spreader but vibrates really bad on bench under no load at WOT in low rpm its fines. This has happened to me more then once and its a bit frustrating the more this happens the less i want to take head off for inspection
Expert:  Donald replied 1 year ago.

Thanks for your response. Is your engine bolted to your bench?

Customer: replied 1 year ago.
its not as bad when its bolted to bench still seems far too much vibration compared to a new one. When not bolted to bench its really bad
Expert:  Donald replied 1 year ago.

Now that you have your engine again, what if you re-attach your manure spreader back to it, and see if the vibrations will improve.

Expert:  Donald replied 1 year ago.

An engine will vibrate noticeably more, when it is not attached to anything, that requires its power.

Expert:  Donald replied 1 year ago.

You was not experiencing this problem before you removed your cylinder head?? How old is your engine?

Expert:  Donald replied 1 year ago.

I do not believe that your cylinder head is causing the excessive vibrations. Something has to be spinning out of balance.

Expert:  Donald replied 1 year ago.

I would like to make a suggestion to you.

Customer: replied 1 year ago.
This morning i took the head off again cleaned everything very well also i took out the exhaust valve and make sure it was seating properly cleaned it as well put it back together and now its much better now. The reason i cleaned the exhaust valve and seat was because i noticed was a very light orange tan color.
Expert:  Donald replied 1 year ago.

Dan, thanks for letting me know. So, cleaning your cylinder head resolved our problem?

Expert:  Donald replied 1 year ago.

This is good to know. Did you have a major build up, of carbon in your combustion chamber, and on your exhaust valve?