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Topic: Best Way to Unstick Intake Valve on Honda 2000i?

Posted By: ralphnjoann on 12/16/09 04:34pm

The intake valve is stuck open. I can see the shaft after removing the carb. I can also get to the top of the stem by removing the valve cover. Any ideas on how to get it unstuck?

Posted By: Art D on 12/16/09 04:44pm

My first thought is what I did to a car engine with a stuck valve; pull the head so you can get an idea why it's stuck. If the valve stem looks straight and true, soak it with, or in, lacquer thinner. The will disolve any gunk or gum. Then you may have to add a bit of torch heat to the head to get the valve to move.

Geaux LSU

Posted By: vance on 12/16/09 04:58pm

More than likely you need to pull the head and check the valve. If it was stuck open and you tried to start the engine, it is probably bent now and you could also have damage to your piston.

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Posted By: I am still wayne_tw on 12/16/09 05:09pm

ralphnjoann wrote:

Any ideas on how to get it unstuck?

Take it to a qualified technician who will have the tools and expertise to do the job correctly.

Posted By: jauguston on 12/16/09 07:32pm

Use a good penetrating oil like Kroil or PB Blaster and spray top and bottom. Let it soak for a day or so with repeated spraying. Try tapping on the stem on top and see if you can get it to move. It may go down a little and then pop back up. Another thing you can try is get a piece of brass or aluminum rod and bend it so you can get it through the spark plug hole and under the head of the valve gently pry up on the valve. If you get it moving mix a strong solution of gas and Sea Foam and run it. Also get a can of Deep Creep (Sea Foam in a spray can) and spray it in the air intake when it is running. It will smoke like crazy but it should free things up - doesn't work pull the head.

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Posted By: blacksea on 12/16/09 08:06pm

If the valve is stuck open, most likely it's a mechanical issue... pending the engine hasen't been sitting for eons allowing oxides, etc. to accumulate around the stem which, if you force it can and will wreck the guide...
Pull all the spark plugs and rocker cover. If the engine rolls over and no other valves are sticking or bumping as the piston nears TDC or BDC there should be literally no resistence other than the cam of which is relatively constant for parasitic drag through every revolution (trust me you'll know it as you roll it over by hand or with a wrench as you'll literally feel a clunk or some serious resitance and if you do stop trying to roll the engine over... the head needs to come off).
Watch all the valves move and take a good look at the springs to see whether or not a spring is broke (highly likely) or one of the keepers jumped out of which is terribly rare. Something else too, the valve could already be bent however I've no clue the model of your engine... if it's a belt driven OHC, jumping one cog... even two won't create an issue... more than this and you have an issue. With this said... you'd have more than one bad valve... you'd have 4 bent intakes.
If the spring is good and the valve refuses to meet the seat it's time to take the head off... penetrating oils, etc are a great idea but the problem is chunks of oxide can fall off and find their way between the cylinder and piston which can in all reality wreck the bore as oxides are terribly abraisive.
Something else too, you can pull the intake manifold and take a look at the valve to see whether or the portion of the valve operating in the guide is clean.... you'll see a definite mark where the valve operates in the guide... if it's clean, the spring assembly looks good, the valve is most likely bent of which is an indication of other issues and the head needs to be repaired.
For what it's worth it use to be a pretty common issue with heavy stationary engines that sat around for months at a time... Since the valves are on the same plane as the piston (vertical to the piston) rarely was there damage... at any rate some mouse would dig a hole through the filter and set up house keeping in an intake runner. The rest you can imagine.
Unfortunately there's really not a short cut to do it safely... good luck to you.

* This post was last edited 12/16/09 08:32pm by an administrator/moderator *

Posted By: jauguston on 12/17/09 08:30am


Did you read the post title? Its a Honda one cylinder portable generator.


Posted By: C-Leigh Racing on 12/17/09 11:10am

When I was in the lawn mower repair business, 95% of the repairs I did to the engines was fuel related, stuck valves, gummed up carbs & jets, the other 5% was more or less a failed part which sometimes is normal because of wear.
Old stale gas almost put Briggs & Stratton out of business because of owners leaving gas in the mower tanks over the winter months, turning gummie, carb floats sticking & gas flowing through the carb & right down into the crankcase mixxing with the engine oil.
They were replacing engines left & right & knew full well it was stale gas causing the problem to begin with, but they still replaced them.

If your generators been sitting anywhere from 3 months to when ever, that gas in the tank has gone stale from all the chemicals (what little there is) leaching out. After that the gas is starting to get gummie & sticky which is probably why that valve is stuck.

Since you have the carb off, take a can of carb cleaner, some of the good stuff that still has acetone in it & spray a good load of it down through the intake & then cycle the crank over slowly a few times to swish a good coating of it onto everything.
Be sure if the engine has a cut of to turn it off, you dont want a spark from the plug or from the wire to light the mixture up or cause a fire, then let it sit for awhile so the acetone can get to that gummie stuff sticking the valve.
I have seen people take a piece of rope & poke it into the plug hole & get enough on top of the piston to bump the valve face & cause it to close.

This gas we buy today, its realy not worth the time it takes us to go to the store, put some in a jug & bring it back home, its just cheap but not when we pay for it.
The idea is for you to fill your tank today, burn that out & get another tank full tomorrow. That about the only way to explain it or else it would last longer than it does.

Ok, now you found this problem out on your generator, wait till next summer when you pull that string trimmer out of the shed & try to start it up.

Posted By: blacksea on 12/17/09 11:22am

jauguston wrote:


Did you read the post title? Its a Honda one cylinder portable generator.


OOPS... i was for some reason, thinking two litre, not 2kw.... ah, still the same techiques less all the overhead cam stuff... haven't had a mouse build a nest in anything this small... yet.

Posted By: ralphnjoann on 12/17/09 11:41am

Thanks everyone. Here's what I did to unstick it. Maybe this will help somebody else.

I sprayed it with PB Blaster and let it sit. Then I removed the rocker arm assembly and the valve spring. I clamped a large pair of vice grips to the tip of the valve stem just below the valve spring retainer groove. The vise grips were vertical.

Next, I used a large screwdriver and a block of wood to free up the valve. I stuck the screwdriver through the opening in the vise grip jaws above where the tips were clamped to the valve stem. I rested the tip of the screwdriver on the block of wood which rested on the edge of the head. The block was thick enough so that the screwdriver was at a right angle to the valve stem.

By repeated lifting up of the screwdriver handle, I was able to apply a vertical force which was centered over the valve stem. It took a bit of doing, but it came loose.

I put everything back except the spark plug together and filled the crankcase with oil and pulled the starter cord a number of times to dilute the PB Blaster and any other contaminants. I then changed the oil, installed the spark plug, and pulled the starter cord. After a couple of pulls, it fired right up.

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