The Home Machinist!

I have a Honda 5.5 h.p. motor in an RMI engine and it won't run smooth unless it's on about 3/4 choke. While I can get any old Ford flathead running even with only half it's parts, I've never been able to handle these little one-lung engines. For some reason, they remain outside my skill set.

Because it will run smooth at 3/4 choke, I don't think it's an ignition problem; seems like an air/fuel problem. I cleaned the plug anyway as I know these guys can be particular about that. Drained the gas and replaced with fresh. Pulled the carb bowl and see no evidence of debris. Float and valve look to move OK. Shot some carb cleaner down the throat to no avail. Pulling the carb looks like a fiddly job with governor and throttle linkage and a fuel line that is carefully placed just so that it's almost impossible to get to to disconnect.

Getting this thing into the truck and to the lawnmower shop is not something I want to do as it's at least an hour's worth of time and then there is no easy way for them to work on it when I get it there. I'd probably have to make another trip with my work stand.

So do any of you have any ideas as to the problem? THANKS!

_________________
Greg Lewis
Eyeball Engineering — Home of non-interchangeable parts
Our motto: That looks about right.
Turning perfectly good metal into bits of useless scrap since 1983.

It could be a question of old gas. Do you add Sta-Bul or other fuel treatments to your gas? You might have a varnish build up in the jet.

_________________
www.BuckinghamCentralRR.com

Thanks, Bobby:

I added the Sta-bil before shutdown and drained the carb. Replaced gas with new.

_________________
Greg Lewis
Eyeball Engineering — Home of non-interchangeable parts
Our motto: That looks about right.
Turning perfectly good metal into bits of useless scrap since 1983.

Greg:

Check the specs. It could be a problem with the wrong fuel orface, you know, jetted for a higher altitude so the engine is trying to run too lean where you are in the California central valley. Running with the choke partially closed would richen the mix if the fuel orface is too small.

Just a thought.


Bill

not sure of your calif .fuel but the alachol added stuff is causing major headaches in small engines lots of junk breaking loose and mrssing with partialy plugged jets /orfices and restrictive flow fuel lines. it the weed wacker motors it attacks the rubber diaphrams so they crack and wont push fuel.

if it ran ok before this is my suspicious idea.

Greg,
I have found that the new alchy fuel leaves little balls of jelly behind if it sits awhile. These get stuck in the tiny orifices of the fuel tube. This in turn leans things out to the point of having to add more and more choke. The only way have found to get these out is to take the carb apart and blow everything out. I use tiny gauge pins to poke through the tiny holes to make sure they are clear. A good spray of carb cleaner and then put things back together. Checking the float level is important too. The alchy fuels tend to swell the rubber tips on the float valve points. Good luck!

_________________
Bruce Mowbray
Springville & Southern RR
TMB Manufacturing & Locomotive Works

Thanks for the tips, guys. Bruce, you are probably right. [Head hanging down, guilty look on face.] I admit to leaving it for (gasp) a year and a half with gas in the tank. Even though I added Sta-bil to the fuel, it was as yellow as lemonade when I drained it. I found a couple of Youtube videos on cleaning those carbs, which was good since there are a couple of orifices therein that I would have missed. There is also a small filter bowl next to the main bowl that had some gummy residue in it. So the jelly beans Bruce mentioned may have formed in this little bowl and ended up in the jets. The videos suggested that it's usually the main jet. Even though it looked clean, there must have been a few molecules of something alien in there. Runs fine now. Thanks again. (And I won't leave gas in the tank again.)

_________________
Greg Lewis
Eyeball Engineering — Home of non-interchangeable parts
Our motto: That looks about right.
Turning perfectly good metal into bits of useless scrap since 1983.

Take the air cleaner off so you can choke it with the flat of your hand or thumb. Run it wide open, choke it untill it slows to about half the RPM, un choke it, let it rev up to full speed, choke it again, do this three or four times leaving the throttle wide open all the time. This causes the engine to suck fuel thru the carb big time. Used to do this all the time to single throat Chevy's, Ford's, etc. Sometimes that was all it took. Gees, I may have dated myself.

Bill W.

_________________
Plum Cove Chassis, freelance body - 2008
Wabash 569 - Allen Mogul - April 09-Jan 12
Bob Snippe Alco S-4 - Feb 12

I had a similar problem when my snow blower developed a small leak in the fuel hose that allowed it to suck air into the hose.

Yup. Those engines were very forgiving. There is a story I could tell about a Model A Ford than ran with the idle jet bouncing around in the intake. The only reason it was discovered is that the engine would sometimes run terribly and then mysteriously run OK. But that was because said jet got stuck in an intake valve and held it open, and then would fall out leaving the valve to work normally, only to get sucked in again! With those engines, I think you could put gas in a spritzer bottle feed 'em by hand.

Makes me pine for the days of carburetors and breaker point ignition, when true jalopies could be had and run. They were cheap to buy and easy to fix. Lots of fun. How we kept from killing ourselves I have no idea. Today, you can't work on 'em because of the electronics and you can't run the beaters because they won't pass smog. Sigh.

_________________
Greg Lewis
Eyeball Engineering — Home of non-interchangeable parts
Our motto: That looks about right.
Turning perfectly good metal into bits of useless scrap since 1983.

Time to get out the small number drills (#60-#80) and carefully clean out the jets. I have never had good luck with off the shelf carb cleaners getting the varnish and goo out of the jets, so I prefer to use the drills. Just be careful to remove varnish, not brass, otherwise the engine will run rich. The mainjet is usually replaceable for the aforementioned high altitude jetting; so you could just replace it with a new one. Idle circuits can be a pain since they are more convoluted than the main jet - sometimes you have to remove welch plugs to get to everything.

Good luck!

_________________
Jim P.

N&F RR - 12" Gauge Live Steam - http://www.nfrailroad.com

could try Brake Clean, the stuff removes everything

_________________
If it is not live steam. its not worth it.

Visit my website here.