Not very good at remembering model numbers but if this is the current engine model it is a nice little engine. Its a little smaller, lighter unit over previous Honda's, it is an OHC/OHV, internal belt driven cam. They have been in use several years now and have really had no major teething problems like the first generation hand held mini.

To be honest I haven't had a need to tear one down yet so I am not certain of ring number but it will be at least two as it will have some form of oil control ring being it uses a 4 stroke oil sump.

It uses a diaphragm carb like most 2 strokes so it can be ran inverted and thus has the same conditions any other similar carb regarding old fuel problems. Besides those typical user related carb failures the number one problem we see is overfilled sumps. They only hold something like 2 ozs of oil and some folks are either in the thinking a little bit more is OK or just don't pay close attention to being correct. You end up with a big mess of oil blowing out the carb if it is overfilled. Have once even seen a blown valve cover gasket due to the excessive internal pressures caused from over filling.

There is an impellar in the sump which mists all of the oil when running. When overfilled it all cannot mist. Honda doesn't say so but my thinking is the engine shouldn't be inverted until the engine has warmed up for a couple of minutes to allow oil to warm and mist.

Have not used the line trimmer for actual work but have used the mini tiller. Based on the tiller use my impression is it produces similar if not better power as similar sized 2 strokes. And the putter purr is so much more pleasent to my ears then any 2 stroke.

Good morning Navada Walrus
Thanks for writing such a detail posting. What is diaphragm carb, what dose old fuel do to it?
You have any knowledge on Stihl FS110 or FS130 engine? Sounds like people do think the commercial Stihl are good fromthe response of my other posting. Stihl is one of my final choice trimmer. Also Stihl is like Honda, don;t post any detail of the engine construction and parts diagram. Any comments on the 3 trimmers that I mensioned? I prefer 4 cycle mainly I don't like the smell of the 2 cycle, big difference!! 4 cycle have a lower tone that is not as screaming like the 2 cycle.
You working in a lawn equipment company? You seem to know a lot about lawn equipment. I am an electronic engine by trade, always like gas engines, from model plane when I was young to cars when I got older. This is really my toys!!!
Have a nice day.

Diaphram carburetors have no float to regulate the fuel supplied to the jets. They use a spring loaded valve working against the built in fuel pump to regulate fuel supplied to the jets instead. Because they have no float, that needs to float, they will operate in any orientation (upside down or sideways).

Check it out here http://www.zamacarb.com/pdfs/TechGuide_2007.pdf

Nevada is a genuine certified Guru.

Having said that, I'll go on to say get a 2 stroke. The smell and scream are part of the fun. You can in fact, for a short time anyway, run your 2 strokers with castor oil and remind yourself of model airplane days. Lubrication is great but the gum is horrible.

Thanks Weed Cutter
I have download the file and going to read it later tonight. That ok about the model airplane, this is more fun and useful. I can play with the motor and get something done. Believe it or not, this is cheaper than the model plane engine stuff if you get into the real fancy brand. I bought some used glow engine on ebay cheap and open it up, I know what you mean about gum. The ring stuck in the grove, ball bearing balls don't run at all!!!
Yes I actually went on Navada Walrus (Bob's) page and look at his history, very interesting. How about you, are you very involve in this field also. I am surprised that people in this business like Bob, Canguy, they been in this field for so many years and still have the interest to get on this kind of forum and help people ( newbys) like me. I am an electronic engineer by trade, into gas engine as hobby( model planes cars and now lawn equipments) Anything smell gas, I like it!! I gave my wife all the excuses to buy the best toy for a tiny little 5000sqft yard!!!!

BTW, to everyone: I start to do the experiment of putting 30:1 ratio in both my Echo HC150 hedge trimmer and my Shindaiwa EB3410 4 cycle blower. I pull out the plugs and inspect it. I'll do it again after 2 months and see whether it foul up or not and I'll post the result. I am using Shindaiwa One with Sta-Bil in 91 Octane Gas from Chevron. We'll see.

I heard about too lean a mixture on 2 cycle or hybrid 4 cycle will hurt the engine because of high temperature and lack of oil in lean mixture. Then the ones with separate oil like Honda trimmer will fare a lot better if the mixture is too lean because the oil supply remain the same and oil will carry heat out even the mixture is too lean. Is this true from your experience?

Have a nice evening

yungman I repair the stuff, outside of formerly having a small yard where I used an old Snapper and Ryobi trimmer I have little actual in use experience.

1 or 2 rings have little to do with engine quality. Its more of a feel good deal then any real benefit. FS 110/130 are OHV 4 stroke engines using 2 stroke fuel, no seperate oil sump. There is another major brand using a similar system as Stihl but we aren't involved with that brand so I can't even recall the name. Shindaiwa maybe, just not sure.

The 4-Mix [4 stroke,mix fuel] Stihls in a way are the best of both worlds. 4 stroke torque and sound along with always having fresh clean oil passing through the engine. I just have a little trouble getting away from Honda when practical because of Honda's overall quality. The current mini 4 stroke OHC they are using is light enough to make pratical for someone in the mid size range of trimmers.

What everyone needs to realize, like it or not, the 2 stroke in all likelyhood will be dead in 5 or 10 years. I don't care what they say, its gonna be real hard to keep them affordable and make them emission compliant as regs get stiffer. That is why Stihl and others who are long time traditional 2 stroke engine companies are getting a jump by introducing variations of 4 stroke engines in their line up.

weed cutter, genuine certified nut perhaps, guru is too nice. But thanks.

Hi Bob
I went onto your web page and check it out. You are big time at this and you have been in this for a long time!!! You still have the interest to share your experience? Hats off to you. I like my trade also ( electronics) but when I have time, I rather chat on this forum!!!

The other 4 mix must be Shindaiwa, I just bought a 4 cycle blower use gas oil mix. They call it C4 technology. So far so good. It is definitely not gas saving as I heard from others. The dealer fill up half the tank, last only for about 40 minutes. I didn't even go full throttle, they have a limiter switch to block the trigger from going all the way for lower noise.

Sounds like you prefer Honda. I think I am leaning towards Honda also. Being a toy for me, I have a Shindaiwa C4, so I want something different. Between Stihl and Honda, I think I go for Honda. I have very good luck with my Troy Bilt TB475. It is a 4 cycle with separate oil. I know, everyone laugh at Troy Bilt. I put it through some heavy use, I use it to weck everything, big or small. A lot of time I keep forcing it against tall and thick weeds and you can really hear the motor laboring, You should see how much lines I gone through. I am terrible. I just keep on pushing. The carb went out ones, I think mainly I have old fuel. I use it hard, let it sit for months and abuse it again. It's been 4 years already. Compare with My Echo hedge trimmer and even Shindaiwa C4, The Troy Bilt 4 cycle is still the easiest to start. Always start by the second pull. I want to buy the Honda just because I want a new toy ( telling my wife the Troy Bilt is going !!!)

Have a nice evening.

You know, this is a 2 way street. I learn stuff on these forums as well. Just recently someone made a suggestion about using shaving cream to fill the cylinder while installing a spark plug thread insert. This to keep the metal shavings out of the cylinder and allow doing the repair without consuming the time to remove the head or cylinder. That's just a cool little trick.

I may never get the chance to try it, haven't been to work for a couple of months now due to a back problem. May end up on disability and never get back. But it's a good example how these forums can still teach an old dog new things.

Hi Bob
I did sent you an email to you regarding to back problem. I don't want to talk about that in here, please check your email. Just want to emphasize that I am not a doctor and I don't know your condition, just want to share my own experience with my own back problem so it might possibility give you some idea. Take is as a grain of salt!!!
I was on that posting also about using foam. I just wonder what did he end up doing.
I will go back to your web page when I am not that busy. I am still taking a class now and it take up all my time.
Do you agree on my posting that Honda 4 cycle with separate oil is more forgiving on lean mixture because oil go directly to parts regardless of lean mixture and oil can carry heat away. In the mix oil engine, if it is too lean, not only it burn hotter, less lube reach the moving part too where separate oil will keep on working.

Only to a very small degree. Go back to my first response in the following thread, focus in on the destruction test with no oil in the mix.

Here is a link that might be useful: fuel mix

I download the parts manuel of the GX25 and GX35. They are using TIMING BELT!! Are they reliable, do this need changing like the rubber timing belt in cars?

I mentioned they use an internal timing belt back in my first post in this thread. Similar in design to Honda's GC/GCV 160/190 engines. They are designed to last the life of the engine. If one were inclinded to rebuild the engine after much wear it would at that time be advisable to replace the belt as part of the rebuild.

Extreme early production of the GC/GCV's did have some problems with the cam but not directly with the belt. The trimmer/mini tiller engine has had no cam/belt problems that were wide spread and none that I have seen. The engine has been in use for 2 or 3 years now and is a bit of an oddity in the sense that as a new design it really had no teething problems.

"To be honest I haven't had a need to tear one down yet so I am not certain of ring number but it will be at least two as it will have some form of oil control ring being it uses a 4 stroke oil sump"

2 compression rings
1 oil control ring

"Are they reliable, do this need changing like the rubber timing belt in cars?"

Only if the teeth strip or of the belt breaks, there is no recommened service on the belt in the Honda Service Manual.

If the belt does break or the teeth strip the only thing that needs to be done is install a new belt , there is no chance of piston to valve collision on the Honda OHC GX25 or GX35.

"Also Stihl is like Honda, don't post any detail of the engine construction and parts diagram. "

All the engine information including service manuals,parts diagrams and owners manuals are available free on the net. Also bochures and animations of how the oiling systems works in on the net.

Thankyou both for the information. That is a good piece of information.