Hacking The Honda Clone - small frame

The head gasket most will use for this is about .010.
There needs to be about .030 to .040 bump space between the piston face and cylinder head.
I think using the head gasket would not hurt.

I do lap the heads as you suggest Bruce because I find it gives a head and block a finish that offers maximum grip in a head ( and I have been doing this since the mid 80s on Honda engines ).

As for a sealer if you use a clone or Honda Steel gasket they have a sealer applied to them already.
I find this works real well and most of the time you can reuse a Honda head gasket a few times without much worry on a mild engine.
Here is your typical coated steel gasket with sealer

The other one you see is the thicker GX160 head gasket.
It adds about .060 and will decrease the compression on a GX200.

There are some plane steel gaskets too.
Those I would spray with some sealer just to be safe ( I use some permatex head gasket sealer works well )


fancy to build your own ignition? :grin:
this might help …



Yes, this is what we have been looking for to solve the problem of a delay circuit creating a different retard at different RPMs.

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What is your intended generational RPM ?
You want your timing set for that range.

I build clones that turn 7000 rpm and manage just fine to run static timing even though its hobled by the propagation delay induced retard…
I have a hard timing understanding why you would need more range than the OEM Honda UT2 ignition can provide with an manually indexed flywheel set the intend RPM range.

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Sorry, wrote “different RPMs”, meant “varying RPMs” for transportation applications.

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I am still confused why you are trying to make a part that already exists in the OEM parts inventory.

We are still talking about the the Honda clone ?

Yes, Honda clone may be my problem. Sorry for going off topic. Please explain what you mean by “manually indexed flywheel.” Does the Honda have a simple way to index the flywheel? The circuit proposed by Koen allows timing adjustment on engines without changing flywheel position.

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Yes use a timing light and move the flywheel to where it works the best at the RPM you want.

I keep getting an error on this video, but from what I have watched he sets his timing as I do.
One difference is I set a pointer on the PTO side of my engine and mark my primary clutch.
I run the engine under load, take a ride, stop pop the flywheel and advance or retard until I find a combination I am happy with.

This way I know exactly what I am getting and can record it in my log for later as reference.
You should have a log on your engine to record everything about it so you do not repeat mistakes and can trouble shoot issues in the future.
I do not use a key.


Hi Wallace,
I value your knowledge very much, it gives me helpful insight in finding ways to improve the work i do here.
Here the honda clone exist in many brands, more or less compatible
The way how people uses them here differ as much as people use the same knife to cut there steak or cut the three…
One engine should be able to all what they can imagine :wink:
I am trying to find ways to use the engine as efficient as possible, with the charcoal gasifier ofcourse, under different and or changing loads. Also being less depending on “poor” quality gas when running on low rpm"s
Automatic timing might be an option or could you point me towards even more “fool proof” ?

Popping the flywheel is considered heavy work here :grin:

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As far as I am concerned there is only one way to know how much timing is needed and how to achieve your goal.

Your going to have to adjust the timing and do some static test of load and rpm and make a table.
From there you will know exactly what timing you need for a given load and rpm.

Then you will have to test the Honda Ignition and compare its performance with the table.
You will have to advance and retard the timing with the flywheel and see where it improves your power and performance and where it does not.
This way you will know if this is the right ignition.

Some thing will have to be done for compression increases and then repeated again for timing,

Every time you change a variable in the equation all the results change.
This is a lot of trial and error until you fond the right combination.

This is exactly the same way I build then a tune a race engine.
Its never a done deal until exhaust all the possibility and analyze the data.


Would it not be easier for frequent timing changes to move the coil rather than the flywheel?

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Not really, there is no safe way to mount the coil.

Well there was a kit from race parts supplier Raceng.
They stopped making this, and it was not intended for timing changes on the fly.
You could how ever stop make a timing change and put your cooling shroud back on with out flywheel removal.

No easy way to do this, that’s why tuning takes all day lol
Seriously though once you have the tables made up you can fairly accurately predict what timing you need.

I think I see a point coming when I will have to make these tables, but I will only do it for one build.

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My concern: changing fuel in a certain % will also changes the power output from that engine.
So those changes would require adjustments…
Putting that in perspective with a poor farmer in Thailand…
1 engine, 1 pump, 1 gasifier and 1 fuel in combination is not the problem…
Try the engine on low rpm for high pressure or high rpm for irrigation…


Koen this does not change the fact you need to build the engine and test it.

You need to build a simple to reproduce engine.
I stated before use the 14cc head on the GX200 engine, try 30 deg Before TDC that’s a good starting point.
Make up some tables based on that engine.

THEN try the Honda CDI Ignition with the exact same engine combination and run it through table for power and fuel consumption.

That’s the shortest route to some useful data.
Different engine builds will perform different.
Generally I know more compression will require less timing.

But this will all change with a different piston like the Z4M because the turbulence in the chamber will change and compression is higher…
The 18cc Honda head and the z4m piston are similar in compression to the 14cc with the dish but combustion will be different again because the chamber shape is different.

Now do you understand what I mean by needing to make tables to test different combinations so you can predict how the engine will work?
No one has done this.
I have a lot of experience building these engines but I am not sure about how they will react to the fuel and what changes in timing will give best results.

What I am saying my friend is you have to design an engine with trial and error.
Its just like the gasifier itself you learn from it and adjust it and change it as you learn until you find what is best.
But use the scientific method of recording all your data and build a table that shows you what works otherwise you are just guessing from one change to another trying to compare what you think is happening to what you thought was happening


Hi Wallace,

I am with you in this, in fact you’v got me into modifying the engines… :grin:
But i have to keep it simple, its not only for myself playing around…

First results, comparing adding H2O vs timing adjustments…:
i realligned the ignition 15 degree and the result is:
same pump now reaches 3300 Rpm with less effort for starting , even under load.
Gain, without water, 500 Rpm, gain vs water is 200Rpm

so , i am definitively going to implement that

The new 160 Honda and clones already have a thin headgasket, so, can’t work on that yet

Next is the CDI, where can i find it as a part ? and what is the cost …

Tomorrow going to re allign the Lifan, but not sure to eliminate the H2O, for the higher RPM’s i desire, a little testing won’t hurt :grinning:


Not sure what this means. At first glance it looks like adding water (hydrogen) you gain 300 rpm but then take water away and advance timing 15 degrees you get 500 rpm gain?


That’s what I got out of it.

I’d be interested to see what differences there are in load capacity between: (stock, gasoline/petrol), (stock, char gas without water), (stock, char gas with water drip), (timed, char gas without water), and (timed, char gas with water drip).

E.g. If one hooked it up to a generator and found the (stock, gasoline) could crank out 2,000 loaded watts, where to the others match up? I’ve heard that straight char gas without water or timing can derate an engine by 50%, so say that can only produce 1,000 loaded watts of electricity (obviously test this to find out exactly). Where would the others line up in terms of producible shaft power?


I spend a lot of time getting these engines to put out more than 6 hp

Basic tuning and removing the restrictive exhaust and air filter can add 2 hp around 4500 rpm.
This is way more RPM than we can manage with wood gas I fear.

But the same tricks still apply.

All the restrictions that can be removed should, the engine must be able to breath to compensate for the lower BTU rating of the fuel.
The gasifier IS the biggest restriction and it can not be helped.
But a good welded exhaust made from pipe with 3/4 inch ID will make a difference as will a large free flowing muffler off a small car.
The pipe should have as few bends as possible and be about 2 feet long to the mufler.

Inside the head’s ports there are some rough edges, it would not hurt to knock these off so nothing feels sharp inside.
Lash for factory setting is .003, but I prefer to set it to zero after the valves have been lapped in head ( this engine makes lash when it warms up it will not tighten )

Timing should be advanced to 25 Before TDC for GX200 as a starting point and 30 for a GX160.
This is based on a gut feeling.

ALL new Honda T2 engines us a Modified CDI ignition I will get a part number for this later.

Where possible on a rebuild use the Z4M Honda piston in a GX200 block ( this piston was designed for the T1 Gx160 but it fits the 200 )
Any GX160 head will fit the 200 but I would prefer the 14cc heads used on Chinese engines or the older Honda 160

Look very close at this head and see the shape of the chamber and the dark patch of carbon around the edge.
This style of head has what is called a quench and when combined with the Z4M will make for very good mixing and it will speed up the burn time in the engine.
It will also raise the compression to 11.5:1 or there abouts depending on tolerances and gaskets used.

Done too the full conclusion of my suggested build I suspect this engine may recover 10% or 20% of its lost power.
Maybe it could pull 5 hp.
More important it will make maximum use of its fuel.
At wide open throttle it will not run hot, not exceed its design limits and the cylinder pressure should not harm the rod bearing ( should not is not the same as I know for a fact ).
At wide open throttle its pumping losses will be the lowest too and with the compression and timing advanced it will be real close to what I think the area for best thermal efficiency is.

But I am guessing based on race engines.
I never built this engine.

As I type this I am confronted with the unfortunate passing my beloved 1971 Ariens snow blow that already has a high compression engine on it.
It may well see the light of day as prototype gas clone this summer unless some mystical and magical happens that lands me hundreds of dollars worth of parts for a Ariens 910006 series tractor.
The grieving continues…
But I do have that head and still have an older flat top piston could add to old smoky to run some real world tests


As you can see I’m half ways there. Black marker on bar stock and bolt head. Tried the belt sander but did not like it. My belt is dull so it’s almost as slow as sand paper. Also it is impossible to set the head on the moving belt without being out of parallel.

Sand paper is slow but if your in no rush this will work. I should of got a courser sand paper. i found it more accorate if i set it on the paper then move forward, lift up, bring back to start postion, place on paper and repeat.

Can’t sand any tonight because I have to sow a patch on my coveralls…

Practice makes perfect…


yes Don,
To be more clear, same pump under load, always same load conditions:
2800 rpm , no water no timing changes
3100 rpm with water drip
3300 rpm only timing
3460 rpm with timing and water drip…