Hacking The Honda Clone - small frame

Bruce, I should try going narrower than stock and see how that works. Maybe CDI has a hitter spark than points? Maybe a narrower gap advances your timing, i don’t know… I looked at moving the pickup but not enough room under the tin housing. I plan on tying Wallace’s method of lapping the flywheel to the shaft. Then toss the key and set the flywheel anywhere on the shaft next torque to spec.

Marvin, I sure would like to try other heat ranges… :wink:

Carl, yup lots of goodies out there. A lot of the hot rod stuff don’t apply to us because of our low rpm but lots to learn from the race community… :relaxed:

Jeff

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I was just looking around at some articles about small engine timing and came across one about tuning by exhaust temp. This seems so much simpler and less expensive than an O2 sensor. The idea is to mount a thermocouple in the exhaust flow close to the engine port and watch for the highest temperature. Both too lean and too rich will give a drop in temperature as will timing that is too advanced which causes ping. There may be problems with this approach on gasoline because we can overheat the head with the optimum smaller jet size or if airflow through fins is blocked. I think with charcoal gas, which is cooler, we can safely test for optimum mixture and for best timing by simply watching the temp. We might also be able to check the effect of water and oil drip. Keep in mind that use of these drips will also affect optimum timing.
Bruce

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Bruce, interesting stuff. Gas still burning out the exhaust might confuse the interpetation.

Jeff

Hi All
I do have limited woodgas fueled (not charcoal gas) experiences using the brand of E3 spark-plugs in different four-stroke small engines. Helps a lot on the misfiring and power smoothness.
These have a square holed positive electrode. Unlike side-gapped spark plugs like the Bosch Quad’s it is still possible/easy to open and close up the gap on these. All my bought 3E’s were just a single legged positive electrode.
Actually used these with noticeably better results for 7 years on all of my gasoline fueled four stroke outdoor equipments: point type/magneto’s; points-battery; and CDI’s.
www.e3sparkplugs.com/lawn-mower-spark-plugs
Ha! My expensive Stihl’s 2-cycles still get their designed for standard Bosch plugs.
The Wife’s Hyundai and the Plymouth mini-van get Nippon Denso and Champion/NGK platinum’s. The Ford pick-up semi-platinum Autolites.
Processor “smart” ignition quality sensing/adjusting systems; OBDII’s!! are spark plug brand and style picky in my experiences. Careful. Problems? Go back to the OE manufacturers engineered, spec’ed plugs.

Regards
Steve Unruh

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Hey Everyone,
Just thought I’d throw this out for general info.
The phrase exhaust gas temperature brought me back to my Cessna 172 days. Here’s a link to EGT and the parameters that effect mixture control, etc. What happens to my normally aspirated engine when I climb Pike’s Peak? A good read in general and a must for automation. Temp, altitude or elevation, air pressure, etc.
http://www.gaceflyingclub.com/Member%20Download/LeaningArticle.pdf
Pepe
I removed a statement here from another article, which I can’t seem to find right off.

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I have seen many rants against E3, but they have worked for me. My bottom line: a clean but poorly designed plug works better than a well designed plug that is fouled. Some suggest reading the condition of used plugs and adjust brand based on temp. Colortune plugs are made from clear glass so you can see the color of combustion thru the plug body.
Bruce

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I looked around a bit more about EGT (exhaust gas temperature) and found that tuning is not quite so simple as shooting for the highest temp. Several experienced mechanics agreed that O2 and EGT sensors are better as diagnostic tools than tuning tools. Bottom line: “When the engine sounds crisp and makes great power, you’re there.”
Retarded timing can raise the exhaust temp a lot while giving lower power because more unburned fuel is passing into the exhaust stream.
It seems that a combination of head temperature and EGT works best to read burn conditions.
EGT and head temp should both be high and rise together. Remember head temp changes slowly because of the mass of metal and is also affected by ambient conditions.
EGT will rise going from rich to lean then drop after passing stoichiometric AFR (air fuel ratio). Note that neither maximum EGT nor ideal AFR necessarily give best performance/economy because of many engine and load variables.
Advancing the ignition will lower EGT. A rising head temp with dropping EGT under load is a sign of detonation (often audible as knock or ping under load with acceleration) which is caused by too much spark advance.
When AFR is going too rich the head and exhaust will both cool.
The preferred approach to finding the ideal EGT, which is not necessarily peak temp, is to start rich and under load then go lean until power/torque drops. Note the EGT just before power loss.
A little bit (50 degrees?) cooler EGT on the rich side is generally best for overall performance.
This optimum EGT point can be used thereafter to approximate best AFR and read combustion conditions.
Bruce

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Hi Jeff
Its my favorite and most used engine :stuck_out_tongue:
So, i hope to learn some tips and tricks here :wink:

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Well, ran out of time this weekend before I could do some head work.

Got some stuff rounded up. Gasket, sealer, valve lapping compound and valve tool. Not to mention sand paper (plus the tile) to mill down the head. I also have a belt sander and a small mill but will give the sand paper and granite tile a try. Might also work as a surface plate. Not much of a hight gage there but its all I got. Maybe I should have got two tile to level each other out a bit more with some lapping compound or just test them out with some blueing.

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I am working on this ignition for the Honda clone, a kind of programmable digital ignition, going to use a hall sensor instead of a pickup coil.
http://www.sportdevices.com/ignition/ignition.htm

And this tutorial i did find very useful to modify my GX35, probably going to do the works on the GX200 and the GX160 as well

And the cherry on the pie…
A wet dream for the tuners…

http://www.ecotrons.com/products/gaseous_small_engine_fuel_injection_kit/

and many more useful stuff

very cool fuel injection set up… didn’t see a price but that’s all good.

and many more good stuf, programmable ignition included, and throttlebody’s, and a small turbo set,… and :stuck_out_tongue::stuck_out_tongue:
:stuck_out_tongue:

The briggs junio 206 kit is 699…

Here is the small engine ECU. It is the same chips, not the same board… It looks like the ecotrons used the rs232 serial port instead of the usb port…

http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=KIT33812ECUEVME

Picked up a 14cc head from eBay, left. The used one will get a shave job and I’ll try that one first.

I traced the shape of the 14cc on paper then cut it out. Placed the paper on the used head so you can get a feel for the size reduction. Sure could use more time.

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Did you ever do anymore with this?

Robert, ran out of time last year. Life gets in the way… :frowning:
Now all kinds of snow removal problems. I plan to work on it before spring but you know how that goes… Going to make an easy to make depth gage.

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For what its worth…

The Harbour Freight Predator 212 with the cast aluminum valve cover part number 60636 combined with the GX160 clone head 14cc yields a machine with well in excess of 11.5:1 compression.
The exact number is hard to pin down because of the choices of gaskets and internal tolerances of the engine without measuring things.

Now for your ignition all new Honda engines are using a newer CDI system for the UT2 that retards ignition at low RPM.
This can be adapted here to do the opposite.
Honda part number 30500-z5k-003
This will require a timing light and some tinkering, but you should be able to make a clone that starts without a kick back or bad habits and advances to around 30 BTDC at full speed.

Both of these modifications are bolt on with no machining required but you will some hand tools, a deep understanding of small engine repair and a timing light.

For those interested a lot of good info can be found at Bob’s 4 cycle forum in the predator and clone sections about hot rodding these small blocks

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The ragged edge of clones is using the predator.
Here’s something I have been working on not related this forum.

The reason I post this is there is a new generation of heads like this welded 363 ( a canted valve head ) that all come with larger valves than the older GX200 based motors used.
This might lead someone with mill here to try and weld up and mill down one of this very big chamber heads to make a better producer gas motor.
But its a lot of work…

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