Advance timing on small engines

So I was sitting in my ‘WK Thinking Chair’. No, it doesn’t have a heat exchanger or cooling pipes. As Don Mannes, just an assigned chair to step back sit down and think.
After talking to Steve U Mon night, he mentioned something about only obtaining about half the horse power from small engines. I know I heard of this before. I then thought of Wes not being able to advance his timing. I then Googled ‘ho to adjust timing in 15 hp kohler’. I fortunately ended up finding out it’s possible. My question is, will this help? It seems logical to me. If so, is there a suggested starting point on what I should adjust it to? I am thinking I can find out the results by running the generator full speed before resetting the timing and then again after.

Hello Bill ,

I have very limited experience with the small motors but have learned a little . I have a generator and I think the speed or rpm is set for 3600 rpm . It would run poorly on standard timing . I cut a new key way in the fly wheel and advanced it . The generator ran good after the time advance . In 2008 gave many demo across the US . I haven’t used it much the last few years but did demo it a while at Argos ( Chris may have some video )

I Kansas a few years back at a woodgas get to gether Billy Boes had a small generator but was having trouble with it producing good power . We advanced the flywheel , started up on the same gasifier and about the same throttle as before and it created enough power to blow the test lights .

The problem with the small motors if you advance the fly wheel to run good on wood they are hard to crank if you try to start on gasoline and will kick back while cranking

To avoid the cranking problem on a small test motor I had once ( lawn mower motor pulling alternator ) . After advancing the flywheel I connected a small 4 cylinder dist to the crankshaft via short rubber hose and hose clamps . Also had a battery and coil . I could start up on gasoline with the dist , points , and coil . ( set retarded and easy to pull start . ) Once the motor was running and gasifier warmed up I could kill the dist and in-gauge the advanced flywheel spark on the fly .

Mike LaRosa visited once while I had this going and laughed a while about it .

Thanks for the info Wayne. How many degrees do you think it should be advanced?

Hello Bill .

I’m thinking I advanced about 20-25 degrees .

The problem with the small motors is it hard to switch the time back and forth


Wayne, I posted a video of your vertical shaft generator years ago. 2006 ?? I will try to find the link and post it here in another post but I think you already have it on your youtube page. Found it but it is reduced for dialup
When I was at your place several years ago now we ran your generator off the truck and you had me do some grinding while you made your video and I also made one of you feeding the now sold diesel rabbit. I think that was 2010 ??? I uploaded the videos from your place but I’m not sure what the titles are. The tornado hit a month or so later ?? … You set the speed record the next year ???
on that vertical generator you had a pinto distributor on the bottom of it and you would start on gasoline with that, rev it up and pull the spark plug wire and move it to the stock system. I’d be in cardiac arrest after that …
I have to get back to work … Mike

Here’s ‘Before’ and ‘After’ videos of the engine/gasifier combination Wayne mentions above:

Before: 13HP Honda running on woodgas - YouTube

After: KS woodgas gathering - YouTube

You can hear the difference!

Thanks Wayne, Mike and Billy.
I still have a little more to do with the PTO and mounting the gen head. I feel more encouraged with my little tractor.

Hey BillS
I got stuck with this article downloaded as the only thing to read back two years June ago with 672 local recorded lighting strikes, off-line for days.
This is an excellent one to read, and reread. Then go back and re-read for engine ignition timing warnings and guidelines.
Halfway down he gives different timing ranges for different fuel types from regular unleaded gasoline to aviation/racing gasoline, to E-85 to methanol, to methane/propane.
THIS is relevant for needed differences between different stages of woodgas’s made; versus charcoal gas’s.

3/4 the way down he gives ignition timing ranges for different engine configurations based on spark plug locations to the piston and exhaust valve.
The new sub-section Tractor gasifing guys NEED to read this and see why with their wide range of engine configurations they will be all over the board too for ignition timing improvement needs.

How to know? How to know?
I can tell you TOO MUCH. My very best street sleeper race car a plain-Jane bone white 1969 Saab V-4 told me with aluminum beads splashed onto the spark plugs that I’d gone a bit too far ignition advancing.
Many of the cylinder head machine shops observations about “porous casings” were really just seeing metals granular structure changes caused by combustion chamber detonations. This is in the high end combustions tech literatures. Piston makers talk about this a lot also.

For your engine, your fuel, your loading: you step advance until no more power improvement. THEN Back off 2-3 full 5 degree steps for engine metals safe due to variable hot weather heating conditions!
Small engines as air cooled are much more sensitive to this.
This will also give you a safety margin for your own made woodgas variabltly from start of batch to end of batch.
Boom-go-bang cartridge to the balls-limits reloading gives much to learn about visual reading metals heat/pressure warnings changes.

Now re-read this small engine article again. Most tractor and all vehicles even back with “dumb” in distributor centrifugal advanced would crank and start up with springs retracted timing retard set back. Running engine than flung out speed timing advance. Higher speed, advance more. Add a manifold vacuum actuating pot advance - then light load sensed, advance some more. Engine loaded dropping manifold vacuum, then un-advance. All this later done electronically.
Small engine you have NONE of this.
OR . . . some of this . . . in a combo of electronic built-in to the coils controller (counting rpm for cranking spark set back and calculating one step advance for power RPM spark advancing); camshaft cranking RPM “bump” valve lifters; or camshaft attached “timing” advancers/retarder mechanism. Here I AM talking just possible Kohler variations.
All other manufactures doing the similars.

My expect only 50% engine power on wood gas was for just a plug in the supply gas to the aircleaner box systems adapts. Simple. Straight forward. Works. No fuss. No muss.
You can “get back” quite a bit of gasoline power equivalency by mixer/carburetor side optimizing.
Both Dutch John and I documented independently getting an average of high 60% equivalency doing this without any ignition timing changes at all. We were both using very good overhead valve modern “highish” compression engines at 9 to 1. We both raw wood gasify pushing for the densest energy richest fuel gas mixes.

Play with this on single cylinders and intake pulsations can kick your ass but good.
Maxgasman had much good advice recently to say about this on GaryG’s Yahoo Charcoal Gasifier’s Group. Intake side AND ignition timing. Things only experiences could have taught. Things I wished I read before my first three single cylinder mixer improvement attempts failures!

This small engine article show that some of these little beasts can be compression raised and valves flow improved too. All for racing prices.
Combine the three:
Compression ratio boosting
Intake, induction, mixer optimizing
Timing improving
Easy to see possible 90% gasoline power equivalencies!

Read this engine timing article now again. COUNT the cranking/starting kick back damage warnings. Heed these or break something.
Ha! I’ll remind you I have two Kohler engines set back almost just like yours. One, though, is the wife’s.

I just found it so much easier to engine gen/head change, gross oversizing. Gives me then gasoline FI dual fueling capability. Engine thermal and mechanical cushion to handle any foreseeable situation.

Steve Unruh

Jeez BillS I did not mean to kill your thread talking!
I said how to tell with detonation and no further power increase you were advancing too much.

What BillyB gave you with audio on his videos was how to tell more advanced could be used by ear.
MikeL talks a lot about this by listening for woodgas still burning coming out of the exhaust.
This is kindda’ hard to hear with a 3600 RPM aircooled screamer.
Pipe/then hose out the exhaust away from the engine helps that ear to discriminate for adjusting.
Slow it down a bit to 2200-2800 RPM helps some with the noise. You’ll find little power improvement timing advancing past Best found their up into the 3600 RPM range anyhow. Use your found LOADED Best for 2200 to 3600 RPM.
A better way . . . engine exhaust temperature.
Aircraft, commercial marine, trucking and big stationary use this a lot. At your Loaded RPM you can independent of fuel/air triming adjust for best timing by the lowest exhaust temperature. You MUST do this independent of air/fuel exhaust temperature trimming. Very well documented for spark ignition liquid fuels you fuel/air trim for best power-economy with a HIGHER exhaust temp.
Woodgas I think you want for maximized power at engine LOADING to be looking for the lowest fuel/air trimmed exhaust temp. “I Think”. Sure like to hear some other experienced opinions on this last point.
Gasifier/IC engine combo it IS the engine exhaust where I put my one and only in-stream pyrometer!
Exhaust temperature unless engine LOADED are worthless to use.
Steve Unruh

Billy, you managed to get almost everyone that was there at the same time. Sorry about the strip show but it was freaken hot!
I tried to find video of the light show you did but could only find a few stills. Hope all is well., Mike

Hey Billy,
I noticed the tilted hopper in the video. If I recall correctly, you put this idea up last fall? I’m curious about catching the condensate in the hopper. Did you design for that? If so how? If not, are there any draw backs because of it? I don’t remember seeing anything following up this idea.

Hey MikeB! I think I dropped 5 pounds that weekend just from sweating! The dip in the river was a refreshing break.

Bill, the condensate is collected the same way as a flat top hopper. I prefer the tilted lid for two reasons: condensate that collects on the lid will run to the side of the hopper then down to the bottom condensate trough instead of dripping back onto the hopper wood; secondly it makes for easier loading if the hopper is a little tall! My first gasifier with a tilted hopper still required a 6’ step ladder to load. Revisions have not been as tall. I will have more to post on this soon as my truck build progresses…