Vulcan 500 Diesel Swap and Cody's Other 2 Wheeled Goofs

I have a 1990 Kawasaki Vulcan 500, 500cc parallel twin. I have yet to make it reliably run on gasoline(runs too lean, impossible to start etc). I would like to make a small charcoal updraft gasifier(either a Simple Fire or a Flute) off of saddlebag mounts for the reactor and filter unit.
My only issue is the bike has dual carburetors. I’m thinking there would be a balance of flow sort of issue with gas not getting equal distribution into the engine.
The bike is already ugly as sin so I’m not that concerned with looks, I might try to make up an air box out of PVC and rubber fittings since the stock airbox no longer forms a seal around the mouths of the carbs.
That tall ammo box got me thinking of doing this on my bike. I could even use the gas tank to store my water drip.
I got this bike for free from a family friend that has passed away so I hate to see it not running, plus it would be a real earcatcher to say it “rolls coal”.

I guess my first question would be, should I attempt to build an air mixer that goes into both carburetors or should I try to find a way to bridge both intakes into one larger carburetor since it would be then running exclusively on woodgas? The carbs use rubber slip fittings to connect to the air intakes.

I’ll follow with some photos of the bike in the morning when I have daylight.


Hi Cody , you should have no problem with a twin carb into single , have done it many times years ago when i have built up BSA lightings and thunderbolts , as long as the ports are of equal length and Dia it should suck well into both ports , just make sure the valves and guides are well seated as any wear will cause a problem for both cyclinders

Good luck ,cant wait to see it running


Hi Cody,
I’ll second Dave’s suggestion. Make an airbox that both carbs can pull from. Your chargas will enter this box mixed with just enough oxygen to burn when sucked into the cylinder, compressed and ignited by the spark. This will also mean that should there be a back fire, all the chargas in the air box will burn making a explosion. Therefore, try to keep the air box as small as possible thus keeping the potential backfire small.
Welcome to the “dark side”
Gary in PA


This bike has maybe 3000 miles but it’s been dropped at least once. I had to replace the stock mufflers with small tractor mufflers! They’re nice and loud but it didn’t help me with my lean conditions. Originals were so dented they were leaking from the endcaps so I think that was leaning it out as well.

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I’m not familiar with Kawasaki carbs but a carb is a carb is a carb. First I’d get it running well on gas. Pull the carbs, clean them and if different jets are not available drill out the ones you have incrementally. If they aren’t working now you got nothing to lose.


Did an upjet, forgot how badly this thing backfired through the carbs even when it worked stock.
Yeah I think I’ll save a motorcycle gasifier for another one. Maybe I’ll gasify a small 4 stroke bicycle I have laying around.

hello Cody, that sounds like a neat charco gasifier project, and it wont eat much charco. could be fun too drive aroud the black top, if you got places drive it on.

hello Cody, that sounds like a neat charco gasifier project, and it wont eat much charco. could be fun too drive aroud the black top, if you got smoth places too drive it on .I like too build a small bike unit too, i think it would be a little less power, though not much less with charco fuel.


Hi @glgilmore Gary, good to hear from you. Are you planning on Argos 2021? I hope you are. Yes another one joining the DSOG the Dark Side Of Gasification.

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I have a 212cc Honda clone crate engine with a 20° spark advance flywheel, it would wreck a bicycle if it was fueled with gasoline so I might be able to tame it with chargas! I don’t have a dyno but it is definitely over 7hp. I might not put that on a bicycle though as I have an old Yamaha dt175 enduro frame laying around with no engine.
I’ve got a zillion projects, when I get frustrated with one I put it on the backburner and move to another previous one. Keeps me from fudging something up, haha.

I need to get better at frame fabbing and try to copy the old timey Drop Loop motorcycle frames and build it from the ground up for chargas. Ever since I saw that WW2 era news clip about that delivery boy and his chargas motorbike it inspired me.


hello Cody, that sounds like a neat charco gasifier project, and it wont eat much charco. could be fun too drive aroud the black top, if you got smoth places too drive it on .I like too build a small bike charco powered, when time permits, if it ever does.


I mentioned earlier the engine is toast. I don’t really want to sink money into this engine because it was already screwy since I got it. I’m going to drop in my Chinese 10hp Yanmar clone with a 40 Series Comet CVT copycat.
I already have a 1990 Kawasaki EX500 Ninja rear wheel and it’s a direct drop in to replace the cog belt rear wheel. #50 chain size should go over the 510 motorcycle size.
Just need to yank out the engine and old electronics that won’t be needed anymore. I know the battery that starts the 500cc twin will also start the Diesel.
Charging system won’t be enough to run lights, I wanna say it only charges at 4 amps so I may have to remove the rope start and drive an alternator off that side. Speedo is front wheel driven so that’ll be staying. She doesn’t have turn signals (optional).


Took me all day to pull the bike out. Friends came by so I decided to relax with them. I forgot how lightweight this bike is, and it’ll weigh even less once I get all the unnecessary stuff off of here. I need to get a new tumbler for the steering lock, since anyone can just rope start the engine unless I remove it. 411cc’s of diesel compression is hard to turn over even with the release but it’s nice to have incase the starter goes out somehow.

Too bad nobody makes a clockspring starter for these modern single cylinders or I’d install one of those.

Since this will be controlled with the twist throttle I either need to make a moveable block to prevent it from shutting off the injectors while riding and move it out of the way for shutdown, or use an air cleaner flap to choke kill the engine when it’s time to stop. I know old big rigs had them as a final emergency kill setting so I don’t know if that damages the engine, but I do know using the compression release to do so will wear it out.

I would like to eventually mount one of those little VZ21 turbochargers on here to squeeze out just a little bit more power at top end.


Gas engine is almost out. I did find that some of the wires were rubbed raw and shorting on each other via the kevlar cog belt. Not very bright engineering Kawasaki c’mon. This thing is freaking heavy even for an all aluminum engine, this is why I’m a Harley and old school British guy, the engines are separate from the transmission!


Engine is out. I ended up just knocking the bike over onto it’s side to get it out. To mount and dismount the diesel I’m going to try to have it float out of the frame using a block and a floor jack.

Also the sprocket assembly from the Ninja 500 fits the Vulcan wheel. I have a whole Ninja wheel but it has less spokes and wouldn’t match.


I absolutely hate cog belts, you have to remove the swingarm just to get it off. So glad I’ll be changing to regular chain with a master link.
I think to cleanly mount this engine I may have to bias the piston a little bit forward. Not by too much.

I’m also looking for a decent oil filter relocation kit so I can extend the time between oil changes. It does have an oil pump it isn’t just splash lubrication.

I will have to replace the throttle on this bike because it used a double cable push pull setup. Plus the cable is old and sticks in the tube.


As it sits, the engine will just barely fit in the frame. Like I said earlier it will tilt forward just a bit. But luckily the starter solenoid isn’t touching the front of the bottom tubes. I’ll weld in some 1/4" flat bar stock as my mounts and maybe have room for a rubber washer to dampen some vibration. Or it will shake my fillings loose who knows. I won’t attempt any fitting until I have the CVT in later this week but I do have the rear wheel back on. My hopes are that the sprocket coming off the CVT will line up with the swivel point of the swing arm and will prevent me from needing a chain tensioner.

Lucky for me I use a Frisco style gas tank so it rides on top of the backbone, no clearance issues there.

If I need to scoot the engine any further I will have to cut some of the downtubes and give it a fatter belly.

I’m already anticipating that.


Flip flopping between projects today and yesterday. I got the 40 series CVT and it’s very awkwardly big. Bigger than I anticipated. It also uses a special belt that doesn’t match a BX or AX size type so it would be hard to replace if I need it fixed ASAP.

I’m going to go with a manual V Belt primary and chain secondary. I have a cast iron double groove sheave so I can also run a small tractor alternator to charge my battery and run the lights. It will fit a BX style V Belt which would be just right for this 10hp engine. I already have some 3/4" keyed shaft and pillow block bearings laying around, and no shortage of pulleys to play with gear reduction.

I’ll see about using the original clutch handle but if the spring is too strong I’ll move to a foot clutch. Speed is not important, and these engines prefer to be full tilt anyways. 3600 RPM I’m figuring will maybe be 45 miles an hour and still have enough to climb hills.