Harbor Freight Greyhound 79cc engine

On other forums people asked if the harbor Freight 79cc Greyhound engine could be adapted to a bike. Many said no, the engine was too big to fit inside a frame. I'm here to tell you that it can be done. Here's the story of Kilroy and Fossil's Greyhound.
My brother Jim (Fossil on this forum) decided to try this Greyhound engine, as the price was right. The engine is around $100 at Harbor Freight. He hit me with this project with little more than two weeks to go before the rally at Cape Henlopen. Could we have it done in time? The first question is, did we have a suitable bike to try to fit the engine in? Jim came over and we picked through the 20+ bikes on my garage (almost all vintage balloon tire bikes), then it dawned on me. I have a Schwinn Corvette cantilever frame bike that would surely take that engine! We dug it out of the corner and made some measurements, and yes, the engine would fit! So, we're off to the races.
The bike was close to being a basket case. One fine Wednesday (a week and a half before the rally) I set upon the bike to change that. While I worked on the bike, Jim worked on the engine, stripping it of the gas tank, muffler and air cleaner. He then fitted a Whizzer WC-1 air cleaner. While he was doing this, he was having a custom mount fabricated.
After a day's hard labor on the bike, it emerged fully stripped and with two coats of primer. The next day I reassembled it with an aftermarket springer by Pyramid, heavy duty rims with 12ga spokes, new fenders by Wald, a new seat off a Huffy Cranbrook, Whizzer handlebars and a Whizzer rack. Because of rust issues, the crank and chainring did not clean up as well as I had hoped so they got sprayed in primer as well. The first photo shows the bike reassembled and sitting in my living room, awaiting the engine (and the chain guard, on which the primer was still drying). That weekend I delivered the bike to my brother so he could fit the engine. So, now you're probably thinking what gearbox are we planning to use? Enter Quenton Guenther and the new EZ Q-Matic drive. Jim and I are both EZ dealers, so he was able to get Quenton to ship a pre-production example of the drive to us. It arrived the day I took the bike to Jim to be fitted with the engine. Two days later Jim returns the bike to me, with the engine and drive in place. It's now up to me to fit the chains and the rest of the bits and pieces to make this a motorbike. We used the hardware from an old GruBee kit that Jim had on hand, such as the throttle and the tank. The next photo shows it sitting in my living room, now beginning to look like a motorbike. But Jim really didn't like the peanut tank, so he ordered a tank from Whizzer. It arrived just before the rally. We loaded up the bike to go to the rally, and we discovered that there was an alignment issue regarding the drive chain. It turns out that one of our measurements was off. The idler pully from the kit was used to temporarily rectify the situation until the mount gets modified. We took the bike to the rally, fitted the new tank and tried to fire it up. Nothing, there was no spark. After going through the process of elimination it was discovered that the magneto was damaged. It was bent and twisted. Jim set out to try to repair the magneto, and a little while later we were treated to the sound of the Greyhound engine firing up.
Despite the chain alignment issue, the bike was ridden about a total of six miles that weekend. There were some tweaks that we performed on the bike at the event to make it more rideable (such as a slight re-routing of the exhaust to avoid scorching one's inside leg), and it's still a work in progress, but this concept bike shows that the Greyhound engine can be a viable option to power a bike. Not only did we have a Greyhound engined bike at the event, but Ray from Massachusetts also arrived with one. It too was fitted with a pre-production Q-Matic. I didn't get a good photo of his bike, but it's the yellow one in the fourth photo below.

azbill said:

nice post chris
how is the big engine doing ???
the little 49 is pretty powerful, is the greyhound stronger or just cheaper/easier to find ???
so many questions !!!

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Bill, the bike is over at Jim's so he can get the mods done to the mount that will allow us to align the chain properly. So right now it's not getting any more miles put on it. The Greyhound has more torque, so it will haul our big carcasses up hills better. It's also less expensive (oddly enough) than the Hua Sheng engine, despite being of larger displacement.

skyl4rk said:

Did you use a wide crank?
Is that exhaust obnoxiously loud or is it reasonable?
Does EZ sell just the gear reduction kit without an engine?
(sorry about all the questions)

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No problem. Glad to answer your questions.
No, we didn't use a wide crank, though a wide crank may be necessary on other frames. We were able to position the engine high enough to avoid using either a wide crank or a shorter crank. However, we will be using a pedal entension on the right side because the engine is offset farther to the right than to the left.
The exhaust note is reasonable, but that is to my ears. It's not obnoxious. On Ray's bike he fitted a small muffler to the end of the flex pipe that made it nice and quiet.
The new Q-Matic drive will be available very soon, and it will be sold seperately. Quenton estimated that it'll probably be available around the end of this month. I'll keep you updated.

silverbear said:

Hey Jim,
Thanks for posting this. I'll be anxious to read updates. Given how inexpensive the greyhound engine is, what is your impression of it's quality? Does it run smoothly, apart from the mounting issues of the moment? Anyone? How about the fellow from Massachusetts... what is his experience? Or is it too soon to tell from anyone? What about parts and such for the Greyhound?
How does it feel to be a pioneer? A year from now there may be many such posts on greyhound engines, modifications, upgrade parts, alternative carbs, etc. What about the engine mount setup? What does it look like? Is there any chance you EZmatic folks would be producing them for the rest of us? This is pretty interesting, my friend! This may give us a real and affordable alternative to the HT 2 stroke. The search will be on for donor bikes...
Silverbear

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Silverbear, as far as the quality is concerned, only time will tell. It looks like it's decently made, but our initial problem with the magneto raises some doubts about build quality. It runs smoothly, just as smooth as the 49cc Honda or Hua Sheng engines. It just runs at a lower RPM than the HS, which is happy at 7500RPM. The Greyhound seems to be happier and have more grunt in the 4000-4500RPM range.
Ray (from Massachusetts) found that the small muffler he fitted to the end of the flex pipe robbed the engine of too much power. He ended up fitting the Whizzer-style "fishtail" like ours to the end of his flex pipe, and his bike's performance picked up. The engine mount set up is detailed in this thread: http://motorbicycling.com/f6/my-heavy-duty-4-stroke-engine-11745.html
I doubt that EZM will be producing those mounts, at least for now. It's because the 79cc Greyhound isn't one of the engines EZMotorbikes is offering in kit form. However, Jim might be able to get the same Amish fabrication shop to crank out another mount like ours (the revised version). EZ is planning on putting the Q-Matic drive into production very soon, and those will be available by them selves for those looking to experiment with alternative engines.

Ray, it's good to see you here on this forum as well. Welcome aboard! Jim and I plan to stay with the Greyhound on this bike because of the hills (coupled with our oversized carcasses), but secondly because we have an adjustable pulley on the front which at the smallest setting is giving us a little higher top speed. However, it probably won't quite top out as high as the rev-happy Hua Sheng 49cc.

Update:
Jim just put on a larger front pulley (actually an adjustable pulley), so we should see an improvement in top speed as well as quicker take up by the clutch. We have also put an oversized Worksman saddle on it (the thing's a couch!) for added comfort, as well as set back seat post. The larger saddle may also offer some increased protection from the exhaust pipe. Also to address the scorched inside leg issue, he has applied some muffler wrap to the pipe to help in that regard. More mods are to come.