Lawnmower Engine Retrofit?

[muddawg]

ok im intrigued

but im still leary of different bearings and seals for the two types
im gonna ask around some of the local experts about this

to remedy your oil fill prob id go to the plumbing dept and get a 90 and an extension to fill in the new position

neat experiment

mike

 

[silent]

Vertical to Horizontal conversion

The seals are exactly the same for horizontal and vertical shaft engines of this type. I compared the innards of both horizontal and vertical shaft 3.5 hp B&S engine and as far as oil grooving, etc....no difference. That's why I bothered to do the conversion, it was simple. I work on small engines for a living and I see the insides of these engines every stinking single day. My intent was to produce a kit so that all these old vertical shaft lawnmower engines could be used on go-karts and bikes. You just need a right angle plate with a big hole in it for the crankshaft to stick through plus the mounting bolt holes. The 90 degree pipe fitting you speak of won't work in the stock oil fill location because of the funky threads Briggs and Stratton uses in their fill plug holes however, I never thought of putting it in the oil drain plug hole. I guess I didn't because it would have interfered with the wood plank I was swinging around. You're still gonna need a weep hole or some way to get the correct oil level because the vertical shaft engine in effect has a deep sump when you stand it up. Really it's a plus - more oil so you have more to lose before you seize up the engine anyway!

YMMV

Erin

 

[ZnsaneRyder]

I looked at a few 5HP mowers today, and they don't have the mount holes like the 3.75HP. It looks a bit hard to do sideways.

Also, I just found some GOOD NEWS for folks wanting 4 cycle engines!
Harbor Freight Tools has a 6.5HP engine for $153.00, which is the cheapest deal I've found so far. It's a Harbor Freight brand engine, but it's nearly 200cc, and new, so I may consider this instead of the 3.5HP B&S.

If you are willing to spend over $200 or more, they also had 11HP and 13HP engines too!

 

[stude13]

save your money and time. for kick a-s power get a tanaka 40 or 47 or 47r. you will be legal and grinning on dowm the road.

 

[silent]

You bring up a good point - using these big engines makes your bike a motorcycle as far as the law is concerned. Harbor Freight does indeed sell a cheap engine - it's a copy of a Honda engine - every single part from a Honda engine will fit. If you compare everything, you see the Harbor Freight engines are not built with as good of quality but you can't ignore the price. I have one of their engines myself still brand new in the box.

Out here in the stick of Nebraska, if you were to carefully disguise your bike with a briggs engine with some craft shrouding or covers and kept your speed under control, you could easily get away with riding a bike with a Briggs and Stratton engine on it. And really, it sounds like so much fun, I'd be tempted to go ahead and get my motorcycle license, insure the thing, etc. just to be able to ride legally. Under Nebraksa law, my 2007 Whizzer is illegal so whatever.

Erin

 

[arceeguy]

I looked at a few 5HP mowers today, and they don't have the mount holes like the 3.75HP. It looks a bit hard to do sideways.

Also, I just found some GOOD NEWS for folks wanting 4 cycle engines!
Harbor Freight Tools has a 6.5HP engine for $153.00, which is the cheapest deal I've found so far. It's a Harbor Freight brand engine, but it's nearly 200cc, and new, so I may consider this instead of the 3.5HP B&S.

If you are willing to spend over $200 or more, they also had 11HP and 13HP engines too!

I think that using a old engines from discarded equipment is half the fun of making a motorized bike. IMO, if you are going to purchase a new engine, you might as well buy a purpose built bicycle engine kit and save yourself the custom installation hassles. One of those Harbor Freight Honda clones would make a great go kart engine, but they are too heavy and large for a bicycle IMO.

My project is using an old 43cc pocket bike engine with CVT transmission and rack mounting it to a bike. I just bought a small 110cc motorcycle, so I'm a little distracted from my motorized bike project at the moment. I need to find a donor bicycle anyway, so I'm keeping my eyes open.

 

[arceeguy]

.......it's a copy of a Honda engine - every single part from a Honda engine will fit. If you compare everything, you see the Harbor Freight engines are not built with as good of quality but you can't ignore the price. I have one of their engines myself still brand new in the box......

........ I'd be tempted to go ahead and get my motorcycle license, insure the thing, etc. just to be able to ride legally. Under Nebraksa law, my 2007 Whizzer is illegal so whatever.

Erin

I have found that the Chinese Honda clones are pretty decent engines. I have a 3500W generator with a Jiang Dong 6.5 and it never fails to start when I need it. I also have a small 1000W two stoke generator, a clone of a Yamaha generator, and it is also a reliable runner. My son's Pep Boys mini bike has a Lifan Honda G100 clone engine and it runs great. I bought these products with low expectations and was pleasantly surprised with the quality. My new Lifan LF110GY-3 motorcycle is a knockoff of a Honda CT-70 "Trail Cub" motorcycle. It has a larger engine than the original (110cc vs. 70cc), electric start and a four speed transmission. It cost less than $1000, street legal, gets 80mpg and I'm hoping to get about 55-60mph out of it after I change the sprockets which are geared for trail riding, not speed. Had to get a motorcycle license though. If you are out to save gas and have reliable transportation, a small motorcycle or scooter might be better than a motorized bike since you can ride with traffic instead of having people dodge you while you ride along the shoulder. But I realize that a lot of people may be motorizing bikes because they are either too young for a drivers license, or are adults that may have lost their license and need to get to work.

Some may say that a motorcycle or scooter is not "original" like a motorized bike but scooters are very rare in my area, and my small motorcycle gets more attention than a Corvette. People are always asking me "how fast", "how much", "what mileage", etc. Four years ago, I'd have been laughed at - but with gas over four dollars a gallon, all of a sudden I'm the coolest cat around!

 

[ZnsaneRyder]

Today I got the 6.5HP engine from Harbor Freight!.
I put Castrol GTX 10W-40 in it.

It's now bolted to my trailer after about a couple hours of cutting and drilling more tube steel and bolting it all together.

The 6.5HP was on SALE for only $129.99 and a pawn-shop 3.5HP ( I had on layaway) was the same exact price, and they both are big, might as well get a NEW engine. Also the pawn 3.5HP shop motor was harder to start.

The new 6.5HP engine started 1st time after choke. The engine starts always the first time, I'm amazed! It won't start without choking it, but it starts every time you choke it on the first pull. It has a large muffler and is a quiet engine. I still want to get another muffler to quiet it down more.

I'm going to need covers for sure. It's a little big, bright-blue, and stands out for sure. For testing, I'll just have the bare engine, but if I want to really go anywhere, I'll cover the engine. It's taking some time and money to finish it. Not done yet.

I still have to get the right size belt, and more metal and nuts and bolts for clutch levers, and a cable. Also I have to make a way to throttle the engine on the bicycle. Maybe a handbrake????

I'm hoping that there's enough torque so I can run low RPM and go down the road with this bigger engine, at 20mph or so, to get it quieter than a go-kart at high RPM, and also save gas for more MPG.



On the Lawnmower part of the thread, My dad has an old B&S powered-lawnmower, and I'm still thinking of trying to make a sideways-conversion to make another one. It's easier by far to use a horizontal engine, so it would be challenging.

 

[arceeguy]

A 6.5HP Honda clone will get you more than 20mph for sure!
Use a Comet torq-a-verter and you'll be doing 40+ and still have plenty of low end.

 

[ZnsaneRyder]

A friend mentioned to me that you can twist a belt to run a vertical engine with a horizontal drive, as long as the belt is long and the pulleys have some distance between them. I'd like to try it.

I started a new thread on the 6.5HP trailer so we can continue the lawnmower discussion in this thread.
http://www.motoredbikes.com/showthread.php?t=12502

The bike trailer is now running, and was a LOT of fun on the first test drive today! Due to complications of the design, I went to a rotary clutch for the belt, and it works well, and has lots of power.

The HP and speed seems rather excessive, and I imagine that a lawnmower engine on a bike would be similar due to the larger size of these type of engines, and the lack of weight with a bicycle.