Hello Everyone - I need some advice and information...

[Old Timer]

I'd like to build a rear "rack mount" system with a 4-stroke engine. Mounting the engine, installing a rag-joint sprocket, and connecting the two with a chain seems pretty straightforward. Where I'm fuzzy is... what type of clutch system is commonly used on these set-ups? Pictures and links for a clutch set-up are greatly appreciated, because I'm not familiar with the terminology. There's not much discussion about these "rack mount" set-ups online. Does anyone besides Staton make a kit for a rear-mount bike? I haven't found any other models. Staton makes good stuff, but $650 is beyond my budget. One last question: Why do 4-stroke engines never come equipped with a standard manual clutch (with a clutch lever) like the 2-stroke engines do? The 4-stroke engines always need some sort of elaborate centrifugal clutch system.

Thanks in Advance for your help. My Best Regards...

 

[Wrench]

I'd like to build a rear "rack mount" system with a 4-stroke engine. Mounting the engine, installing a rag-joint sprocket, and connecting the two with a chain seems pretty straightforward. Where I'm fuzzy is... what type of clutch system is commonly used on these set-ups? Pictures and links for a clutch set-up are greatly appreciated, because I'm not familiar with the terminology. There's not much discussion about these "rack mount" set-ups online. Does anyone besides Staton make a kit for a rear-mount bike? I haven't found any other models. Staton makes good stuff, but $650 is beyond my budget. One last question: Why do 4-stroke engines never come equipped with a standard manual clutch (with a clutch lever) like the 2-stroke engines do? The 4-stroke engines always need some sort of elaborate centrifugal clutch system.

Thanks in Advance for your help. My Best Regards...

Wecome to the M/B world
@darwin and @Sidewinder Jerry are a couple of 4 stroke rear mount guys.
Maybe they'll chime in shortly to help with some advice

 

[Gordy]

@Sidewinder Jerry knows alot about rack mounts. He could help ya with where to find them.

As far as clutches go if you want a wider range of gear apposed to a fixed ratio a CVT (constantly variable transmission) is a good option. Otherwise a centrifugal clutch.

before we stary posting links we need to know a few things. What engine do you want to use? What bike? What speed? Do you live in a hilly area or need to climb hills?

And lastly, there is a company that makes a 3/4 shaft manual clutch, but it cost $300 and is out of most people's price range.

 

[Sidewinder Jerry]

I use a Staton Inc rear rack mount. My kit is over 13 years old. So though expensive, certainly worth the longevity. Most states in the USA have an automatic transmission clause. This is the reason for the centrifugal clutch. It also simplies the fact there's one less procedure to concern yourself with.

Oh and my kit is on its second bike. The Sidewinder is a little over 2 years old.

 

[darwin]

I only have experience with friction drive rear units. They're plug n play plus reliable if dialed in right. Keep in mind they're a fair weather kit, water is not a FD's friend. Besides Staton, I think Bike Berry or Bicycle Engines sells a Chinese made FD kit that's cheaper, you get what you pay for. On Staton's site you can get a Honda 50cc kit for about $450. Choose the right roller if buying, upgrade the bearing too if choosing. My opinion, the Honda GX 50 is the best 4 stroke legal motor you can put on a Staton kit.

 

[zean]

Yes, back in the day I purchased two 47Rs and two Honda GXH 50s kits. The Hondas with that adapter for David Staton’s 18:1 gearbox were fitted to two giant stilettos in frame. Those Honda 50s would do more than 40mph. I wish he made more in frame kits. That giant stiletto was excellent: solid, stable, smooth. The best shifter kit built in my opinion. The Tanaka 47Rs are still in the shed.

 

[Amwicr]

I'd like to build a rear "rack mount" system with a 4-stroke engine. Mounting the engine, installing a rag-joint sprocket, and connecting the two with a chain seems pretty straightforward. Where I'm fuzzy is... what type of clutch system is commonly used on these set-ups? Pictures and links for a clutch set-up are greatly appreciated, because I'm not familiar with the terminology. There's not much discussion about these "rack mount" set-ups online. Does anyone besides Staton make a kit for a rear-mount bike? I haven't found any other models. Staton makes good stuff, but $650 is beyond my budget. One last question: Why do 4-stroke engines never come equipped with a standard manual clutch (with a clutch lever) like the 2-stroke engines do? The 4-stroke engines always need some sort of elaborate centrifugal clutch system.

Thanks in Advance for your help. My Best Regards...

Probably easiest if you can do a little bit of welding and fabrication, but not necessary.

Bike berry makes a couple rear mount kits I think. But people have problems with bikeberry.

 

[Hunter]

I had one of those Bikeberry 38cc friction kits it was decent quality but the roller bearing was super loud for some reason, The engine its self ran good wasn't crazy loud. not sure if you can change spindles or change the bearing but I 130lbs on my trek 800 singletrack would do 30Mph. not sure about pulling power uphill but I'd pull one of those kid trailers just fine but you could definitely feel the wind. on one tank of gas I could get about 7 miles its a pretty small tank.

 

[Old Timer]

Hello Gentlemen,

After much consideration, I'm going to install a 4-stroke Friction Drive system as Darwin suggested. I'm 57 years old, so speed and performance are not my concern. I'm happy to cruise around at 10-15 mph. My main concern is reliability. In my younger days, I had plenty of "semi-employed" chums who would pick me up on the side of the rode in a moment's notice. Those days are long gone. My friends and brothers are all married with 2-3 kids and 2 jobs. If I get stuck on the road, I'm on my own. There's no one coming to get me.

All things being equal, the 4-stroke engines are more reliable and less maintenance than the 2-stroke. That's what I need. And from what I've researched, if installed correctly, the FD systems are quite reliable. As long as I keep the carburetor clean, change the roller and roller bearings periodically, and change the back tire occasionally, I should be all set.

The other thing I like about the FD system, is if I DO get stuck, I can simply lift the engine off the back tire and pedal myself home (just like riding a regular bike).

I'm going to buy the FD kit from Staton. It's $100. You can't beat that deal. I'll pair it with one of these GX50 clone engines:

Amazon.com

www.amazon.com

Or this Lifan:

LIFAN 1.5 HP OHC 4-Stroke Clutch Drive Engine with 360° Horizontal/Vertical Mount Operation LF139F - The Home Depot

With patented LIFAN Technology and years of automotive, motorcycle, and power equipment experience we have created this 1-of a kind 360°, clutch drive, 4-stroke engine. Great for residential or commercial

www.homedepot.com

I know the Honda GX50 is the gold standard, but that's beyond my budget right now. I think that GX50 clone would do a good job, and Lifan makes good engines. The Lifan engine gets poor reviews on the Home Depot site, but that's because the people on there don't know how to install it correctly. I bought a Lifan motorcycle engine years ago, and I had great luck with it.

The Staton FD system is far superior to the Bikeberry crapola. Plus, Staton lets you choose your roller size, and you can swap it out anytime. The Bikeberry kit comes with one size roller, and that's it. No choices.

I'm gonna try the 1" roller, because I'm 200 pounds, I have lots of hills in my area, and as I said, top speed is not my concern. I'd rather have the torque for take-off and hills.

Last but not least, the FD system is reasonably priced. I already have a bike, so my total cost will be roughly $250.

I don't like the idea of an "in-frame" set-up for a 4-stroke engine, because you have that wide engine in the way of your pedals. You have to change your crank arms... and there's no way that can be a natural pedaling position. It's just my opinion, but I think in-frame set-ups are best suited for 2-stroke engines.

The rear "rack mount" system is cool for a 4-stroke engine, but unless you buy the Staton kit, it's a DIY project. No one else makes a rack-mount kit, and I just don't have the time for a DIY project.

So, there you have it: A 4-stroke FD bike with a Staton Kit and a GX50 clone or Lifan engine. For my situation, it makes the most sense.

If I was 20 years younger, I would do a 2-stroke in-frame bike, and spend hundreds of hours tinkering and upgrading. I do enjoy tinkering. And if I got that bike stuck in the road, I could call my posse for help. But at this stage of my life, the 2-stroke in-frame bike is just not practical.

Thank you all for your help and suggestions. I hope I didn't bore you all to death. LOL I just want to say, this is a very active and helpful community on here. I'm glad to be a part of it. Thank you all for the warm welcome.

I found a great thread on here about tires for a FD bike. The "Inova Swiftor" and "Continental Town & Country" look like great options. There's 4-5 more great suggestions.

 

[Gordy]

I would go with the lifan for the name and parts available. In your situation friction drive 4 stroke sounds like a great choice. I'm looking forward to seeing what you come up with