EZ Motorbike Installation

EZ MOTORBIKE INSTALLATION

The purpose of this thread is to focus on the installation procedure for the EZ Motorbike. Much has been written about installing two stroke HT engines, but the same is not true for the four strokes. Since more of us are switching to four stroke engines, more documentation is needed. This is my first foray into the world of four strokes, so in that sense I am a newbie venturing into the unknown and this thread is dedicated to those also new to this system and to those wanting to find out what is involved.

The first important step is figuring out what frame is appropriate for the engine. At the EZMotors website there is an ongoing list of appropriate bicycle frames which is being added to as time goes by.. If yours is listed, you’re good to go. If not, do some hard looking and measuring, as a four stroke engine kit takes up more in frame real estate than a little HT two stroke engine.
In my own case I picked a vintage Schwinn straight bar frame (panther, hornet, motorbike, etc.) which was a questionable choice. While I love the looks of this classic, it has much less space available than the popular cantilever frame. My feelings are that you want a well made heavy frame, good wheels which preferably have heavy duty spokes and good brakes. Frame and wheels are the foundation of your build. This is going to be a motorbicycle capable of being pedaled, but it is a serious motorbike above all else.
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Preparing the bike to receive the engine and transmission takes more time and attention than the actual installation of the kit. The engine is wider than a two stroke and it is almost certain that you will need a wider crankcase set. There are two types made for two different types of BB (bottom bracket). Older bikes and single speed cruisers generally used a one piece crank and more modern bikes with a derailleur and multiple speeds use a three piece crank. Wider versions of the crank set are available for both types and a three piece crank can be used with the one piece BB provided an adapter kit is employed. My choice was simplified further by knowing that I would also need to use a smaller sprocket to make as much room as I could for the engine to sit as low as possible in the frame. It always looks better low, and in my case it was the only way the engine had a chance of fitting. (Bicycle Engines, Motorized Bicycles, Bicycle Motors, Motored Bikes: 2-Stroke & 4-Stroke Kits! is a source for both the three piece and one piece cranks.)
So my one piece crank set came and I immediately removed the larger sprocket. The replacement was from a kiddie bike I found at the dump, one with 36T. It required me to file out the smaller sprocket’s round center hole to fit the hexagonal (keyed) shaft which came with the wide crank. I clamped the two together and filed until there was a perfect match. It only takes a minute to install the new crank set, but pay attention when you remove the old set to see the way they go back together and which way the bearings face (with the ball bearings inwards toward the bike). This is a major accomplishment since now there is vertical space opened up much needed by the engine. This is a good time to add grease to the bearings if they look like they need it. Sometimes new bearings have little grease, for some reason, so you decide while it is already apart.
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Next in line is installing the engine mount. Before you do you might want to take a piece of old inner tube to place around the frame to protect the paint from the mounting hardware. It also provides a bit of cushion. I used pieces of thin scrap leather contact cemented to the mounts themselves for a nice clean look. It may be overkill, but on my build I wanted to be sure the rear mount could not get pulled down any from the torque of the engine so right under the rear mount I clamped a discarded seat post clamp which I had spread apart and then tightened down. That mount is rock solid. The photos pretty well tell the story here. You want to be as level as you can manage it and with the mount fastened lightly in place it is a good time to set the motor in there to see how things look. In my case it was tight with just a hair of clearance from the cross bar above. In hindsight I realize that I could have opened up the side slots a bit with the Dremel tool or a round file and been able to snug the plate down another half inch or so and gotten it absolutely level to the ground. If I ever take the bike apart for a new paint job, I’ll open up those slots a bit. But it fit in there well enough.
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I checked the pedal clearance with the engine and was still in trouble. My engine is so low that even with an extra wide pedal crank I needed to bend the crank arms outward a bit. I’ve never done this before, but know that it is one of the options for widening out the crank arms. I clamped a vise I have to picnic table (don’t have a sturdy workbench) and located a couple of pipe sections in different lengths, got out the propane torch and switched to a maps tank which is supposed to deliver more heat than propane. I discovered heat was not necessary for the initial bend outwards from the 90 degree bend already there, but I did need to use the longer pipe for adequate leverage. It took some muscle power and I went a bit at a time. I removed the crank and tested it on the bike a couple of times to see if it was bent enough. When it was I traced that bend on a piece of cardboard as a template so that I could bend the other arm to the same angle. A second bend for each arm would be necessary to draw the pedals back to being parallel to the ground, but I wanted to do that after the engine was cinched down snugly and in line with the driven sprocket on the wheel. (When it was time to do the secondary bend midway between the original 90 and the pedal I did need to apply heat for several minutes with the torch.) Bending the crank arms looks daunting, but really isn’t. If you don’t have a vise, someone you know probably does. And a vise is a good thing to have in your shop, a pretty basic tool. It is unlikely that you will need to bend your cranks since you probably have a frame with more room in it than mine does, so your engine does not have to be in the basement. With a cantilever frame you should be good to go without bending.
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A word about the rear sprocket. Your kit may have come with what is called a ‘rag joint’ which sandwiches the spokes between metal plates and pieces of rubber. This can be done and there are some very good tips on doing so if you look on Motorized Bicycle: Forum, Engine Kits, Manuals, And Help , a great resource for all motorbicycle enthusiasts. There are good step by step photos and procedures there for successfully using the rag joint, but a much better option is a rear wheel with an upgraded sprocket and hub adapter made by Creative Engineering, one of the sponsors at the linked forum. It is available at Pirate Cycle and it may be that your dealer can procure one for you. For ease of installation and a bullet proof transfer of power from the transmission to the rear wheel, it is the best way to go in my opinion.

You can now attach the clutch assembly to the engine if you have not already done so. I have some pictures here which show how to do it and it is also explained here by the guy who designed the transmission, Quenton Guenther


"Hi,

In order to install the Q-Matic drive using the 25-9260, 15260, or 15255 belt it will be necessary to attach the drive mounting plate with the top front 6 MM bolt [do not completely tighten the bolt]. Wrap the belt around the front motor pulley, place the 3/16” key in the slot in the crankshaft, push the pulley onto the motor crankshaft [see photo]. Align the pulley in line with the rear drive pulley and tighten the allen set screw. Lift the rear of the drive plate then carefully install the remaining three 6 MM bolts [be very careful to start the bolts straight]. Tighten all 4 mounting bolts, being careful to not over tighten [see photo].

To increase belt life, we suggest taking off slow and increase speed gradually."
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The photos are self explanatory. I used blue Locktite (buy it at the hardware store) on the bolts and also on the Allen screw on the pulley. So now with the clutch attached we have the engine in place. Before cinching it down (we may need to move the engine from one side to the other a bit) it is time to install the drive chain. Put it in place and see if you need to shorten it by one or more links. Take care not to shorten it too much or you will end up needing to add a link or a half link. Your chain came with a master link.
Shortening the drive chain. You may or may not be familiar with a tool called a ‘chain breaker’ which does not actually break the chain, but drives the pin out which allows the chain to come apart at that link. Simple, one would think, but a regular light duty chain breaker which is good enough for your pedal chain is not strong enough for the #41 chain which drives your wheel from the engine. (Links for #41 chain are available at hardware stores, auto parts and tractor supply stores). It is good chain. And it is because it is good chain that you will need either a heavy duty chain breaker or do it another way. I do it another way. Look closely at the photos. Once you have determined where the pin needs to be removed grind down the part of the pin which protrudes from the link on one side. It is mushroomed out slightly and you want to get it flush with the surface of the link. I use my trusty Dremel rotary tool, but a drill with a little grinding wheel attachment works well and you can even use a file. It isn’t as if you’re going to be doing this often, so doing it by hand this way works well enough. Once you have the pin ground down you will need a punch and a hammer. I like to either use a nut or a socket under the link so that when I strike with the hammer the pin is free to come out. Another favorite way for me is to use the vise with just a slight opening of the jaws for the pin to go between. Setting the chain on heavy metal is better than wood which cushions the blow. I like the vise best, but since you may not have one I have done it here with a nut, which you surely do have. Once the pin is starting to back out and the punch has bottomed out you can drive it the rest of the way with anything of the right dimension. I keep a worn out rotary tool shaft on hand for that purpose, but anything of about 1/8 diameter will finish the job for you, probably even an old and broken drill bit. So the pin is out. Put the chain back on the sprockets and join it with the master link which replaces a full link. The little open faced clip has to be facing (with the closed end) in the direction the chain is traveling or it will come loose later on. So picture in your mind how the chain is going to move… with the bike sitting upright and if you have the master link sitting on upper part of the loop the chain forms as it goes around… the upper part of the chain is traveling toward the engine, so that is where the closed part of the clip faces. It is a small thing, but if you get it backwards and the chain comes off under power your chances of finding that clip again are slim to none. Do it right in the first place and also do yourself a favor and pick up a master link (#41) at the hardware just to have as a spare. If you have a tool pouch on the bike, put it in there for of mind. It is also a good idea to have a half link as that may be all that is needed to take out too much slack in the chain. While you’re at it, you might want to pick up a half link (#43) for the pedal chain, too. It is worth the extra time getting the chain tension as right as you can from the start.
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So the chain is in place and it is time to check alignment between the clutch drive sprocket and the driven sprocket on the wheel. Once you are satisfied that things line up (the chain forms a straight line) you can tighten down the engine. At some point in this alignment process you may have discovered that the chain runs in to your rear fender if you have one. Mine did, so I removed part of the fender. Trying to bend it out of the way doesn’t work very well. You can do this job with either a small cut off wheel on the rotary tool or even a drill, or you can use tin snips which will probably necessitate removing the fender while you do so. That’s why I like the little rotary tool so much. I can do fine surgical work with it and do a clean job of removing metal and giving the chain free travel without having to remove the fender. (Now cinch down the engine bolts.)
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O.K. We’re getting close. Now it is time to attach the throttle cable to the carburetor. The photos show where the cable goes. Note that the little slotted end point where the cable fits into is free to turn around. It has a recess meant to be a receptacle for the end of the cable which keeps it in place. If you are using the kit throttle it is of the right length and will take you just a minute to do. Simple. If you are using a different throttle and the cable is not of the right length, you can use a little cable stop or holder such as the one shown in the photo. It has a screw which tightens down and holds the cable in place. The kit throttle is an easier install which I eventually used, but I wanted to show the alternate just in case. Attach your fuel line as shown in the photo. You will want to install an inline gas filter to keep gunk out of your carburetor. The two lines which came attached to the carburetor should remain. The one in the top position is a fuel overflow in case you dump your bike, for example, which you aren’t going to do of course, but just in case. The one at the bottom of the fuel bowl is so that you can drain the gas out of the tank. You might want to change that one to a longer hose so that it can go into a gas can.
And that’s it. Put some gas in the tank, open up the petcock valve so it can flow to the engine. Put the choke on (the arrow turned toward the transmission side of the engine is OFF. Pointed toward the pull cord side is ON. You might want to check the knot on the pull cord to see that it is big enough to not pull through the handle. If it looks doubtful, add another knot. A word of caution here regarding the pull start... don’t release the pull start handle and allow it to snap back against the engine, as that can cause damage to the main spring. Give it a pull or two to start the engine, let it warm up a few seconds, move the choke to the half position for a few seconds and then to the off position. It does not take long to warm up. On the left side of the engine is a black adjustment screw which adjusts the idle. The little brass adjustment screw is for lean/rich adjustment which can be tweaked later after you see how it is running. We’re done, Bud. All your bolts and nuts are in good order? Brakes are functional? Got a helmet? Are you ready for some smiles? See ya later. Have a great ride and stay safe…

I see that I need to take a couple more photos of the lines and adjustment screws, which will follow later. I may have gotten something backwards here or otherwise just plain wrong. Let’s look at this thread as something ongoing to improve upon and add to. So please correct me where this needs improvement. Apologies for the parts which may seem over explained for what you already understand. It was written for the newbie, who I used to be myself not so long ago. I’m also hoping that others will contribute similar installation threads for other four stroke engines and drive systems for the better understanding of us all. Knowledge is power. Respectfully submitted,
Silverbear

Thank you all for the kind words. I do hope the thread is helpful to first time builders. I have yet to take photos of the fuel lines and adjustment screws on the carburetor, but will. Seems like I go to do that and end up climbing on the bike and going for a ride instead. It is the peak of the leaf change here in the northeast of Minnesota and each warm day is a gift to be savored, so the truant in me insists upon a bike ride and I always listen to that twelve year old voice inside. Ha!
I had thought there might be some corrections or suggestions for improvement from someone. Please, feel free to improve upon this or add from your own experience. I have thick skin and certainly won't be offended. If your installation/mounting experience is different from mine because your bike frame is different, this is a good place to talk about it and maybe share a photo of your build. You guys are the experts; I'm the newbie.
SB