nightcruiser
New Member
I got my first 2 Grubee Skyhawk GT5 kits this summer and boy have a learned a lot in a little time! Here's a summary of things to know when you set out on your project, things I learned along the way but wish I had known ahead of time...
First off, COUNT YOUR SPOKES! I had a standard (late model) mountain bike, Specialized RockHopper Comp circa 1990, I just assumed it was a standard wheel and the kit would just fit... LOL The sprocket kit is designed for a 36 SPOKE WHEEL, so you need to COUNT 9 PAIRS OF SPOKES on each side. Turns out I have a 32 spoke wheel (8 pairs), so I was in for extra "fun" installing the kit on my bike. If you have a choice in the matter get a bike with a 36 spoke wheel, it can be done on wheels with different numbers of spokes but might be more than you bargained for if you don't have good tools and lots of patience. When you have 9 pairs of spokes the 9 bolts on the sprocket (and rubber pieces used to mount it which is called a "rag joint") match up with the spokes and bolt down evenly resulting in a balanced sprocket without too much trouble.
Second thing, the manual is gonna be pretty useless! Some things I thought were important were not clearly defined by the manual, like order of assembly of the rag joint sprocket. (btw, order is sprocket, rubber, spokes, rubber, bracket, washer, lock washer nut!) Still read the manual thourougly front to back, but don't expect every answer to be in there for you.
When you mount the engine lots of things come to mind, wrap your frame with tape and set the engine in there and fiddle with it a bit. Fit the engine on the frame making sure there is clearance for all the parts, carb, exhaust, make sure spark plug cap can come off and on etc. (more on that later) You want to mount the engine so the carb is as level as possible, but getting a solid grab on the bike posts is important, as well as chain angle. Balance out those issues to come up with the best mounting position. Make sure you have room to slide your carb off, you're probably gonna need to do that a few times. When you mount your engine it's a good idea to wrap some rubber around your frame under the clamps, this protects your frame from scratching and also helps you get a solid no slip grip, and I would imagine it helps dampen vibration a bit. A section of an old inner tube works great, use a piece of innertube rubber under just about any part you mount to your frame.
Speaking of innertubes, if you are using an older bike you probably want to check the tires/tubes/BRAKES/cables and replace anything that is old or worn. Having an engine on the bike is gonna be rougher on the bike than the designers envisioned, so your bike should be better than up to spec to be a safe ride with the engine. So, your probably gonna be getting some new innertubes anyways, do yourself a favor and get good ones. I never had flats on my pedal bikes but got one right away with the engine, so I am going with the self sealing innertubes now, they don't cost much more than regular ones. I also added rubber rim rings over my plastic ones (cause my tube got pinched on the inside at the rim) and I added the tuffy tire liners to help keep my wheels inflated. Having a motor on your bike might get you further away from home, major bummer if you get a flat!
When you unpack your kit you will notice they give you a spare for a couple parts.... You can pretty much throw away any parts they give you two of, cause they are crap! I couldn't understand why I got two spark plug caps, two master links for the chain. First ride my spark plug cap broke, second ride my master link popped.... Now I get it! LOL The good news is this stuff is not hard nor expensive to replace with a part that is real. I had a quality master link here so I used that instead of the spare crap they gave me and it worked just fine.
The chain is crap, if you weigh over 100lbs you should replace it. A #41 roller chain (like a farm equipment chain), a wider 415 chain or just a better quality 410 chain will do you good, anything but this Chinese chain they give you. A 410 chain is 1/8" wide, the 415 chain is 1/16" wider than the 410, and the #41 is 1/16 wider than the 415. If you must use the kit chain do yourself a favor and use a better master link, or even better, when you break the chain to size it use the chain tool to mend the chain with the original rivet. A one piece chain with no master link is gonna serve you better, specially when you have a chain where every link is a weak link! LOL
The spark plug cap is just crap, very brittle, probably not going to serve you very long. After my first one broke I put on the spare and immediately went about replacing the cap and wire. I just went to the auto parts store and asked to see their single plug wires. I found a wire with rubber right angle spark plug boots on both ends for $4, I cut it in half and used one half on each engine. To replace the wire you need to twist the old wire out of the CDI unit. I used pliers, some say the wire is barely glued but both of mine were really glued in there good, so when I twisted the wire broke off inside the CDI. Don't panic! LOL just take some small tools like an exacto knife, small screwdriver, nail etc and carefully pick out the rubber from the old wire. Soon enough you will see the tip of a wood screw emerge, that's right, the plug wire just threads on to the wood screw, that's how it is connected (electrically and physically)! Once you have all the rubber from the old wire removed enough for the new wire to fit in there, put some silicone around the outside of the new wire and thread it down on the wood screw in the CDI. Get it nice an tight then smooth the silicone around the top making sure to seal it off really good. Let it dry then your good to go. If you used the plug cap that came with the kit you must have figured out that you need to screw off the cap on the spark plug to fit it, with the new wire you will need to put the cap back on the plug.
Speaking of plugs, they gave you two of those too... hmm.... better throw ém away! An NGK BP6HS plug will only cost you a couple bucks, even if you have the new improved three pronged plug in your kit a better plug is in order. I saw a nice improvement in how my engine ran after I installed the NGK plug.
The throttle leaves a lot to be desired. I haven't replaced mine yet, but that's coming... It is over all just cheap, the cables need to be adjusted all the way out to be right. It will work, so this is an optional upgrade, but I think you will see like me that you would be better off with a more solid throttle.
Depending on your frame your muffler might interfere with your cranks, mine did big time. To bend the muffler a bench vise, pipe wrench, rubber mallet and/or blowtorch are your friends! I tried the clamp and lean, and hammer, but had to bend too far. I ended up having to torch the pipe cherry red and grab ahold of the end of the muffler (with oven mitts or a welding glove etc) and lean on it (while the pipe and flange were clamped in the vise). I was afraid at first to grab the flange with the vise for fear of bending it, but in the end that is just what I had to do cause there was no other way to get the big twist I needed in the pipe. It worked out fine for me, the pipe got a little scarred up from the process but it's where it needs to be now and works fine.
The gas tank is probably gonna be just filled with crap, I freaked out how much stuff was in mine. I just used water, rags and patience to clean out the crap from the tank and then set it in front of a fan for a long time until I was sure it was dried out. If you don't do this don't expect your first ride to be long, the debris from the tank is gonna clog up the little fuel filter in the fuel valve in no time! On the subject of gas, make sure you turn off the gas after every ride. Do not let the bike sit with the gas on and engine not running. You don't want a gas leak, and the gas can actually flood through the engine into the muffler. Just get into the habit of turning the gas off, you'll remember to turn it on after it stalls out on you!
continued next post....
First off, COUNT YOUR SPOKES! I had a standard (late model) mountain bike, Specialized RockHopper Comp circa 1990, I just assumed it was a standard wheel and the kit would just fit... LOL The sprocket kit is designed for a 36 SPOKE WHEEL, so you need to COUNT 9 PAIRS OF SPOKES on each side. Turns out I have a 32 spoke wheel (8 pairs), so I was in for extra "fun" installing the kit on my bike. If you have a choice in the matter get a bike with a 36 spoke wheel, it can be done on wheels with different numbers of spokes but might be more than you bargained for if you don't have good tools and lots of patience. When you have 9 pairs of spokes the 9 bolts on the sprocket (and rubber pieces used to mount it which is called a "rag joint") match up with the spokes and bolt down evenly resulting in a balanced sprocket without too much trouble.
Second thing, the manual is gonna be pretty useless! Some things I thought were important were not clearly defined by the manual, like order of assembly of the rag joint sprocket. (btw, order is sprocket, rubber, spokes, rubber, bracket, washer, lock washer nut!) Still read the manual thourougly front to back, but don't expect every answer to be in there for you.
When you mount the engine lots of things come to mind, wrap your frame with tape and set the engine in there and fiddle with it a bit. Fit the engine on the frame making sure there is clearance for all the parts, carb, exhaust, make sure spark plug cap can come off and on etc. (more on that later) You want to mount the engine so the carb is as level as possible, but getting a solid grab on the bike posts is important, as well as chain angle. Balance out those issues to come up with the best mounting position. Make sure you have room to slide your carb off, you're probably gonna need to do that a few times. When you mount your engine it's a good idea to wrap some rubber around your frame under the clamps, this protects your frame from scratching and also helps you get a solid no slip grip, and I would imagine it helps dampen vibration a bit. A section of an old inner tube works great, use a piece of innertube rubber under just about any part you mount to your frame.
Speaking of innertubes, if you are using an older bike you probably want to check the tires/tubes/BRAKES/cables and replace anything that is old or worn. Having an engine on the bike is gonna be rougher on the bike than the designers envisioned, so your bike should be better than up to spec to be a safe ride with the engine. So, your probably gonna be getting some new innertubes anyways, do yourself a favor and get good ones. I never had flats on my pedal bikes but got one right away with the engine, so I am going with the self sealing innertubes now, they don't cost much more than regular ones. I also added rubber rim rings over my plastic ones (cause my tube got pinched on the inside at the rim) and I added the tuffy tire liners to help keep my wheels inflated. Having a motor on your bike might get you further away from home, major bummer if you get a flat!
When you unpack your kit you will notice they give you a spare for a couple parts.... You can pretty much throw away any parts they give you two of, cause they are crap! I couldn't understand why I got two spark plug caps, two master links for the chain. First ride my spark plug cap broke, second ride my master link popped.... Now I get it! LOL The good news is this stuff is not hard nor expensive to replace with a part that is real. I had a quality master link here so I used that instead of the spare crap they gave me and it worked just fine.
The chain is crap, if you weigh over 100lbs you should replace it. A #41 roller chain (like a farm equipment chain), a wider 415 chain or just a better quality 410 chain will do you good, anything but this Chinese chain they give you. A 410 chain is 1/8" wide, the 415 chain is 1/16" wider than the 410, and the #41 is 1/16 wider than the 415. If you must use the kit chain do yourself a favor and use a better master link, or even better, when you break the chain to size it use the chain tool to mend the chain with the original rivet. A one piece chain with no master link is gonna serve you better, specially when you have a chain where every link is a weak link! LOL
The spark plug cap is just crap, very brittle, probably not going to serve you very long. After my first one broke I put on the spare and immediately went about replacing the cap and wire. I just went to the auto parts store and asked to see their single plug wires. I found a wire with rubber right angle spark plug boots on both ends for $4, I cut it in half and used one half on each engine. To replace the wire you need to twist the old wire out of the CDI unit. I used pliers, some say the wire is barely glued but both of mine were really glued in there good, so when I twisted the wire broke off inside the CDI. Don't panic! LOL just take some small tools like an exacto knife, small screwdriver, nail etc and carefully pick out the rubber from the old wire. Soon enough you will see the tip of a wood screw emerge, that's right, the plug wire just threads on to the wood screw, that's how it is connected (electrically and physically)! Once you have all the rubber from the old wire removed enough for the new wire to fit in there, put some silicone around the outside of the new wire and thread it down on the wood screw in the CDI. Get it nice an tight then smooth the silicone around the top making sure to seal it off really good. Let it dry then your good to go. If you used the plug cap that came with the kit you must have figured out that you need to screw off the cap on the spark plug to fit it, with the new wire you will need to put the cap back on the plug.
Speaking of plugs, they gave you two of those too... hmm.... better throw ém away! An NGK BP6HS plug will only cost you a couple bucks, even if you have the new improved three pronged plug in your kit a better plug is in order. I saw a nice improvement in how my engine ran after I installed the NGK plug.
The throttle leaves a lot to be desired. I haven't replaced mine yet, but that's coming... It is over all just cheap, the cables need to be adjusted all the way out to be right. It will work, so this is an optional upgrade, but I think you will see like me that you would be better off with a more solid throttle.
Depending on your frame your muffler might interfere with your cranks, mine did big time. To bend the muffler a bench vise, pipe wrench, rubber mallet and/or blowtorch are your friends! I tried the clamp and lean, and hammer, but had to bend too far. I ended up having to torch the pipe cherry red and grab ahold of the end of the muffler (with oven mitts or a welding glove etc) and lean on it (while the pipe and flange were clamped in the vise). I was afraid at first to grab the flange with the vise for fear of bending it, but in the end that is just what I had to do cause there was no other way to get the big twist I needed in the pipe. It worked out fine for me, the pipe got a little scarred up from the process but it's where it needs to be now and works fine.
The gas tank is probably gonna be just filled with crap, I freaked out how much stuff was in mine. I just used water, rags and patience to clean out the crap from the tank and then set it in front of a fan for a long time until I was sure it was dried out. If you don't do this don't expect your first ride to be long, the debris from the tank is gonna clog up the little fuel filter in the fuel valve in no time! On the subject of gas, make sure you turn off the gas after every ride. Do not let the bike sit with the gas on and engine not running. You don't want a gas leak, and the gas can actually flood through the engine into the muffler. Just get into the habit of turning the gas off, you'll remember to turn it on after it stalls out on you!
continued next post....
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