First build checklist!

[FNTPuck]

Hey everyone, first off I just want to say thanks since this forum has already been a HUGE help. For a little background, I am what most people would call a "hobbyist" with a ton of different interests and am looking to add MBs to my list of passtimes. I currently build and host servers for a living but have 15+ years of experience building motorcycles, cars, and high performance computers. I was also heavily involved in BMX and built many bicycles in the 90s. After seeing a couple MBs riding around locally I got to researching about them and was hooked. I spent a few days lurking on different forums, before feeling comfortable enough to post.

I am looking at starting my first build(s), and just want to make sure I am not missing anything or if any experienced builders have suggestions since this is all new to me. I initially wanted to build a Stingray or fat tire bike, but after reading about the issues with offset mounts, jackshafts, frame mods, etc I decided to go simpler for my first build just to get the hang of it before I tackle something like that in the future. I purchased the gasbike GT6 complete kit(https://www.gasbike.net/collections...ts/gt6-pro-racing-66cc-80cc-motorized-bicycle) as my first build platform instead, thinking it would be a bit simpler than piecing together a custom job as a newbie. I understand the setbacks in these cheap chinese parts though, and for the price it seems worth it to use an an upgradable starting point so I am trying to do what I can before even assembling it to make it reliable. The kit comes with an upgraded 415 chain already, but here is what I have done/added so far:

- Read stickied thread "HT Engine Specifications" and most of the dragonfly75 page to familiarize myself with the Chinese 66cc 2strokes. This forum has been a WEALTH of information
- Got the upgraded steel hardware kit from SBP, and will use blue loctite where applicable. I have experience with Chinese hardware so of course the stock hardware is going straight from the box to the trash where it belongs.
- Purchased an automotive inline fuel filter and will remove screen from petcock in tank to prevent clogging(will also clean tank well before installing)
- Also purchased the NGK B6HS plug to replace cheapo generic one, supposedly one heat range colder for my high Florida summer ambient temps. Will also check plug wire connector and adjust or replace as needed.
- Purchased a front brake setup to not rely on just the coaster brake (a big heavy cruiser with a 3hp motor and only coaster brakes sounds crazy?!?)
- Didn't see this listed but I purchased some thin 70durameter neoprene sheet(firm, chemical and gas resistant - same stuff as automotive mounts use so it should last ages) to use as isolators for anything touching frame to reduce vibration and prevent damage to frame.
- Everything will be installed with TQ wrench to proper specs to prevent pulling the threads out of the case.
- Will check all gaskets and trim/replace as needed

Anything else worth doing to a new motor before even installing??? Is it worth replacing the head studs, or just some loctite on the nuts OK? I have experience with 2strokes since I used to ride dirt bikes, but zero experience with these little Chinese gems. I plan on making many more builds, and have already started imagining what my custom "Dream bike" would be!

 

[motorizedbikeguy]

Glad to see you're going for reliability and safety. Don't forget about the sprocket adapter if you're not going with a shift kit. You want a hub mounted sprocket adapter, not the default one that clamps to your spokes. I wouldn't get the adapter with the hose clamp on it, it's a bad design. The best design uses two hex screws. It's also a very good idea to grease your wheel bearings with quality grease, especially if you have a cheap bike. Also, I would avoid the temptation of replacing the head studs with one of the hex screw sets you see online. They're harder to deal with and you increase the risk of damaging the aluminum threads in the block. Just stick with the default studs and replace the nuts. If you want to get a little further into the nitty gritty, it's a good idea to replace the delicate little wrist pin bearings with a brass\graphite bushing. When the needle bearing fails (which can happen at any time), it'll probably destroy your engine, whereas the bushing will just wear down over time and then you can replace it if you notice some noise and extra play.

Didn't see this listed but I purchased some thin 70durameter neoprene sheet(firm, chemical and gas resistant - same stuff as automotive mounts use so it should last ages) to use as isolators for anything touching frame to reduce vibration and prevent damage to frame.

That is a bad idea. That will place excessive stress on the engine and mounts and cause damage over time. Moderate vibration through your entire bike is better than extreme vibration primarily in the engine and mounts. Metal on metal (with as much contact area as possible) is how these engines are designed to be mounted. If you're worried about discomfort from vibration, get a good suspension post\seat and wear comfy gloves.

 

[FNTPuck]

Glad to see you're going for reliability and safety. Don't forget about the sprocket adapter if you're not going with a shift kit. You want a hub mounted sprocket adapter, not the default one that clamps to your spokes. I wouldn't get the adapter with the hose clamp on it, it's a bad design. The best design uses two hex screws. It's also a very good idea to grease your wheel bearings with quality grease, especially if you have a cheap bike. Also, I would avoid the temptation of replacing the head studs with one of the hex screw sets you see online. They're harder to deal with and you increase the risk of damaging the aluminum threads in the block. Just stick with the default studs and replace the nuts. If you want to get a little further into the nitty gritty, it's a good idea to replace the delicate little wrist pin bearings with a brass\graphite bushing. When the needle bearing fails (which can happen at any time), it'll probably destroy your engine, whereas the bushing will just wear down over time and then you can replace it if you notice some noise and extra play.

Awesome, thanks for the tips. I will do some research on the hub mounted sprocket adapters. Are they unique for coaster brake or multi-speed freewheel hubs, or do they all work universally? I will leave the head studs alone and just replace the nuts on them, and grease both wheel hubs. I have plenty of high temp graphite bearing grease and didn't think of that but it makes sense. They likely just have a tiny dot of cheap thin grease that won't last long at 25+mph.

That is a bad idea. That will place excessive stress on the engine and mounts and cause damage over time. Moderate vibration through your entire bike is better than extreme vibration primarily in the engine and mounts. Metal on metal (with as much contact area as possible) is how these engines are designed to be mounted. If you're worried about discomfort from vibration, get a good suspension post\seat and wear comfy gloves.

They are very thin sheets and very firm rubber .032" and 70dura - less than 1mm thick and HARD(can't leave a mark with a finger nail). I didn' want anything that would make the mounts bow outward from making the tubes too thick so went with very thin sheet. If you still think that would effect the mounts negatively, I will leave it off and I guess just cut to fit duct tape on the mount to prevent scratches. My thinking is if I ever remove, replace, or upgrade the motor to a different mount style it won't have big ugly scratches on it...but it sounds like it causes more harm than good so I will skip that.

Thanks! Not even done with my first one and already hyped for my second improved build! Trying to stay relatively simple at first since I tend to go overboard on things.

 

[FNTPuck]

Answered my own question with a bit of research for the hub adapter...bit expensive compared to most mods but with how important the sprocket mount is I am definitely going that route. Thanks again!

 

[motorizedbikeguy]

Yeah, the hub sprocket adapter is pricey, but definitely worth it. I consider it a mandatory upgrade that should come default with the kits. Spinning your wheel via the spokes instead of the center of your hub is just a bad idea when you consider how the wheel is designed and the forces involved. Make sure to measure your hub first to make sure you get the right size. Another thing to consider is the chain tensioner. The default one is not very good and can move around if not mounted with a bit of extra work. There's much better chain tensioners online, like the spring tensioner that mounts to your engine cover, or the kind that mounts to both bars in the back. When it comes to scratching your frame, I think you should just come to terms with the fact that once you install a combustion engine on a bicycle, it will never be the same. The hot oil and exhaust from the default pipe alone can damage the paint.

 

[FNTPuck]

Yeah, the hub sprocket adapter is pricey, but definitely worth it. I consider it a mandatory upgrade that should come default with the kits. Spinning your wheel via the spokes instead of the center of your hub is just a bad idea when you consider how the wheel is designed and the forces involved. Make sure to measure your hub first to make sure you get the right size. Another thing to consider is the chain tensioner. The default one is not very good and can move around if not mounted with a bit of extra work. There's much better chain tensioners online, like the spring tensioner that mounts to your engine cover, or the kind that mounts to both bars in the back. When it comes to scratching your frame, I think you should just come to terms with the fact that once you install a combustion engine on a bicycle, it will never be the same. The hot oil and exhaust from the default pipe alone can damage the paint.

Best price I found on the proper sized hex bolt hub adapter was from mzmiami on ebay, $45 shipped with a sprocket. In state too so should get here quick...I picked up two of them since I jumped the gun and ordered a second bike already for an improved build #2, using what I learn from this first build . After reasearching and comparing how they mount I agree that it is a "must have" mod...can't believe I was going to use the rag joint style clamp on those tiny spokes.

They each came with sprockets too so I got a 39 and a 41, and the kit comes with a 44 so I have plenty of options to tailor it to what I like. Not looking for crazy top speed since these are cheap $120-$150 bicycles and if I go that serious I would also want to replace the spokes, hubs, add disc brakes, etc. I trap 160+ on my ZX14R in the 1/4 mile but 40mph on a walmart huffy isn't my idea of fun!

Maybe when I install my welder outlet and start really having fun I'll build something nuts...

Bikes are both here already but email says the motors won't be in until the 12th...and I ordered on the 30th an paid an extra $50 for supposed faster shipping .

Thanks again for the tips - even spending 4 days reading the stickies and researching forums before even registering there were still plenty of things I missed, so I am definitely thankful for the help. Once the motors come in I will start some build threads to get more feedback and share my progress.