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Old 01-07-2015, 08:15 PM
Dirtynails Dirtynails is offline
Motorized Bicycle Newbie
Join Date: Jan 2015
Location: Arizona
Posts: 11
Default Hey, new guy here. Planning builds for 8 bikes on MTB frames. Recommend some parts?

So, long story short I am planning on building 8 bikes for everyone in my family. We would mostly be using these to just tool around on 99.99% but to be totally transparent I'm building them as a last ditch "get out of dodge" transportation system juuuuuust in case **** ever hits the fan and the roads are clogged. I only mention this because I want you to understand why I want to build the most durable bikes I can. They need to survive a 90 mile trip 2/3s of which is a windy mountain highway. My family already knows I'm crazy and I don't mind if you guys think that too as long as you will still give me advice on the builds

I can't go with dirt bikes because they are too hard for everyone in my family to learn how to ride (older folks).

I can't go with bicycles because not everyone in my family has the level of fitness required (heavier folks).

I can't go with mopeds because they are vintage and aren't reliable enough (been down that road).

So that leaves motorized bicycles. Worst case if one breaks down it can still be effectively pedaled by one of the younger fitter members. Ok, phew now that we got all of the crazy tin foil hat **** out of the way lets get our hands dirty and talk builds. FYI I have limited experience with bicycles but I have a ton of experience with vintage mopeds and scooters. Please feel to chime in with suggestions on sources, models, company etc. I plan on building every bike as close to a clone as possible for part redundancy.

Bike: 2014 Diamondback Overdrive Sport 29'er
Solid company, mechanical disk brakes, decent gears and derailers etc, front suspension, hard tail rear, wide tires, good bang for the buck. I want to buy new and there are a lot of places with last years model still on sale.

Motor: flying horse 66/80cc kit
It's my understanding that these aren't actually 80cc right? It seems like all the companies out there are just selling the same Chinese motor under different names. Is that correct or is there one that's better than the others in terms of build quality?

Exhaust: SBP expansion or custom
It seems like people are pretty happy with the SBP kit. I have made custom expansion exhausts in the past and its a pain in the ass. I especially don't want to do it 8 times if I don't have to. I am looking for torque to carry people plus gear and a single wheel trailer up hills not looking for top speed performance.

Carb: how is the carb that comes with the kit? It looks like a dellorto knock off. Decent? Do most people just throw on a high flow k&n knock off and rejet? Anyone ever bore them out or step it up a mm or two? Are there larger intakes available in that bolt pattern or do you have to get creative?

Ignition: Are the stock CDI's reliable? Are any of the performance ignition upgrades more reliable? It's a fairly cheap part to replace but I would rather avoid replacing them if I can just buy a better one.

Other random aspects of the build

Anyone here live in a hot state and taken their bike for a long ride in the summer? Assuming you were properly jetted have you ever had overheating issues? If so do you know of any other 50cc heads with larger fins that line up to the bolt pattern of the cylinder? I have a few moped heads laying around but would prefer to be able to just buy 8 pocket bike heads or something.

The stock mounting system most people use seems kind of wonky. Unfortunately these bikes are aluminum and I can't weld that but I could outsource it. Is it worth welding engine mounts to the frame or are custom brackets and a nice thick bushing good enough for an abusive ride.

It seems some people go with a 415 HD chain and I would like to as well but won't you get lateral slop on the gears doing that? Less chain breakages are great but I don't want to get that at the expense of a wrecked gear. Are there other options for durability?

Case matching:
I assume the 66/80cc kit is just slapped on. Is there enough material in the case to dremel it out and match the ports on the cylinder? If so have you done it and is it worth it?

Minor issue but has anyone switched to something more comfortable when under power? I realize bicycle seats are designed for pedaling but hopefully thats not often something padded and long.

I know there's a 4L version for sale for cheap but to be honest I hate the look lol. Anyone found a good source for a long (plastic maybe) tank in the 1-1.5gallon range?

Well I'm sure there's more that I'm not thinking of right now but that's the big chunk of it. Have two bikes and two engines arriving Monday. Going to build two all the way up. Break in the motors and then do a test ride fully loaded with my brother in law. Can't wait to get my nails dirty again!
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