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Hey guys. New poster here, someone referred me to this forum because you guys are apparently the ones to ask about this sort of stuff. So thanks in advance.

Currently looking at buying a ready-to-ride bike for this year's riding season, and so I have something to have fun on while I'm working on putting my Yamaha YSR project together.

Because of my love for minis and the comforts they offer - the ability to store and work on your bike in your apartment, light weight, ease of transportation, overall cheaper cost - I will probably be buying a mini of some sort. Currently I'm looking at either an 85cc two-stroke, like a CR85 or RM85, or a Honda CRF150R, which is four-stroke but essentially the same bike. The CRF150R is about 30-40% more expensive, so I'm a little skeptical about this (I live in Russia, I'm on a strict budget, and bikes are expensive here).

The thing I want to know is, can those 85cc bikes be made reliable and long-lasting enough to pull duty as a supermoto fun-bike? I am planning on commuting on this bike sometimes, and that would mean about 5-10 miles of city traffic. I am not stupid so it's not going to be WFO running at 12,000 RPM's for 10 miles at a time, more like putting along in 6th gear at 40-ish mph, staying off the pipe. Will this sort of use cause the engine any real "harm"? I'm ok with changing top ends on an as-needed basis, of course, but I'm wondering if it'll end up eating a crank bearing or force me to put in a new piston every month as if I was doing actual racing on it.

Also, what is the bottom end durability like? Which bike, of the big four's 85cc or older 80cc offerings, be the better choice? I would assume something with powervalve, so Yamaha is probably out?

Part of the reason I want a mini is because I can "camouflage" it as a 50cc moped and avoid registering, paying taxes on it, having to get a Class A motorcycle license. Well, and because I am pretty small and light, and feel less than comfortable on full-size dirt bikes.

Thanks again in advance, guys! looking forward to your answers.

P.S. The bike will likely end up getting a larger 125cc engine swapped into it at the end of the year (Yamaha DT125 or Husqvarna SM125R engine, I haven't decided exactly yet), which I hope will give me better reliability, more power, and better torque for real-world use.
 

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I think it could be made to work but would not be ideal but you already know that. Some things to keep in mind are street able tires might not be very sporty in the size range that will fit the bike. If you need lights you going to have to add a entire electrical system, the minis don't have lights or a battery.

In the USA the cost of tires and electrical could buy a moped then you would have the moped for work and a dirt bike for weekends. Be sure to check that out before you start. Also in the USA some states will not let you put a dirt bike on the road other don't care.
 

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I think it could be made to work but would not be ideal but you already know that. Some things to keep in mind are street able tires might not be very sporty in the size range that will fit the bike. If you need lights you going to have to add a entire electrical system, the minis don't have lights or a battery.

In the USA the cost of tires and electrical could buy a moped then you would have the moped for work and a dirt bike for weekends. Be sure to check that out before you start. Also in the USA some states will not let you put a dirt bike on the road other don't care.
Hey Nick,

Thanks for the answer. I was planning on getting a set of 12 or 14" SM wheels from a pitbike or something of that nature and making some custom spacers, assuming the axle was the right diameter and could conceivably be made to fit, so streetable tires aren't a big deal.

For lights, I would probably be modifying the stock stator to add a lighting coil, at least a small 35w output one, in order to run some sort of LED tail light and a smallish light up front for visibility and legality reasons. Never done this sort of thing, but it could be good experience and fun as a project. If that doesn't work out, I would be using a total-loss battery system to power an LED taillight.

US laws don't really concern me as I'm literally half the world away :lol: Cops here don't really check for anything aside from proof that it's a 49cc moped. Even helmet laws are very laxly enforced. I have a plan for getting past the 49cc displacement question, so the rest doesn't really concern me either.

Hopefully someone with more hard tech knowledge or experience can chime in and tell me which of the 85cc engines is more hardy and reliable. I have read that some of the newer Honda CR85's have a very thin exhaust port bridge which can cause quick ring wear. Information like this is very much what I need, so if anyone has anything to contribute, I'd appreciate it a lot. Don't be intimidated by my text walls!

Thanks a lot guys.
 
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