Thread: stroker motor

YOu need to start thinking about cost/tradeoffs here. If you add a stroker crank, cylinder, camshaft, carb, portwork, oil cooler, and updated clutchpack with springs...you are talking to the tune of about $600 to move your motor from 72cc to 110. Add more to that for CDI conversion. And you still have a 3 speed with semi auto. That does not sound to me like a good investment, truth be told. I've been around these motors for a long long time and once you start popping in parts that do not maintain the level of honda quality, you no longer have honda reliability. Now...think of this alternative...you could purchase a chinese mid-block in 120-150cc range, 4-speed, manual clutch motor that is cdi and comes with carb, oil cooler kit, and all wires for anywhere between 300-500 bucks. This motor will most likely trounce the 110 you would build and provide superior torque and higher top and cruising speeds.

I don't want to talk anyone out of building the small block motors...I want to keep people thinking. What do you want to use the motor for? Then select appropriately. Either option still requires you to purchase an exhaust to get the most out of your mods.

If you buy the chinese motor for 400 you still have the original motor to do with as you please...a good runner will fetch 250 on ebay or you can hold onto it.

Originally Posted by mike649

whats with the 12volt crank anyway,i mean is it added cos?12 gotta be better than 6,lol.then i would need a 12 volt battery and change the light bulbs any thing else i'm missing here?minds set on that 52mm crank,iwant a full 110 cc"s

Honda used 3 different crankshafts; 3-speed, 4-speed and 12v. The terms are used as conversational shorthand. Okay, so what the does this all mean anyway? In the simplest terms, crank snout tapers are specific to flywheel bores and flywheels are specific to stator assemblies. You cannot mix & match. The crankshaft, flywheel and stator are a complete assembly. With 12v cranks, conrod length is different, as well, requiring a different (12v) piston with the correct compression height; again, no mix & match.

If you want to use a 12v crank, then you'll need to source the matching flywheel, stator + CDI module, 12V flywheel cover, matching piston, plus mod the LH case for the magnetic pickup. It's all good and most of the performance parts available are made for the later model 12v engines. It's mainly a matter of cost, for most builders. 12v electrics & CDI are light-years beyond breaker points, in every way. If an extra $300 investment, up front, doesn't bother you and you have the engine building talents necessary, there's no reason why you can't get satisfactory results this way.

It's what I'd call "domino effect" when building a stroker motor. Both Trailbikes & Dratv sell good parts. The latter has more 6v parts, at present. The former has complete kits, that are simpler to deal with than piecing one together from a parts list w/descriptions.

Markus makes a very good point about verifying actual compression ratio. For a street bike, I wouldn't go much higher than about 10:1. Pump gas octane has been slowly falling for the past 2 seasons, ererily similar to what happened circa 1980. A little safety margin, like 9.5:1 CR might pay you back in the not-so-distant future, with very little effect on performance.

so i'm loking at about a $1000 or better in parts?i saw a honda nice reconditioned motor on the net for $1000 and that was a 4speed manual i believe,maybe this would be the way to go?

Originally Posted by mike649

so i'm loking at about a $1000 or better in parts?i saw a honda nice reconditioned motor on the net for $1000 and that was a 4speed manual i believe,maybe this would be the way to go?

If you want to get serious regarding tuning, a Honda Nice engine is surely the best way to go. I own three of them, one bought reconditioned in pretty good shape. Unfortunately, "reconditioned" nowadays often seems to mean something completely different in Thai than "reconditioned" usually means in plain english. You may be lucky and receive a proper engine for your money, but don't complain if you find yourself rebuilding the motor after buy investing a wealth into replacement parts.

Even if you receive a good engine, be prepared to spend at least the same amount you've paid for the motor into tuning parts to transform a tractor motor capable to transport at least three persons and two live pigs half around the world without oil service into a reliable, agile racing machine.

Who told you decisions were easy in this hobby?

Regards,
Markus

Fatcaaat makes some good points, so does Markus. My own personal spin on choosing an engine (if you haven't developed a migraine already) is that you're the only one who can make the call as to what's best. Fully-tuned Z50-based Honda, Chinese or Honda Nice all have their pros & cons.

Figure out what you want from the bike (miles, type of riding, how long you want to keep it, will you pursue other upgrades later on, etc), as well as the build project itself, then you can set some goals and begin working toward them. It's the most cost-efficient route.

Building a Z50-based motor, like the CT70, into a 110-124 tune can be a lot of dollars per hp. PRC motors offer the most hp per dollar. The Nice is the smoothness & durability champ, bar none. Each has its own place in the small bike scene. Money matters but, so do other parameters, thus your logic may be different then someone else's. FWIW, I understand Markus' view of the stock Nice, but also don't completely agree with the "tractor" assessment. But that's for another discussion...

Been away for few day in Adventure Land in Des moines,Iowa.So what chineese motors are good?I see a few Lifan owners,but hear stories how the gear box is not up to par.

Originally Posted by mike649

Been away for few day in Adventure Land in Des moines,Iowa.So what chineese motors are good?I see a few Lifan owners,but hear stories how the gear box is not up to par.

Mike - I have been chewing on China vs. stroked stock. I have come to the conclusion that the stroked stock is the expensive if you go the 12v cdi with a four speed. Not to mention it is probably the most difficult to source parts. And when you are all said and done the reliability is only as good as the parts you throw at the motor like Fatcaat said.

Rather than buy a Lifan or Jialing or similar I would go for a Daytona 150cc motor for a bit more cash, probably a wash cost wise for the stock stroker. After my freebie china motor dies I'll buy a Daytona, unless Fatcaat sells another rebuilt nice, I shouldn't have passed that opportunity to my buddy. The Daytona motors are designed in Japan with R&D in Japan too. The motors are built in China but heavily controlled than the other China motor builders.