How to get a 70cc 4speed in frame?

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mrblack98

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Oct 30, 2012
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north carolina
A), china girls cant be bored because they are aluminum with a very cheap chrome coating. B), the more mods you make, the harder they are to properly tune and therefore the more risk of a shorter engine life. C), realistically 40mph, maybe a little more with a shift kit.
By properly tuned you mean the engine running lean or something? I have a buddy thats a pro with these little engines I can get his help with that.

What about the thatsdax-DAX KTMC GP50R engine? Do we know anything about its performance/reliability/easy of mounting?
 

bigbutterbean

Active Member
Jan 31, 2011
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Lebanon, PA
"new carb, expansion pipe, gaskets, intake, etc. with a SBP shift kit" - none of these will in any way increase the "risk of a shorter engine life" & in fact could prolong it if installed properly - the only "risk" is that due to the increase in preformance you may be tempted to abuse the motor more.

Adding an expansion chamber is the single most significant "upgrade" available for these motors, as it is an intrinsic part of a two stroke system - a two smoker will run w/o one ofc, but poorly in comparison. A new carb isn't nearly as significant a change if the one you have functions properly w/the correct mixture. Upgrading gaskets to ones that don't leak is a commonplace "modification" (repair) & "intake etc." is best achieved through no more than gasket & port matching, another minor "repair" that is required due to the lack of quality control.

I would like to point out that "shift kits" do not give you any more speed than what could be achieved w/o one, provided only that the final gear ratios are the same - the difference being that in that instance the single speed would need assistance during initial acceleration as it'd be geared tall.

If anything shift kits marginally reduce potential maximum top speed through added friction/drag - the additional chains, bearings & sprockets each taking a small toll.

The application of a shift kit improves acceleration and gives you the option of reducing cruise RPM, both valid reasons for installing one & the latter may well increase engine life - if you're willing to deal with the additional maintenance a shift kit requires.


Actual stock speeds vary wildly due to the random quality, but unless major modifications are attempted (reeds/moped top end/etc), realistically it's very unlikely you'll see 40mph+ even with all the mods you mentioned (flat ground), but you may get close. What you'll get is a far smoother running motor that's more powerful than stock and if not abused, should be at least as if not more reliable as you've fixed the factory flaws.
When I said modifications, I was not referring to upgrades or repairs, but rather to actual modifications to the engine itself, such as porting and reeds or increasing compression. These things have a much more significant impact on performance than any bolt-on "upgrade" or repair, and if your engine is not properly tuned after making these modifications, it can absolutely affect engine life. In fact, any time your engine is not properly tuned it can affect engine life.
 

bigbutterbean

Active Member
Jan 31, 2011
2,417
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Lebanon, PA
By properly tuned you mean the engine running lean or something? I have a buddy thats a pro with these little engines I can get his help with that.

What about the thatsdax-DAX KTMC GP50R engine? Do we know anything about its performance/reliability/easy of mounting?
the engine you are referring to is a clone of a clone. The original engine design was Morini, an Italian engine. Ktm used to put morini's in their mx bikes, and then Morini went out of business and ktm designed their own clone. The ktmc is a clone of ktm's design. Performance wise, I would imagine comparable to a Morini, which means 10,000+ rpm's. Reliability depends on using the proper oil and maintenance. Ease of mounting depends on your fabrication skills.
 

mrblack98

New Member
Oct 30, 2012
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north carolina
the engine you are referring to is a clone of a clone. The original engine design was Morini, an Italian engine. Ktm used to put morini's in their mx bikes, and then Morini went out of business and ktm designed their own clone. The ktmc is a clone of ktm's design. Performance wise, I would imagine comparable to a Morini, which means 10,000+ rpm's. Reliability depends on using the proper oil and maintenance. Ease of mounting depends on your fabrication skills.
Well needing fabrication skills would up the difficultly I'd say haha. Now I know with 2-strokes you have to mix oil and what-not, but other than after the initial inspection and gasket upgrades etc. what maintenance is needed, are we talking replacing bearings, greasing, or what?
 

bigbutterbean

Active Member
Jan 31, 2011
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Lebanon, PA
The type of maintenance depends on the engine. I know with morini's, you have to watch the clutch nuts because they tend to slip. Basic bike maintenance is going to be the same regardless of what engine you choose. Lubing chains, greasing wheel bearings, keeping cables lubed, etc. Its also a good idea to check the entire bike over periodically and make sure everything is operating correctly, check tire pressure, check the brakes, etc.