Bent6

Member
Jul 30, 2000
107
0
My 7 year old son is ready for a bigger bike. He has just about outgrown his PW50, and he is ready for a "real" bike with a working suspension. He is approx 48" tall and 44lbs. We have been looking at the KTM Jr Adventure. They are nice but cost too much. I've found some used 50cc race bikes which fit him well for much less. The bike I have in mind is a Polini which I can get for $1200. Sorry I don't yet know the year or model. I understand this is a race bike and is not suitable for trail riding. He will only be riding on a mini race track. Will the bike still cool and run OK if he isn't riding at race speed?

The main question is can I some how detune the bike to roughly 5hp until he gets some seat time? I have access to lathes and mills so I can make restrictors for the intake or exhaust if needed. Also, the bike is 2-3" too tall. Can I lower it somehow?
 

David Trustrum

~SPONSOR~
Jan 25, 2001
1,396
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If you are careful you can make a spacer preventing the carb slide from fully opening. Make sure it cannot jam the slide but this should not be hard.

You could try bending the reed stops in a bit but I would go with option 1 as it is simple & easily tunable/removable. You could add a section into the header &/or dwell section of the pipe but this will be a hassle for a temporary mod when the little monster demands more power after a month (or a day).

Try taking the seat foam off & carve some from the bottom of the foam. Retain it so it can be put back in when junior experiences another growth spurt. Or get his boots built up with an extra sole at a boot repairer.

You can take shocks & forks apart & fit spacers limiting damper travel but I suspect the cheapo shock will not be rebuildable.
 
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