what it do to everyone

Discussion in 'Introduce Yourself' started by thuginfc, Sep 22, 2009.

  1. thuginfc

    thuginfc Member

    alright im new here (well been a member but have just been reading all the useful posts) i have had all kinds of problems with the mounting of theese chinese 80cc 2 strokes the first one i had bought onthe bike already 3 days old from a freind who broke the mounting bolts off in the motor i drilled and tapped and everything was dandy till the nex day of riding i look down and no bolts holding rear mount.Realized that i was 30 miles from home so tried to baby it back home but it cracked the crankase on the front mounting bolt.(probably my fault) So i just order a fresh kit to throw on the bike used rubber insulators for vibes and sick bike parts bolt kit and only tightened mounting bolts to a little under 10 ft/lbs it was running fine until i look down one of the rear bolts were gone(broke inside motor) this time i tried using a screw extractor and it too broke off inside. was pulling the crankcase apart to take to machine shop to have better mounts welded on but the crankcase kinda crumbled apart in my hands as i was taking it apart. Odered new crankcase and gaskets and have 2 complete kits for parts


    My main questions for you all are:

    How do you split crankcase without damaging it?

    How tight do motor mounts need to be?

    why do theese things snap bolts off in them so easily even grade 8?

    also how long should i expect to ride on of theese jet black motors for before having anymore serious problems?


    also will post pic of my ride when i get my iphone cable from my house
     

  2. Welcome to the forum.
    Usually two stroke engines on dirt bikes etc use a special crankcase splitter tool(Check ebay). Although I haven't pulled one of these little bike engines apart yet(Crankcase) ,it should be pretty easy. I have done dirt bike 2 strokes & many others though. Just unbolt it & separate the two halfs,but don't force anything & pry on any machined gasket mating surfaces or you will damage them easily. Do a search on this site & the other web site motor bicycling forum & ask the other members. I'm sure someone has. After many years of being a professional auto & aircraft mechanic you get a "FEEL" of how tight a bolt or nut should be without over tightening or breaking it on non critical components. All nuts bolts & screws are required to be torqued to specs on aircraft. I can tell you from experience that 10 foot pounds of force on a small 6mm bolt stud is too much. You should be using inch pounds on small bolts & nuts not foot pounds. I just did a google search & found a Honda recommended torque for a 6mm bolt or nut to be 7.2 foot pounds or 86.4 inch pounds (Just multiply foot pounds times 12 to get the required torque in inch pounds) and use medium strength lock tite also to prevent them from coming loose. Also make sure the bolts or studs are not being bent or twisted when they are installed. If you have any other questions just ask me. TTL
     
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