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Old 08-30-2013, 05:00 PM
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Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: Broken engine mount screw-tapped to big

Originally Posted by TheRealDune View Post
Hello everyone, my trouble is consistent with my new hobby. I came back from a ride to see that my engine mount screw on rear of engine was missing....Wait a minute its not missing its broke inside of the engine case. Ok , figured out I needed to drill screw out since it was broke deep inside of case. Drilled out, bought all thread m6-grade 10.9 so this would never happen again, bought tap and die metric set. Came home cut my engine mount bolts from 1 meter all thread, screws cut perfectly. first screw went into engine mount hole that was fine, tapped the other hole but now it looks bigger than the other one ... So now my new bolt slides into the hole without grabbing the case.....once again I am in another dilemma.....I found helicoils at hf for 4 bux, they have 3/8 and 1/4 ,not sure which one to get and it only comes with heli coils, no tap no thread starter tool just coils....can I use my metric tap set to tap the hole for the helicoil to fit in or do I have to use a special tap that comes with more expensive kits on the net?
At my local Autozone auto parts store they sell kits with everything needed to tap the hole and install a helicoil/thread inset for the original M6x1.00 thread stud, you can also thread it up to 1/4-20 size if the hole isnt to wall-erd out.

Yes they ain't cheap and you can probably buy a new engine case for what the kit cost, but it is a simple and easy fix that will get you back on the road quickly and that set of threads will be bullet proof from there on out, use loctite on all the mounting fasteners, had the same issues when I built my first bike, loctite was the cure for all of my engines fastener issues.

New case for $15 plus shipping

best wishes

I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!
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