Broken engine mount screw-tapped to big

TheRealDune said:

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?

Click to expand...

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.

http://www.autozone.com/autozone/ac...ir-system/_/N-26gb?itemIdentifier=516472_0_0_

New case for $15 plus shipping
http://www.kingsmotorbikes.com/bike_motor_part_crankcase_body_66cc_2450_prd1.html

best wishes

Map

Never use any thread lock type materiel. Except now. Map knows, and he told ya.

When you say install a new case , I hope you realize you'll be tearing the motor completely apart .

Wow....... that hole must have got wal-erd out bad.......!

There are other ways to fix that thread in the case but it takes the right stuff and the know how, I have included a link here that shows how simple it actually is if you have the tools, a simple propane torch, a power drill of some type, a small Stainless steel brush, a small can of acetone or just a can of carb cleaner, some aluminum brazing rod and asmall grinder or just a simple Bastard file, correct drill bit and M6x1.00 thread tap and you can make that thread good as new and actually stronger than the aluminum itself. I've used the stuff and it the aluminum is CLEAN.... and its used right it works great.

By the way you dont need to have a gas grill to heat the engine, that would be a disaster and blow the grill sky high probably.....LOL! just get inside a garage or work shop or in a place out of the wind so you can see what you are doing and there isn't air or wind blowing against the aluminum you're working on because aluminum cools quickly and you have to maintain the temp for the brazing rod to flow correctly and bond right.

http://youtu.be/TaSORWC-BMU

As Huffy D said, you will be taring down the engine completely if you replace the case, it isn't hard to do if you are fairly mechanical minded and you have the right tools for the job.

vids that show most of what you will encounter with a tare down.

http://youtu.be/kRAb-wLfTok (tare down)

http://youtu.be/m110nAUyDQw (back together)

Hope this helps

TheRealDune said:

thanks map I really appreciate all the help, I will be studying these

Click to expand...

You're very welcome, I just hope you can get the problem resolved asap and get back to riding, I know these things can be frustrating but there are always new things learned when we have to do a fix for the first time.

Map