Tighten your bolts!

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likearock111

Guest
Hey MBers,

I just wanted to put a little note up here regarding my own difficulties with my 70cc 2-stroke, so maybe other people can learn from my mistakes. Always Always ALWAYS check your bolts for tightness after every ride. I used to be in the habit of checking them every 8-10 rides or so (most of mine are short, ~5 mile joyrides). Not only was this bad for performance, it was also probably pretty unsafe. Well, I've changed my ways.

A while back, my engine started having the typical "bogging" symptom after a certain amount of time spent at WOT. The threads on here pointed me toward checking the carb and checking for air leaks. So, I took apart the carb, cleaned it, rebuilt it, replaced the black rubber o-ring I had installed between the intake manifold and the carb, and sealed it all up extra tight. I also replaced the intake and exhaust gaskets.

None of this worked. And, on top of everything, it started leaking black semi-burnt fuel/oil. In the process of trying to figure out where the heck the black stuff was leaking from, I discovered that one of the bottom 4mm bolts that holds on the left-side front cover had completely fallen out, and the other three bolts were pretty loose. I don't know what you call this cover, but it's just in front of the cover that goes over the drive gear. So, long story short, I replaced the missing bolt, LocTited all of the main bolts on the engine, and now my engine runs better than ever!

So, moral of the story: check your bolts! It might save you some frustration, money, or even some road rash.

-Rock

PS: Mods, this may go better in the 2-stroke section, since it has to do with HT performance. I was just thinking that tightening bolts is more generally applicable than just 2-strokes. Either way.
 
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L

likearock111

Guest
I decided to replace my fuel line today. When I went to twist off the auto-grade rubber fuel line from the petcock (using very little force), the stock petcock literally broke in half at the base of the threads, next to the gasket. :( Must've been a hairline crack there, or something. At least it didn't take too much effort to fish the threaded portion out of the hole, though. Now I need to try to hunt down a 10mm, 1.0 thread pitch fuel petcock before this weekend.

Any suggestions? Do moped stores carry these things?
 

BradJ80

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Might be a bit difficult to find a M10x1.0 threaded petcock quickly. Perhaps you could locate a M10x1.0 barbed hosetail fitting from a industrial fittings/plumbing supplier, and buy an in-line petcock?

Hopefully you can get the broken off section out of the tank.

Also, I used loctite on EVERYTHING. Be careful which loctite you use because some loose strength with heat.
I also replaced most bolts and nuts with quality locally made parts.

Brad
 

Mountainman

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Kind of wondering about these petcocks -- my friends broke in the same place -- not even a hundred miles on his MB... Anyway -- if needed an easy-out should make for quick removal of broken part in tank -- handy tools to have around... Your local lawn mower shop may be the fastest place to find a new petcock - or Napa Auto Parts -- if you are not wanting to wait for UPS from the web... Happy Riding from - Mountainman
 
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I decided to replace my fuel line today. When I went to twist off the auto-grade rubber fuel line from the petcock (using very little force), the stock petcock literally broke in half at the base of the threads, next to the gasket. :( Must've been a hairline crack there, or something. At least it didn't take too much effort to fish the threaded portion out of the hole, though. Now I need to try to hunt down a 10mm, 1.0 thread pitch fuel petcock before this weekend.

Any suggestions? Do moped stores carry these things?

I believe reading other posts from Pablo the petcock is 1/8'' npt...
 
L

likearock111

Guest
There's a lot of good input here. Thanks, Brad, Mountain, and Mister! I think I'll see what my local Napa can do for me, and maybe go the hosetail + in-line petcock route.
 

Skyliner70cc

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The stock petcocks often break if overtorqued. It often is necessary to overtighten the petcock to get that stock junk gasket to seal properly. I use a softer gasket and use threadseal so I can tighten the petcock to a reasonable level without worry of a leak.
 

D_M

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I decided to replace my fuel line today. When I went to twist off the auto-grade rubber fuel line from the petcock (using very little force), the stock petcock literally broke in half at the base of the threads, next to the gasket. :( Must've been a hairline crack there, or something. At least it didn't take too much effort to fish the threaded portion out of the hole, though. Now I need to try to hunt down a 10mm, 1.0 thread pitch fuel petcock before this weekend.

Any suggestions? Do moped stores carry these things?

When I went to Lowe's yesterday to hunt down a chain (no luck), I looked through their small engine aisle (the one with the chainsaws in my local store). They have a selection of small engine repair/maintenance parts, like Briggs-Stratton filters, etc. They also have some fuel filters and a package that says something like "universal fuel hose with shut-off." Looked like it would work.
 
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