What a leak down / compression test WON't find...

[TownsendsFJR1300]

Not Yamaha (or marine related but it's slow here).

A small, 2 stroke weed eater that would not start...


There are two tabs bolting the lower end to the top end-major vacuum leak to say the least.

The BROKEN bolt was from the tab that was NOT broken.
The intact bolt held the broken tab nice and tight (with a Loctite)

The black "string like thing" is the o-ring that seals the two cases (that blew out).

A parts machine now...

[walleye1]

Weld the tab back on.

[TownsendsFJR1300]

Weld the tab back on.

The other broken bolt is loctited in the other side. To tear down, weld, re-assemble would cost easily twice the price of a brand new machine..

I did get the customers other 4 stroke machine running again-so he does have one machine..

[zenoahphobic]

Looking at the photo, I take it the conrod is broken. So there was a catastrophic failure that forced the head to separate from the case
Interesting two bolt flange design with an orang. I wonder if the loctite was used at manufacture to supplement the strength that just seems inadequate provide from those two small bolts on their own?

[TownsendsFJR1300]

Looking at the photo, I take it the conrod is broken. So there was a catastrophic failure that forced the head to separate from the case
Interesting two bolt flange design with an orang. I wonder if the loctite was used at manufacture to supplement the strength that just seems inadequate provide from those two small bolts on their own?

Nope, conn rod is fine... Spins over great! Why the initial broke bolt and the other tab broke, I've never seen that before.. No outside apparent damage(like a major drop). Loosening, yes...



My favorite, personal weed eater is similar to this one with just TWO bolts holding the cylinder/head, to the lower crankcase.

When the idle rised and I could not get an adjustment (normal idle speed), I eventually found the cylinder loose from the block (not as bad as this). (It was leaning out with the crankcase leak)
I took a lazer temp of the block running, it was well under 200F degree's. Pulled mine apart, needed a new base gasket, trued the one surface with a file (the tabs were bend some).

*Red Loctite is good for a bit over 400 degree's F.*

Cleaned everything spotless, re-assembled and used a BUNCH of RED Loctite on those two bolts.
That was at least 3 years ago, still running like a top...

Basically, a cheaper machine. Better machines, use 4 bolts. My "back up" weed eater, uses 4 bolts and has TWO main crank bearings, NOT 1 (as pictured above). I don't use that often as it's set super lean from the factory with NO carb adjustments to fatten the mix. Once warm, it's not bad..

[zenoahphobic]

I see the conrod clearly in your second picture. That first picture shows it pointing upwards away from the cylinder whichever way I look at it.

So the repair would only be to reattach (weld) that lug, a new bolts and perhaps a new O ring. If there was more meat left on the flange you may have gotten away with assembling with the broken bit and cap off with a solid washer. Done that before on broken model engine mounts.

[walleye1]

Won't tell you if you have a bent rod eather.

[TownsendsFJR1300]

I see the conrod clearly in your second picture. That first picture shows it pointing upwards away from the cylinder whichever way I look at it.

So the repair would only be to reattach (weld) that lug, a new bolts and perhaps a new O ring. If there was more meat left on the flange you may have gotten away with assembling with the broken bit and cap off with a solid washer. Done that before on broken model engine mounts.

He dropped of another 4 stroke edger (major knock inside besides other things)..


I showed him the broke flange and broke bolt. He said he was just using it, then heard a noise.

I suspect either the one bolt fatigued and broke first, or the tab, then the bolt.

The broken bolt in the block alone (to access-FULL TEAR DOWN), and remove would be several hours alone.
Plus pay someone to weld it? I wouldn't do all that work on MY machine, it's simply not worth it. Much cheaper to buy a new unit (maybe $100.00)

[TownsendsFJR1300]

Now this one was fixable (some welding too to the belt enclosure)


How's this old belt compare to the new belt?" Basically, 4 standard "V" belts, BUT as ONE belt:





New belt installed:




The beast:

[99yam40]

those teeth do not look very sharp.
how wide is that belt.
I need to get a pic of the old stump saw in the old barn that is falling apart.
granpa used it back in the old days(40s or 50s I guess) to cut off stumps at ground level

[TownsendsFJR1300]

those teeth do not look very sharp.
how wide is that belt.
I need to get a pic of the old stump saw in the old barn that is falling apart.
granpa used it back in the old days(40s or 50s I guess) to cut off stumps at ground level

That belt is about 4" wide, $40.00.

The tips are not sharp at all. They have 3 "corners" (if you would to rotate them around in 3 positions).

My customer wanted the rounded (worn headed) teeth removed and rotated.. Easier said than done..
Busted the one hardened cutting tip trying to get it out (with an air hammer as it was rusted TIGHT in there-nature of it's use)

He needs to pick up more cutting tips and I'm going to try knocking them out from the center of the bolt (combo bolt/cutting tip).

I can get em out, just a matter of if they'll get destroyed or come out in one piece...

The nut's that hold them on are just about round ("sanded down", round from a 6 point)

[walleye1]

Pick up a nut splitter.

[99yam40]

that was my 1st thought also, but I cannot see the nuts to tell if they are in the open enough to get a splitter on them.
Nut splitters work well and you do not have to beat things to death with a chisel and hammer or air chisel

[walleye1]

Gas ax will work too

[TownsendsFJR1300]

The nuts are about rounded off. I was lucky the wrench even grabbed them..

*On a Yamaha note, cleaned a Yamaha golf cart carberator last week, (the owner brought me JUST the carb, (couldn't transport cart here).
He needed a new intake gasket and installed it along with a new vacuum fuel pump in the last day or so. Still wouldn't run.. ;(


Went over there (hate house calls), disconnected the drive belt for safety.

Fuel pump was working, carb getting fuel, a spritz of starting fluid down the intake, nothing.

Spark tester installed in-line, firing off... Grounded the plug to the block and while cranking, spark would come and go.

Inspect a bit closer, I can literally move the inside insulator and "internal wire" ever so slightly-NOT good, but good for me!!


Threw another spark plug in (too short, wrong plug but correct threads). FIRED RIGHT UP!! (Then removed that plug)


Re-installed the drive belt, the owner had a new, correct spark plug ordered AND was a very Happy Camper!!