10 H.P. Tec. Issue

[DSLDAW]

Hi, Does anyone know about a starting issue on Tec's where the recoil
starter keeps locking up solid,just about every other pull? I can feel air coming out of the head at certain times during the cycle,but doesn't
the exhaust valve open up for the air to go into the exhaust manifold
only,or is the some sort of vent in the head? Or is there something
seriously wrong with this brand new engine? It's very hard to start,
choke or no choke on,but runs great once it takes forever to start,so
I'm very confused as to what's going on with this engine? Please help.
thanks

 

[Motra]

By "locking up" do you mean it is very hard to pull through the compression stroke or that you actually need to do something?/change something?/repair something? to get it to eventually start? You might be having a problem with the compression release making it difficult to pull.

 

[DSLDAW]

By "locking up" do you mean it is very hard to pull through the compression stroke or that you actually need to do something?/change something?/repair something? to get it to eventually start? You might be having a problem with the compression release making it difficult to pull.

It will actually lift the bike in the air as I'm pulling the cord at certain times,
once it totally jambs up. It's beating me up,since I have to put my foot on
the rear axle to keep it on the ground when it locks up. It's weird,since when
it locks up,if I go to pull it again,right away,it will still be jammed,but if I wait
a few seconds,it will pull through one complete cycle again.I heard of people
saying there was some sort of mechanical or electric release button or cable
these engines have on some equipment,but this engine came off a genie,just
the way it was.At first,I thought it was vapor lock,but disconnected and
emptied the fuel delivery to the carb,and the same thing. What's really weird
is when I first ran the bike,with a few once gas tank from my RC car,I don't
remmember having any starting issues. That plastic tank was wide open,with
the fuel cap loose. I put a new Honda tank on the frame,and it seems,that's
when it started. Even with the cap off the tank,still the same,so I pretty
much think it's not vapor lock,what do you guy's think? Thanks.

 

[Motra]

It sounds like a compresion release issue. The carburetor on those is mounted low on the engine so if fuel was leaking past the float needle it would just leak out the back side of the carburetor and come out the air filter, it wouldn't run uphill to the engine. The compression release is an internal mechanical part that operates automatically every time you start the engine, there's no external button or cable, and if it isn't working correctly it would cause the issue you're talking about (it would lift the bike off the ground). You might even try changing the oil to a 10w-30 (make sure the engine is at running temperature first). If it has a thick oil in it and you're in a colder climate there's a ton of drag when everything's cold.

 

[Ruppster81]

Not sure if your engine has it but some have a flywheel brake. I think it goes on the inside part of the flywheel so check for that maybe?

 

[DSLDAW]

It sounds like a compresion release issue. The carburetor on those is mounted low on the engine so if fuel was leaking past the float needle it would just leak out the back side of the carburetor and come out the air filter, it wouldn't run uphill to the engine. The compression release is an internal mechanical part that operates automatically every time you start the engine, there's no external button or cable, and if it isn't working correctly it would cause the issue you're talking about (it would lift the bike off the ground). You might even try changing the oil to a 10w-30 (make sure the engine is at running temperature first). If it has a thick oil in it and you're in a colder climate there's a ton of drag when everything's cold.

I'm in Central Florida,so the synthetic 10W-30 should be fine,since it's kept
in my garage all the time.Thanks for the info. It's got to be an issue with the
compression release mechanism.I did turn the air filter bracket 180 degrees,since it was interffering with the jackshaft bracket,but that shouldn't
have mattered at all. I'll try to get an expanded schematic of the engine,to
see what's up with the release mechanism and maybe see what could be
causing this issue.I do feel air coming out from the side of the head when
the cylinder is on the compression stroke,so I'm still lost to what else could
be doing this. The engine does run fine,once it starts,so a warped cylinder
or something,just doesn't sound like it's the issue.Thanks again for the feed-
back.

 

[Motra]

Yeah if compression was leaking due to a head gasket problem it would lessen compression and cause the opposite situation, it'd be easy to pull. These engines are "forced air cooled" which means they have a fan that blows air over and around the cylinder and head area so is it possible you're feeling that air?

 

[DSLDAW]

Yeah if compression was leaking due to a head gasket problem it would lessen compression and cause the opposite situation, it'd be easy to pull. These engines are "forced air cooled" which means they have a fan that blows air over and around the cylinder and head area so is it possible you're feeling that air?

You may be right. It does have a plastic fan that's mounted between the
flywheel and recoil starter. It felt as if the air was coming in the opposite
direction from the head and not in the direction that the fan blows toward
the head.It felt like a vent was just opening up at certain times,during the
compression cycle. I don't recall any other small engine I've seen,that has
a compression release mechanism on it. The mechanism should be mounted
on the cam,don't know exactly how it works,or why it may not be functioning
correctly? Anyone know about these release mechs? Thanks.

 

[Motra]

All of the 4-stroke small industrial engines have an automatic compression release. Normally they operate on the exhaust valve, they very slightly and very briefly open the valve on the upward compression stroke at cranking RPM. Once the engine starts the mechanism rotates by centrifugal force so it doesn't contact the valve lifter at running RPM. You're right, it is on the camshaft. There's a small spring on it that may be damaged or it could just be sticking.

 

[DSLDAW]

All of the 4-stroke small industrial engines have an automatic compression release. Normally they operate on the exhaust valve, they very slightly and very briefly open the valve on the upward compression stroke at cranking RPM. Once the engine starts the mechanism rotates by centrifugal force so it doesn't contact the valve lifter at running RPM. You're right, it is on the camshaft. There's a small spring on it that may be damaged or it could just be sticking.

Thanks so much. I'm glad to hear that someone has some knowledge of
what's involved with the release mechanism. The engine was brand new,
came off a Coleman Genie that just sat in my garage,waiting for a Hurricane
to hit Fl.,which never came,and I needed an engine to get my mini on the
road,so it came out. The really bad part was,that this 10HP Tec,should
have a 1" crank bore,but this one was a special 7/8" one,which really pissed
me off.I did the impossible,took a 4" Makita grinder to the tapered shaft and
ground it down by hand,to 5/8",so I could put a new centrifugal clutch I
had bought.A 3/4" would have been less grinding,I know,but I got it for
another engine,that just didn't cut it. I took my time and the crank came
out so concentric,that you'd think it was cut on a lathe,no wobble or nothing,
got super lucky. It was a stupid idea,but it did the job and I got the clutch
to fit perfect with no vibrations or issues. I had no problems besides the
pull cord locking up and the engine not starting well either. It would take
a good 20 minutes of getting all scraped up,while I played with the choke
and had the bike flying through the air on every other pull. That's why I gave up and just dropped the Honda 5.5 in.It would start on the first pull,every
time,so who needs to keep getting beat up,just trying to start a minibike?
I'm sure I'll miss the great torque of the 10HP,but with a lot less aggrevation,
I'll be much happier.Thanks for the info.:grind: