Offset Timing On Tecumseh

[GoAlterBridge]

Hi everyone, I got a minibike I started a while back up and running. It's using my old Tecumseh 5 HP. I've done a little porting and polished the intake and exhaust, also ground down the eyebrows, and increased the compression. It pulls me up the small hill in my driveway okay, but I want a bit more power and/or top end. I know that they don't make offset keys for Tecumseh like they do for Briggs, and I'm trying to find a different way to offset the flywheel. My question to you all is whether the person that answers a question in this ( http://en.allexperts.com/q/Small-Engines-Lawn-1746/2009/8/tecumseh-14hp-timing.htm ) link is correct in saying that you can shift the flywheel forward without a key in since, "The key doesn't actually hold the flywheel in place, it's just a reference."
If so, that would be really cool. Sorry I made it real long, and I hope someone can make sense of it.
Thanks guys.

 

[toofarnorth]

It seams like the flywheel would eventually move on the crankshaft with no key, you hear about people that have sheared their flywheel key so it must be holding something. Have you thought about elongating the holes in the coil so you can shift it forward?

 

[freakboy]

retard the cam timing by a few teeth or is this a OHV? 5 HP go about 5 or 4 teeth clock wise.

 

[Russ2251]

retard the cam timing by a few teeth or is this a OHV? 5 HP go about 5 or 4 teeth clock wise.

Please back this up.

 

[Rickracer]

With the cam even one tooth out of time, it will not run. what I would do is file about .020" off the flywheel key (left side, facing the end of the crank, and off the top part only if possible), then rotate the flywheel in the normal direction of rotation against it while tightening. You can run without a key, but you must lap the flywheel and crankshaft with valve grinding compound for a perfect fit before doing so, or it will shift and throw the timing off, usually at the worst possible time.

 

[Kaptain Krunch]

retard the cam timing by a few teeth or is this a OHV? 5 HP go about 5 or 4 teeth clock wise.

a few TEETH??? Man your engine must be magical if it runs like that.

And yes, flywheel key is necessary, I've sheared a few keys in my day, plus have fun getting it accurately advanced.

 

[jr dragster T]

I don't see any engine running with your cam timing off + - 4 or 5 teeth. That's enough to pretty well go from the base circle of the cam to halfway up the nose. Without a load of lash I don't even see the cam sliding in.

 

[freakboy]

my freind did that to his racin mower 8 teeth and it worked great acctualy. just try it.

 

[Russ2251]

my freind did that to his racin mower 8 teeth and it worked great acctualy. just try it.

Please back this up.

 

[freakboy]

i will when i get back in school and my freind can give me the web address to post it here

 

[jr dragster T]

Sorry, My piston and valves have a 0.90" restraining order. I'd hate for them to meet each other.

 

[CoyCaller]

Try this:

Buy a Briggs and Stratton offset key.

Get a micrometer and measure the offset.

Get an new key from the hardware store.

Get a file or a carbide bit with a sharp angle for a dremel.

Make your own key.

Use the Briggs key as a reference for degree of offset.

Just an idea.

 

[freakboy]

works only on flat head tyler it would be dumb for doin it on a ohv engine

 

[jr dragster T]

works only on flat head tyler it would be dumb for doin it on a ohv engine

I see....

 

[freakboy]

Around 2 tomorrow i shall get the link up if i can remember to ask him and if the internet in school isnt COMPLETE ****.

 

[jr dragster T]

Sounds good.

 

[freakboy]

i belive what he said was it opens the valves up earlyer when the pistons going down and last longer it sucks more fuel and air in there and closes when it starts going back up.

 

[jr dragster T]

But usually in a 4 stroke timed in properly the intake valve cracks open about 3* in the hole and stays open for about 75% of the intake stroke approximately. 4-5 teeth is ALOT and I mean ALOT of timing.

 

[Rickracer]

I still say....

With the cam even one tooth out of time, it will not run....

 

[freakboy]

http://www.camcraft-cams.com/index.php?page=tuning-tips

gotta apply the same consepts.