GAB Version CHEAP.0 Tecumseh OHH50 172cc 5HP

[bob58o]

First test run was good.
I used the muffler to make sure I wasn't too lean.

The wheelie power that I forgot about since I learned how to ride it on day one, has once again returned and surprised me a bit.

After getting used to how it was to ride, NOW I popped the wheelie up again.
NICE!!!!
The governor is still in, but there is a noticeable difference. Nothing crazy drastic, but noticeable.

One burn on my hand from fixing the clip that attaches the governor arm to the carb.

One burn on the back of my knee from walking back off the bike and hitting the exhaust.

At least it only hurts in one spot, right???


On the fence about removing the gov.
I've read Tec rods break at normal operating speeds?
I've also read removing the gov doesn't mean that many more RPMs?
I've considered adjusting the governor linkage as well.

Hmmm?
$60 for a rod on a $40 engine, that I put $75 into and may be removing with no future plans??????

 

[bob58o]

Looks less burny?
Check out the hanger for the exhaust.

 

[bob58o]

Here.

 

[bob58o]

Bike stand.

 

[bob58o]

Without reading the new plug yet....
I'm guessing it should read lean when I take it out.

I think these types of carbs (on utility engines) are jetted lean, at least in the past decade or so.

Free flowing intake and exhaust should make it leaner. I am running the muffler to be safe at first.

I have opened up both the pilot and main jet by 1 bit size, but think I am still lean.

It is hard to start cold. No choke, so I still must keep priming the carb. (About same as when I first got it stock).
There is a bog when wacking the throttle from idle.
I guess even 4 stroke carbs with Accelerator Pumps experience this "Dreaded Bogg" when whacking the throttle from idle.
Soooo I may be overreaching by thinking I have the knowledge or experience to "Cure" the "Bog".
Some say, "That's how you have to drive a 4-stroke, Roll into WOT gradually".
I say one or more of the Circuits just needs some GAB.
I may try to mess with the "Transition Holes / Progression Holes" behind the Welch Plug.

There are such things as lean bogs and rich bogs I guess.
I find it hard to believe that I will be too rich, but one size was a 25% increase in pilot jet opening area, so it may be possible.

Going to ride for about another 15 minutes (to let the bike warm up and give about 30 minutes of total riding on this plug) then kill the engine and see how it starts once warm. After that I can try some plug readings.

---------- Post added at 09:56 AM ---------- Previous post was at 09:08 AM ----------

Technician's Handbook.

Like 100 pages.
http://www.manualslib.com/manual/801502/Tecumseh-Ohh50-65.html?page=1

RN4C!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
WONDER WHY THE SHORT PLUG IS USED??????????????
Going to try the E3.18
With techumseh, OHH is overhead valve horizontal shaft. OHV is over head valve vertical shaft.
I wonder if OHV is used for Over Head Valve in this case?
http://www.homedepot.com/p/E3-13-16-in-Spark-Plug-for-4-Cycle-Engines-E3-18/202279704

 

[bob58o]

So much stuff in the technician's manual.
What a score!!!!!
Who'd a thunk I could tell you what cutter is needed for valve seats?

 

[bob58o]

Took the E3.12 out. Looks lean. Very lean?
Maybe I can exchange it again, back to the E3.18? Lol
That is with the muffler. I will be working on adjusting my non adjustable jets with no extra jets!

 

[bob58o]

The E3.18 fits.
I also turned the engine over a few times to make sure nothing was hitting.
The piston on the plug or the Valves on the Plug.

Seems OKEY DOKEY to me??

Boosted Compression Here we come!!! LOL
I'm guessing ~1.5cc which is surprisingly significant.

If CR was ~8.0:1 then the Compressed 172cc would fit into a volume of 21.5cc (seems reasonable with stock gasket and deck height????

Now compress that same 172cc into a volume of 20.0cc (1.5cc less) and you get...

172/20 = 8.6 CR!!!!

Can't find what stock CR was, but it was less with the smaller plug.

0.7cm*0.7cm*3.14159*0.95cm = 1.46cc

---------- Post added at 12:27 PM ---------- Previous post was at 12:20 PM ----------

Wish drilling the idle jet didn't require removing the carb.
Going to add fuel cut off valve inline to replace damaged section of hose.
Hopefully this will prevent vise grips from damaging the fuel line any further during the jetting process.

Going to work on the main jet first.

Using the muffler as a "Safety Stop", going to go up in main jet size until I am happy.
Then I will work on the Low Jet in a similar fashion.

Then I will take the muffler off and repeat the process.

 

[bob58o]

Shut off valve.

 

[bob58o]

This hole was partially blocked I think.
It supplies fuel to the Idle Circuit according to this picture.
I tried to poke a bread tie wire and thought it was too big, then POP - through it went.
Looks like some gunk on the wire (maybe still from the insulator I stripped off?).

Any whhoooo, going up in main Jet size!
Where was I, 0.037"?

Lets try 0.038"
and hope it starts better and has better throttle response?

 

[bob58o]

This carb has 22mm ID on the Air Filter Side
The venturi is 13mm ID on the Dark Side of the Moon.

---------- Post added at 01:55 PM ---------- Previous post was at 01:23 PM ----------

The i found 0.039" before I found 0.038"

I measured at 0.99mm which is like a #99 Jet by some standards.
0.03897"

Stock was like 0.0358 (0.91mm) or a #91 Jet

17% more jet opening area vs stock.

Not sure the relationship or base numbers, but an example of 17% increase in AIR flow would be taking

35 CFM

to

41 CFM.

Or from 30 CFM to 35 CFM.

This seems at least ball park (or order of magnitude) reasonable.

 

[bob58o]

Poking that little hole made starting and idling 1000 times easier.
That must have been ONE issue.

Also I learned what the lean "BBWOOOOGGG" sound is.
It only sound like "BWWWOOOGGG" cause somebody said so.


Bog still there, less noticeable.

Spark plug looks too clean
No noticeable smoke ring.


Moving quickly along to 1.05mm or #105 jet or 0.04134"

https://www.youtube.com/watch?v=wWf3uzxOdKI

 

[Hellion]

Post #90 brings back memories from a few summers ago. I also poked some fine wire through that very same hole and found success.

Stay away from ethanol in your gasoline if you can. Ethanol draws in moisture and H2O in your gas is bad news. That's the main carb killer in my estimation.

 

[bob58o]

Progress!
Plug getting a bit darker.
Bog getting better.
On to 1.10 mm

---------- Post added at 04:26 PM ---------- Previous post was at 04:21 PM ----------

Fishtails on a minibike (in wet grass)..
And rolling wheelies (on the street)...
Most fun I've had all week!!

Wait until I take this muffler off!!!

---------- Post added at 04:54 PM ---------- Previous post was at 04:26 PM ----------

Post #90 brings back memories from a few summers ago. I also poked some fine wire through that very same hole and found success.

Stay away from ethanol in your gasoline if you can. Ethanol draws in moisture and H2O in your gas is bad news. That's the main carb killer in my estimation.

Joliet Airport has 90 octane ethanol free for under $4 a gallon.
Can fill Red Gas Cans!!

https://m.youtube.com/watch?v=UPbymWrqXGc
It's got a Cop motor so it'll run good on Regular gas! LOL


---------- Post added at 04:55 PM ---------- Previous post was at 04:54 PM ----------

Without the muffler safety stop, I'd be afraid to go up to 1.10mm, but here we go.
One more test before work.

 

[Flyinhillbilly]

This is why I love my doodlebug.

 

[bob58o]

This is why I love my doodlebug.

I assume you mean the fishtails and wheelies!!

---------- Post added at 09:25 PM ---------- Previous post was at 09:23 PM ----------

The 1.10mm started to show some color on the plug.
Also seemed like more HP at top speed.
Took longer to slow down when killed?? Same gov settings so must of been more torque??
Moving in the right direction.

Want to look rich with the muffler before I take the muffler off.

1.15mm main jet is next.
Is it just me or is this hole starting get big???

---------- Post added at 09:31 PM ---------- Previous post was at 09:25 PM ----------

Want it tuned to slightly Rich in this 80 degree weather,
So it won't be too lean when driving in winter's 30 degrees F

 

[bob58o]

On to the next one.

1.15mm = 0.0453"

I guessing this will be close to where I want to be with the muffler.

It will be too rich when I start to loose top end power and the plug looks dark like milk chocolate.

Once I reach a point where power is dropping or plug looks darkish, I will take the muffler off and continue.

NASCAR RAY SAYS I SHOULD KEEP A NOTEBOOK. HE MUST NOT READ MY THREADS!!!!

Who can watch this garbage???????
https://www.youtube.com/watch?v=FC6biTjEyZw

---------- Post added at 01:54 PM ---------- Previous post was at 01:11 PM ----------

I've just read that the Briggs Flathead Springs work in the Tecumseh OHH engines.

http://www.dynocams.com/category/springs-flathead/
1.36" - 1.49", 16lb - 22lb.

Some of these engines have a plastic cam gear?
Here is a steel one that supposedly fits if you have a plastic one.

Tec 33158 / 37040
http://www.psep.biz/store/tecumseh_camshaft.htm

---------- Post added at 01:59 PM ---------- Previous post was at 01:54 PM ----------

Nascar ray also says my exhaust's diameter is too small and the exhaust is too restrictive.

When nascar ray has a minibike that beats me in a race, i'll change my exhaust.
Until then, i say prove it!!!!

---------- Post added at 02:51 PM ---------- Previous post was at 01:59 PM ----------

OK,
Just test drove the bike with the 1.15mm (0.04527" Diameter) Main Jet.
Still with muffler.

Bog seems gone (or at least minimal).
Didn't notice an increase in Power over the last jet size.
Possibly less power, probably very similar.

I think it will be a little darker if I look at the plug.

If I had to guess, the top end is a little rich, but this helps with the bogging issue.

Now that I am close, I am confident that I can work on the bog/idle/starting without enriching WOT too much.

Time for a plug reading. Hopefully is looks dark enough for my liking, then I'll take the muffler off and Fine Tune.

I will get WOT where I like it with the main jet, then if the bog returns without the muffler, I will start on the idle jet and progression holes maybe?

---------- Post added at 02:59 PM ---------- Previous post was at 02:51 PM ----------

NOTE TO SELF:
82 degrees F
61% Humidity
1.25 - 1.30mm main jet
With Muffler

This is the Main Jet Range I like at the moment with the muffler.

 

[bob58o]

I went bigger.
1.20mm. Starting to get silly???

Drove it for 30 minutes.
Did a 1/4 mile WOT run that finishes off with a steep hill slows down the bike.

How much I slow is my new Dyno.
Makes sense?
I swear this had most power.

Going to get some standard (non E3) plugs and start cutting

Or I will hook up the tach and see RPM at top of hill.

 

[bob58o]

So I went bigger?
1.25mm
15 minutes of driving. Same or better results on the full speed WOT HILL test.
Same or better results when Whacking the throttle Wide Open from idle and stop.
Up hill, from a stop, leaning forward, whacking wide open has no bog. It pulls the front up.
Same on flat.
Same down hill.

Throttle response is good from idle and from all other throttle positions.
It returns to idle nicely.

Keeps getting better and plug doesn't look bad.

Going to 1.30mm.
It is crazy right???

It is still not very easy to start cold. I will play with the idle jet later.

 

[bob58o]

Poker tourney.
Final table.

Note to self:
Folding a winner keeps you alive.
Calling with a loser sends you home.

Wish me luck even though it doesn't exist!!!