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Topics - Goeytex

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1
Coffee Shop / Rev Limiter Instructions Attached
« on: March 30, 2011, 03:47:54 pm »
Attached is updated instruction sheet for the Rev Limiter for those of you
that have one or are considering getting one.

Goeytex

2
Coffee Shop / Tachometer Adapter Plans
« on: March 15, 2011, 09:53:08 am »
Attached is a schematic diagram for a Universal Tachometer  Adapter for Briggs Engines. The diagram is divided in to color coded sectional blocks for clarity.

This device takes the signal from the kill terminal on a Briggs Ignition and converts it to a signal usable by any known tachometer, including Automotive Tachometers, Equus Tachometers,
Digatron, Mychron, etc.

The output is jumper selectable for the above via JP1 and is also jumper selectable for either 5v TTL output, 12v pulse output, or Digatron "Open Collector Output".

This device uses an inexpensive ($2.95) Picaxe 08M microprocessor to do most of the work. This entire circuit will fit on a 1.5" X 2.0" proto board from Radio Shack.  

The microprocessor is programmed via programming port J1 and a serial cable attached to your PC. The programming software is free from Rev-Ed. The serial programming cable costs about $7 or
you can make your own using an old serial mouse cable. Contact me for more info / instuctions.

The total cost to build this is about $20 assuming that you have a soldering iron, a volt meter and few basic hand tools. All of the components are available from either Radio Shack, Mouser, or
Spark Fun Electronics.  I can supply a pre-programmed microprocessor at cost plus shipping for those who just want to make the board and not mess with programming.

It you have ever wanted to to get into electronics and / or embedded microprocessors this would be a great first project.

The programming code is attached in file TA_Code.txt  I will be posting a 10 page DYI Instruction Manual on this in a few days.    

Bill

3
Coffee Shop / Rev Limiters Available
« on: March 04, 2011, 11:34:26 am »
As some of you know, I have designed and tested a Rev Limiter with a versatile tachometer output
for mower engines.

I had to turn down some of you that wanted to order because I got behind in
production and didn't think it was fair for you to have to wait.  

I am now caught up and can produce units faster and more efficiently.  Now it is 5 business days
from order to shipment.

Now is the time to order one these while I am caught up.  Here are the basic specs of what it does.

1. Dual Microprocessor Based.  
    One microprocessor handles the Rev Limiting function
    A second microprocessor handles the Tachometer Output

2. Rev Limit is user Programmable from 3,200 to 10,000 RPM with no chips to buy.
   Accurate to within 50 RPM.

3. Tachometer output compatible with inexpensive Automotive Tachs
    like Sun Pro and with single pulse tachs Like Equus.  Have now added a
    Digatron Compatible Output.

4    Can also Select either a 5V TTL output or  a 12v pulse output.  This gives
     the tachometer section a truly "Universal"  output that can work with
     just about any known tachometer.  Nothing like this on the market.   

5.  Remote warning LED can be Dash mounted that lights up when 200 RPM
     from the Programmed Limit.  ($8.00 Option)

6.  Designed to save your $$$ engine in case of a drive line breakage or other failure.

I decided not to raise the price.  So it is still 89.00 plus 7.00 Shipping in the US.  

I really need to sell a few more  of these to recoup my costs and to pay back my
investor who graciously helped pay for some of the development and component cost
to make this available to mower racers.

Contact me Via PM if you are interested.  Or by Email
  
bill.roth  <at>  comtrotech.com

Bill Roth  /  AKA Goeytex
PH:  512- 940 -3474

4
Briggs Flathead / RPM Question
« on: February 02, 2011, 12:39:10 pm »
I am developing an electronic ignition for Briggs & Tech singles which includes Flatheads
and OHVs.  Also Briggs Opposed twins.

What I need to know is what is the maximum RPM of your engine and the max timing advance.    Please give Engine type, RPM, and max timing 

Examples:   Flathead    6750     28 degrees
                OHV          7200     30 degrees
                Opposed    6250     25 degrees 

This is a poll to determine optimal coil selection and not meant to initiate a discussion on the virtues
or lack thereof of High RPM or Lower RPM engines or the best timing setting.   

Thanks

Bill

5
Coffee Shop / Hard Starting Solution
« on: January 21, 2011, 11:18:56 am »
Hard starting solution ?

I was reading in the pulling section, and it seems one method
of easing starting on high compression engines with a lot of
advance ... is to crank the starter for a while and then
turn the ignition on.  This gives the starter time to get
the flywheel up to speed and to develop inertia before the
ignition fires.  This is done manually with a switch.

This process can be done automatically with a relatively simple
circuit.  The circuit diagram is attached.  Feel free to build
it and use it.

How it works:

When the starter switch is energized a short pulse is sent to
the 555 timer chip.  The timer chip turns on the relay via Q2
and disables the ignition for a short period (250ms) based upon
the values of R4 and C2, giving  the starter time to get up
to speed.  After the 250 ms delay, the 555 timer times out,
and the the ignition enabled, and the engine starts. The delay
is adjustable via R4.  

6
Coffee Shop / Poor Man's EGT Recorder
« on: January 12, 2011, 09:22:19 am »
A poor man's peak temperature recorder can be made using 2 thermocouples and 2 Thermocouple amplifier chips connected to a low cost microcontroller. After the race or test run,  the recorder is connected to a PC or a laptop where the peak temperature is displayed along with the time and RPM.  So the PC display would look something like this.

EGT    RPM     Time  
1100   6240    44    


CHT    RPM     Time
244    5820    48


Interpretation :

At 44 seconds into the run the EGT peaked at 1100F and the RPM was 6240
At 48 seconds into the run the CHT peaked at 244F and the RPM was 5820

A real time display of EGT and CHT could also be displayed on the PC or laptop
in the shop or while the engine was connected to a dyno.

Cost ?   About $100

Yall let me know if something like this would be a useful alternative to
an expensive Datalogger like a Diagatron or a Mycron.

Bill                      

7
Briggs Flathead / Cranking RPM ?
« on: January 07, 2011, 08:40:41 am »
Hi,

Assuming a good starter and a fully charged battery at about what RPM will the starter spin a Briggs engine ? 

8
Coffee Shop / Poor Man's EGT / CHT Monitor
« on: January 05, 2011, 03:52:34 pm »
Get a PID Controller from EBAY.  Make sure it is a 12vdc model. 
These come with a  3 ft   "K" type thermocouple.

Has a bright  Digital LED Display that constantly reads out
temperature.

Panel mounts in the dash. 

Configure it so an alarm sounds or a light comes on when temperature
reaches a pre-programmed value that you set. 

Can be used either for  EGT or CHT.   Or use 2 and monitor both.

Total cost ?   36.00 ea  plus shipping.

PM me and I'll tell you exactly what to get. 

9
Briggs Flathead / Electronic Ignition Design
« on: December 15, 2010, 06:36:49 pm »
While I am waiting on finished boards for the rev limiter I thought I would do some
preliminary work on an electronic ignition system. 

It seems with highly modified engines running as much as 30 degrees advanced timing that
starting can be a problem. So I thought that a system that had a simple bulit in advance
curve might be helpful.  This can be done several ways but I thought I would try to keep it
simple.  Here are some options I thought of.

1. Run  15 degrees advance up to 1500 rpm, then jump to the max as set by the user
   For example: Initial timing is 15 degrees. Timing remains at 15 degrees up to 2000 RPM
   At 2000 RPM the timing jumps to max ( 25 degress or whatever the user sets)

2. Start at 10 degrees advance and then advance in relation to RPM.
   For example: Initial timing is 10 degrees (0 - 1500 rpm)  As the engine speed in
   increases  beyond  1500 the timing advances in relation to RPM.   After 1500 timing
   advances linearly from 10 degrees at 1500 RPM  to 28 degree at 5000. Beyond  5000,
   timing stays at 28.
 
I am sure there are other ways that might be even better.

So what I need from the engine builders here is to know what would be your ideal advance curve / method ?   Let's start with singles. Briggs Flathead and OHV.

Bill

10
Coffee Shop / Rev Limiter Update
« on: December 14, 2010, 11:57:31 am »
Update:

The board supplier (Speedy PCB) has proven to be unreliable on delivery times. This has caused the delay we are experiencing in delivering final Rev Limiter units.  The boards should have been done over 2 weeks ago. I am now being told that the boards will be done early next week.

This is unusual because I have done business with this company before and they did fine with an order of 1,000 boards.  I trust that the boards will be here by Tuesday or Wednesday of next week. All other components are here and ready to go.  

There is over $400 invested with the board supplier and over $800 invested in components. I have put in well over 100 hours of my time in design, development and testing, not to mention George's testing efforts and feedback from others. While there has been a bump in the road with unfortunate and untimely delays, this will all pay off in long run for racers wanting to protect their engines.  

I just want everyone to know that I committed to getting these out as soon as possible while not comprising on quality and reliability. I will post another message as soon as the boards arrive.  

In consideration of the unexpected delays, and in order to get these out as fast as possible, I have lined up an "employee" to help me build and test the units as soon as the boards get here.

My apologies for the delay.

Bill Roth

11
Briggs OHV & Vanguard / Intek V Twin Oil Leak
« on: September 05, 2010, 06:49:17 pm »
I recently got an Intek Twin model 407777.  The owner said he sold
it because it was leaking oil on the exhaust and was afraid of a fire.

Visual inspection showed the right hand side of the engine was covered in grease
and oil from top to bottom.

I pulled the skins off and found that the hose going from the engine breather
was not connected to the intake air box.

After a thorough degreasing there is no evidence of gasket leakage anywhere

Could this be all that it was?   A disconnected breather hose ?

Bill

12
Briggs Flathead / Briggs 28 Overhaul
« on: August 24, 2010, 11:44:00 am »
I pulled the head and valves on a recently acquired flathead ( 282707-0110-01) and found
some scoring in the bore and a broken ring.  The exhaust valve was not seating well due to carbon build up.

I have a machine shop that will bore the cylinder for $45.  Unfortunately the dealers here do not
stock sufficient parts to do an engine overhaul.  

Since the scoring is fairly deep and the machine shop wants the new piston  I was thinking .030 over
but the local dealers say they cant even order a .030 over piston.  Confirmed by Briggs.  

The option with OEM parts is to get a .020 over and hope the bore job gets the grooves out.   The bore  is not
sleeved as confirmed by the magnet test.

Question1 :  I can get a Stens 30 over piston and rings  from Jacks.  
                     $59 for Piston and Rings $28.00.   Know of any others ?
                     Will using this piston disqualify for IMOW ?

Question 2:  Who do you recommend for engine parts?  Best Service ?    

Heres what I plan to order for a basic overhaul

Piston & rings
Piston Pin & retainers
Rod & Rod bolts
Gasket set
Spare head gasket
Valve springs
Tappets
Flywheel Keys

Am I missing anything ?    

Bill


13
Tecumseh Engines / Tecumseh V-Twin Blowby ?
« on: August 07, 2010, 09:12:02 pm »
Hi,

New here and thinking about building a racing mower.

I just acquired ($50)  a Yard Machine (MTD) mower with a Tecumseh 20HP V Twin
with the idea of making some kind of racer out of it.

The motor seems to run ok.  However when I remove the dipstick when the engine
is running,  oil and smoke sling out.  I hear a faint "ticking" coming from the motor after
it warms up.

The motor doesn't appear to smoke at the exhaust and it starts very easily.  Power
seems ok,  but I can't really tell for sure because the mower has  single speed
trans-axle with one of those variable speed pulleys that seems to be slipping.

Question: Is this normal crankcase aspiration  or more likely a case of blow-by indicating
the need for a tear-down and overhaul?   

Thank for any advise.

Bill

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