MTD Tractor Starting problem

[bgsengine]

Arkie,
Where do you purchase the "good rubber cups"? I lap a lot of the old Briggs and Tecumseh flatheads and find that the suction cups that come on those lapping sticks are not very good. Does anybody have a link to any lapping sticks that have GOOD suction cups?
Michael

I gave up using them ages ago.. I switched to using heavy rubber band - get a large one, snip it in half , wrap a turn (or two, sometimes) around valve stem and just pull back and forth (like using a cable saw or strip of emery cloth) works for both L-head and OHV (but with OHV its easy enough to just chuck up the stem in a variable speed reversible drill run at its slowest speed back & forth) .. the rubber band trick does require making sure the valve stems are clean and dry (no oil, so rubber can grip them) and with practice you can get the valve to pop up and down on the seat to let lapping compound re-distribute..

[Arkie]

Creia:
Good question about source for GOOD rubber suction cups?

I do not have a source or know of a source for good cups: Maybe someone will chime in about such.
Over the years I've accumulated my rubber cups, some are Briggs and some are automotive and I think some are from kids toys. I store them in a plastic bag inside the refrigerator section of an old fridge in the shop along with some glues, gasket compounds, silcon gasket compounds, etc.. The operating fridge section keeps rubber stuff from dry rottening or getting hardened. You would be surprised how long some of the gasket compounds and glues such as super glue gel and liquidwill last if stored in a fridge @ 40F.

Lefty: I have not watched any You-tube, for using a drill and lapping. I just started doing the drill thing several years ago (as a redneck idea) and it's worked good for me. When using a vari-speed drill I just run on slow with a slight tug on the drill and keep a ear open and if you hear a slight squeak or the valve starts a slow chatter or vib add some lap compound or smear the existing compound back onto the valve's face and pay attention to the lap pattern on the valve face and on the seat) Just keep a heads up and do not let the lap compound get down onto the stem or into the valve guide. I sometimes have to use just little bit of light grease with the compound if the compound not oily enough.

Using the rubber hose connected to the OH valve stems and the drill's chucked dowel keeps direct side pressure from being applied to the guide and stem as the valve is being spun slowly.

Right about the lick and stick when doing L heads. (hit and miss) I usually have to de-grease the valve's head really good and sometimes have to buff the valves head so as to polish and de-grease on a fine wire wheel first to start selecting the cups for a good lick and stick. Sometimes I can use the slow speed drill and a suction cup on the top of L-head valves using the rubber hose coupler if the cup sticks good.
I've thought about, but never tried super gluing anything to the L head valves surface for spinning the valve. I have some fast setting glue that would do such (glue rubber or even another old valves head to the top of the existing valve) but just never played with such because could lap them ok with the drill after some hit and miss.
Just never did like the manual hand lapping of valves using the Briggs method similar to building a fire rubbing (spinning) sticks together by the boy scout method. Propane lighter is faster for that.

[Arkie]

creia wrote:

Where do you purchase the "good rubber cups"? I lap a lot of the old Briggs and Tecumseh flatheads and find that the suction cups that come on those lapping sticks are not very good. Does anybody have a link to any lapping sticks that have GOOD suction cups?
Michael

I'm thinking or trying a really good type of hook and loop velcro, type with the peel and stick backing for a quick connect disconnect to the l-head valves for spinning with a drill when lapping instead of the rubber suction cups.

I briefly looked at McMaster Carr for a good grade of Buthl small suction cups. Price is ingly high each.

[lefty]

Not sure if this is a ridiculous suggestion or not but has anyone tried a strong magnet? Maybe one stuck to the end of a wooden dowel with some adhesive? Assuming the stick close enough to the center. Maybe glue a rubber tube between the dowel and the magnet to provide the needed flexibility.

[creia]

Arkie,
Where do you purchase the "good rubber cups"? I lap a lot of the old Briggs and Tecumseh flatheads and find that the suction cups that come on those lapping sticks are not very good. Does anybody have a link to any lapping sticks that have GOOD suction cups?
Michael

I gave up using them ages ago.. I switched to using heavy rubber band - get a large one, snip it in half , wrap a turn (or two, sometimes) around valve stem and just pull back and forth (like using a cable saw or strip of emery cloth) works for both L-head and OHV (but with OHV its easy enough to just chuck up the stem in a variable speed reversible drill run at its slowest speed back & forth) .. the rubber band trick does require making sure the valve stems are clean and dry (no oil, so rubber can grip them) and with practice you can get the valve to pop up and down on the seat to let lapping compound re-distribute..

Very interesting technique Brian! I plan on trying this on the next engine. Thank you for the information.
Michael

[creia]

Not sure if this is a ridiculous suggestion or not but has anyone tried a strong magnet? Maybe one stuck to the end of a wooden dowel with some adhesive? Assuming the stick close enough to the center. Maybe glue a rubber tube between the dowel and the magnet to provide the needed flexibility.

Lefty,
I do not think your suggestion is "ridiculous" at all- I think you are on to something here! They sell some REALLY strong small magnets that could be epoxied to the end of a wood dowel. I plan on giving this a try in addition to Brian's rubber band technique. Some very good information coming out in this thread!
Michael

[bgsengine]

Not sure if this is a ridiculous suggestion or not but has anyone tried a strong magnet? Maybe one stuck to the end of a wooden dowel with some adhesive? Assuming the stick close enough to the center. Maybe glue a rubber tube between the dowel and the magnet to provide the needed flexibility.

Lefty,
I do not think your suggestion is "ridiculous" at all- I think you are on to something here! They sell some REALLY strong small magnets that could be epoxied to the end of a wood dowel. I plan on giving this a try in addition to Brian's rubber band technique. Some very good information coming out in this thread!
Michael

Yes it could work.. But me, and my technical mind, only real issue I can think of with something like that is how the metal particles that are worn away will react with the magnet, and sort of "gum up" the lapping compound a bit instead of it being squished out and rinsed away (I only use water soluble compound) but if it works, it works.. Like I said once I started using rubber bands (and/or drill) they worked so well for me, I didn't bother trying anything else.. I hated using magnetic tools in places where it was important to be really clean- main reason is ferrous metals can retain some magnetism and attract stray metal shavings (and hide them from view) and eventually get in to where they can start some serious damage.. (Even after using magnetic base with a dial indicator, such as checking valves or timing, I very often would keep having to clean off metal parts that picked up magnetism from the base..) - Just so long as you remain aware of that possibility, then I see no real issue with using a magnet either..

[lefty]

Not sure if I should be posting on this thread but it's the same machine and the same problem, which has resurfaced. She's busting my chops again. My apologies if, given the elapsed time, I should be creating a new topic.

So I'm confident about compression and fuel. I can see the fuel spewing up into the carb. So I figured I'd attack ignition as I've never been super confident in it on this machine. Using some instructions from youtube, I'm getting 4700 ohms from the spark plug wire to the armature. Not sure if that's meaningful

In the spirit of expediency, I'm thinking of just replacing the coil and the ignition switch, since they are relatively inexpensive and I can then take them out of the equation. Is that a prudent approach?

I feel like I've eliminated everything else. Taken care of any compression and timing issues, fuel issues, etc.

Thank you.

[Arkie]

Left:

My engine would start and run good when cold but;
I just got through with a B&S old model twin cylinder about 18 hp that had the no start issue after the engine had been operated and got really warmed up. I could not shut the engine off after it was being used for mowing for about 30 min or longer or it would not start, just crank and crank. I could install a new set of spark plugs and it would be ok for awhile than same thing again. I could see little gas spit back up into the carb throat when cranking fast but I've found this to be normal on the Briggs twins when they don't start, even though compression is good and valves are adjusted correctly. (it's their nature to do such which is misleading when they don't start and cranking fast)
Spark testers and viewing both plugs indicated fire, compression good. I could let it set until it completely cooled of and it would re-start easily and fast. If it eventually started when hot it appeared flooded, usually had to be started with a full throttle hot, no choke.
Very hard on starters when such is happening also.

Here is an example of a clone mag that might be for your rig. Do not assume that the spark plug lead points forward, some are actually point backwards for the proper polarity. (China thing)
Also make sure you do not order anything that ships from China right now, might take 6 mo's to ever get to USA.
https://www.ebay.com/itm/595304-Ignitio ... SwHP1dy6IY

I finally installed a new clone $15 magneto on it and two new plugs and it's been good every since.

I see your is a single cylinder OHV. I would consider just installing a $15 clone ignition coil and a new spark plug and give it a go. Instead of spending $60 on the genuine B&S mag) I'm assuming you have re-checked and made sure your valves are still sealing good after your lapping them. I've had good luck on the cheap clone mag's when installed on Briggs engines.
I've tried the Napa Auto supply $70 2 year warranty Briggs mags and had them fail in and out of warranty. (usually out of warranty, so I just started testing the cheap clones with good results. Be sure you do not install it upside down, some Mag's have a very faint UP or this side UP on the plastic coil and the kill wire tab and/or the spark plug wire may be pointed the opposite direction from the mag now in use, therefore it's easy to just install what looks the same and it's wrong.

I would not install a ignition switch just yet, just disconnect the kill wire at the engine block area so as to make sure the kill wire does not have any grounding up set (any high resistance for example that would weaken the spark) going towards the ignition switch. Just be aware If the engine starts with the kill wire disconnected you will have to apply choke if you want to kill the engine or have a wire extended off the kill wire to ground and kill.

My engine had a bad mag and I've heard rumors the mag getting weak when hot is not uncommon. You also CANNOT fully test the briggs pointless type magneto because of electronic hidden deep inside. The old points type coils could be resistance tested primary and secondary and also tested on a coil spark tester to get an idea, BUT I've seen quite a few of them indicate OK but intermittent or erratic on a engine, especially the outboard engine type points coils I have a Merc-Tronic coils tester and I've sdeen it test coils as OK but when placed on engine probably due to vib's the coil would get erratic.

Appears you had two issues with that engine, valves and now something else.
Make sure the cooling fins are clean and all the air shrouds are on your engine so as it's not overheating.

Let us know what you try .

[lefty]

Thank you. I will.