Export thread

HOWDY All !

I've been spinning my wheels for hours searching for tecumseh service bulletin 107 or microfiche card 30 to find the elusive rpm set points for this TVXL195-150241 engine on a Snapper 28088TE rear engine rider made in 1991.

From what I can ascertain from the readily available Tecumseh Service manuals there are five adjustments to get the engine into spec. (not including the speed bracket alignment adjustments for full choke)

1) fuel mixture at idle (what rpm)?
2) fuel mixture at high speed (what rpm)?
3) Throttle held against the "crack screw" at idle speed (what rpm)?
4) Governor Override low sped (what rpm)? (tech man says 600 rpm higher than the idle speed :confused2
5) Governor Override at high speed (what rpm)?

Can someone please simplify this for me? I looked over the charging circuit rpm tests and logic tells me it has to spin between 3300- 3600 rpm to charge the battery at high speed. Low end I've read anything between 1000 and 2500 rpm.

Thanks!

Normal Idle should be 1200 - 1400. WOT - 3400 - 3600

If I was working on that engine this is what I would do.

1. Throttle set at high speed, I don't worry about RPM's.
2. Adjust high speed mixture screw in until the engine starts to stumble, then back out 1/8 turn.
3. Drop the throttle down to a low speed, again I don't worry about RPM'S.
4. Adjust idle mixture screw in until engine starts to stumble, then back out 1/8 turn.
5. Move throttle to high speed and adjust to 3200 RPM's.
6. Move throttle to idle speed and adjust to 1600 RPM's.
7. Repeat steps 1-6 to check for any changes to mixture, the engine should stumble if when you turn the mixture screws in 1/8 turn.

If the engine stumbles when going from idle to high speed, turn idle screw out an extra 1/8 turn. You may have to got through these step a couple of time to get the engine to run smooth. This is also assuming that the carb is clean and in good condition.

I don't worry about governor override unless I have changed the governor settings or there has been a problem with the governor in the past.

Thank You Rivets! ...and Thank You Honda Tech!
... for a straight forward answer. I'll run with these two approaches when my gumption gets back up to speed.

I was a trained Calibrator (35H20) in the ARMY, so I'm no stranger to tweaking electronics. It skillset kind of flowed over into small engine carburetor adjusting for me as well. What the books cannot provide is the trained ear (calibrated ears or eyes) of a Guru! I'm still trying to develop my hearing skills with chainsaw adjustments in 2 cycle engines to get the burbling at the high rpm. Anybody that has fooled with them knows exactly what I'm speaking of. :laughing:

I've only messed with Tecumseh engines on a limited basis, namely this model Snapper RER and a TroyBilt SP chipper vac. Not being employed now in my "approaching the golden years" I have to do this to keep my sanity, but once everybody learns you kinda know what you're doing it's like having a pickup truck in an apartment complex.

I'll let you know how it goes after a cal session with the stoicheometric ratio! LOL

So I thought I'd post on what I've learned and the Snapper project status. I'll post a few pics too for grins and giggles.

After reading the Tecumseh literature- like 10 times- on the Speed Control Bracket, the 63226 (now 632991) carb pre-sets and the governor override adjustments I had another go at adjusting the engine yesterday. I actually cut about an acre of hillside with pretty good results too. Then Murphy stepped in and showed he is alive and well.

The Tecumseh stumbled a bit telling me it needed fuel so I high-tailed it up the hill headed to the workshop to refuel. I didn't make it- it died.

Long story short, I filled the tank only to find out later the ignition coil went KAPUT!! No fire on the plug. I also discovered it burned about 6 oz of oil in the 2 hour session (not good!). So now I have two more problems to solve.

Here's a condensed synopsis of this TVXL195 learning curve:

1) the speed control bracket should be renamed to "the choke control bracket". It really only serves 2 purposes from what I could tell. It actuates the choke lever on the carb to full open position when the operator moves the "throttle" cable to FAST/CHOKE. It's actually kind of counter-intuitive in it's design. (The bracket has the kill switch on the underside. I bypassed the kill tab when I stripped out the safety switches and wired it direct to the ignition switch, so it's really unnecessary in my project.) One other thing it does is serve as an anchor point for the spring attaching to the governor override lever.

2) I had to get the notion out of my head that the throttle control cable actually moved the throttle shutter. It doesn't. The Governor lever does all the work to maintain the engine RPM under load. It has a solid-wire link connecting directly to the throttle shutter. The governor lever has a fairly larger arc of movement which moves the throttle shutter relatively quickly. I learned that the governor override lever dampens the quick response of the governor lever using two springs. The best way my mind can describe it as the top strand of barbed wire between two fence posts wherein the first post is sloppy and the second firmly planted. Tug on the wire at the sloppy post and you get the mental picture. (if that makes any sense)

3) To simplify #2 a bit- just think of a fixed RPM engine. The Governor Override lever has a high RPM and low RPM screw to limit its arc of movement. I almost decided to set the rpm to 3300 rpm by fixing the spring loaded screws in place for a best compromise engine speed such that the governor override lever didn't move at all.

4) The 632256 carb bowl adjustment and the fuel mixture screws are adjusted like one would expect on an older engine... for a best compromise engine sound. The "crack" screw (aka- engine idle rpm) worked best for me set with the throttle lever held against the screw for the actual low rpm set point. I adjusted to 1500 rpm for this speed. The governor system immediately takes over and comes up to 3300-3600 rpm after I released the throttle. I could get a lower rpm by pulling back on the operator throttle cable but that only serves to partially close the Choke butterfly and restrict the air allowed in the engine. Messy to say the least!

So I wrote up my own procedure and tried it from scratch. I'll try and post it later after I've dissected the ignition coil to find out what the failure mode was.

One step forward, two steps back.