OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines 12HP engine assemblyttings

Hey all i have a 1989 victa pro 12 the engine is a briggs and stratton model 281707 type 0213-01 code 89062211. in the re assembly of the engine and the timing is there anything in particular to look out for eg timing settings. Also i would like to know more about the carburettor settings and tuning.
All help is always appreciated
Leshby

Howdy, the timing marks to watch out for, is a centre punch mark on both the camshaft gear, and the crankshaft gear. These dots will be located on the side of a tooth on both gears, and are to mesh together. Once thats right, it's plain sailing. As for the carby settings, the float level is usually not adjustable, and usually all there is to do is the mixture, if your carb is adjustable that is. If it is, it's easy. I'd say wind it all the way in, then back out 2 full turns. That's normally fairly close for a Briggs, then with the engine running, wind it in so that the engine starts to die, then wind it out until the same happens, then wind it back in a little. It should run pretty sweet then. Check it by working the throttle and making sure it revs smoothly. If you haven't done it, it'd be worth cleaning out the carb while it's off.

Cheers, hope it helps.

Leshby, the camshaft has to be put back in place with the timing marks (on the timing gears) together. The B&S overhaul manual says this:
NOTE: Model series 94000, 171700, 191700, 251700,
and 252700 have a removable timing gear. When
installing timing gear, have inner chamfer toward
crankpin. This assures that timing mark will be visible


Note that your engine is a later model which replaced the 251700 and is generally similar to it.

You can read that part of the overhaul manual (or the whole manual if you want, by using the back and next buttons at the top of the page) at this URL:
http://www.tpub.com/content/recoveryvehicles/TM-5-4240-501-14P/css/TM-5-4240-501-14P_243.htm

Your carburetor is probably the large one-piece flo-jet, which looks like this:


Verify that is the carburetor you have, just in case you turn out to have something different. There are three tuning adjustments on the carburetor: the idle speed, the idle valve (i.e. idle mixture), on top of the carburetor, and the needle valve (i.e. main mixture), underneath the center of the float valve. Be gentle with both of the mixture screws: do not turn them clockwise until they run out of movement unless you are very gentle with them, since you are forcing two soft brass surfaces into contact with each other, over a tiny surface area. Here are the overhaul instructions for that carburetor:
http://www.tpub.com/content/recoveryvehicles/TM-5-4240-501-14P/css/TM-5-4240-501-14P_115.htm

If the engine is currently not capable of running and you want to start from scratch with the carburetor adjustments, B&S recommend an initial adjustment of 1.5 turns anticlockwise from fully closed for the idle mixture, and 2.5 turns from fully closed for the main mixture. Remember, be gentle in finding the fully closed point (mixture screw fully clockwise) for both those screws. Also, clean out the fuel tank and fuel line before you begin any tuning process - if they contain much dirt you will then need to clean out the carburetor as described in the manual. Here are the mixture adjustment instructions from the B&S manual:
Carburetor Adjustment
Start engine and run to warm up. Then place governor
speed control lever in "FAST" position. Turn high speed
needle valve in until engine slows (clockwise - lean
mixture). Then turn it out past smooth operating point
(rich mixture). Now turn high speed needle valve to
midpoint between rich and lean. Next, adjust idle RPM.
Rotate throttle counterclockwise and hold against stop.
Adjust idle speed adjusting screw to obtain 1750 RPM,
aluminum engines; 1200 RPM, cast iron engines.
Holding throttle against idle stop, turn idle valve in (lean)
and out (rich). Set at midpoint between rich and lean.
Recheck idle RPM. Release throttle. If engine will not
accelerate properly, the carburetor should be readjusted,
usually to a slightly richer mixture.


The ignition timing is not adjustable on that engine. The ignition system is electronic (breakerless) and the timing is set by the key that locks the crankshaft to the flywheel. Check visually that the key has not sheared, because if it has, the ignition timing will be wrong. Note that the key is made from zinc, not steel, so that it will shear easily if the blades strike something they can't handle. This protects the crankshaft from torsional failure due to the flywheel's momentum.

Have got it all together for the second time now have pulled it down and looked at timing marks and it can only really go one way when the marks are lined up( rotated crank around a million times to see) the carby is a large one piece flojet. pulled it down cleaned checked and reset baseline settings. Back to firing it up and all it will do is wind over and give an occasional cough no fire. Have checked spark got plenty have gone over everything i think it is the carby. It is really starting to annoy me. The last thing on the list to do! That is the reason i pulled the motor apart to check the timing. I just dont get it.

1. Are you choking it? If it's a cold engine, you will need to.
2. Is the spark plug wet or dry?
3. Is the compression OK?
4. Have you tried priming it? Just squirt a small amount of petrol in through the spark plug hole immediately before trying to start it. (Don't use the choke.) If that makes it fire, run briefly, then stop, fuel is not moving from the carburetor to the intake pipe. We can talk about what causes that, if it turns out to be what is happening.

Have tried choking from what i can see is that the fuel is in the choke end but does not appear to be pushed into the inlet tube Why???

The fuel should be evaporating in the venturi - there should not be liquid fuel back further than the throttle butterfly valve.
Does it have compression?
Is the spark plug dry?
Does it fire if you prime it?

All the ones I have played with when the choke is on have liquid floating aroud in the throat of the carb.

Another thing if it doesnt fire when primed to check would be valve clearance and flywheel key.

It has compression spark plug has lightest amount of fuel

Umm, this might sound like a stupid question, apologies in advance, but is it a new spark plug? I've had many plugs over the years that seem ok, but don't work properly under compression. One of those freaks of physics, but the way I understand it, compression actually compresses the spark as well. To me it sounds like everything else is there, so it should be going.

Greg, the firing voltage required does increase with higher air pressure around the plug. That is why you are supposed to test the ignition system with a plug gap of 0.060", compared with the 0.025-0.030" you use on the actual spark plug. So trying a known good plug is a worthwhile step in a situation like this. Note that a new plug is not necessarily a good plug - we've had a few defective new plugs reported here recently.

Leshby, have you tried the priming test? Have you checked the flywheel key? Those items were on my initial list of tests to make, half a dozen posts ago, and you haven't reported on the results.

Hello it is not a new spark plug but is a good one i believe the machine key in the flywheel is new.have still to do the priming test.Have had the air filter off and when cranking it gives a puff of air and fuel out of the carby. isn't that supposed to suck not blow?? Also with the 89 victa pro 12 30" deck the RH side ejection chute (or discharge chute or guard) is there any other models which i can get to fit it?

Hello, With my 12 Hp Briggs and Stratton engine i have assembled and disassembled and reassembled. Have checked the timing marks and the flywheel key and the timing key all OK. when trying to start has tons of spark. I get the lightest amount of fuel on the spark plug. The carby has fuel in it. When winding over the carby with air filter off blows out fuel and air isn't this suppose to suck not blow. What have i done wrong. Please help!!!

So did you check the valve clearance? I am betting that there is none and the stem of the valve needs a bit removed.

leshby, I agree with Joe - if it puffs mixture back through the intake without firing, then the camshaft timing is wrong, the valve is sticking, the valve is not seating properly, or there is negative tappet clearance on the intake valve. You've checked the camshaft timing carefully, so you need to check that the valve isn't sticking, and check the tappet clearance. As Joe said, if there isn't enough clearance, the way that is corrected on side-valve Briggs engines is by grinding away the end of the valve stem. This must be done accurately, both in terms of getting the end surface precisely square to the stem, and in ending up with the precise clearance you need. Remember, you have to lap the valve into its seat before you finish-grind the stem-to-tappet clearance, because the valve will move downward in its seat when it is lapped in. If the valve or seat has been eroded by leakage, it might take quite a bit of lapping, and therefore move downward quite a way.

Before you grind the valve stem, check carefully that nothing is holding the valve open. Apart from sticking, it may be obstructed by some piece of garbage between the stem and tappet, or the valve retainer may be damaged or out of position.

Hey dont get it set the valves assembled started first kick. ran for like a dream 5 to 10 mins then stopped and siezed. What the. Will pull it down tomorrow to find out why!!!!!

Sounds as if the intake valve was not sealing, and you've overcome that. So far as the seizing is concerned, too many things could have gone wrong with the assembly process to guess what it is. Please let us know, preferably with pictures.

The most common cause of seizure is lack of oil, but when an engine has just been assembled, several other possibilities arise.

Yes i had a drama had a pickup of crap in the bottom end. lucky i pulled it up when i did before it did heaps of damage.Pulled down set and checked everything cleaned and repaired Started and runs great just have to fine tune the carby and the governer side any sugestions.Sorry i didnt take pics. was too busy cursing myself about the pickup in the bottom end.

As a first guess I wonder if you remembered to oil the crankpin when you assembled the big end? Anyway, all's well that ends well. Tuning the carburetor should be easy when the governor is working properly, just follow the Briggs instructions quoted in my post earlier in this thread. At this point I do not know whether you have a mechanical governor or an air vane governor, but my first guess is that it is a mechanical type, like this:


You can read the details on it here:
http://www.tpub.com/content/recoveryvehicles/TM-5-4240-501-14P/css/TM-5-4240-501-14P_148.htm

I expect your 28000 engine will be similar to a 25000 engine - the 28000 is not specifically covered by the manual.

yes it is the mechanical governor which seems a bit sticky,doesn't seem to come back down to idle correctly Will see what its doing tomorrow.