1976 Princess Auto Missing and boging at mid - full throttle

#1
Hi Guys, New to the site and looking for help

My Father in law has this cool mini bike
Its a 1976 Princess Auto with a Tecumseh motor. Well it wouldn't run and gas poured out the carb.

So we replaced the condenser and the points and spark plug
I had the carb ultra sonic cleaned and I installed a carb kit and new float. I set the float level with a 11/64 drill bit I believe. Ive had the carb off about 4 times and cant find the problem

So now the thing first up and will idle forever, but when you give it fuel at about half throttle it starts popping and bogging and puffing smoke. It will eventually die if you don't release the throttle. you cant get enough power for the clutch to start.

Any ideas?
 

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#3
When you replaced the points, did you time the engine? Good idle and no accelleration is almost 100% an out of time engine. Timing the engine after a points change is a necessary procedure, and called for in the service manual. The manual is linked at the heading of the Tecumseh section here. You need a dial indicator or accurate means of measuring piston depth in the hole, as well as an ohm meter, or continuity tester.
 
#4
I also check the compression 110 psi. The spark plug is suited up. No matter how I move the adjustments, it seems too rich
As Dave said above, if you replaced the points, the timing needs reset. Check out the link below for a good video on setting timing.. They use a V60 as an example, but the procedure is the same for all. You don't have to have the Tecumseh tool, instead you can remove the head (requires a new head gasket) and use a dial indicator and a longer 5/16 bolt secured into one of the head bolt holes as the stand for the indicator. hope this helps..

 
#5
looking at your carb picture looks like the welch plug wasnt removed,did replace the needle seat and do you have parts left over from kit?
 
#10
the motor will sit and idle all day. Even when I try to rev it out and it tries to stall, when I let of it goes back to really good idle.
Yes, that is EXACTLY what they do when the timing is off. You do not simply time these at TDC and button them up. If you remove and replace the points, you have changed the timing, and you must go back and check/set the timing. (Granted, some of us get lucky and don't have to, but the book is specific on this, as has been my experience)

LOL, I had one of them that would idle like an old hit and miss, probably 300 RPM, easy to start, sounded cool at idle. It wouldn't accelerate either until I took it back down and re-timed it.

But by all means, get a ten dollar carburetor from Ebay and give it a try if that's what you want to do.
 
#11
Yes, that is EXACTLY what they do when the timing is off. You do not simply time these at TDC and button them up. If you remove and replace the points, you have changed the timing, and you must go back and check/set the timing. (Granted, some of us get lucky and don't have to, but the book is specific on this, as has been my experience)

LOL, I had one of them that would idle like an old hit and miss, probably 300 RPM, easy to start, sounded cool at idle. It wouldn't accelerate either until I took it back down and re-timed it.

But by all means, get a ten dollar carburetor from Ebay and give it a try if that's what you want to do.

Nope i'm gonna check the timing today. Thank you for the info! I will report back after

Thanks
 
#12
Nope i'm gonna check the timing today. Thank you for the info! I will report back after Thanks
As you pull the flywheel off, take a good look at that flywheel key. All it has to be is slightly dented from a backfire to knock it out of time. What engine is that? A small screen and sideways photos on my end, so I can't be sure. The measurement "in the hole" (BTDC) varies significantly with which engine is being timed. Those numbers are in the back of the service manual. In the video above, the technician is using .080, but that is for early big blocks and most likely the wrong numbers for you.
 
#14
I can see "40" in your photo. If it's HS and not H, you need to have your piston .035" before top dead center.

Note that the wires have to be disconnected from your points when you do this. The nut for the wire post must be on and snug to provide proper tension on points arm. Piston to TDC first, ensuring the slop is taken out by turning the crank a tad. You'll see the slop at TDC when you start messing with it. Zero your indicator.

Now rotate your crank backwards until you see .035" "in the hole" which is your BTDC number.

You then rotate your stator plate (after loosening the two 1/4-28 bolts) to the point at which the breaker points just open electrically. One lead of your meter/continuity checker goes to that stud, the other to ground of course.

Tighten down the stator plate and recheck. (It moves when you do that and gets frustrating) Attach wires, button it up.

A lot of members here know how to do this, and those familiar with Tecumseh points engines have experienced what you describe, but no one likes to come out in public and troubleshoot an engine, then describe repair procedures- because often, the individual doesn't do it correctly, and comes back on bitching about getting bad advice, while making the helpful curmudgeon who has nothing better to do than hang out on a dying forum look like a dumb ass. :D

So please. I don't need any more help looking like a curmudgeonly dumbass with nothing better to do than hang out on dying internet forums. LMAO!!! And by all means, others can chime in or PM you with better ideas. And check that flywheel key.
 
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