The engine stalls when giving it more throttle. The new points were gapped at .020 on the high side of the cam and cleaned before starting, the piston was set at .035 btdc with a dial indicator, a electronic meter set on ohms was used while moving the stator plate to see the break in continuity at the points and the bolts tightened, and 2 carburetors adjusted 1 1/2 turns on the main and 1 turn on the idle air screws ( tried one older and one new carbs). The engine starts easily and idles but when turning the throttle it stalls. Did I miss anything that should have been done to this engine ? Sorry if this question has been asked before in the forums . Any help would be appreciated. Thanks
Tecumseh HS40 Help needed . Idles only.
Hi Ski, it looks like you did this correctly, but not being able to accelerate from idle remains indicative of an out of time situation. I've performed this job several times, and still have problems sometimes. A couple of things:
When you put the engine at TDC, were both valves closed? Did you rock the crank to deal with the inherent slop in the crank/rod and re-establish TDC? Did you re-check the timing after the magneto bolts were torqued?
I apologize for not being able to provide more insight, but as I said, it appears you have a firm grasp on what you're doing. Unfortunately, you have to do it again, because I am certain you've got the carb and cam set right, and an inability to accelerate, yet start and run at idle are exactly what an out of time Tecumseh does. Good luck, please keep at it and let us know when you get it running right.
When you put the engine at TDC, were both valves closed? Did you rock the crank to deal with the inherent slop in the crank/rod and re-establish TDC? Did you re-check the timing after the magneto bolts were torqued?
I apologize for not being able to provide more insight, but as I said, it appears you have a firm grasp on what you're doing. Unfortunately, you have to do it again, because I am certain you've got the carb and cam set right, and an inability to accelerate, yet start and run at idle are exactly what an out of time Tecumseh does. Good luck, please keep at it and let us know when you get it running right.
Dave has it I believe. I have experienced what OP is describing after going through the Tecumseh book routine on timing adjustment. I have done 4 Tecs so far where the book procedure has failed me. At the risk of undermining Dave, this is what I did on all 4-
1. Full CCW of the stator, lock it down
2. Bring piston up on comp. stroke
3. However you are measuring, dial-in 0.035" from TDC
4. Go at the points until your meter indicates a break. Approach it from both sides until confident. Lock assy. down.
5. Back the piston away from TDC and then approach that theoretical 0.035 until your meter reads open.
6. Check the points gap
In all of my cases, which were half-dead engines on either new or used points, this procedure produced solid lug-lines. You might wind-up with a 0.017" points gap up on the lobe, could be a little more or less.
1. Full CCW of the stator, lock it down
2. Bring piston up on comp. stroke
3. However you are measuring, dial-in 0.035" from TDC
4. Go at the points until your meter indicates a break. Approach it from both sides until confident. Lock assy. down.
5. Back the piston away from TDC and then approach that theoretical 0.035 until your meter reads open.
6. Check the points gap
In all of my cases, which were half-dead engines on either new or used points, this procedure produced solid lug-lines. You might wind-up with a 0.017" points gap up on the lobe, could be a little more or less.
No undermining here! You make an excellent point. :thumbsup: I have also gone that way, in fact, I actually time it backwards from the book.
To put a finer point on what you said, "screw the point gap." LOL, it is what it ends up being, depending on how the mag plate is. At this point, that is beyond what the OP is looking at, but the "point" is, you do not need a full .020 gap to fire the magneto. As little as .016 is enough.
Oh and Ski, you get a lot of movement by just tightening the damn bolts. You almost have to have them "snugged up" when moving the stator plate by "tapping" it with the end of a screwdriver, so that when you do go to torque them, the plate doesn't move out of time.
To put a finer point on what you said, "screw the point gap." LOL, it is what it ends up being, depending on how the mag plate is. At this point, that is beyond what the OP is looking at, but the "point" is, you do not need a full .020 gap to fire the magneto. As little as .016 is enough.
Oh and Ski, you get a lot of movement by just tightening the damn bolts. You almost have to have them "snugged up" when moving the stator plate by "tapping" it with the end of a screwdriver, so that when you do go to torque them, the plate doesn't move out of time.
Both of you guys know these things are finicky as I do but I'll add one tiny clarification: The wire junction nut has to be rock solid tight before the points are set (that crazy points spring steel will give you false readings later if the points are not set correctly to 0.020 to begin with). The OP should be reminded the flywheel is torqued to 55 lbs-ft and a scored key will make life miserable.
I need to talk to [MENTION=20377]buckeye[/MENTION]...he's missing somethin':laugh:
I need to talk to [MENTION=20377]buckeye[/MENTION]...he's missing somethin':laugh:
I had a similar issue with one of my Tec HS50 engines was running fine after a tune up for a while then would not go over about 1500 RPM, all of a sudden back firing spits and sputters with a little black smoke out the tail pipe, below that RPM ran good, I changed everything from spark plugs, magnetos, points, condenser and coils several times also changed carburetors turned out to be cheap points made in china I had a bunch bunch of them, I had to bend the points for proper alignment and then they worked, there are recently made points out there that claim to be Tecumseh they are not. I bought some older Tec NOS points for inventory so I don't have that problem again what a pain in the @#$%. As to the timing it might not make as much a difference as some think, last year I modified a magneto that I could adjust timing with the engine running and bike up on a stand, I dialed in the timing by driving the bike each time I made an adjustment, ended up where it belongs about .035" BTDC. I drive my bikes on the road at higher RPM so my thoughts were I might need a little more timing for better torque, turns out unleaded fuel burns faster so no change needed. That's been my experience with a problem like this post.
Tony
Tony
Last edited:
Shoulder bolts with wave spring washers, washers on those, threaded adjustment rod w/lock nut, swivel, ........ I didn't adjust it while driving just on the stand then drove it, it's not hard to do, some hardware from McMaster-Carr, I made 2 complete setups I still have the parts in my stuff somewhere, stock performs good no need for it.
Tony
Tony
^I am not sure how this applies to the assumption that point gap may be causing OP's issue(s). You're collection of parts to move the ignition frame isn't necessary but perhaps not for the reason you pointed out. The manual procedure may be misleading in that it mentions first setting points gap to 0.020". Of course you need spark to occur at 0.035" BTDC but this doesn't mean that needs to occur in conjunction with maintaining 0.020" on top of the cam lobe. Full capacitor discharge can occur with as little as 0.014" terminal air gap.
Nobody here is definitively stating the problem can be solved with attention to point gap, it's merely a suggestion.
Nobody here is definitively stating the problem can be solved with attention to point gap, it's merely a suggestion.