Force 50 hp, hard to start cold although timed and synced properly

[ZandoR]

Hi there!
​my Name is Leo, 18 yo and Im from Germany. I bought a Force 50 hp longshaft about a year ago, knowing that it was having Trouble to start up. Because I have some experience working with engines I thought I might get by cheaper Fixing it up by myself, which Im still hoping for.

First of all here is some Basic info:

Serial No. starts with OE... (will post the whole number tomorrow if necessary) and I believe it to be ) 92-94ish
Compression is 125 psi on cyl #1 and 130 at cyl#2
I have a strong, consistent, blue spark that jumps a gap about 2cm (7/8th of an Inch?)
I set the Timing to 32-34 deg static, as shown in the seloc shop Manual
Cleaned the carb twice, also took the welch plug out (looked super clean allready) and set the mixture screw to factory specs
Checked the reed valves -> were a bit sticky, some were having a gap of a few hundreds
Got new plugs for it (Champion BUHW)
Cleaned all the grounds I could find
After turning it over for about 5 - 10 sec with the priming Solenoid on the plugs get pretty wet, not drowned though
The voltage Regulator is toast, but repolacement is on ist way

It fired up twice, after draining almost the whole Batterie, which is not suffiecient enough to take it out for a spin. When it was running it did fine, idling down to about 800rpm, not missing a beat.

My starting procedure is the following:
Turn it over with choke engaged and high idle on until it coughs (or spits out Flames down the exhaust, about 15cm Long AWESOME, not helpful however lol)
Shut the high idle and turn it over some more. It then stops to cough after about 10- 15 secs. Sometimes it backfires, but only if the Timing is retarded all the way (idle). This only occuring when attemting to start it, I dont think its Timing related. WD 40 didnt help starting it either, which would suggest that its not fuel related.

I will do the fuel pump tomorrow, but other than that I dont have any more clues. If you want me to perform any Tests just let me know, ill do them right away.
I see this as a challenge, so hopefully I can fix her up with your help. Thanks in advance, this Forum is great, having so many talented mechanics on board!

Im happy for every Response that I can get, so please keep the great work up!

Best wishes, Leo

 

[Nordin]

First of all check the flywheel key. Backfire might be a shared flywheel key.
Then reset the timing at WOT to 28dgr BTDC static (32-34dgr is a bit to much).
Static is cranking speed with the starter.
Start from there and inform us about the progress.

 

[ZandoR]

Thank you sir!
​Will do that tomorrow, as ist almost midnight here.
Guess ill stick a screwdriver in the top cylinder and see if the Timing marks on the flywheel align with the Timing sticker on the intake manifold.
Or would it be better to take the whole Thing of? Momentarily i dont have a flywheel puller, but I could try with a triangular shaped block of Wood.
If thats a bad idea ill try to get my Hands on a puller, its just not as easy to get non metric stuff over here.
Well, ill let you know what my findings are tomorrow.

best regards Leo

PS: sorry for the spelling mistakes, my Auto correct is just doing whatever it wants and I cant catch all of em

 

[Jiggz]

Don't pull the flywheel yet. You're correct insert a screw driver on top cylinder, remove the bottom plug to ease rotating the flywheel. Determine the highest point of the top cylinder with reference to the screwdriver and then check if the TDC marking on the flywheel aligns with the stationary marker. If it does, then the flywheel key is not sheared.

If the TDC markings are not aligned, then pull the flywheel and replace the key. Additionally, as mentioned you need to retard the current timing to 28 BTDC. Make sure the idle screw setting is correctly set, i.e. if you retract the idle screw to be barely touching the engine block, the throttle should be fully closed. I am referring to the carb throttles situated at the back of the carb or at the carb's throat. You will need to remove the air cover and probably a flashlight to see it. Note with this position, the hash marking on the cam advancer should align with the slot on the eccentric screw roller. If not adjust the eccentric screw. This is critical for setting the idle and making sure the throttle is slightly open during starting.

After the preceding, check the WOT position with the control lever in full forward and the throttle should be in full horizontal. If throttle is not in full horizontal position, adjust the tie rod swivel. Thereafter, you can adjust the idle screw (bottom of timing tower), again double check to make sure the throttle is slightly open and the cam's hash mark should now be below the eccentric screw roller's slot position.

Finally, set the idle mixture screw to about 1 1/4 turn out from lightly seated. You can adjust it later after you get the unit to finally run.

As for starting procedure, don't forget to prime the unit with the primer bulb. Usually all it takes is 4~5 presses of the primer bulb.

 

[jerryjerry05]

The choke/ primer could be adding too much fuel into the system.
​Pinch off the hose to the primer and see if that makes a difference?

You are using the choke/ primer when starting?

 

[ZandoR]

Wow, you were dead on: timing from the top cylinder seems to be 185 deg off. Looking at the bottom one its about 5 deg. I will try to borrow a flywheel puller tomorrow so that I can have a look at it. Btw is it possible to make a flywheel key myself out of waste metal? Or will it just not hold up ?
Actually I have a spare key of a 75' Johnson 15hp, but I guess it wont fit.

Jerry, yes I am using the choke. If i dont hit it the motor doesnt even pop. Can it actually be that it lets in too much? (I always thought it was just opening a bypass, not a pump)

Well thank you! I didnt think of this, although i have read it in a few other threads. Ill try to get'er done tomorow.
Ill let you know how it goes.

Best wishes, Leo

 

[Jiggz]

And yes, you can just make your own key. The key is designed not to hold the flywheel but more of an orientation key. What holds the flywheel in place is its matching surface with the tapered shaft. Applying the correct torque to the flywheel nut is critical to ensure it stays in place.

 

[jerryjerry05]

When making your own key.
Make sure you don't over heat and loose the temper and make the metal soft.

The primer adds a shot of fuel when it's activated.
It has a diaphragm and if it's bad it will add fuel every time the motor turns over.
Try pinching it off?

 

[Chadomosis]

Mine had a similar problem a while back and it turned out to be bad coil packs. They still fired, which was the strange part, but they were not consistent. Once I replaced them, however, it has run perfect for quite a few years and still going strong.

 

[ZandoR]

The new key is on its way, should be here in about 3-5 days. I removed the sheared off key from the flywheel and crankshaft, looking good so far. Actually everything worked out nice. I just noticed that the flywheel nut was quite loose when I disassembled it. Im stoked to see if it will run after the replacement.

Jerry: if it doesnt run right ill try out what you hve sad!

Chadomosis: Interesting, I always thought that they would either worked or be shot

Best wishes Leo

 

[Chadomosis]

Yea, that's what I thought also. Needless to say, that made it a tough diagnosis...

 

[jerryjerry05]

The torque is 85# on the nut.

 

[ZandoR]

Thanks for the Input!
Is that foot Pounds or Inch Pounds? (not to familiar with the imperial System as we're metric over here)
Just let jme know so that I can convert it.

Thanks alot and best wishes,
Leo

 

[Jiggz]

That will be foot pounds.

 

[Nordin]

It is about 115 Nm in metric system.
If you have some valve grinding compound such as Carbo Rundum use it and lap the flywheel and cranktap before you install and tight the nut.

 

[jerryjerry05]

Sorry I forget we have some distant close neighbors!!
Tell you what I'll do.
You pay postage I'll send you a SAE torque wrench FREE
Send ma a PM with shipping details.

 

[ZandoR]

Jerry, thank you so much. Your generosity is overwhelming. Especially since I am "the perfect stranger" that you dont even know in real live. As you dont encounter such every day, I cant stress enough how thankful I am.

I also want to thank everybody else for being such a great help and tossing in so many helpful tipps and tricks. I am still waiting for the parts. The post Office estimates that thell arrive on tuesday, so I'll Keep you posted.

Best wishes,
Leo

 

[ZandoR]

Seems like I owe you big time, now with the flywheel key replaced (I tried out your trick with the
valve grinding compound, worked like a charme!)it starts up just immediately.
It has a slight miss when cold but after 20 seconds it just purrs like a kitten, so I dont bother.
Just out of curiosity: I noticed a little flame going through the fuel return line when it misses.
What could be the cause of that? Hopefully I can take it out on the water the upcoming weekend
to see how she performs.
Thanks so much again!

Leo

Btw: I am running it on muffs

 

[jerryjerry05]

The "miss" at idle is the air screw.
​It needs adjusting.
Or the fuel recirc system needs cleaning.??
​On the side where the fuel pump is a cover shaped like a dog bone.
It has a reed and a screen.They can get clogged and need to be removed.
​The screen is NLA and not really needed.
You can get screens from a smoke shop or e-bay.
Or install a small filter inline.
A miss can also mean the reeds are defective???

I'd start with the air/fuel mix first.
​Motor warm, in gear at an idle.
1 and 1/2 turn out for initial adjustment.
​Then while running, turn the air screw in 1/8th of a turn at a time.
​Wait 10 seconds before the next turn in.
​Do this until the motor bucks, kicks or misfires.
Then turn the screw back out 1/2 turn.
That should stop the backfire or miss.
If not then look into the other things I mentioned.

 

[ZandoR]

Thanks Jerry,
​Ill get to it right now and have you posted in about an hour