Johnson 3 cylinder pop N crackle at Idle.

I have a Johnson 1998 3 cylinder 35hp that has a rough idle. It starts fantastic every time. I have had it on the water 2 times since I purchased it. First run was ok only had a little serge in the throttle at speed but generally was fine running it at different speeds for about 20 mins.

Secon time out it started*great, put it in gear at low speed for about 5 mins then the over heat alarm came on, water was pumping fine and I turned the motor off. I*started it again fine and the heat light stayed off with no alarm, I gave a few throttle squirts and was ok but a surge in the*power happend a couple of times but was ok. I ran at low*throttle for about 10 mins and was fine, I turned the motor off for about 10 mins then*started it again, it was running rough and*had an air backfire then stalling, then tried it again, it started and I put it in gear to take off and had no power then it stalled. It wouldnt start again.
I got it home on the hose and it starts fine the next day..


I Still have the Oil tank on it and*my mechanic told me*to run the*petrol tank*mixture *at 50/1 but mark the oil tank with a black texter to see if the level has moved.
If anyone could help befor I take it to the Mechanic that would be fintastic.
Stokes.

Take the automatic oil tank of and throw it away as far as you can !!!-------Next step on this motor is a compression test.--Report the results.----------I am working / rebuilding some of these 3 cylinders 25 / 35 HP motors this winter.-------------Great motors but easily ruined by careless operation.

I have the same motor in a 1997 25 hp 3 cyl. version. Get that auto oil system off there, mix manually 50:1. I had a similiar issue a couple years ago. Would start fine, take off then go to SLOW mode, it was "peeing" water fine. Mine was a faulty thermostat. As racerone said, good little motors when well maintained.

I would like to pick up another good used one.

Yes these small 3 cylinder 35 HP motors use the same main bearings as the 70 HP 3 cylinder.

racerone, You wouldn't happen to have a '1996 - 2001 25hp 3cyl short shaft version in good shape would you, for sale? We have 25 hp restrictions down here where we hunt on public land. Also, do you know if there were any other differences in the 25 hp vs. 35 hp other than piston size (larger bore) and carburator jet size??? I think the timing spec. was a couple degrees different between the two (25 & 35) also, I think!

I have 3 of those that I have apart for inspection and re-assembly, 1997 models.-------------They are 2000 miles away from you,no shipping.-------------The 35 has bigger bore and I think the 25 block can be bored out to fit the 35 HP pistons.

Yeah, thats true (distance). Looks like a 25 to 35 conversion would be pretty easy.

There are quite a few folks from the southern states that work up my way.----You never know somebody might be willing to transport one.------The 35 HP version is quite powerful and I have seen a couple of shattered clutch dogs.---Not beefy enough I think.

racerone, PM'd you!

Can someone please, please post a value for acceptable compression on this model? Since it is a looper, I have assumed around 90 to 100, but I would like to be sure.
I have one that I have posted on before, that I can literally turn the flywheel with one finger, but the comp is seemingly good at 100.
So why so loose I am asking myself.....

(I have not really hijacked this thread...it seems to be off topic by itself anyway....)