Johnson 9.5 Hp Boged Down ????

[william66]

I have a 1970 Johnson 9.5 hp will crank on second pull every time and will acelerate to high rpm wile in neutral but in gear seems to get to about 1500 or so rpm can anyone tell me where to start looking ? runs fine untill you get a load on it has new plugs gaped at .30 and running 97 oct. gas mixed at 50:1
Thanks for any help

 

[dew2]

Re: Johnson 9.5 Hp Boged Down ????

Start with a compression test if its ok the next woulb be a good carb clean.

 

[boobie]

Re: Johnson 9.5 Hp Boged Down ????

Has it got spark on both cyls when running?

 

[kbait]

Re: Johnson 9.5 Hp Boged Down ????

Properly check spark/compression. If good, try running it with the cowl off. If it performs normally then, you have an exhaust leak which is choking out the engine, likely the shift shaft seal under the powerhead or the big rubber suspension seal. Good luck!

 

[kbait]

Re: Johnson 9.5 Hp Boged Down ????

And ps.. use non-oxygenated (non-ethanol) fuel if you can find it in your area. These motors don't need 97 octane. Cheapo gas is fine.

 

[william66]

Re: Johnson 9.5 Hp Boged Down ????

well call me stupid ! turns out I have a coil on 1cyl. that wasnt firing never would have thought it, as easily as it was starting ... and I only started it the once in a barrel filled with water for about 5 mins. so I have ordered a coil and hope to have it by the middle of the week
Thanks to everyone !!!

 

[kbait]

Re: Johnson 9.5 Hp Boged Down ????

It's amazing how smooth they run when one cylinders' spark is completely dead.
Remember to cut 1/2" off the end of the plug wire before securing into new coil to ensure a positive connection. Also, pull the pointsets and file out all pits on the contact surfaces and get 'em nice and shiny and reset to .020" while your in there. Check out 'top secret files' sticky at the beginning of this forum for loads of great info...

Good luck!

 

[william66]

Re: Johnson 9.5 Hp Boged Down ????

Thanks to everyone for the help after a new coil and points and condensers it seems to be running pretty well now ! need to check and see if I am running the right spark plugs I just slaped in a set the same as the old owner had in it but not sure if they are the corect ones ? and had one blade bent on the prop so i had in fixed now just need all this rain to clear out to get back on the water its about time for the crappie to spawn

 

[kbait]

Re: Johnson 9.5 Hp Boged Down ????

My chart calls for champion j4c's.. I'd use j6c's if used exclusively for slow trolling.. Gap at .030"
Congrats!