setting hi lo needles

[gain11]

'62 jhnsn seahrse 10hp need help seeting the hi and lo speed needle valves. I've got a manual but it covers so many models I'm not sure it's right. I can't seem to get smooth operation at all speeds. either it misses (jerks?) at lo speeds or hi speeds depending on the combination of the two settings. Normally does not miss at higher rpms.Also can't seem to get it to idle if I let off gas, it will die although it will stay running at lo rpms if I hold throttle?

 

[Paul Moir]

Re: setting hi lo needles

Follow Joe Reeves post here. The carbs on all those old 2 cylinder johnny/rudes are adjusted the same way, 3hp - 40hp. <br />If you can't get it to work well at low speeds, no doubt one of the tiny idle mixture passages are cloged, and you should rebuild the carb. You may notice that the low speed knob doesn't do much if the idle circuit is badly clogged.<br /><br />PS - did you run through the link & sync? (Synchronize carb to timing)<br /><br />The jerk, or sneeze is symptomatic of a lean condition. If it's not the carb, it could be that you have a primary compression (crankcase) air leak. Check crank seals, spray soapy water along the crankcase seam, check gaskets, etc. Carefuly check your spark plugs, as they might point to which crank chamber has a leak.

 

[OBJ]

Re: setting hi lo needles

Hi ya' gain.....<br /><br />Try this....run the low speed needle in till it GENTLY seats and back out 1 to 1 1/2 turns. Run the high speed needle in and back out 1/2 turn. Put the rig in the water and warm up. Run WOT in gear and set the high speed needle for best speed. Now slow down and set the low speed needle for best low speed operation. Turn the low speed needle in about 1/8 turn at a time and allow the engine to respond. Don't get it to lean.<br /><br />If this fails to get the engine in tune, may be time for a tuneup including carb overhaul and points and condensers.<br /><br />Keep us posted.

 

[gain11]

Re: setting hi lo needles

i didn't run the sinc thing you stated but I was reading another post where a guy said he was using j8 plugs and I believe it was you that said these will cause a misfire at mid idle speeds. That's the plug I am using. Better get some j6c's huh? The Clymer manual I have doesn't really show where the idle valve or jets or whatever you called it are. Would there be another name?

 

[Paul Moir]

Re: setting hi lo needles

Ah, the real problem he had was he had RJ8C spark plugs. The R stands for a resistor inside the spark plug body, to suppress radio interference. Unfortunetly, it also suppresses combustion in our outboards. <br /><br />The J8C is way too hot and your risking preignition and piston damage by using it. You're supposed to be running the much cooler J4C. I don't think that'll fix your problem, but it won't hurt!<br />I'm not real familiar with the Clymer's manual for this timeframe. I've only thumbed through it a couple times. But the idle circuit's smallest passage are tiny holes drilled just before and after the throttle plate in the throat of the carburetor. They are precision sized, so be gentle with them. They are connected through drilled passages to the fuel in the bowl of the carburetor. In between the two is the idle mixture control screw - that "low speed" knob on the front of the carb, which acts like a valve.<br />Link and sync (carburetor sychronization) is probably covered in the ignition section. The idea is to open the carburator when the spark is advanced so much.<br /><br />I hope this helps!

 

[gain11]

Re: setting hi lo needles

Thanks a million Paul.