|Posted on Thursday, January 06, 2005 - 11:25 pm: ||
Hi my name is Todd and this is my first time with the group.
Can you please help me with some questions about a S-T P55?
1. What is the hottest NGK sparkplug that I can use to prevent fouling?
2. What gap should the points be set to?
3. Why is SAE30 engine oil used and not marine, motorbike or chainsaw 2-stroke oil?
4. How do I replace the packing in the water pump and can I use brass shims to take up the slop on the pump body as it is very noisy?
5. What are the torque settings for the head studs etc.?
6. Does the motor have a thermostat and where is it?
7. What is the safest way to wire in an ignition/kill switch?
Any help would be greatly apppreciated.
Thankyou Todd Dunstone.
Post Number: 224
|Posted on Friday, January 07, 2005 - 07:24 am: ||
Todd ,My answers to you .
1 .I am sure you wont find a listing and recomendation for NKG plugs for ST engines.What i do is go to my local Auto tune or similier and ask them for their old spark plugs. When a car goes infor a service the first thing they do is change the plugs. I end up with NGK BP5EY and Bosch SuperRO 642, both 14mm ...they seem to be ok.
2 Points gap....depends on magneto .the Lucas type .012'' .
3 Oil the special ''two stroke oils '' were not around when the recomendations were made only the good old SAE 30. Use the special oils by all means , you can use less which means less chance of ''oiling up''.
4 Not quite sure what you are getting at here. The packing replacement is straight forward. Just undo the nut ,the one with the notches on it . Use a ''C '' spanner if you have one .Greasy hemp is used but i now use a Teflon packingbut dont make it to tight ,just nip up the nut and let a little drip of water persist,it lubricates the pump piston.
5 Torque settings for the cylinder head, Not an issue ,as long as you dont overdo it ,just pull them up in a even sequence.
6 No thermostat.
7 Kill switch . Connect a lead from the LT connection on the Magneto through your switch and then to the engine [earth]
Post Number: 346
|Posted on Friday, January 07, 2005 - 09:12 am: ||
Peter my experience with the modern two stroke oils is they wont hurt the old time two strokes they just have a bad habit of not burning in the upper chamber and come flying out the exhaust. It is my underdstanding they are formulated for very high temp burning as in chain saws,weed whackers and such. Incidentally they are also intended for very high swept piston speeds. This means that with the 40:1 mix used with SAE non detergent 30 weight oil most of the oil burns in the upper chamber and only a small percentage goes down the exhaust pipe as oil. The cylinder walls in old time two strokes are basically cold compared to a chain saw. A sea water cooled two stroke could not be operated over over 143 degrees F with out serious salt percipitation filling up the water jacket. I wonder if changing the ratio of modern two stroke oil/fuel would change the situation sufficient to permit safe operation of these old timers? Any suggestions as to what that ratio would need to be? Would the not burning in the upper chamber problem acually change for the better? I certainly have no idea and I am reluctant to try on one of my pets. Regards, Dick
Post Number: 225
|Posted on Friday, January 07, 2005 - 11:49 pm: ||
I am sure you are correct in this case Dick . I am speaking from a non sea going experience.All my engines are trolley mounted and i take them to rallys. So they just tick over all day . Now and then i open them up to get rid of that accumulated oil in the crankcase. The modern two stroke oil works well in this case. They hardly smoke much to the pleasure of those exhibiting next to me. We had acase once at a show ,one of the boys was running an engine on Kero . A food stall down a bit complained. So we shut the whole show down for an hour . Hardly had any visitors . When we started up again the crowd came from all corners ....they love the exhaust note!
Todd should use the old SAE 30 to be safe.
|Posted on Monday, March 06, 2006 - 02:10 pm: ||
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