A Few Running Anomalies - Help Please
Posted: Wed Apr 19, 2006 7:45 am
Got my TC-102 onto the boat (12' alum dinghy) and onto the water at last.
She starts fine: 1 or 2 pulls (unless I flood, or over choke it).
I may have it a bit too low in the water at present, but will raise it next trip.
It has gallons of water at the outlet tell tale after my recent head de-rusting sessions.
The water temp at outlet is not hotter than my hand can stand, but the head/cylinder and exahust pipe are far too hot to touch. Is this normal?
It runs (in my newbie assessment) well at idle, well at half speed, and well at full speed.
It blows not too much smoke.
But ..... after about 5 - 10 mins it seems to run slower and more labouriously. I swear the speed of motor and boat has dropped 20 - 30% after half a mile or so. Also, it seems to occassionally ... lurch ...slip... miss power ..... cavitate a little .... sort of like hitting a "heavy water patch" or something. I look around to see if I hit weeds or something, but no.
I have checked the plug gap - it is OK at 20 thou.
I have checked the points gap - it is OK at 20 thou.
I have correct fuel mix at 25:1 (previous owner said so).
I just gave the carbie a full strip and clean.
After a break or 5 - 10 mins, it starts fine and has full power and speed again, only to slow about 20% after 5 mins.
Hmmmm? What might cause this "tiring", this "labouring" of the engine when warm?
Could it be too deep in the water, too much exhaust back pressure?
Could it be compression rings/gasget/housing leakage when hot?
Could it be head cracks opening up when hotter?
I have a NKG A7 plug. Should I try a Champion D16 for a comparision test?
Also, the prop I have is a 9 and 1/4" 4 blade which seems like overkill in the power department. Might a 2 blade be more suited to a 4hp on such a small boat and for better speed?
Swami.
She starts fine: 1 or 2 pulls (unless I flood, or over choke it).
I may have it a bit too low in the water at present, but will raise it next trip.
It has gallons of water at the outlet tell tale after my recent head de-rusting sessions.
The water temp at outlet is not hotter than my hand can stand, but the head/cylinder and exahust pipe are far too hot to touch. Is this normal?
It runs (in my newbie assessment) well at idle, well at half speed, and well at full speed.
It blows not too much smoke.
But ..... after about 5 - 10 mins it seems to run slower and more labouriously. I swear the speed of motor and boat has dropped 20 - 30% after half a mile or so. Also, it seems to occassionally ... lurch ...slip... miss power ..... cavitate a little .... sort of like hitting a "heavy water patch" or something. I look around to see if I hit weeds or something, but no.
I have checked the plug gap - it is OK at 20 thou.
I have checked the points gap - it is OK at 20 thou.
I have correct fuel mix at 25:1 (previous owner said so).
I just gave the carbie a full strip and clean.
After a break or 5 - 10 mins, it starts fine and has full power and speed again, only to slow about 20% after 5 mins.
Hmmmm? What might cause this "tiring", this "labouring" of the engine when warm?
Could it be too deep in the water, too much exhaust back pressure?
Could it be compression rings/gasget/housing leakage when hot?
Could it be head cracks opening up when hotter?
I have a NKG A7 plug. Should I try a Champion D16 for a comparision test?
Also, the prop I have is a 9 and 1/4" 4 blade which seems like overkill in the power department. Might a 2 blade be more suited to a 4hp on such a small boat and for better speed?
Swami.