physicistkev
New Member
So I just picked up a 1996 speedster that has a throttle/power issue. It is a bit difficult to start but not unbearable. All cables (throttle, choke and direction) are smooth and clean. Rear cylinder has 142psi and front cylinder has 140psi compression. Spark plugs look good, slight charcoal color and are not excessively wet. If anything they are a bit on the lean side.
The problem goes like this. Once started the boat will use up to 1/4 throttle and not really exhibit any issue. Maybe a slight bog, but nothing really out of the ordinary. Once you pass 1/4 throttle the engine will either bog down or it may carry the RPM up to full throttle, usually bog. If it continues to gain RPM, I have no idea if I am reaching peak RPM or not, but it starts to plane and then the engine just bogs down. It might maintain high RPM for 2 - 3 seconds. If you leave it at WOT it will run for at least a few more seconds. I really haven't left it there to see if it actually stalls or not. If it bogs down the RPM drops, but it continues to run.
I can get it passed the bog by rapidly going from 1/4 to 3/4 throttle until I hear the RPM climb above a certain point and then it will really rev up. However, it only maintains high RPM for a few seconds and then slowly, over a second or 2, drops down to barely 1/4 throttle speed.
It feels like a rich condition, but the plugs don't show it. I guess it could be bad gas as I don't know how long the gas has been in the tank, but it's unlikely. It is most likely a fuel delivery issue, as though the tank isn't staying pressurized or the fuel lines are clogged. The carburetor was rebuilt last year, and the seller had the receipt. The exterior of the carb looks terrible so I am very tempted to tear it apart and clean it, but I wanted to see if anyone here had a better place for me to start looking.
Thanks,
Kevin
The problem goes like this. Once started the boat will use up to 1/4 throttle and not really exhibit any issue. Maybe a slight bog, but nothing really out of the ordinary. Once you pass 1/4 throttle the engine will either bog down or it may carry the RPM up to full throttle, usually bog. If it continues to gain RPM, I have no idea if I am reaching peak RPM or not, but it starts to plane and then the engine just bogs down. It might maintain high RPM for 2 - 3 seconds. If you leave it at WOT it will run for at least a few more seconds. I really haven't left it there to see if it actually stalls or not. If it bogs down the RPM drops, but it continues to run.
I can get it passed the bog by rapidly going from 1/4 to 3/4 throttle until I hear the RPM climb above a certain point and then it will really rev up. However, it only maintains high RPM for a few seconds and then slowly, over a second or 2, drops down to barely 1/4 throttle speed.
It feels like a rich condition, but the plugs don't show it. I guess it could be bad gas as I don't know how long the gas has been in the tank, but it's unlikely. It is most likely a fuel delivery issue, as though the tank isn't staying pressurized or the fuel lines are clogged. The carburetor was rebuilt last year, and the seller had the receipt. The exterior of the carb looks terrible so I am very tempted to tear it apart and clean it, but I wanted to see if anyone here had a better place for me to start looking.
Thanks,
Kevin
