after full engine rebuild, the ski is running fine for approx 15 mins then seems to surge and will only rev to half throttle ,as everthing is new in the engine department i cant open it up to full throttle but at the moment i am only getting half throttle ? seems to rev up fine on the drive and out of the water with hose connected any ideas ?
720 gs still not running right ,need advice please
- Thread starter daz20vt
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Carb adjustment...
When you put the motor in, did you look inside the throat of the carb while pulling the throttle open full, to see that the plates are opening all the way? Are you running a heaver mix of oil for break-in? Are you using the right oil? What do your plugs look like? Do they show signs of leaning out? What was the compression after you rebuilt/replaced the motor?
Give us a shoot back!...............
When you put the motor in, did you look inside the throat of the carb while pulling the throttle open full, to see that the plates are opening all the way? Are you running a heaver mix of oil for break-in? Are you using the right oil? What do your plugs look like? Do they show signs of leaning out? What was the compression after you rebuilt/replaced the motor?
Give us a shoot back!...............
:agree: Seadoosnipe is correct...we need more information to help.
never checked carb as you say but will have to have a look at it now, using normal oil pump and premix the petrol at 70/1 ratio as breaking in, using seadoo mineral, oil plugs are new and look normal,sounds crisp when out of the water,would a faulty rectifier cause this problem as i said before runs nice for approx 15 mins then slowly dies down will do a compression test and let you know regards daz
Rectifier?....
No Daz, I don't think your rectifier would be causing this. I'm wondering if your leaning out and starting to run hot. If so, your temp sensor should pick up on this and warn you.
The other thing I'm wondering is if you may be drawing a vacuum on your fuel system by having a stopped up vent line.
You said "oil plugs look normal", I'm going to assume that a typo and it was meant that your spark plugs look normal.
Check your fuel tank for a vacuum the next time you take it out and you start having this problem. Make sure you turn off your engine so you can hear it, then loosen the cap to see if there is a vacuum on it.
If not, then you may want to check your carbs. You don't say what year your GS is, so I don't know if your running single or twin carbs. If your running twin, you'll need to check for syncro.
Let me know what year GS your running.
No Daz, I don't think your rectifier would be causing this. I'm wondering if your leaning out and starting to run hot. If so, your temp sensor should pick up on this and warn you.
The other thing I'm wondering is if you may be drawing a vacuum on your fuel system by having a stopped up vent line.
You said "oil plugs look normal", I'm going to assume that a typo and it was meant that your spark plugs look normal.
Check your fuel tank for a vacuum the next time you take it out and you start having this problem. Make sure you turn off your engine so you can hear it, then loosen the cap to see if there is a vacuum on it.
If not, then you may want to check your carbs. You don't say what year your GS is, so I don't know if your running single or twin carbs. If your running twin, you'll need to check for syncro.
Let me know what year GS your running.
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All Things Custom
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Sounds like junk in the carbs to me... or a bad oil pump... You said the motor was rebuilt.
Did you go through the carbs? or test the oil injection? you dont know how often I get skis that come to me with blown motors with less than 10 hours on them.
Customers pay someone to rebuild their motor without finding the cause of the first breakdown. Which is usually plugged carbs. They put the new motor in and re-install all the bad/faulty parts that caused the first motor to go and destroy the new motor.
Then bring it to me only to find out it needs a new top end and a simple carb rebuild. (or at least the filters cleaned)
Did you go through the carbs? or test the oil injection? you dont know how often I get skis that come to me with blown motors with less than 10 hours on them.
Customers pay someone to rebuild their motor without finding the cause of the first breakdown. Which is usually plugged carbs. They put the new motor in and re-install all the bad/faulty parts that caused the first motor to go and destroy the new motor.
Then bring it to me only to find out it needs a new top end and a simple carb rebuild. (or at least the filters cleaned)
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Amen!
That can't be said enough..........It's been said over and over and over. Especially to those that come into the forum to look for a temporary fix to something, rather than find the "Root Cause" as to why it won't work to begin with......or why it broke to begin with.
If the part wasn't on their to begin with, then putting something on to help it out, defies the logic in finding out why it isn't working the way it's suppose to as the manafacturer designed it to!.............:agree:
That can't be said enough..........It's been said over and over and over. Especially to those that come into the forum to look for a temporary fix to something, rather than find the "Root Cause" as to why it won't work to begin with......or why it broke to begin with.
If the part wasn't on their to begin with, then putting something on to help it out, defies the logic in finding out why it isn't working the way it's suppose to as the manafacturer designed it to!.............:agree:
HI BUD, been out today on the ski and tried the fuel cap for vacum as you said only made a very little hiss as i removed the cap, started it up again but made no difference, i even removed cap at about 20mph expecting it take off but again no difference engine is running cool, so it looks like carb off next, its a 1999 gs single carb i will let you know if i find anything in the carb cheers
Keep us posted on you cure to the problem...I bet it is in the carb too.
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