96 gsx 5620 mid range problem
- Thread starter jaspruden
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jaspruden
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I got complete assmblies, housings and all.
jjsinaz
Active Member
Update:
Resynced the carbs using the sound method they were a bit off. Adjusted the carbs 1 turn out on the LS and 0 on the HS Mag; 1/4 on the PTO.
Went to the lake on Sat without the airbox on but with the flame arrestor in place. Adjusted the LS screws slightly to smooth out the idle. Took it out and it seemed like the flat spot was not nearly as bad and it was running good. As I ran it more the flat spot seemed to "adjust" itself back to the way it had been. When I put the airbox back on it it ran like crap Ran rough in the 5000 to 5500 range where it used to be smooth. Took the airbox cover back off and it solved the 5000 to 5500 problem but still have the flat spot. Leads me to think it's rich, since when you restrict the air with the airbox on it runs worse and pulling the choke slightly makes it even worse
I'm going to have to go back to the drawing board on those carbs. I am going to go through the original set with a fine tooth comb and then put those back on. I think I'm going to get a different gauge to measure the pop off. Was using the gauge on my HF air regulator to measure it and not sure of the accuracy of the chinese gauge.
Resynced the carbs using the sound method they were a bit off. Adjusted the carbs 1 turn out on the LS and 0 on the HS Mag; 1/4 on the PTO.
Went to the lake on Sat without the airbox on but with the flame arrestor in place. Adjusted the LS screws slightly to smooth out the idle. Took it out and it seemed like the flat spot was not nearly as bad and it was running good. As I ran it more the flat spot seemed to "adjust" itself back to the way it had been. When I put the airbox back on it it ran like crap Ran rough in the 5000 to 5500 range where it used to be smooth. Took the airbox cover back off and it solved the 5000 to 5500 problem but still have the flat spot. Leads me to think it's rich, since when you restrict the air with the airbox on it runs worse and pulling the choke slightly makes it even worse
I'm going to have to go back to the drawing board on those carbs. I am going to go through the original set with a fine tooth comb and then put those back on. I think I'm going to get a different gauge to measure the pop off. Was using the gauge on my HF air regulator to measure it and not sure of the accuracy of the chinese gauge.
jaspruden
Member
Last year when I checked the compression, both cylinders were at 130.
This weekend I had it on the water this weekend with new plugs. When I pulled them to check them I also had a normal pto plug and a dark mag plug. Got the compression tester out again and probably have my problem located. The pto was still at 130 but the mag has dropped to 100. I suspect that for me to get this motor back to a reasonable performance, I will have to to a top in job on it.
I think I have located a donor jet ski (hull in poor condition and out of service for more than 5 years) of the same make and model for a realatively cheep price. I may do a compression check on it and do an engine swap. I might do a top end job this winter on this one.
This weekend I had it on the water this weekend with new plugs. When I pulled them to check them I also had a normal pto plug and a dark mag plug. Got the compression tester out again and probably have my problem located. The pto was still at 130 but the mag has dropped to 100. I suspect that for me to get this motor back to a reasonable performance, I will have to to a top in job on it.
I think I have located a donor jet ski (hull in poor condition and out of service for more than 5 years) of the same make and model for a realatively cheep price. I may do a compression check on it and do an engine swap. I might do a top end job this winter on this one.
Well here is what I surmise from all this.
The engine runs poorly when the carb is using negative preasure to draw fuel.
Low compression or bad crank seals cause this.
The engine runs good on top end. After 4500 ish the carbs transition from vacuum driven to airflow driven and this is also when the main jet kicks in...
A test for proof would have been to go to a 100 pilot jet which would have given more than enough fuel to work with a low vacuum signal.
Low compression was causing all of this.
Also another weird thing isthat if you have too good compression it leans out at just before 4500 which needs larger pilot jets.
And another weird one. If you over clearance the raves, I mean allot! It will make the low end very smooth but will lack the punch and the raves dont have the same effect when they open.
The engine runs poorly when the carb is using negative preasure to draw fuel.
Low compression or bad crank seals cause this.
The engine runs good on top end. After 4500 ish the carbs transition from vacuum driven to airflow driven and this is also when the main jet kicks in...
A test for proof would have been to go to a 100 pilot jet which would have given more than enough fuel to work with a low vacuum signal.
Low compression was causing all of this.
Also another weird thing isthat if you have too good compression it leans out at just before 4500 which needs larger pilot jets.
And another weird one. If you over clearance the raves, I mean allot! It will make the low end very smooth but will lack the punch and the raves dont have the same effect when they open.
I have first over bore OEM 787 pistons for $75 each shipped and I can program a new OEM DESS key to your grey box for $75(the key itself is $55) plus shipping if it helps.
He has one cylinder at 130 psi and one at 100 psi. Time for a rebuild.
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