08-01-2013, 04:40 PM #1
- Join Date
- Feb 2012
GP1200R drive / intermediate shaft question
VF3 reeds and spacer plate from I.R.
Acc. pump and chokes removed, 125 main, 110 pilot, 43 pop-off press.
Free flow exhaust
Sealed pump shoe
Top-loader intake grate
Solas Concord 'Set-Back' Impeller - YF-CD-13/20-SB
130-130-130 psi compression
New sylinders and pistons a few weeks ago.
What rpm and speed should I expect get with these mods?
I think my spline in the drive shaft is starting to get worn out, because i just found out that there was no shims under the motor mounts, and I am also lacking 3-400 rpms from what I think i should have. It is also possible to move the intermediate shaft to much up, down and sideways. Because of that it is also impossible for me to align the engine properly. Before i could only move the intermediate shaft in these directions when the pump/driveshaft was removed from the ski. The intermediate bearing feels fine I when rotate it, and the bearings and seals in the pump was replaced a few weeks ago.
Does anyone have any comments on this?
My plan is to replace my 2000 Gp1200R intermediate and driveshaft, and also the intermediate bearing/seals, just to be sure.
Is there any benefits to go for the 2002 version of these, and will they fit?
08-01-2013, 09:39 PM #2
The only benefit to going with a newer model shaft would be worth it if you went to the late model pump and spacer then you would have to go with a dynafly prop.
When you replace the intermediate shaft and drive shaft and get it all tightened down. slide the motor back so the couplers slide together without the rubber insert in place so you can shim the motor true to the intermediate shaft. sometimes the rubber dampener can push the shaft so it seems true. after you get it shimmed wright you can slide the motor forward and install the dampener and make sure the shims are in place and tighten everything down just make sure you leave about a 1/4 inch +- between the motor coupler and the intermediate shaft.
08-01-2013, 10:56 PM #3
- Join Date
- Jan 2006
- Texas City, Texas
To your first question, you have the potential to get into the low 70's with your mods, but just because you have the mods..... well a fast boat it does not make. The engine needs to be tuned, and you are capable of getting approximately 7200 rpms provide it is a cool day, with high O2 content, low fuel level in the tank, good ride plate, the angle of the moon and stars etc, etc. It can be done, but it takes work.
Yamaha did not put their GPR together in a hap hazzard way. There is a way built in to make the drive train components pretty much align them selves. For the engine, the stock shims are absolutely needed for alignment purposes. If you do not have them, then you should get them. I believe in the GPR manual that the two aluminum couplers between the engine and intermediate shaft should be between 75 and 100 thousandts.
The pump needs to be aligned, and this is done properly when the transom plate is mounted properly to the hull. From the factory, a very high percentage of GPR pumps were not aligned. There are 3 "ears" on the 11 oclock, 1 oclock, and 2 oclock positions on the aluminum transom plate. THEY SHOULD ALL TOUCH the fiberglass tabs built into the hull. If you do not have the pump lined up properly, you can align the engine till the cows come home, and you will still eventually loose you intermediate shaft again due to poor alignment. You will still hear the impeller clanging against the wear ring and if the alignment is bad enough, feel the vibration through the throttle when you accellerate. You will also have trouble installing the pump and removing it. If you align your whole drive train, the pump shaft should slide right into the intermediate shaft "like they were made for each other" presumeably because they were.
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