01-04-2009, 04:01 AM #1
- Join Date
- May 2007
- Buzzards Bay, Massachusetts
Has there been any progression on the 1500cc attempt for a GPR?
I'm trying to get a head start...even though I am slightly behind as usual. Anyways Lowell did an amazing job on one of my machines last year...want to convert them to 1390s this season or 1500s if the supposed bugs have been worked out. I'd like to keep my existing FI system and be able to just do an engine bolt in and go...if its not possible on a 1500 just let me know so i can not waste anyones time.
Hope everyone have a safe and happy holiday...im staring out my window in mass at 18 degree weather and crappy snow wishing for the warmth of summer again.
01-04-2009, 09:02 AM #2
contact hopatcongGPR, he has the 90 mm pistons etc.
01-04-2009, 09:06 AM #3
I own two 1500 motors built by Lowell that use these 90 mm pistons so I thought I should comment on your question. I have a 1530 (90 mm pistons, 2 mm stroked crank) in one of my skis. I have built a second 1500 motor (90 mm pistons, OEM crank) that I haven't installed in a ski yet.
First off, Lowell (and one or two others) have figured out how to build a big motor that makes lots of HP. Things like port timing etc have been figured out.
These motors make a lot of HP. A ski with one of these motors is a blast to ride. Hang on because it can get you where you want to go in a hurry. (There is simply no comparison to a stock ski, any stock ski 2 or 4 stroke for that matter.)
Even though with carbed skis there have been BBs as large as 1500 or even larger most EFI BBs have been 1390 or smaller. This has been because the EFI controllers we use are limited in how much extra fuel can be added.
It is a relatively simply process to convert a EFI ski to carbs so one option for adding a larger motor to an EFI GP1300R would be to simply use carbs. This option works well and is pretty much plug and play because the carb jetting and ignition timing has been figure out by others.
However, with the introduction of the SHO there are some new off the shelf products available that can help us in our search for more HP for EFI motors. R&D offer a complete fuel system upgrade kit for the SHO. In theory this could also be used on a GPR. The R&D set-up raises fuel pressure. They also offer replacement injectors for the SHO, these may not be needed for the GPR.
There are a couple of board members that have done quite a bit of work with EFI motors. I think in 2009 we will see some more advances for EFI motors for the GPR.
01-04-2009, 01:09 PM #4
01-04-2009, 01:55 PM #5
01-04-2009, 02:02 PM #6
01-05-2009, 04:48 PM #7
The OEM fuel sender includes a built in fuel pump regulator. This regulator sets the maximum fuel pressure at 45 lbs.
It would be interesting to see what the maximum fuel pressure would be
if this regulator was removed or disabled. Maybe sufficient fuel pressure for our needs could be attained without replacing the fuel pump. Maybe it is just the regulator that needs to be replaced?
If the fuel flow can be increased then maybe we no longer need to restrict ourselves to 1390 CC for an EFI motor. This would potentially allow 88 to 90 mm pistons and stroked cranks to be used.
05-03-2009, 07:38 PM #8
i got the fuel problem solved let me know
05-03-2009, 07:45 PM #9
theres at least 10 EFI 1500cc gpr's in miami... they run anywhere from 83-86mph
last one i saw was running rich (black plugs) but his settings where 11-11-11 at 70psi
05-03-2009, 09:00 PM #10
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