ATS_Aaron
X-
- Location
- Shady Shores, TX
I've got my ski pretty well dialed in. The last two modifications should ahve helped bottom end, but they really didn't in fact ATS_Scott thinks the bottom end got worse.
MSD total loss. 27 degrees initial timing to 5500, then retarding to ~16 degrees around 9k.
higher compression domes (200 psi)
The engine is 946cc Lamey PV billet cylinder, +8mm Crankworks stroker crank (thanks Team Scream), Team Scream ported cases trenched and epoxied by DASA (girdled by me), older Novi 48mm dual carbs jetted by me.
The midrange and top end are INSANE! The ski accelerates FAST, like 1000cc sport bike fast.
The problem is the bottom end just isn't there, well I think it's there but I can't get the pump to hook up. If you do a real slow bounce like to do a flat water back flip is just barely hops out of the water, but if you can carry a little speed and then hit a good setup wake or a boat wake it goes nuts.
If I stand in the back of the tray and half throttle it, it will just about yank me off, but if I go full throttle it feels like I have less thrust. I don't think it's a jetting problem either, Superramjet rode it and said he thought the impeller was slipping down low too.
I need to get the tachometer back on it to make sure it is revving out like I think it is by ear, but I seriously believe the problem is the impeller is ripping free. I have spent most of the summer trying out different impellers. I started with a 13/18 Solas with all the Impros modifications and am up to a 14/19 Hooker with a TBM pump stuffer on a blue printed stator. That is a huge gap, considering that Impros recommends like a 10/16 Hooker to replace the Solas 13/18. I've got a Skat 15/20 big hub impeller to try out today, but that is basically my last ditch hope for getting the stock pump to work.
I called Skat Trak yesterday and told them I legitimately thought I was making 160hp and wanted a pump with good bottom end and I didnt' care if it wouldn't do over 35mph. They said I should go with their one piece billet 148mm pump. This was all great, until we got to the price:
pump $2200
drive shaft $420
reduction nozzle (might include the trim setup?) $720
That's like $3500.
Ouch. Have I really gone this far?
So am I desperately looking at other options, like:
older style 148mm Magnum pump. I've seen these for GP1200's and they usually sell used for under $500. What reduction/trim setup could/should I use? I think these setups start out as a 155mm setup and get resleeved down to a 148mm by Skat track. That means it could be HEAVY like the 140mm Skat Trak Magnum...but my ski has no foam out back and floats NOSE IN so I could use a little weight out back. Who else has run the older style 148mm setup, what else do I need? If it's not setback can I use my stock driveshaft?
Ratti's 145mm setup? I asked him about it and he said it worked great with his 1000cc XScream motor. Unfortunately it may already be sold.
Skat Trak mentioned some of the crazy Japanese guys are actually going to 155mm pumps! There is a 155mm skat Magnum on PWCToday right now.
Thanks in advance,
Aaron
MSD total loss. 27 degrees initial timing to 5500, then retarding to ~16 degrees around 9k.
higher compression domes (200 psi)
The engine is 946cc Lamey PV billet cylinder, +8mm Crankworks stroker crank (thanks Team Scream), Team Scream ported cases trenched and epoxied by DASA (girdled by me), older Novi 48mm dual carbs jetted by me.
The midrange and top end are INSANE! The ski accelerates FAST, like 1000cc sport bike fast.
The problem is the bottom end just isn't there, well I think it's there but I can't get the pump to hook up. If you do a real slow bounce like to do a flat water back flip is just barely hops out of the water, but if you can carry a little speed and then hit a good setup wake or a boat wake it goes nuts.
If I stand in the back of the tray and half throttle it, it will just about yank me off, but if I go full throttle it feels like I have less thrust. I don't think it's a jetting problem either, Superramjet rode it and said he thought the impeller was slipping down low too.
I need to get the tachometer back on it to make sure it is revving out like I think it is by ear, but I seriously believe the problem is the impeller is ripping free. I have spent most of the summer trying out different impellers. I started with a 13/18 Solas with all the Impros modifications and am up to a 14/19 Hooker with a TBM pump stuffer on a blue printed stator. That is a huge gap, considering that Impros recommends like a 10/16 Hooker to replace the Solas 13/18. I've got a Skat 15/20 big hub impeller to try out today, but that is basically my last ditch hope for getting the stock pump to work.
I called Skat Trak yesterday and told them I legitimately thought I was making 160hp and wanted a pump with good bottom end and I didnt' care if it wouldn't do over 35mph. They said I should go with their one piece billet 148mm pump. This was all great, until we got to the price:
pump $2200
drive shaft $420
reduction nozzle (might include the trim setup?) $720
That's like $3500.
Ouch. Have I really gone this far?
So am I desperately looking at other options, like:
older style 148mm Magnum pump. I've seen these for GP1200's and they usually sell used for under $500. What reduction/trim setup could/should I use? I think these setups start out as a 155mm setup and get resleeved down to a 148mm by Skat track. That means it could be HEAVY like the 140mm Skat Trak Magnum...but my ski has no foam out back and floats NOSE IN so I could use a little weight out back. Who else has run the older style 148mm setup, what else do I need? If it's not setback can I use my stock driveshaft?
Ratti's 145mm setup? I asked him about it and he said it worked great with his 1000cc XScream motor. Unfortunately it may already be sold.
Skat Trak mentioned some of the crazy Japanese guys are actually going to 155mm pumps! There is a 155mm skat Magnum on PWCToday right now.
Thanks in advance,
Aaron