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Just installed my coffman rec pipe

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AdamA96XP said:
Sounds pretty good .
What other mods have you done other than the pipe? Carb work or anything?
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Thanks! No, just had the engine rebuilt top to bottom last season is all. I want to at least put flame arresters on to kind of even out the added performance on the exhaust side, but still in the early stages of that. Do you have any mods to your xp?
 
If that is the pipe I'm thinking of then it has no water jacket and runs really hot under the seat. Be careful not to let any wires or hoses rub into it. Your carbs will need larger low and high speed jets with the pipe and flame arresters. I would get a digital tach(like a Trail Tech) so you can measure the results of your adjustments. Pull your spark plugs to inspect their condition often. You want to see some brown color because grey or white means your gonna burn a piston.
 
No mods here, bone stock. Just put a new engine in it a few weeks ago. What kind of performance gains have you seen with the pipe?
I know those things aren't cheap . It deff gives it a different tone, sounds pretty sweet.
 
Matt Braley said:
If that is the pipe I'm thinking of then it has no water jacket and runs really hot under the seat. Be careful not to let any wires or hoses rub into it. Your carbs will need larger low and high speed jets with the pipe and flame arresters. I would get a digital tach(like a Trail Tech) so you can measure the results of your adjustments. Pull your spark plugs to inspect their condition often. You want to see some brown color because grey or white means your gonna burn a piston.
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Yeah this one has no jackets, i wondered about that too. I did make sure to zip tie and clip my wires and hoses near it. Guess I'll have to ride with the seat off for a few times to make sure everything stays ok in there. I am at about 4200 ft with stock jets and pretty low pop off pressure, so I am already running a bit rich, so I wonder if I can get away with stock jets. I will have to proceed with caution and check my plugs carefully. Thanks for the heads up on the pipe temp.
 
AdamA96XP said:
No mods here, bone stock. Just put a new engine in it a few weeks ago. What kind of performance gains have you seen with the pipe?
I know those things aren't cheap . It deff gives it a different tone, sounds pretty sweet.
Click to expand...

Honestly, I don't know a whole ton about the pipe outside of what I have read from various forums, supposedly the coffman has a good rep and the rec pipe is good for low to mid range (so I have heard) which should be good, rather than rapping the engine out and needing a higher pitch impeller.

I won't be able to test it until it warms up in the spring, but I look forward to it for sure. I scored the pipe from a dude on this forum a while back, it's brand new other than the flange being used. 200 or so if I remember correctly, they were like double that new I think. The lady (Pam) at coffman, was very nice and sent me some tuning instructions.
 
That's awesome! Good luck in the spring. The 96xp has some power, now you just have alittle more!
 
Well the right way to do it is start with a fresh solid motor so your one step ahead of most there!

The 787 doesnt really respond to any one mod very well so I wouldnt expect much. Did you put a rev limiter in already? I would assume so...how about water injection?

I would plan to mill the head to about 180 psi, run premium, flamer arrestors, and some jetting. Then you should start feeling some difference. then from there a prop if you dont already have one, and maybe a set of carbs.
 
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Minnetonka4me said:
Well the right way to do it is start with a fresh solid motor so your one step ahead of most there!

The 787 doesnt really respond to any one mod very well so I wouldnt expect much. Did you put a rev limiter in already? I would assume so...how about water injection?

I would plan to mill the head to about 180 psi, run premium, flamer arrestors, and some jetting. Then you should start feeling some difference. then from there a prop if you dont already have one, and maybe a set of carbs.
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Couldn't agree with you more nick I have modded many 787 seadoo's and I can tell you that the best thing you can do is like nick said mill the head for 175-180 psi with a safe squish flame arresters a prop some nozzles and a set of carbs. We did these mods to a friend of mines xp and the thing absolutely rips 62 mph and gets there in a hurry it runs on 93 octane and is as reliable as your every day ski. Now we used a factory spec 1 pipe but the Coffman is a decent pipe and should have a noticeable difference over a stock pipe but without supporting mods it's not gonna be anything spectacular.




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Thanks guys, I actually thought about milling the head too since it probably is a fairly cheap mod. Minnetonka, do you have any good priced flame arresters?
 
As for the rev limiter, I have not done anything yet. But it revs way higher than my other two. (well it sounds like it does) I have not ever heard the rev limiter kick in, so I wonder if it does not work or the previous owner disabled it, not sure if the MPEm controls it on that year. For water injection, I have a jet in the water port by the flange running from a t fitting that is unregulated. As for the tailcone, and the water box, I still have it hooked to the stock regulator. Not sure how that will work, but I can't find any t fittings with jets to hard jet it like the manual says. I am open to any advice though if you have any.
 
That is a short pipe with a long hose between it and the waterbox to keep cool. I would definitely take your first wet tests with the seat off and see how things go. I think your water regulator cuts most the water at high rpms so be careful.
 
rotaxrule1 said:
As for the rev limiter, I have not done anything yet. But it revs way higher than my other two. (well it sounds like it does) I have not ever heard the rev limiter kick in, so I wonder if it does not work or the previous owner disabled it, not sure if the MPEm controls it on that year. For water injection, I have a jet in the water port by the flange running from a t fitting that is unregulated. As for the tailcone, and the water box, I still have it hooked to the stock regulator. Not sure how that will work, but I can't find any t fittings with jets to hard jet it like the manual says. I am open to any advice though if you have any.
Click to expand...

If you could....please post the instructions.

I highly doubt your MPEM is modified, but if you have never opened your ebox there could be a rev limiter module hiding in there from the previous owner.

You need to verify. If it doesnt you will not really have ANY difference from stock. You cant make any more speed if you arent turning more RPMs.

On the water injection, its good for midrange punch. I have all sorts of fittings, injection solenoids, etc if you need anything.
 
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Here are the instructions. Looking at them again, I see what you are saying for rev limiter mods, I was thinking this pipe was a low to midrange pipe originally and didn't have top end gains. Note the water line routing, I may be interested in a jetted t fitting because my water regulator is trashed anyway and leaks.
 
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