Seadoo 650 flame arrestors

[shantico]

I have Ocean Pro flame arrestors on my 94 SPX 650. I have had some major piston siezing issues. I need to know about rejetting my carbs, and what to set the hi/low mix screws at so that I wont run lean any more. Just when I think I got it right this time, the engine dies and I have another either burnt or siezed piston problem. I also have 175 psi compression with this Westcoast head someone installed years ago. Im guessing I need to drop that down to 155 or so? Please help.

[dsolie]

Re: Seadoo 650 flame arrestors

Yes, drop the compression in that head.. You might not need to re-jet the carbs, what's in there now? Give us high, low jets as well as N&S size please (if you know the pop-off, that would help a lot).

Your massive damage could be from the head...

Quick question for you.. When it seized the first time, did it damage the head, and it so.. why did you re-use a damaged hi comp head?

[shantico]

Re: Seadoo 650 flame arrestors

First thing, I bought this ski used and I'm not totally sure what the dude did to it. When the engine first had problems, the pistons had pits in the center just below the plugs and on the side. I figured the oil pump wasn't doing its job because the lines were old and dry rotted. I bench tested the oil pump and replaced the lines as well as threw some oil in the gas 50 to 1. The same thing happened again a few months later. I bored out the jugs one size and rebuilt the top end again. This time I had help from a mechanic that I knew, I thought I might have done something wrong the first time, not to mention it had a full tank regular 2 stroke oil that I changed out to seadoo oil after some research. The head seems to have no damage at all, maybe a couple slight scratches in the bowls. It is a Westcoast BEP7500 running at around 170 to 175, or at least thats what my $30 compression gauge reads. I also had 87 octane fuel in the tank because thats what the manual said I could use. I know now that is not true with this head. The jets are 120 and 65 which my shop manual says they should be 125 and 60? I just went out and pulled the needle and seat and there was no info stamped on them. Thanks, and I will be buying my motor from you guys next time!

[dsolie]

Re: Seadoo 650 flame arrestors

The N&S info is on the bottom of the seat.. REAL SMALL.. Should be a 1.5 or 2.0 or something like that..

JETS ARE WAYYYY TO SMALL.. for a 650 with F/A's.. Typical jetting for a STOCK 650 (94 SPX) is 60/125 with BR8ES plugs (7's are only for 587's)..

I am thinking it may be more of a uber lean condition on top of the high compression. Is there any other markings on the head (are the domes removable)? Is there anything that says how many CC's the head is?

How about a few pics too..

[shantico]

Re: Seadoo 650 flame arrestors

The N/S says 2.3 and your right, very hard to read. I would assume that I can get the domes out of that head and change them, however, I am not sure how yet. I might just buy whatever head you recommend me to get. The size of the bowls is probably printed on the part I cant see until I get them out. I took some pics but I am not sure how to attach them to this thread. I will gladly e-mail them to you or just let me know how to attach them. Thank you so much for your help.

[dsolie]

Re: Seadoo 650 flame arrestors

email them to dans@designbyothers.com and I will post them up..

If you want to try posting, click on "go advanced" beneath your reply box, and you will see a spot to manage attachments.


Also, I think 2.3 may be a little high.. will have to dig back out the book.. But I thought 1.5 was stock, and 2.0 is what you should be using with F/A's

[shantico]

Re: Seadoo 650 flame arrestors

Sorry for the delay,
Here are some pics of the head and top end. I wish I could have
gotten you a pic of the one piston with the siezed rings and the major scaring, but It was at my fathers machine shop when I got the photos. I will get those to you ASAP.. In the mean time I hope these help. If you could, Just let me know what high and low jet, what needle and seat, and what head to get and I think I'll be ready to try again. This time with a fresh tank of 93 octane. By the way, just how bad is running regular 2 stroke oil in a Seadoo anyway. My tank is full of seadoo oil, but it is light green because I mixed it with the remaining 1/4 gallon of regular oil that was left in the tank. Thanks again! Shane

[John Kubiak]

Re: Seadoo 650 flame arrestors

.....By the way, just how bad is running regular 2 stroke oil in a Seadoo anyway. My tank is full of seadoo oil, but it is light green because I mixed it with the remaining 1/4 gallon of regular oil that was left in the tank. Thanks again! Shane

If that oil was a nice, clear amber color and a sweetish smell, then there is no problem at all, that was Sea-Doo mineral oil, and is fully compatible with their synthetic (and vice-versa0

[dsolie]

Re: Seadoo 650 flame arrestors

Those domes look like they can come out... Push on them from the top (little hole) and with some force, they should pop right off. Let me know what CC markings are on the domes please.

To re-jet properly (your at sea-level, or about, right?).. You increase up 10% and up bump up the N&S size..

So, here is where I would start..
67.5 pilot
137.5 high
2.3 N&S
get your pop-off to around 20

A head can be found off of ebay for fairly cheap.

[shantico]

Re: Seadoo 650 flame arrestors

Thanks for the help, I'll follow all of your advice and let you know how it goes. In the mean time Ill work on getting those bowls out.

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