97 seadoo 800 gtx wont start help

[ReeseBlaisdell]

I have a 97 seadoo 800 gtx that won't start. It cranks and backfires but will not even try to fire. Just did a top end rebuild, replaced the coil pack and the lanyard kill switch and I am really getting frustrated and could just use some help. I cleaned the carbs and even tried putting two stroke gas down the cylinders and still nothing.

 

[ToddinTO]

Wow, i just lived throught this exact experience with my 97 GTX!!!

The new replacement coil i put in was flakey, and the rotary valve was outta spec on the high side.

Mine started out ( When i bought it) with the magneto off the flywheel and i was not getting a spark....

 

[GGuillot]

I have a 97 seadoo 800 gtx that won't start. It cranks and backfires but will not even try to fire. Just did a top end rebuild, replaced the coil pack and the lanyard kill switch and I am really getting frustrated and could just use some help. I cleaned the carbs and even tried putting two stroke gas down the cylinders and still nothing.

What's the background on it? Have you had it running before? Why was the top end rebuilt? What's the compression after the top end rebuild? Did you rebuild the carbs with OEM kits needles/seats? test the pop off on the carbs? Did you take the rotary valve cover off? Why did you replace the coil? you verified there was no spark prior?

I know I'm asking a lot of questions, but there's a lot that can't be overlooked and you need to provide more detailed information how you got to this point.

 

[POPPS]

Since it was top end rebuild only, that would rule out rotary valve timing and incorrect stator ring position. I would check the dess post connections, ( spark runs through it) . Also check your connections ( and fuses) in the rear electrical box, grounds especially. Pull the plug at the top of the electrical box and check for corrosion. Check the ground wire that goes into the rear electrical box, and make sure it is secured to the negative of your battery. Remove the orange plug to find hidden corrosion. Pull the front electrical plug, and check for corrosion, remove the orange plug to find hidden corrosion. Do a resistance test on your pick up coil (180 to 300 ohms) . Coil packs rarely just go,they will run for a short while, 40,50 ft, get warm, then fail. Check your connections in the front electrical box. It's possible that the CDI is gone, that would kill all spark. Check the easy breezy items first that won't cost you any money.

 

[ReeseBlaisdell]

so some background on me I consider myself a small engine mechanic and I've been very successful fixing engines in the past so I have gone through most of the basics. I bought the jetski non running and the previous owner said that the engine has been replaced. When I got home to try to start it and it wouldn't start so I checked for spark and it was very faint. I put fuel down the cylinders and it had popped so I cleaned the carbs and checked the diaphragms and everything was good. I tried it again and after a lot of cranking it started and ran for three minutes or so and in this time I was driving it. When the engine hydro locked due to a leaky exhaust gasket which I replaced and when I tried to start it again it wouldn't stay running. That's when I pulled the engine to replace the stator and pickup, to try to improve spark and I noticed it wasn't charging. While the engine was out I decided to take off the head and take a look inside. I found grey sludge on the number 2 cylinder and decided to move forward with a rebuild because I couldn't trust the previous guy. I was right so in doing this finding that the number 1 wrist pin bearing was seized. I replaced both bearings, honed the cylinders, and replaced all of the gaskets. The piston rings were in good condition, (engine rebuilt by previous owner.) I got the engine all back together again both cylinders 110 PSI compression and the starter died so I couldn't try it. I pulled apart the rear electrical box and found that it had water in it before and the screws inside the coil pack had rusted off and the wires fell out when I touched it. While I was in there I cleaned all connections and put it back together after replacing the coil. I also replaced the kill switch because it was touchy. Since then I have tried to start it multiple times and have had no luck, it just won't start. It has great spark and cranks over well. Yesterday I pulled apart the rotary valve and sucked grey nasty fluid out of the bottom of the crank case (due to head gasket not seated, fixed that) I reset the valve with the #1 cylinder at TDC to 147 degrees, put it all back together again cranked it for 15 seconds and it backfired out the exhaust tried it again and it did it again and that is where i'm at now.

 

[ReeseBlaisdell]

I used to work at a small engine shop and I have a fair amount of experience with two strokes.

 

[mikidymac]

First off if your compression is at 110psi your top end is done and it will not start.

With it backfiring it sounds like your timing is off.
You need to follow the manual exactly and make the correct marks at 147 degrees from the bottom on the MAG intake port and 65 degrees from the top of the MAG intake port and then be 100% sure the cutout in your valve matches them. You can flip the valve over to move a couple degrees.

Finally if you had a wrist pin bearing seize and you did not replace the crank it is going to destroy the new one.

 

[GGuillot]

The piston rings were in good condition, (engine rebuilt by previous owner.) I got the engine all back together again both cylinders 110 PSI compression

As Miki mentions above, 110 is low, this engine after a top end rebuild should be 150. Honing and reusing pistons on these 2 strokes doesn't really work well, you should consider a cylinder bore and a new set of pistons. Anything much below 130 on the 787 isn't going to cut it. You didn't do a proper top end rebuild, and you need to readdress this before wasting any more time trying to get it to start.

I pulled apart the rear electrical box and found that it had water in it before and the screws inside the coil pack had rusted off and the wires fell out when I touched it.

Yesterday I pulled apart the rotary valve and sucked grey nasty fluid out of the bottom of the crank case (due to head gasket not seated,

Both indications the engine has been flooded at one point, you may be on borrowed time even if you get it running. The crank bearings will prematurely fail once rust sets in.

Personally, and I've been through this after acquiring my flooded 97' GTX, start over, pull the engine, with the service manual close by go through everything. Replace accordingly, I was at $900 with the engine rebuild acquiring what I needed. Those carbs and the fuel system need particular attention, new OEM kits, needle/seats, pop off test, etc.. Don't skip steps where it calls for 515/518 or synthetic grease. Chase threads, follow torque values and sequence, use a degree wheel, etc. Inspect, verify, and clean everything. It's not a quick job to accomplish, take your time.

I'm not trying to doubt your abilities, but details area important if you want it to start and be reliable.

 

[ReeseBlaisdell]

is there some where I can have the engine rebuilt professionally?

 

[GGuillot]

is there some where I can have the engine rebuilt professionally?

SBT does core swaps, they send you an engine and you send yours back. You can price it out, the shipping cost you'll find out when on the phone with them, goes by zip, they're located in South FL.

I'm sure people local near you could rebuild it, or a seadoo dealership could. But, I think your best bet is to roll up your sleeves and do it yourself, it's the least expensive route to take. My first jet ski engine was the 97' GTX resto project, that was 2 years ago You'll get all the guidance you need right here on the forum. Just ask questions when you have a concern.

 

[ReeseBlaisdell]

the 787 engine I have is made out of the bottom end of a 95' and the top end of a 98' with a few 97' and 96' parts does this matter?

 

[ReeseBlaisdell]

my problem here is that I just started college, to become a precision machinist nonetheless. and I don't have much time or a good shop just the back of my truck. I might think about it but if anybody has a 787 that they would like to sell let me know.

 

[GGuillot]

my problem here is that I just started college, to become a precision machinist nonetheless. and I don't have much time or a good shop just the back of my truck. I might think about it but if anybody has a 787 that they would like to sell let me know.

I wish you luck with getting the time, money, and a place to work on it. The forum is here to help you in the process when you do work on it. You don't need us to convince you what to do, you'll need to figure that out going forward. Sometimes if the budget and time doesn't mesh it may be a moment to take a step back and reassess why you got it and if you want to keep it.

 

[ReeseBlaisdell]

if I do go forward what should I do about the cylinders? bored and coated or new sleeves.

 

[GGuillot]

if I do go forward what should I do about the cylinders? bored and coated or new sleeves.

Most people send them off and get them bored and fitted with new pistons, a vendor like Fullbore.com will do this kind of work and do it properly. If they get overbored the RAVE valves may need a trim so they don't make contact with the pistons. When you get the cylinders back, all you need to do is wash em real good and assemble the engine. Reman cranks and balance shafts are available at vendors like SBT, they do core swaps sending you the component and you ship the old one back.

 

[ReeseBlaisdell]

I made it home this weekend and I got my compression tester and retested the cylinders and they are 125psi on number one and 123psi on number two is this good? I know its not great but should it work?

 

[GGuillot]

I made it home this weekend and I got my compression tester and retested the cylinders and they are 125psi on number one and 123psi on number two is this good? I know its not great but should it work?

Others on here can provide an opinion, but I'm gonna say anything below 130 is too low and it needs a new top end rebuild.

 

[ReeseBlaisdell]

that's what I was thinking I just pulled and tore down the engine and I will send the cylinders off tonight.

 

[mikidymac]

Agreed, anything below 120 and it typically will not start well in the water.

 

[ReeseBlaisdell]

I'm still wondering why I couldn't get it to start at all even though it wasn't in the water. (p.s. the cylinders are on there way to full bore, I bought the platinum 800 rebuild kit with a new crank) also when I took the cylinders off I found the crank case half full of water...again.

 

[ReeseBlaisdell]

I Shure hope this works.

 

[POPPS]

Water can get in at the manifold, the head pipe, and perhaps you have crack in the sleeve or The barrel. Perhaps you are not aligning the barrels properly when you attach them to the manifold.

 

[mikidymac]

If you are already having fullbore do the cylinders and crank why not just have them assemble the entire engine.

I would also rebuild the balancer shaft.

 

[GGuillot]

I'd be cautious, Fullbore has a pretty quick turnaround with cylinder bores, but full engine rebuilds take months. All Summer I've seen some frustrated customers on the FB forum that dished out a $1000+ and haven't seen their engine after several months.

 

[ReeseBlaisdell]

so the reason I am doing it is because money and time.