97? GTS (pics)

[Dutch]

Ok so I was on hear yesterday with some questions about my newly acquired GTS, I did some work this afternoon, and took some pics of my progress. The first pic shows the compression readings of the cylinders. I looked over both cylinders and pistons and they look ok and there is no scoring or pitting on the cylinders. My question is should I replace the crank seals or just re-do the top end with new pistons, and having that been said should I do both pistons or just the bad one? And can anyone tell me the exact year of the ski? Dutch

 

[kustomkarl]

By the looks of the pistons it had some detonation problems. What did the spark plugs look like. I would replace both pistons and re-do the top end. 150 is ideally the compression needed. As for the year of the seadoo the black tag has it as the last 2 digits I can't read it on the forum but you could on the hull.

Karl

 

[JPX]

Do both pistons.....you're already in there.

I suppose if you are WAY cheap and were just slapping parts on, you might get away with getting the one bad one fixed......this type of behavior is best reserved for those that have old/used/extra parts sitting around to improvise these types of less-than-ideal repairs.

For the time and trouble, I'd just do both so I don't have to go back in there anytime soon.

By the way, I love this photo!

 

[derek]

see why i told ya to have a couple before you looked at it? what does the head look like? this doesn't look as bad as i expected. i would do the rear piston and retard the timing a couple of degrees. don't do the front until you are gonna bore the motor out.

 

[Dutch]

Ok heres the head derek, now ive done this on sleds before but wanted your input. The left one (back piston) you can see is the bad one, I usually just take my dye grinder and smooth out the dome. Think that would be a good idea? I found out that its a 98 and not a 97 and I looked on the engine id tag and found the type to be a 717 but im sure its the same as a 720. Dutch

 

[Dutch]

I found a rebuild kit on dennis kirk but I need to verify the bore size. Will this kit work at 82mm? What is my std bore size, I know that the motor has never been bored out so its still std. Dutch

http://www.denniskirk.com/jsp/produ...Id=5&productId=p148809S&leafCatId=&mmyId=4806

 

[derek]

82 is the stock bore. if you clean up the high spots in the head you will lower comp ratio a little. also a good way to reduce rear cyl detonation. the head isn't as bad as i feared. go get a set of dial or digital calipers. another 25 bucks well spent. the digitals can be set to metric. the dial caliper you hafta convert. unless you buy a metric one. can you read the writing on the top of front piston? it should say 81.95 mm or 82.19 if it is .25 over. if you are gonna do both, bore it out. if you are gonna use the bores you have, don't waste money on front piston.

 

[Dutch]

so touching up the head would be a good idea? Im not going to take off a bunch I just want to smooth it out a bit. Dutch

 

[derek]

if you are gonna run the head you have to remove the high spots. otherwise they will heat up and act like glow plugs and cause detonation. then check the compression. if it is 5 or 10 lbs lower than front that would be a good thing.

 

[Dutch]

I have one more question, I just got the re-build kit today and im about to start, do I need to take both jugs off and replace the base gasket if im only doing the back piston? And when I remove the jug am I going to have to mess with the rotary valve? Looks like I just need to un-bolt the exhaust and then the jug. Dutch

 

[derek]

no prob with RV. jug comes right off the top. clean gasket surfaces, paying particular attention to exhaust side. that is where water is. intake side is dry. the rings you can squeeze together with fingers and finesse the jugs over them. there are tiny roll pins inside the piston ring grooves to keep the rings from turning. that way ring ends aren't going thru port openings. make sure the pins are at the ring end gap. it is possible to get the ring over the pins. it will then be very difficult to put cyl over rings. watch this detail carefully. have you removed the bad piston yet? if not a lot of 720 motors have uncaged needle bearings in the top end. that means when you push the piston pin out 34 tiny needle bearings will fall into the crankcase. not a good thing. (and i am not 100% sure it isn't 35 or 36) it would be best to do this with motor out of ski and lying on it's side. it is much easier to put pistons and cyls on with motor out. if you are doing this in the ski, stuff holes with rags and duct tape over the rags. good luck, but you make your own by being careful and taking your time.

 

[Dutch]

Sounds good, ill have an update tomorrow. Dutch

 

[Dutch]

Well, everything went smooth, and the needle bearings didnt have a cage so its a good thing you had me tape the case Last question, what is the torque sequence and foot Lb for the head bolts. Dutch

 

[derek]

not as much as you think. 17 ft/lbs. both cyl to case and head. on head, start with 4 center bolts in a star or x pattern. work out to the ends same way. so you bought the dennis kirk kit? both pistons? if so, use them both. keep the front one and you still have an emergency spare.

 

[Dutch]

Update: 7/31
I now have 150 #'s in both cyliders but I still have no fuel to the engine. Anybody know where to get a carb kit? Dutch

 

[seadoosnipe]

....carbs.

Yeah, you can get one for about $35 dollars at www.sbtontheweb.com

 

[derek]

start from scratch with the free and cheap stuff. several people here say kits aren't usually necessary. grey fuel lines? 1/4 inch autozone automotive fuel line. replace it all. in the process, you will have a chance to check out all of the fuel system. possible blockages; fuel selector valve. pickup-baffle assembly in tank. all filters especially the little one in the carb. and if it is stopped up, it won't allow fuel to get there in the first place. make sure you didn't forget to hook up the pulse line to the crankcase. that is the actual fuel pump drive-if drive is the correct misnomer.

 

[Dutch]

Thanks guys, I have bought new fuel line and know I think ill get a kit, (Ripped diaphram) Does anyone know how to tell if the oil injectors are working properly? Dutch

 

[derek]

fill it with oil to an easy to id level in the tank. then premix to 50 to 1. then watch the oil level over a couple of tankfuls of gas. worst that'll happen is fouling plugs and extra smoke. i never heard of somebody killing his new engine with too much oil.

 

[Dutch]

Derek, I think Im screwed! I broke the check valve that goes on the top of the motor side butterfly. Can you buy these anywhere or will I have to get a new carb? Dutch.

 

[derek]

can you get me a better pic? blurry. this is the single carb? get me a pic of carb where this was. i know a guy who has a pair of these carbs from a twin 720 speedster.

 

[Dutch]

Yes, its a single carb off a 98 GTS. Heres a bunch of good pics for ya.

 

[derek]

the 3 nipples that aren't broken are the fuels and the pulse. this is some kind of vent. i just looked at all of my carbs (not installed on motors) and don't see this fitting. this fitting. does the hole inside go into the bore of the carb (where the air goes into motor) or does it go down into the fuel chamber below it? the broken end is where the hose goes, and the good end snaps into the carb? where does the hose that attaches to this fitting go? does the check valve in the fitting allow stuff (air or gas) into the carb or to leave the carb?

 

[Dutch]

Yes, you can see in the last pic the broken piece sits on top of the carb opening (bore) and theres a little spout that goes strait down into the opening right before the slide (butterfly). Not sure weather it lets gas or air in or out of the carb. The black hose there connects to the broken piece and the other end of the black hose goes to some sort of mech. pump triggered by the throttle linkage. I jb welded it and im going to out it on sat. Dutch

 

[derek]

triggered by throttle linkage? i think it is some kind of add-on accelerator pump. can you send me pic of pump and throttle linkage? also chase down other end of pump and see what lines it has and where they go. the 2 screw holes either side of the broken fitting are where twin versions of this carb go on mounting brackets. so, if this is squirting fuel IN at this fitting, you gotta watch that patch job. pump fuel into hull. you get a free flying lesson when it lights. also, if it is an add-on, it is non sea-doo parts. means available in the general aftermarket somewhere. maybe lowes or home depot? or J C Whitney? or Summit Racing? try unhooking the whole set-up. if you just did carb, you might have fixed problem this was a stop-gap fix for.