2001 gtx 787 RFI Top end rebuild

wlong1957

Member
Just replaced pistons and cylinders in my 2001GTX 787 RFI in place without removing the engine.. I used SBTs' cylinder exchange with standard sized pistons. Initially It started right up but would not idle and just stall out. Then no start at all. It seemed to be a fairly straight forward job. The only problem I had was getting the fuel rail reattached with the bolts underneath. I didnt have my compression guage at the lake but I am wondering if its a fuel issue. Can I just test fuel delivery by unbolting the fuel rail and see if gas is spraying from each injector. I did verify spark and fuses.. There was fuel pressure when I disconnected the fuel like from the rail. Also could a sluggish battery prevent firing?

Next step- 1.Verify compression (I did verify ring gap and piston clearance prior to assembly and they were in spec)
2. new battery ( I have a new one I can activate and charge) 3. Remove fuel rail and see if it sprays.

Any advice on what to look for next?

Thanks in advance
 
What was the compression readings before you did the cylinder exchange? Could be a clue as to what the issue now is, having the injectors Spray fuel is not conclusive evidence that they are working correctly, I had a ski Doo 600 SDI that was t firing correctly on one cylinder, I attempted to clean and test the injectors myself but even though they appeared to spray correctly visually to me the problem wasn’t resolved until I sent them out to be cleaned professionally
 
The initial readings on the PTO cylinder was 0. Mag was 60. The PTO cylinder was clearly damaged. Mag cylinder not bad for a 23 year old jet ski. But that was with a cheap amazon guage set. Ill test this weekend with one I got from Harbor Freight if any better. Just to help rule out compression. I dont think that would be it as the rebuild with two separate cylinders was fairly easy.

If I have air, Spark, Compression and fuel then it should start. I hope

Thanks for the input
 
I have a nice tester I paid $50 and I think it is spot on. As far as compression causing it "not to run" that is more of an issue in the water. Lots of skis run fine till you put them in the water or they warm up in the water and won't restart. One thing I don't like about RFI's. In my experience I've never been able to get one to fire by adding premix into the cylinders or in the intake. I guess I'm always getting enough fuel... ha ha.

Did you check to make sure your injector plugs are in the correct locations? the PTO plug can be swapped accidentially with the Rave solenoid plug. The Air Pressure Sensor and TPS on the throttle body can be swapped as well. You might get to the point of doing the electrical checks on the individual sensors but lets hope not.

I'd buy a pair of these before I went any further. These babies tell you a lot about what's going on and you can watch real time.

Spark Testor.jpg
 
The initial readings on the PTO cylinder was 0. Mag was 60. The PTO cylinder was clearly damaged. Mag cylinder not bad for a 23 year old jet ski. But that was with a cheap amazon guage set. Ill test this weekend with one I got from Harbor Freight if any better. Just to help rule out compression. I dont think that would be it as the rebuild with two separate cylinders was fairly easy.

If I have air, Spark, Compression and fuel then it should start. I hope

Thanks for the input
 
The initial readings on the PTO cylinder was 0. Mag was 60. The PTO cylinder was clearly damaged. Mag cylinder not bad for a 23 year old jet ski. But that was with a cheap amazon guage set. Ill test this weekend with one I got from Harbor Freight if any better. Just to help rule out compression. I dont think that would be it as the rebuild with two separate cylinders was fairly easy.

If I have air, Spark, Compression and fuel then it should start. I hope

Thanks for the input
0 and 60 pounds are some pretty wacky low numbers, like you mentioned probably a good idea to pick up a better quality compression tester. Make sure you have a good strong battery, could you tell when you had it apart what the cause was for t low compression before the rebuild? I would start with a fuel pressure test and a professional injector cleaning. I had an 05 MXZ 600 that lost compression pretty quickly due to a bad injector, no fuel Or improper fuel equals improper lubrication
 
Took the head off and the mag piston chipped. Rings broken and the cylinder broken. The PTO piston looked better but the bottom ring was broken.
If you look at the pics you can see where I marked the location of the bottom and top ring pins. I might have 2 minutes run time.

I know I seated the piston with the rings in the correct position. Otherwise I could not have gotten the piston in the cylinder. Piston and rings were from SBT with cylinder exchange standard diameter. Unfortunately I dont think their no fault warranty applies to parts. So either I do it again or part out the ski.
 

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Took the head off and the mag piston chipped. Rings brpken and the cylinder broken. The PTO piston looked better but the bottom ring was broken.
If you look at the pics you can see where I marked the location of the bottom and top ring pins. I might have 2 minutes run time.

I know I seated the piston with the rings in the correct position. Otherwise I could not have gotten the piston in the cylinder. Piston and rings were from SBT with cylinder exchange standard diameter. Unfortunately I dont think their no fault warranty applies to parts. So either I do it again or part out the ski.
Ohhh... I thought that all that damage was from before the cylinder exchange with SBT? But this is the present condition after the cylinder exchange? Be great to see what the guys with more experience have to say but I will guess that ports weren’t chamfered correctly causing a ring to catch and break
 
Ohhh... I thought that all that damage was from before the cylinder exchange with SBT? But this is the present condition after the cylinder exchange? Be great to see what the guys with more experience have to say but I will guess that ports weren’t chamfered correctly causing a ring to catch and break
That is the damage after reassembly. I assumed the SBT exchange was ready to bolt on. I did verify ring gas and ring clearance to the cylinder prior to assembly. All I can do now is contact SBT and see what they say.
 
That is the damage after reassembly. I assumed the SBT exchange was ready to bolt on. I did verify ring gas and ring clearance to the cylinder prior to assembly. All I can do now is contact SBT and see what they say.
For sure, contact them. It doesn’t look like much if any chamfer from the pics but hard to tell in pictures.
 
I contacted SBT. They said it would not be covered under warranty as they said the c clip came loose and damaged the sleeve. So no warranty coverage. I had to remove the c clip in order to remove the damaged pistons. If they were still in place how could that cause the damage.

So I guess now I will try to find someone to resleave the cylinder and get new rings and pistons. Any advice on the best person to do this

Thanks
 
Man that's UGLY !! I've never resleeved cylinders I just bought used and did a rebore. I have a good many cylinders now so it isn't an issue for me. I have two local shops that can bore cylinders plus I can do my own in my lathe so... I don't have much cost associated or a waiting period which is really great. I'm curious how much the resleeve and rebore costs. Sounds double expensive. Hope you find a good path to get the ski back up and running. :)
 
I am inclined to think that the rings broke, Either the rngs were defective or caught the port causing them to break and also break the sleeve. Bit regarless I am back to square one. I did see a listing on ebay where they can bore and sell upper kit for 399. Sleeving if required is $75 extra. Or I just may try to find used cylinder and get it bored locally. In hindsight I should have done that initially. I recently had a good experience with Westside Power Sports. They reflashed and cleared the faults on my 2015 GTX ECU.Maybe they will have some used parts.
 
Are you sure you had the psitons installed correctly? Arrow points to the exhaust port.
Also that piston looks dry, no lube or fuel..
 
Yes the arrows were pointing toward the exhaust. I have been looking at these cylinders after removing them. the ports at right angles to the intake and exhaust have sharp edges to the touch to the point that it could cut your finger. I am thinking that the bevel was inadequate and it caught the rings. But who knows. The damage is done. I have another set of cylinders and pistons coming in. Interestingly enough they would not accept any SBT cylinders as a core exchange for the same reason of the issues that I had
 
Are you sure you had the psitons installed correctly? Arrow points to the exhaust port.
Also that piston looks dry, no lube or fuel..
You got me thinking. I looked at the cylinder that was cracked. The intake for the injector had a piece of round red dome shaped rubber adhered with grey paint inside the injector hole. I assume SBT plugs those holes prior to repainting. The other cylinder was not plugged. So in essence I failed to check for any blockage assuming that they were ready to go, So the cylinder ran dry and was ruined.

So if anyone every buys an SBT kit make sure they have removed any plugs or blockages.
 
SBT PAINT PLUG?? PROBLEM SOLVED I THINK

Red Plug inside injector intake. Adhered with grey paint. Injector seated. Plug must have been used to repaint by SBT. The other cylinder did not have this. This was the cause of the failure.. Live and learn.

I sent the pic to SBT. I doubt they will reply . But if they do it will be user error.

So if anyone does a top end with SBT parts. Check for things like this.
 

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SBT PAINT PLUG?? PROBLEM SOLVED I THINK

Red Plug inside injector intake. Adhered with grey paint. Injector seated. Plug must have been used to repaint by SBT. The other cylinder did not have this. This was the cause of the failure.. Live and learn.

I sent the pic to SBT. I doubt they will reply . But if they do it will be user error.

So if anyone does a top end with SBT parts. Check for things like this.
So no fuel due to that red plug? Is that correct?
 
Newest reply from SBT

Will,
The red plastic plug is a spark plug hole cover (external cap). They are placed on top of the head before a new motor is shipped. It would not be in the cylinder exchange kit.

Curtis Yowe,
SBT INC
1401 N MYRTLE AVE
CLEARWATER FL 33755
727 443 0373
727-461-4268 FAX


My reply.

But it was in one of the cylinders that I received in the the cylinder exchange kit and was deeply inserted in the intake for the fuel injector. You can see the residual of the grey paint on it in the picture

Otherwise how would it get there?
 
Finally got the new parts in and reassembled. Starts right up and idles evenly.Bought on ebay from river-rat-rob. The quality of the machine work on these cylnders is light years ahead of the SBT set. It came with WSM pistons.

But now when I depress the throttle it will shut down. I am able to press start again and it will start right up and continuousy run smoothly at idle speed. Candoo shows no faults.

This leads me to think there is a fuel starvation issue. Either physically clogged injectors or an electrical issue.

I followed the service manual on Engine Management and got the following values for the sensors.

Air Pressure Sensor- pins 1&2 5.46k ohms Normal 2.4k-8.2k ohms ,pins 9&2 5.9k normal 3.4k-8.2k
Throttle Position Sensor -pins 3&4 2.183k ohms normal 1.6k-2.4k
pins 4&11 1.146k normal 710-1380 ohms

Water Temp sensor-pins 5&12 2.951k normal 2280-2736 ohm

Air Temp Sensor- pins 6&13 2.885k normal 2280-2736 ohms

Crankcase Position Sensor -pins 7&14 .881k normal 774-946 ohms

Rave Solenoids pin 16&23 29.6 ohms normal 30 ohms


Injector 1- pins 18 &20 3.3 ohms then 2.8 ohms after checking a second time -- normal 2,3-2.5 ohms


Injector 2-pins 19&21 3.7 ohs then 2.8 ohms after checking a second time-- normal 2.3-2.5 ohms

There was voltage to each connector for the APS,TPS and Injectors.

So my question is with the injector values being slightly high, would that account for only running at idle and dying out when pressing the throttle. Does that indicate that the injectors are faulty or clogged. Or does the resistance test only test the coil in the injector. I see aftermarket injectors for $27 on ebay. Original Bosch used $50. I have not tested fuel pressure as I dont have the adapters to connect to the fuel connector at the fuel rail



Is there anything else I should check. Any advice would be appreciated.
 
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Finally found the problem. The rotary gear was broken. I wish I had checked it first.
 

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Ha.... I suspected the rotary gear on a RFI and checked it early in the process BUT... it was night time and not a lot of visibility. The rotary valve came off with the cover plate so I couldn't tell the location. I checked the gear and it seemed to have only a small amount of play so I just timed it and put it back together. About 20 hours of troubleshooting later I pulled the engine. The gear was destroyed. Somebody put fuel in the oil tank and didn't flush and refill with the proper oil. The result was lubrication failure and destroyed gear. Engine had less than 30 hours on it.

I don't see how the gear shaft can be removed without splitting the cases but you'll definitely NOT get all the brass shavings out without splitting the cases. It took a good it to clean it all up. Engine is sitting in my shop ready to install. GOOD LUCK !!
 
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