97 Speedster Starboard Motor won't run

[nitrotate]

Hi guys need a little help here. Been searching but can't seem to find any posts close enough to this:

My port motor runs great. Starboard just stopped running suddenly yesterday. Won't start in water but will start and idles rough out of water but dies when I move the throttle.

• Rebuilt both motors at the beginning of last season, cleaned carbs really well and set pop off correctly
• Boat ran flawlessly all summer last summer
• Winterized it properly by fogging carbs and cylinders
• De-winterized two weeks ago
• Installed brand new marine battery
• Ran great for the past two days on the lake
• Compression is 145psi in both cylinders
• Verified I am getting spark
  • only weird thing is I only get spark to the wire I'm testing if the other is connected to the plug while installed in the motor
• Carb is getting fuel (new fuel)
• New BR8ES plugs (old plugs were nice cardboard brown when it quit running and not fouled)
• No blown fuses in the MPEM
• Accelerator pump is spraying fuel when I move the throttle
• I don't think it's a carb issue because I've swapped over the carb from the running motor and the problem persists
  • Just to double verify tomorrow I'm going to put the carb from the non-running motor onto the running motor and confirm
• Tomorrow I will also double check to make sure fuel is flowing through the lines from the tank

The only thing I can think of now is either some kind of electrical issue I'm not seeing, or some kind of rotary valve issue??

Anyone have any pointers?

 

[etemplet]

Buy this from Auto Zone or Amazon. You may have a weak coil. These will let you know without a doubt if you are getting spark and you can tell if it is weak or strong. I love em' Good Luck !!

 

[nitrotate]

Yep I have one, that's how I tested. Didn't seem weak but I'll test the other motor and compare.

 

[etemplet]

I had a XP that wouldn't start as long as I held the start button engaged. As soon as I let go of the start button the ski would be running. After dark one night I was still troubleshooting the ski and the skeeters were tearing my azz up, I had those testers hooked up. I had checked battery voltage drop and all sorts of stuff and I was determined to find the problem. As I engaged the starter I noticed the testers brighten up when I released the start button and the engine, of course, fired right off. I know it sounds strange but in releasing the start button the engine is still spinning a bit and that is the point at which the engine would start... every time. That would have been a shot in the dark guess but with those testers connected I suspected the coil was weak and the voltage draw from the starter spinning just wouldn't give it the UMPH it needed. Sure enough, the coil was the problem. That's why I love these testers. Good Luck !!

 

[nitrotate]

Ok so I tested the other side and both engines light up the tester about the same brightness. The starboard motor will start and idle but I can't get it to run up over 1500 to 2K RPM (and yes I've tried it with the drive selector in neutral and forward).

 

[etemplet]

You can try swapping the engine wires from the MPEM and see if the same thing happens with the good engine. I hope it is not your issue but the rev limiters on the MPEMs seem to be a problem at times. I do have a Spare MPEM complete and It will be about 1/2 the price people sell them for on the internet. Good Luck !!

Did you check the plug going into the Mag? Sometimes those connections break down. That is what was wrong with mine when I bought the extra MPEM. Good Luck again !!

 

[nitrotate]

You can try swapping the engine wires from the MPEM and see if the same thing happens with the good engine. I hope it is not your issue but the rev limiters on the MPEMs seem to be a problem at times. I do have a Spare MPEM complete and It will be about 1/2 the price people sell them for on the internet. Good Luck !!

Did you check the plug going into the Mag? Sometimes those connections break down. That is what was wrong with mine when I bought the extra MPEM. Good Luck again !!

Let me try that. I assume you mean swap over the coil/wires between engines right. I don't think I can just "use" the left side over on the right can I??

 

[nitrotate]

I swapped the MPEM-to-coil wire from the starboard (bad motor) coil over to the port (good motor) coil then used those plug wires on the starboard motor. Got the same results so I assume both coils are good... I know this doesn't necessarily eliminate the MPEM rev limiter possibility but does the MPEM rev limit the motors independently of one another?

 

[nitrotate]

Ok new update but still stumped on this issue... I swapped the carbs and the good motor runs perfect with both carbs so the carburetor is ruled out. I'm getting fuel flow to the bad motor so that's ruled out. I just ordered two new ignition coils just to see if that does the trick but the spark strength seems the same across both coils at the moment.

Not sure how to test the stator/magneto yet... seems like I need a special test harness??

 

[nitrotate]

Update; I had to leave town for a couple weeks but before leaving I tried the following;

1. Magneto/stator tested out good (checked both motors, similar results)
2. Coils and caps all tested good
3. Swapped carbs and good motor still runs with the other carb so carbs are ruled out
4. Swapped engine wires from MPEM to see if rev limiter on the bad side was the issue and the good motor ran fine so MPEM seems ok

SO, the only remaining possibilities I can think of now is the rotary valve and/or shaft and possibly timing but I'll check the rotary first. Hoping I can get the rotary valve cover, plate and shaft out without removing the motor... I'll give that a shot when I get back home.

 

[nitrotate]

Ok solved the mystery.

Rotary valve shaft was mangled... Got the new shaft in and waiting for new rotary valve covers for good measure.

https://1drv.ms/v/s!Ap_7BbrTfhMn8kqYga-WLtQ4-baH?e=YcPahs

 

[etemplet]

Did you split the engine cases? There is a lot of brass in there and it is likely in the oil tank as well. Gotta clean it all out spic and span, oil lines and all. This picture is from a 787 I'm replacing. This brass is the result of a flat spot ground actoss a section of teeth. Not a lot of metal was removed except in that one section. You have lost a lot of metal.



Yours is probably more like this.

 

[nitrotate]

No, I drained as much out as I could to try eliminating some of the debris. I normally always do things the right way but this time I'm taking the risk. I know I'll probably get roasted for this but I just don't have the time/money at the moment and decided to take the risk since I plan to pull both motors out and completely restore the engine bay and rebuild the motors this winter. Fingers crossed I make it through the season.

 

[etemplet]

Sounds like a plan. Might want to put a 75W-90 gear oil in there. Synthetic. Might dampen the roughness. Good luck !!

 

[nitrotate]

Sounds like a plan. Might want to put a 75W-90 gear oil in there. Synthetic. Might dampen the roughness. Good luck !!

Where exactly do you mean? Doesn't the 2-stroke oil cycle through that bath area?

 

[kustomkarl]

Um you do know you will have to split the cases and remove the crank to install the Rotary Valve shaft.

 

[nitrotate]

Um you do know you will have to split the cases and remove the crank to install the Rotary Valve shaft.

No you actually don't have to. I already pulled the bad one out and installed the good one with the motor in the boat. Technically, yes to do it properly I should have split the case and opened it up to make sure I get any debris out. However, we have a very short season here in Colorado and we have a camping/boating trip coming up next weekend and I also don't have the money at the moment to get a motor alignment tool ($300). Also planning to remove both motors and do a full bottom up restoration of the engines and bay this winter.

So, with that said, I just decided to take a risk that whatever remaining debris I may have missed "could possibly" mess up the rotary valve at some point.

 

[burtshaver2021]

I was under the same impression, that the cases had to be split to change the rotary gear, otherwise I thought the brass gear could be damaged installing it? These are more questions than advice but besides the brass shavings damaging the new brass gear, could those brass shavings not recirculate back into the oil tank from the RV vent hose, then block up the oil filter or get past the oil filter and damage crank bearings and possibly score cylinders if they make it back up there?

 

[kustomkarl]

Here is a copy of the service manual for installing the shaft

 

[nitrotate]

Thanks, yes I have the manual. I know that is the proper way to do it. I'm just taking the risk at this point. Here's a guy who has done the same thing. This doesn't mean I'll be as lucky of course.

Question for you guys, this could change my mind about pulling the motor... Do the 97 Speedster motors need to be precisely aligned with the $300. tool? Or is it possible to carefully mark where the motor sits currently somehow so I can get it back in the same spot and be safe?

 

[etemplet]

Where exactly do you mean? Doesn't the 2-stroke oil cycle through that bath area?

It doesn't circulate very much. A high percentage of the gear oil will stay in the rotary valve chamber. Some people might opt to block off the discharge line to the oil tank. A simple valve would do the trick if that was one's preference.

 

[nitrotate]

It doesn't circulate very much. A high percentage of the gear oil will stay in the rotary valve chamber. Some people might opt to block off the discharge line to the oil tank. A simple valve would do the trick if that was one's preference.

Gotcha, ok thanks. I went ahead and pulled the shaft back out again, sucked as much oil out of the cavity as possible and then I ran my inspection camera all around that area. Interestingly enough, I didn't see even one spec of debris... not even a spec of brass glitter.

I went ahead and put some 75W-90 oil in and reinstalled the shaft.

The RV covers should be here today and I'll get it put back together.

 

[kenneth.mccoy1]

Thanks, yes I have the manual. I know that is the proper way to do it. I'm just taking the risk at this point. Here's a guy who has done the same thing. This doesn't mean I'll be as lucky of course.

Question for you guys, this could change my mind about pulling the motor... Do the 97 Speedster motors need to be precisely aligned with the $300. tool? Or is it possible to carefully mark where the motor sits currently somehow so I can get it back in the same spot and be safe?

I’ve used a jet pump with no shaft in it and a metal rod I bought from ACE to align a motor before and I haven’t had issues, I just lifted the rod in each direction from inside the hull while it was close to the pto wheel and made sure the distance vertically and horizontally was roughly the same compared to the pto. Granted this probably isn’t super accurate but good enough for me as I don’t pull enough motors to buy an alignment tool. I’m sure I’ll probably get flamed for this too lol