Yamaha SUV with bad cylinder

[erie_guy]

It is a very long story, but the final question is: Will a broken reed valve on one of the cylinders result in no compression?

The engine is a re-manufactured 1200 cc. 3 cylinder two-stroke, about two years old. It ran OK until this weekend when it limped back to the trailer on two cylinders and it was running very rough. Compression check was done and showed two cylinders at 100 psi and one at Zero.

Just looking for less expensive answers - hope we don't need a new block.

Thanks for your insights.

Erie_Guy

Port Clinton, OH

 

[Scott Danforth]

center cylinder? if so, probably ran lean and there is a hole in the piston.

 

[erie_guy]

Scott, thanks for your comment but it was cylinder 1 that has "0" compression.

My admiral wants to go shopping for a new ski this afternoon.

Hope I get some time to do additional tests before decision time.

erie_guy

 

[erie_guy]

Scott, thanks for your comment but it was cylinder #1 that has "0" compression. I am to go looking for a new ski later today.

 

[erie_guy]

Scott,

I Inspected the engine last night and was able to see a hole through the #1 Piston. I was able to put a small screwdriver through the spark plug hole and probe the hole. I think I was able to see the connecting rod as well ??

Thanks for your assistance.

erie_guy

 

[WaterDR]

The motors on these things are terrible! I owned one for 10 years and anytime you use it, its a blessing that the motor didn;t take a dump. There are replacement motors, and they seem to be worse. My advise to anyone that has a 1200 SUV, sell before it goes or understand that its only a matter of time.

You now have a financial decision, sell it as is for I am guessing $500 to $900 or buy a new motor and then sell it (for $3000 to $4000). The later being the longer option, but has risk. Expect about $2200 on a dealer trade for a new one. Not sure what a motor costs to install but probably $1500. Just a wild guess though.

In the event that you are a motor guy, you could do the work and save some money. But there is just not a lot to work with market wise.

 

[Scott Danforth]

generally the center cylinder on a tripple goes from being lean. guessing you have a fuel delivery issue on cylinder 1 which took out cylinder 1

 

[erie_guy]

Solution in hand. We purchased a new 16' Yamaha VX. Although we would have gone for a new SUV with a 1.8 liter 4 stroke, they are no longer in production. Some thing about them being too broad in the beam, you can"t get two skis side by side on a trailer. We enjoyed the SUV for 14 years before the oiling system killed the first engine. (tubing hardened and fell off the rear cylinder carb).

The admiral fell in love with the VX Cruiser and we took it home the next day. It is white with black and chrome trim - very elegant and plenty of features. However the stability of the hull doesn't hold a candle to the SUV's. Our kids will probably have a blast with its speed and towing features. Just need a few more summer-like days to get it broken in.

Thanks to all for your comments and suggestions.

 

[WaterDR]

Solution in hand. We purchased a new 16' Yamaha VX. Although we would have gone for a new SUV with a 1.8 liter 4 stroke, they are no longer in production. Some thing about them being too broad in the beam, you can"t get two skis side by side on a trailer. We enjoyed the SUV for 14 years before the oiling system killed the first engine. (tubing hardened and fell off the rear cylinder carb).

The admiral fell in love with the VX Cruiser and we took it home the next day. It is white with black and chrome trim - very elegant and plenty of features. However the stability of the hull doesn't hold a candle to the SUV's. Our kids will probably have a blast with its speed and towing features. Just need a few more summer-like days to get it broken in.

Thanks to all for your comments and suggestions.

Too funny...we dumped our SUV for a 2016 VX Cruiser HO. Much wetter ride but a lot more fun too. Enjoy it.

 

[erie_guy]

To continue the saga --

I am now trying to fix the SUV , It does indeed have a hole thru the #1 piston. I would like to replace only the damaged piston and rings, The cylinder walls on all three cylinders look fine, Problem is the block is a solid casting with three cylinders, It appears I may have to pull the engine to get to the connecting rod and wrist pin. Anybody have an easier way to do it in-the-hull ??

Thanks for any advice you may offer

erie_guy
Port Clinton, Ohio

 

[GA_Boater]

Cut an access hole through the bottom of the hull, replace the piston, then re-glass the hole in the hull. Of course to repair the hull the motor will have to come out.

The motor has to come out to get to the bottom of the motor to R & R the piston.

 

[erie_guy]

Many thanks to GA_Boater:

I was afraid you would tell me that. I'll start tomorrow at first light Ho HO. Soon as I can see the hull bottom.

I do have an automotive engine hoist but wonder how much this 1200 cc engine weighs.

erie_guy

 

[GA_Boater]

Sometimes there are no shortcuts.

Motor is guessing 2-300 pounds depending on how much you can take off like starter and manifolds.

 

[dannyual767]

erie guy, please don't forget this very important thing--you must find out what caused the fuel/oil starvation of cylinder #1 and fix it or you will again toast the future repaired cylinder!

You already mentioned that an oil line had become old and pulled off the carb. I'm assuming all oil lines were replaced with new back then. How are the oil lines now? Are they supple and secure onto their fittings?

When was the last time the carbs have been gone through? If it's been a while, that going to need to be done as well.

If you don't find and fix the problem that caused the hole in the piston, the problem will just continue to take out pistons .

 

[erie_guy]

Thanks, Great reminders.

My first engine seized because of the oiling system hoses pulling off from the rear carb connection. All oil hoses were replaced and the carbs were rebuilt by the shop that installed the rebuilt engine obtained from a Florida supplier.. This rebuilt engine lasted less than three months and also seized because of lack of lubrication ?? - the oil injection system was suspect but the replacement engine supplied by the FL supplier lasted less than 2 years and then this hole in cylinder #1 appeared .

I feel the oil injection is at fault but the ski is almost 18 years old and all the accessories are original. My plan now is go to a premix fuel mixture and discard/remove the oil injection equipment and oil tank. I will also remove and rebuild the carbs to assure the #1 piston failure is not caused by a "lean-burn" combustion and its higher temperatures.

Keeping me fingers crossed for the third time.

erie_guy

 

[dannyual767]

Going premix will definitely take out the oil injection system variable.

I'm glad to hear that you're going to rebuild the carbs. That would be a 100% recommendation from any knowledgeable pwc guy! Assuming you need to replace any parts, be sure to use genuine Mikuni parts to rebuild the carbs. Most of the time, the parts can be reused and the carbs only need a thorough cleaning with carb cleaner sprayed through all passages followed by blowing them out with compressed air. I'd recommend new carburetor base gaskets, though. These can be aftermarket.