Locked-up Yamaha 735

S

Super7

Location
Portland
I bought a used Rickter with a "professionally" built 735 with what the seller claimed had around 15 hours on it. It was set up to run on pump gas at 40:1. I installed an hour meter on it once I got it for all the reasons you do that. Anyway, I noticed that it was not as snappy at about the 2-3 hour mark and by the 7 hour mark it lost all snappiness off the bottom and just ran lousy. By hour 8 it locked up. A couple things I noticed from hour 1 was the fact that the water leaving the twin cooling points had uneven flow--but I didn't think much of it. When I pulled the old style air box covers off I noticed that there was no flame arrestor mesh. That sounds risky to me. Anyway, I blame myself for not checking the spark plugs early on for signs of poor jetting. Once I pulled the ADA head, I found the rear cylinder to be scored on the intake side. I should also add that before the motor gave up, it cranked over slower than normal--that was an obvious sign. One thing that I'd never seen before was the top of the spark plug at the rear cylinder was burned. I am referring to the part of the plug that goes into the boot. The bottom of the plug (in the head) was dry and blackened.
My plan is to send off the cylinder to be repaired and matched with correct forged pistons, replace the crank and fatten up the jetting on the rear cylinder.
Am I missing anything? Could the uneven water flow cause a problem?
As you guessed, I am not a mechanic but I have decided to figure things out and repair my own skis as I can screw up my stuff as good as the "professionals" can.
Thanks in advance.
 
DylanS

DylanS

Gorilla Smasher
Location
Lebanon Pa
Pics?
Any chance you checked temps on your engine after a good burn?
Where did the engine come from and where do you ride?
 
S

Super7

Location
Portland
You have some very good points.
My history with stock 701’s has spoiled me as I never had an issue with anyone of them. Sure, they are down on power but I was never left stranded by one.
Also, I have been mixing gas for decades now—I never buy cheap fuel or oil.
As for the professional builders, I’m not knocking their work and you are correct, once built it is out of their control.
My wallet has taken a beating and as for future rebuilds and such, advice and help from guys like you help a lot.
Thanks for your response.
 
S

Super7

Location
Portland
I’ve done a 180 and decided to pull the motor and sell the ski on FB.
I am just going to shelve the motor and ride my other Rickter with the mostly stock motor.
Thanks again for everyone’s help.
 
KMN

KMN

Location
Minneapolis, Minnesota
It seems every ski you buy, almost no matter who you buy it from or who built it, is not perfect, and for you to feel good about it, you'll need to take it apart and ensure everything is to your standard. At least then, all you have to blame is yourself. It's also pretty common that most people don't know if their ski is tuned well or not. Even the best riders, tuners, builders, are constantly changing things, optimizing, and repairing broken stuff. Pro tip: Nobody has this all figured out.

Uneven water pressure out of the pisser is usual. I'm assuming a b pipe was used in this application. One of the water outlets out of head goes directly overboard, the other goes through the b pipe head pipe, a little to the stinger, and most overboard, so both overboard pissers will be different.
 
S

Super7

Location
Portland
T
KMN said:
It seems every ski you buy, almost no matter who you buy it from or who built it, is not perfect, and for you to feel good about it, you'll need to take it apart and ensure everything is to your standard. At least then, all you have to blame is yourself. It's also pretty common that most people don't know if their ski is tuned well or not. Even the best riders, tuners, builders, are constantly changing things, optimizing, and repairing broken stuff. Pro tip: Nobody has this all figured out.

Uneven water pressure out of the pisser is usual. I'm assuming a b pipe was used in this application. One of the water outlets out of head goes directly overboard, the other goes through the b pipe head pipe, a little to the stinger, and most overboard, so both overboard pissers will be different
Click to expand...
Thanks and that makes perfect sense. I thought I was buying a solid little 735 that was going to last for many hours but it was toast after only 8.
My mistake for making assumptions and not looking into the issue when I first noticed the ski was not running as it did when purchased.

Thanks for the advice.
 
S

Super7

Location
Portland
Big Kahuna said:
Why not list it here?
Click to expand...
My first thought though was to list it locally as the guy I bought it from is well known in the Rickter community and I did not want anyone to think I was badmouthing him or trying to make him feel bad.
There was no intent on his part to sell me a ski with known issues. I know now that I should have at least checked the plugs at a minimum when I first rode it as that would have prevented all of this.
Thanks, BK.
 
Sparkplug

Sparkplug

Location
Red Bluff CA
A 2 cycle yamaha 6m6 based engine is about the EASIEST engine to work on in the world of powersports. No exaggeration.

I'd rebuild it myself. The bare minimum to get it on the water. Probably just needs a good solid hone with some acid and some new pistons. No sense spending 2k to "rebuild" a engine if 250 bucks and 4 hours would get you by for the next 2 or 3 seasons. Everything on them is very easy to spec out and visually check. Even the crank shafts.

You'll be money ahead doing it yourself. But more important than money. Is knowledge COMBINED with experience. Priceless. If you gain that, next time you feel a 2 cycle running ANY differently, you will immediately stop and figure out why.
 
S

Super7

Location
Portland
Haha
I wrote the book on Dasa 1000’s eating it and
I should have read these threads before putting skis in the water.
Live and learn, as they say.
 
S

Super7

Location
Portland
Well, I know it may sound stupid but there is a long backstory that starts with me getting ripped off by a mechanic in Bellevue for over $10k.
I can’t go into details here but it is related to my both buying and selling this ski.
I have another ‘19 Edge that I will never sell and I do not need two of them. As for the motor, I will just shelve it for now. Again, I understand how dumb it sounds but it is what it is.
 
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