Help with 701 flywheel key

Speedfreak

Speedfreak

Location
So. IL
Order one from yamaha. They are like $5 but I tried a bunch of them to keep from ordering one. Well.. after your flywheel comes off a few times then your crank nose is messed up and your flywheel cover will not hold your flywheel back so you have to buy one of those also. It is just not worth it.
 
NVJAY775

NVJAY775

My home away from home.
Location
Gardnerville, Nevada, United States
I was hoping to get the size. There's a couple good machine shops here that have, as I was told, every metric and standard size. Worst case I will go to Yamaha, but I want one real quick. It is what it is, I just want to get lucky so I can ride this weekend.
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
Lowes has them for a couple bucks but if your current one is broken beyond recognition, you'll have to measure the crank and guess.
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
Big Kahuna said:
not really a good idea to try and make one work from Lowes. Order an OEM.
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Why not? All the key is supposed to do is guide the flywheel in the correct place. The flywheel bolt is supposed to keep it in place. Now if the ones from Lowes are bare steel, you may want to reconsider but I haven't looked that close at them.
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
if the one from Lowes is a bit narrower, you may not get the propper alignment. But answer this, I know that it does not actually hold it in place, but if it does not, then why is it when the key shears it gives your trouble. IF it was not used to hold the flywheel in place then why did it sheer and cause the flywheel to move enough around to cause your ski to not run. Something to think about!
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
I never thought that the width may not be right. Although I would think if it didn't throw up a red flag at you, 1°-2° either way isn't going to kill you. I always figured the key sheared because the flywheel bolt loosened, wasn't tight enough, or in issues with aluminum flywheels the dissimilar metals shrink/expand at different rates causing a loose condition.

It's like saying the brakes on the car failed because the pads sucked when actually it was because the brake calipers weren't tightened and bolts fell off.
 
750SX

750SX

DO IT
Location
Palmyra
Big Kahuna said:
if the one from Lowes is a bit narrower, you may not get the propper alignment. But answer this, I know that it does not actually hold it in place, but if it does not, then why is it when the key shears it gives your trouble. IF it was not used to hold the flywheel in place then why did it sheer and cause the flywheel to move enough around to cause your ski to not run. Something to think about!
Click to expand...

It sheared because the bolt loosened.
 
Pro-pulsion

Pro-pulsion

Location
Ontario, Canada
Yeah the flywheel key's main purpose is for proper alignment on the crank. I know from experience that any sheared keys I have replaced was because the momentum from the flywheel was abruptly stopped. This could be from a quick backfire during starting or if the ski swallowed up a gulp of water and partially or fully hydro-locked it. Another time it could happen is if something became caught in the impeller and stalled out the engine. There is actually more to worry about with the wrong thickness than a degree or two. With that additional clearance in there, if the engine suddenly hit a heavy load like half throttle in the air and then the major load up upon water contact, the flywheel will spin from the crank being rapidly dropped in rpms. The same thing will happen if you get a grain of sand caught in the impeller...the ski will idle around but will feel like it's not picking up when you gas it. The added stress from gassing it to get that sand out is another one of those times that the flywheel could get thrown off of alignment. If you want to size match it just grab a vernier caliper or digital one that reads in 4 decimal places and size up the key way width, then measure the key way depth on the crank and flywheel and add them together. There's your most important measurements done. Hope you can get it set up for the weekend, I know I wish my ski was ready hehe :rolleyes:
 
NVJAY775

NVJAY775

My home away from home.
Location
Gardnerville, Nevada, United States
In my case, it gulped a nice bit of h2o. And the flywheel bolt was loose.

Now that I know the exact dimensions of the key, I will see if the machine shops have some extras.

I ordered a stocker this am. Should be here tomorrow, or Saturday at latest.

Can't thank you guys enough for all your help. Once I get it back together, I'll let ya know how it does.

Hey. So it sounds like upon reassembly, the majority likes red loctite on the crank to flywheel surface and also the flywheel bolt? I've worked with it before and know about heating it to free it. Is it safe to heat the flywheel with the electronics behind it?

Thanks again in advance. I just want to do it right.
Jay
 
Pro-pulsion

Pro-pulsion

Location
Ontario, Canada
Umm, I'll tell you my personal opinion about using red loctite...don't. It's great if it's on something like frame work for ATVs or the auto industry, but personally when you have to work in such small quarters on a ski red can be a real pain. A friend of mine flys ultralite aircraft and they have to go through some serious inspections up here before they can be certified for flight. The guy that was doing the inspection on his ultralite is also an engineer and said that if he were to ever have an engine sent to him for repair or any required updates, and red was used on anything aluminum, he would refuse to assist with any technical corrections and send it back. I've noticed that after it dries it seems to crystalize and balls up when removing bolts and has in the past (at least for me) messed up the threads. Obviously the only threads will be on the flywheel bolt and the crank isn't aluminum but the flywheel is so the possibility of something going screwy if you ever had to remove it later on down the road is there. So that one is entirely up to you, anyone that has had good luck with doing it probably knows something I don't, but in my opinion I would just bolt it on dry. If it's never been a problem until now and you've been out for over a year or more on the ski with no prior issues with it then I wouldn't be too worried about it being a repeating problem.
 
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teton

teton

tetongravity.com
Location
Washington DC
Pro-pulsion said:
Umm, I'll tell you my personal opinion about using red loctite...don't. It's great if it's on something like frame work for ATVs or the auto industry, but personally when you have to work in such small quarters on a ski red can be a real pain. A friend of mine flys ultralite aircraft and they have to go through some serious inspections up here before they can be certified for flight. The guy that was doing the inspection on his ultralite is also an engineer and said that if he were to ever have an engine sent to him for repair or any required updates, and red was used on anything aluminum, he would refuse to assist with any technical corrections and send it back. I've noticed that after it dries it seems to crystalize and balls up when removing bolts and has in the past (at least for me) messed up the threads. Obviously the only threads will be on the flywheel bolt and the crank isn't aluminum but the flywheel is so the possibility of something going screwy if you ever had to remove it later on down the road is there. So that one is entirely up to you, anyone that has had good luck with doing it is probably know something I don't, but in my opinion I would just bolt it on dry. If it's never been a problem until now and you've been out for over a year or more on the ski with no prior issues with it then I wouldn't be too worried about it being a repeating problem.
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what aluminum?...both crank and bolt are ss....I would go with what the yamaha manual says, and they recommend loctite....
 
teton

teton

tetongravity.com
Location
Washington DC
Pro-pulsion said:
Keep in mind I did mention the crank and bolts dude.
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that might have sounded overly harsh....the flywheel if stock is steel, eather way the flywheel never comes into cantact with the threads of the bolt, the only thing the bolt does is tighten the flywheel on the flange...so the loctite if used right should not come into contact with the crank flange and the flywheel.....

and with the constant acceleration/deceleration of any flywheel it would be wise to use loctite or some other means of preventing that bolt from loosening...
 
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