Rebuild?

jim · May 21, 2018

Your last claim about the low end not seeing the stresses of the top end demonstrates a real lack of understanding about the engine.

Your lack of ability to read and comprehend on a technical level is the key problem here. Cyclic stresses.

The top end sees cyclic, mostly axial (in-line) forces which go from positive to negative and back almost exclusively, minus some side-loading. The low end takes that cyclic motion/forces and coverts it into rotational. Rotational is still cyclic in nature, yes, but nothing compared to the top end which reciprocates.

If you are suggesting he do the low-end at the same interval as the top end...cool...but is a waste of money. Any maintenance manual will suggest the top end be done multiple times before the low end.

But, hey, you are probably right that they both see the same type stresses. Guess I need to go get my mech engineering degree again so I can understand how forces work.

Big10inch · May 22, 2018

jim said:
Your lack of ability to read and comprehend on a technical level is the key problem here. Cyclic stresses.

The top end sees cyclic, mostly axial (in-line) forces which go from positive to negative and back almost exclusively, minus some side-loading. The low end takes that cyclic motion/forces and coverts it into rotational. Rotational is still cyclic in nature, yes, but nothing compared to the top end which reciprocates.

If you are suggesting he do the low-end at the same interval as the top end...cool...but is a waste of money. Any maintenance manual will suggest the top end be done multiple times before the low end.

But, hey, you are probably right that they both see the same type stresses. Guess I need to go get my mech engineering degree again so I can understand how forces work.

Thanks for ignoring the other forces the crank sees from the drivetrain though. I am sure the forces exerted there are something we shouldn't factor in. You know the forces from the clutches that distort cranks and wear the crank seals. Lets just forget those shall we, more convenient for your argument I see...

Money?????????? Are you high? a couple seals and some sealant plus an hour or less of your time. Less that $50 will cover it. I think you should definitely skip this step because of money. LOL

Show me where I suggested rebuilding the lower end. I simply stated that I have seen leaking seals cause a second burn down. They are cheap and easy to replace. I just do not understand why anybody would buck this?

sno*jet · May 22, 2018

^how about the added stress an average backyard mechanic would cause just trying to get the primary clutch popped off.
Ive seen crank seals go out more from age than mileage. seems like they dry out and leak, an 18 model ridden regularly wouldnt worry me a bit.

jim · May 22, 2018

Thanks for ignoring the other forces the crank sees from the drivetrain though. I am sure the forces exerted there are something we shouldn't factor in. You know the forces from the clutches that distort cranks and wear the crank seals. Lets just forget those shall we, more convenient for your argument I see...

Money?????????? Are you high? a couple seals and some sealant plus an hour or less of your time. Less that $50 will cover it. I think you should definitely skip this step because of money. LOL

Just my opinion and experience...not going to argue...if your goal was to say everyone was wrong and you are right, good job...you did it.

Big10inch · May 23, 2018

jim said:
Just my opinion and experience...not going to argue...if your goal was to say everyone was wrong and you are right, good job...you did it.

My opinion and experiences as well... you started the "argument" if you look back. I understand why you want out though...

jim · May 23, 2018

My opinion and experiences as well... you started the "argument" if you look back. I understand why you want out though...

Well that showed me...another "win" in life you can take back to yourself. You, and others like you, are exactly why a lot of people have left this forum over the years.

summ8rmk · May 23, 2018

With my Zuke i had no problem getting 4,000 miles on a top end. Even at that many miles, pistons still looked good.
No noticable power gain when new pistons inserted, there wasn't a noticeable powerloss before hand either.
But i ride like grandma in the mountains so i shouldn't have a problem getting that many miles..........................

Just did it because i wanted it fresh as i was selling the sled and didn't want the new owner to have it fail on them.

boondocker97 · May 23, 2018

My thoughts are if you're going to change pistons as preventative maintenance on a well running sled with less than 4k miles, mess with as little as possible. Chances of creating a problem could be almost as high as fixing one that wasn't there.

Now if something happened to the motor and a cylinder went down then I'd be inclined to disassemble the bottom end to check things out. Or if you are planning to fully remove the engine from the sled then it's not too much more effort to split the crankcase. Other scenario I'd consider is if you've blown a bunch of belts on a sled and want to make sure the crank is still true and in phase.

Big10inch · May 24, 2018

jim said:
Well that showed me...another "win" in life you can take back to yourself. You, and others like you, are exactly why a lot of people have left this forum over the years.

WTF are you even talking about anymore, not sleds obviously... Seems to me it is guys like you with no real point other than to try and position your enlightened self as sooooo much smarter than the rest of us, that causes friction here. THAT, and Christopher, are the things that have ruined this forum, not me suggesting crank seals are a good idea based on my experiences???

No, clearly the "win" is more important to you, so take it. What a joke.

jim · May 24, 2018

dboivin · May 24, 2018

Yaeger34 said:
Got my questions answered about what changes I can make on the sled and I appreciate the response

Since the my 18 has 3200 miles I am considering just throwing in a top end even though compression feels strong. What is compression on these. Pair of oem piston kits are $200. So I'm sure under $300 with all gaskets and o rings. I haven't done a sled rebuild since the 90s and 2000s sleds. A few banshees and about 20 fourstroke motocross bikes. Anything specific in need to watch for or replace while I'm at it? Is it worth it if compression ia good? Again not sure what compression ia. Thanks again

i wouldn't touch a thing. i would ride it. it aint broke, its not acting broke. put another season on it and then do full preventative rebuild or sell sled and get a new one then.

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