Nytro engine knocking..

[rlcofmn]

seems to me that the 180 kit is no good to the nytro engine.

One failure with 12,000km on it determines that the 180 kit is no good for the Nytro engine????

 

[Dimebag]

 

[kimoajaj]

This sucks dimebag, but the good thing is that you can use the old crank as a decoration in your livingroom. Every morning you wakpe up and walk past it you will remember all the good times it gave you.

Since I know your riding style I honestly have to say that it is incredible that it has lasted so long.
I have never seen anyone throw a sled around like you, awesome.

I also know that you your Nytro has been on its side and upside down many many more times then the average rider (I think hehe) and personally I hate those seconds without oil pressure when you fire it up after a rollover. Can this have something to do with this? I read that the center rod bearing is the last one to get oilpressure after a rollover (or when you have air in the pump).

Someone should make an electric priming pump that you could run a few seconds after a rollover, that would be awsome.

Looking forward to tearing it down, will be interesting.

It`s good to know that this is your first rebuild and not the 3rd.. like it would be if you rode some other brand.

It`s more fun spending $ improving your ride and not spending $ just to keep it running =P.


I guess Harley`s saying "it`s better to be dead and cool, then alive and uncool" suits your engine good.
It`s a Yamaha, doesnt need to run to be cool.

 

[yamaha1973]

Sorry to hear that dime! hope for the best

 

[Off Trail Mike]

Hey Dime:

At least you have all summer to fix the engine....hopefully damage is not too bad.

Do you think it was life at the boosted ragged edge x 12000km's or all those roll overs?

I was wondering about what kimoajaj said about a brief loss of oil pressure once you get the sled back on its skis and restart. Their should be a way to spin the engine without firing the plugs, thus allowing some oil pressure to build before the engine starts to go bang and load up the bearings... Prelube would be the best, but I think it would be a bit heavy

Good luck

OTM

 

[sgilbert]

I would think some kind of bladder cell like in an airplane would do the trick, so it never gets air to begin with

 

[Dimebag]

Do you think it was life at the boosted ragged edge x 12000km's or all those roll overs?

I would think it was a combination. The engine ran flawless every hour until it suddenly failed. No forewarning.
I dont know if the rod bearings can suffer "a little" damage every time you roll over and start up the sled again,
or if they are 100% ok until they suddenly fail?
Is it something that should be considered changed every XX miles if you roll the sled over often?

This sucks dimebag, but the good thing is that you can use the old crank as a decoration in your livingroom. Every morning you wakpe up and walk past it you will remember all the good times it gave you.

Since I know your riding style I honestly have to say that it is incredible that it has lasted so long.
I have never seen anyone throw a sled around like you, awesome.

You know, there are all those people who ride snowmobiles. And then there is those who RIDE.

I can promise you the crank has its place on the living room shelf, next by all the doo-pistons.

Im also looking forward to tearing it down. (Or looking at you tearing it down). Hey man, I wanna do the wrenching myself.
I guess well have to come to an agreement on that point before we start on it..

And once its opened up, thats where the fun part starts. Which parts to get, oem or improved?

Either way, its gonna be fine. Kimoajaj is a skilled mechanic, and he is the primus motor (or optimus prime) on this project.
What do you say? Should we start?

 

[HYFLYR]

Crank bearings often times don't just go. They can take a lot of abuse and slowly fatigue and finally over time fail. We see if often when a person rolls their sled and it keeps running upside down and finally dies. They then roll it over and go about their day and the motor dies a 100 miles later because the crank bearings finally can't take it anymore from the damage that was done previously. I've seen a few motors have this happen now.

Good news now is you can throw rods and pistons at it, turn up the boost and have a lot of fun. Get the JE pistons and carillo rods, that's the hot setup.

 

[Dimebag]

I see.. then I have a riding buddy thats gonna get nervous for his bearings too..
Have you ever saved a crank when the bearings failed, or did it take out the crank every time?

Is it the JE low compresion 9.5:1 pistons?
How much boost can i run with these pistons with everything else like it is today?
Its a MCX 180 kit on 91 octane.

Will there be a noticeable difference in the engine response? turbo lag?

Thanks

 

[Off Trail Mike]

I would think some kind of bladder cell like in an airplane would do the trick, so it never gets air to begin with

SG:

Is that like an accumulator? I was wondering why Yami use a dry sump that is still sensitive to angle. With most guys already using the Jacobson ROV, you would think its pretty easy to adapt something from an airplane engine that keeps oil pressure in the system.

OTM

 

[sgilbert]

if I recall from the A-6 days, they had a bladder cell that was in the belly tank that worked like a water pressure tank, rubber bladder that is kept full by pumping from wings, intended for upsidown manuvers like dime bag rides all day. I have had thousands of blown small engines apart and would say without a doubt that rod scoring adds up over time and eventually talks to you. sometimes causing trouble multiple owners later

 

[ntm_08]

Is it possible to have a bearing with some wear without having a failure later on ?
Or does it eat is self up every time ?

If it`s working is everything OK? or may it be time to change.

Talking about my own Nytro with the same mileage and "abuse".

ntm

 

[sgilbert]

Is it possible to have a bearing with some wear without having a failure later on ?
Or does it eat is self up every time ?

If it`s working is everything OK? or may it be time to change.

Talking about my own Nytro with the same mileage and "abuse".

ntm

seems to me that maximum tight clearance with anything makes it last longer. old school mower engines, once the piston gets some wiggle room, wear exponesially. meaning, near perfect at 1000hrs, some wear at 1250, then shot at 1500. totally differsent, air cooled crap, etc., but the idea is there,

 

[jaydaniels]

Is it possible to have a bearing with some wear without having a failure later on ?
Or does it eat is self up every time ?

If it`s working is everything OK? or may it be time to change.

Talking about my own Nytro with the same mileage and "abuse".

ntm

What happens is when you loose oil pressure, the rod bearing makes contact with the crank and wears away some material. Now you have more clearance between the bearing and crank which results in low oil pressure. Low oil pressure means that further contact between the bearing and crank is likely. More contact means more wear and further oil pressure loss until finally your oil pressue is so low that you have constant contact and then boom. As said in a previous post, it happens exponentially.

 

[yamaha06]

Just a quick question, if having a roll over and then starting the engine and that loss of oil pressure for a few seconds does so much harm on the bearings, what's the difference when doing an oil change and starting the engine and having it knock for a couple seconds before pressure builds up?