Doing the mods to fit my style

[aduncan]

I recently got my bike back from a complete engine rebuild. The mechanic that did the work on my bike told me it was the piston that failed. The nickle plating flaked off the piston, resulting in the oil burning up and the bike siezing in a matter on only about 15 minutes. From full power to seized solid before i even noticed a problem. Oviously it was a bad piston that cause the failure but he also asked me about my riding style and suggested that I modify my bike to better fit it. I was told that the YZ450F is a great platform for all riding styles but not always in its stalk form. It can't be riden full out top gear for more the about 10 seconds at a time like an endro can and it can't be riden slow thru the bush all day either. Not stalk anyway. These are both things that I do from time to time on my old bike. (very old bike haha) So I am wondering what I can do to make my YZ more trail friendly without losing its race bred style. I love to play in the sand pits on the big jumps, and tare up the ditches around my place in the country so I need the suspension that can handle it. But I also often that the bike into tight brush trails where I don't get higher then third gear all day. I am thinking a heavier flywheel will help the low speed riding, and I always run a quality full synthetic oil. Are there any other suggestions for keeping the racey style of the yz bike for a guy that will probably never take the bike to the track?

[grayracer513]

In the first place, the piston isn't plated; the cylinder is. Secondly, the statement, "It can't be riden full out top gear for more the about 10 seconds at a time like an endro can and it can't be riden slow thru the bush all day either (sic)", is wrong from one end to the other.

What year is your bike? No chance it just had that many hours on it already, I suppose? What oil are you using and at what interval do you change it?

[tnl]

It can't be riden full out top gear for more the about 10 seconds at a time like an endro can and it can't be riden slow thru the bush all day either.

I don't think any kind of bike could withstand much more than that unless you do engine rebuilds frequently? Don't think there is anything built into a wr/enduro bike's engine that will allow one to ride full out top gear for more than 10 seconds at a time with out repercussions? If you find yourself in 5th gear at the rev limiter often then a wr would suit your engine/tranny needs better for top speed even after a sprocket change. There are a handful of mods to transform a yz into a wr style bike. Do a search and you'll get alot of opinions.

[todds924]

I recently got my bike back from a complete engine rebuild. The mechanic that did the work on my bike told me it was the piston that failed. The nickle plating flaked off the piston, resulting in the oil burning up and the bike siezing in a matter on only about 15 minutes. From full power to seized solid before i even noticed a problem. Oviously it was a bad piston that cause the failure but he also asked me about my riding style and suggested that I modify my bike to better fit it. I was told that the YZ450F is a great platform for all riding styles but not always in its stalk form. It can't be riden full out top gear for more the about 10 seconds at a time like an endro can and it can't be riden slow thru the bush all day either. Not stalk anyway. These are both things that I do from time to time on my old bike. (very old bike haha) So I am wondering what I can do to make my YZ more trail friendly without losing its race bred style. I love to play in the sand pits on the big jumps, and tare up the ditches around my place in the country so I need the suspension that can handle it. But I also often that the bike into tight brush trails where I don't get higher then third gear all day. I am thinking a heavier flywheel will help the low speed riding, and I always run a quality full synthetic oil. Are there any other suggestions for keeping the racey style of the yz bike for a guy that will probably never take the bike to the track?

I have buddies that race desert WFO all day long on there YZ's....NO PROBLEM!

[aduncan]

Grayracer, my bike is an '07 and it only had about 5 hrs when the engine seized. when it happened my first thought was that my kickstart had jammed because I was running with full power and shut it off for a second to let the rest of my riding group catch up. When I went to kick start and go again I couldn't even move the kick lever. I took it in to the shop I bought the bike from and they told me the bike had no oil in it and the engine was toast. After the rebuild I talked to the mechanic that did the work. I had changed the oil right before riding that day with a four stroke specific AmsOil 10w30. I asked what had cause the failure. The mechanic told me the nickle coating had flaked off. I thought he had said piston but if its the cylinder that is coated not the piston then maybe I confused the two. Anyway, the coating flaked off and the oil burnt up very rapidly and smoked the engine. He then explained to me these things about how the bike was designed to be ridden. Like riding up and down thru the gears, not just full out top gear. And keeping the pase up, not puttsing around. I am only repeating what I was told by a pro mechanic. If anyone knows better I would sure like to hear other opintions.

[aduncan]

As for the mod questions. I went to my local dealer and asked about weighted flywheels like I have read about on here. They looked at me like I was nuts. Where can I find such a thing online and is it possable to go too big on the flywheel. Also what is the wieght of the stock flywheel, I've looked and can't find the spec. I keep finding things like 4 oz over stock but that doesn't tell me what stock is and if 4 oz is a big gain. Also I find my bike has a ton of torque and power but all the sproket mods suggested on here ask to go bigger on the rear. Wouldn't that just slow down your top end? I don't ride tracks so maybe thats an MX thing. I would almost like to get a higher top end.

[dmoney1074]

As for the mod questions. I went to my local dealer and asked about weighted flywheels like I have read about on here. They looked at me like I was nuts.

This is exactly why I refuse to go to the stealership... They know less than the riders. And this mechanic of yours sounds like a real good one ?

Good luck, sorry you had trouble with your bike...

[todds924]

This is exactly why I refuse to go to the stealership... They know less than the riders. And this mechanic of yours sounds like a real good one ?

Good luck, sorry you had trouble with your bike...

As with anything..........There are good and bad Technicians as well as good and bad dealerships. This sounds like a bad one.

[grayracer513]

the bike had no oil in it ... I had changed the oil right before riding that day ...

Hate to say so, but I think I see the problem.

The cylinder is usually the first thing to fail when you run out of oil.

Also, the Amsoil product you're using is not the correct oil for the job. By the book, 30 weight is OK, but IMO it's a little light for a ball bearing engine with a trans. Additionally, it isn't formulated as a trans oil. You should be using Amsoil "Synthetic Motorcycle Oil" (product ID "MCF"), not "... Motorcycle Engine Oil".

[WB450]

As for the mod questions. I went to my local dealer and asked about weighted flywheels like I have read about on here. They looked at me like I was nuts. Where can I find such a thing online and is it possable to go too big on the flywheel. Also what is the wieght of the stock flywheel, I've looked and can't find the spec. I keep finding things like 4 oz over stock but that doesn't tell me what stock is and if 4 oz is a big gain. Also I find my bike has a ton of torque and power but all the sproket mods suggested on here ask to go bigger on the rear. Wouldn't that just slow down your top end? I don't ride tracks so maybe thats an MX thing. I would almost like to get a higher top end.

https://www.thumpertalk.com/forum/showthread.php?t=551161&highlight=Flywheel+weight

[aduncan]

oh really? Damn, so by going with what I thought was a better oil I toasted the engine myself. In the process making me look like an idiot and costing me a ton of money. But if I were to look at the glass as half full i would have to say at least I have a lil more faith in the bike again knowing it was my fault and how i went wrong

[grayracer513]

The fact that the oil wasn't your best choice is a secondary issue to the fact there was none in the engine. That in itself would more than likely not have caused this. It could well be that the cylinder was flawed, and was the part that failed first, but it seems very unlikely, to the point of being a total fluke.

It's much more likely that you made an error in refilling the system, and that the cylinder was damaged by a lack of oil, but I, of course wasn't there.