Maintenance & Technical > KX500 Original
This is why you don't run a CAST piston
quincyman:
I have been riding the same KX500 for 10 years. I am not trying to avoid legitimate maintenance. I have only fried one piston and that was my fault not maintenance issue but rather carelessness after doing carb work. I failed to tighten the airbox side clamp and it sucked air. Boy did it run nice until it seized.
I generally ride by the seat of my pants. I can tell if the bike is starting to lose power and not run up top par. That's when I change pistons. Usually that is a lot more than 50 hours. I have never run a cast piston before, which is why I was asking questions.
I believe there is such a thing as needless maintenance for a recreational rider. We don't put near the abuse on a bike that someone who races regularly or spends a great deal of time in the sand. I don't race and only do sand when it is a part of the ride (not a big dune rider).
I know KX500 riders who are running the same piston after 5 to 8 years of ownership. I doubt they ride near as much as me. I ride every week all year long unless deep snows prevent me. But that riding is now shared between 5 bikes. There was a time when the KX500 was my only ride.
When I saw those pictures and the caption that cast pistons do this I became concerned because I have just installed my first cast piston. If it is the very nature of cast pistons to break apart then I don't plan on running one for too long. But I put the money out and didn't want to panic for no reason. Hence the question.
I put out more money keeping my 5 bikes running right in a year than most do in 5 or more years. So I just don't want to be installing a new piston for the sake of it rather than need. Kinda like the guys who change oil after every ride. 9 times out of 10 that is needless over kill but certainly will never hurt their bikes by doing so. And if you can afford go for it.
I will pull my piston after 50 hours just to check for the hairline cracks. I suspect that is the only way I will find out what I want to know. It sounds like that will be the wisest course of action.
maddoggy:
i find it's better to maintain your bike rather than repair it after a failure. maintanence is almost always cheaper than repair. you guys have alot more years experience on a bike than i do so if you are unanimously against cast pistons there must be experience talkin'. i'll heed the advice and steer clear of the cast. thanks for the info. MADDOGGY
Friar-Tuck:
Doggy, BDI, and all
I think sometimes reading and typing online doesn't always come across as intended.
Sometimes its a blatent shot at some one and sometimes what I type and what someone else reads may be quite different. I would have to think as someone earlier stated where and how a person rides, terrain, money avail to spend, amount of hrs. on the bike and how their equipment is maintained surely must be a factor in the longetivity of the components.
I think 99% of us are here 'cause we just plain love to ride.
I'm sure we all might not agree on much more than that, but heck thats not all that bad, is it?? Please keep coming by and chiming in, lots of guys like me learn more on a few bike forums like this one than spending gobs of money on magazines or the places where it seems flaming and starting fights online is more important than sharing information or hooking up a place to ride.
I don't have an old school machine/bikeshop nearby to hang out at and riding time seems to get harder and harder to come by.
Cast v Forged Ford v Chevy Kawasaki v Honda Synthetic v Standard
Competition; its everywhere, and probably what keeps us all on our toes to try to get a little better.
Take Care,
Tuck \o/
quincyman:
--- Quote from: BDI on June 24, 2007, 05:09:44 PM ---I'm sorry for being rude I'm begining to wonder why I answer questions on hear. I try my best to pull from 25 years of expeirence and I'm not allways right. I have blown up bikes in every way possible and I have made very expensive mistakes learning a lot of things the hard way. I agree lots of people change their oil to much. It Is hard to over maintain a bike. I ride the hell out of my bikes and they have to be maintained at a race level, can your filter be to clean or perhaps your chain could be adjusted and lubed to good. maybe 50 hours is not the right amount of time. Ride your bike every weekend for a year then check it and then at that point you should start checking it every time you ride because catching them with cracks is luck. Usually your engine will look like the ones in the pictures you see on this post soon after they develop cracks. you could have cracks you can't even see without magnafluxing it. If you want to run your bike until the piston and rings are worn out to the point the bike does not run good any more thats your deal but if you don't want the whole engine to grenade and cost thousands of dollars to fix use a forged piston. P.S. thats 50 hours of engine run time you can go riding all day and only log three hours on your hour meter three hours at 35 mph is 105 miles
--- End quote ---
I do pay attention to what people write on these lists. I also try to evaluate where the rider is at in experience. Sometimes people spout what the hear and not what they know (which can also help if what they heard is the truth).
I took seriously this issue about the cast piston and am glad that folks are willing to add information to the thread. Through the years I have made my riding experience much more pleasurable buy reading these lists. Often catching things before they happen cause some one brought it up in a thread and 20 other serious riders jumped in to share what they know.
I am not a bad mechanic myself but am well aware of the fact that my knowledge has come from the school of hard knocks. When your education comes through hard knocks there are usually important gaps in what you know that a professional takes for granted when he works on a bike. Being aware of my own ignorance keeps me from getting to set in my ways about things.
I guess what I am trying to say is thank you for taking the time to discuss this issue.
Polar-Bus:
Well, i've owned 9 new KX's since '83, and run countless stock cast pistons in every one of em', and never had a cast piston "granade fail". I've lost 1 crank (completely my own fault, sucked some sand), and lost 2 top ends, one from a blown base gasket, and the other from ???? (never really figured it out). Both top ends were easy repairs. I hear a lot of pro's and con's to Wiseco's, but in my opinion, when something works so reliable for over 20 years (cast), i'll stick with them.....
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