Two Stroke Motocross
Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: MCGRIDDLE_321 on May 23, 2011, 01:57:18 PM
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well this saturday i destroyed a motor for the 3rd time in 2 years. :'( as much as i love 2 strokes everytime it blows up it costs 1000 to rebuild it. thats not that much less then a 4stroke.
for some reason it always destroys the cylinder.
Josh
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if your blowing up a two stroke motor that fast, there's no doubt you'd do the same to a valve muncher. And 1000 is a third of a cost if you blew a thumper up
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Are you doing the work yourself? I would consider getting the cylinders repaired and replated for much less than an OEM replacement cylinder.
But I can guarantee a 4T will be much more costly if you frag it.
But I have to wonder why you are having so many severe failures. Something is off; jetting, air filter maintenance, incorrect pre-mix, something. I know a lot of people that race two strokes, fast guys, and they do not have catastrophic failures like you are having.
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I second what Coop said, You are doing something wrong, I don't know what, but something is wrong.
Replate the cylinder you have, as a matter of fact if you have replaced the cylinder everytime and still have the damaged ones, have them replated as well. It will cost less than buying a new one. then get two piston kits with gaskets and change the top end out every 40-50 hrs.
use a quality premix at 32:1 if your on anything smaller than a 250.
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Are you doing the work yourself? I would consider getting the cylinders repaired and replated for much less than an OEM replacement cylinder.
But I can guarantee a 4T will be much more costly if you frag it.
But I have to wonder why you are having so many severe failures. Something is off; jetting, air filter maintenance, incorrect pre-mix, something. I know a lot of people that race two strokes, fast guys, and they do not have catastrophic failures like you are having.
and when i said its not that much less then a 4stroke i ment over time, ive gottin 2 years out of a 250f, and it cost us 2500 to replace almost everything when the crank went out. i love 2strokes, i will always have one and race one. im just confused on whats going on.
-jetting is good, runs fine
-change airfilter after every ride, sometime mid day on super sandy/dusty tracks.
- trick 114 with 927 premix, at 44:1 sometimes 50:1
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http://twostrokemotocross.com/forum/index.php?topic=2065.0 (http://twostrokemotocross.com/forum/index.php?topic=2065.0)
I see that you race a lot, so what do you do for maintenance? Tranny fluid, air filter, Compression checks, etc.. And what exactly failed on the motor to cause a melt down similar to the japanese nuclear power plants?
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well me and my dad usually do all the bike work during the week. we usually change oil ever 2 to 3 rides airfilter all the usual bike work, since its 4 days before the loretta lynn qualifier we took it to my engine builder to have him go through it. he said he found some dirt, which broke the reeds, and then the reeds got sucked into the cylinder and bottom end. so all in all it was a snow ball effect. its ok. i talked to my mom, we are either buying a 2011 250sx, which there is only one in washington, or we might get a 2011 250f so i can ride the national if i get my pro points in time, and fix the 250 2stroke to race and practice on.
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if you're getting a new bike and rebuild your old one, don't go for the 250f.
it will make more sense practice and racing both 2 strokes.
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yeah we will see.
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So broken reeds caused $1000 worth of damage :o I find that hard to believe. If what your saying is true, Everyone should watch out, they might drop a reed and destroy the motor...lol
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well me and my dad usually do all the bike work during the week. we usually change oil ever 2 to 3 rides airfilter all the usual bike work, since its 4 days before the loretta lynn qualifier we took it to my engine builder to have him go through it. he said he found some dirt, which broke the reeds, and then the reeds got sucked into the cylinder and bottom end. so all in all it was a snow ball effect. its ok. i talked to my mom, we are either buying a 2011 250sx, which there is only one in washington, or we might get a 2011 250f so i can ride the national if i get my pro points in time, and fix the 250 2stroke to race and practice on.
I am just a beginner/novice (motocross) and I change my oil every 2 to 3 rides. Wouldnt you need to change your oil after every practice at your pace?
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1000 dollars... its about 700 bucks to get a cylinder and piston, thats with my discount from ktm munn racing. we might still have to replace the crank. not sure yet.
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That's weird. You probably just ride a lot, that's why you're going through your motor so fast. Most of us ride 1/3 of how much you do. But still that's pretty quick to go through an entire motor. Anyways I would suggest rebuilding your katoom and waiting for the 2012 250sx.
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Josh, I change my oil every ride and I am doing top ends at no more than 10 hours on my 250. I had the reeds break in mine as well and it didnt destroy the motor. I have blown up my share of 2-stroke though. It just happens, and after a couple times its just time to start with a fresh bike. If I grenade a bike I rebuild it and sell it cuz once it goes once its gonna go again!
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I am pretty sure that when I was racing 85's an 125's we were changing rings every 3 races an piston every 6 races. Each race day was around an hour of riding. We ran premix at 36:1. When we started that schedule we stopped blowing bikes. Mind you bikes were never more than a couple years old and from memory I don't think we ever blew up a 125. There were some 60's and 85's that were blown up working out what worked tho
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- trick 114 with 927 premix, at 44:1 sometimes 50:1
If you are on a 125, this is a big part of your longevity problem.
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Ok, I'm a bit confused and alittle mad at the "tuner." So, was the bike running when you took it too him? I build motors quite often. A reed, is basically plastic. Your motor will take a piece of aluminum from a piston and still not take out a crank many times, so I'd be really really suspicious of someone claiming a reed did. So I really need to know if the bike was running when taken down. I'm calling BS and really would like to see this motor. Alittle dirt also has nothing to do with a reed breaking off. A reed breaks off, if it is flexed back and forth too far and too much. When is the last time you had reeds replaced? If the motor was running fine when you took it in. "TAKE THE MOTOR BACK from the tuner." Man, I'm getting madder by the word. The cylinder will not score from a reed either. So WTF is going on? A reed when breaks off also makes the bike run bad, it will gulp for air when you let off and then get back on the throttle. It won't idle in many cases. It will feel like you have carb problems.
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well me and my dad usually do all the bike work during the week. we usually change oil ever 2 to 3 rides airfilter all the usual bike work, since its 4 days before the loretta lynn qualifier we took it to my engine builder to have him go through it. he said he found some dirt, which broke the reeds, and then the reeds got sucked into the cylinder and bottom end. so all in all it was a snow ball effect. its ok. i talked to my mom, we are either buying a 2011 250sx, which there is only one in washington, or we might get a 2011 250f so i can ride the national if i get my pro points in time, and fix the 250 2stroke to race and practice on.
this statement sounds like you took it in just to have it looked at and freshened up.
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This is interesting but will be very hard to diagnose online but here goes: We don't have enough information to identify your previous failures but maybe some of the information will trickle back. From what you have told us, you have a pretty well maintained machine and put a lot of hours on it. Reed failure is not uncommon but I tend to doubt that the pieces of the reed were sucked into the bottom end and caused a failure. More likely, the reed cracked and caused a lean condition. This could cause detonation and overheating and will cause a seizure.
I doubt it is oil related though I wouldn't suggest 50 to 1 (anymore). As much as you don't want to hear this, I'd suspect jetting FIRST! I would run the manufacturers (either bike or oils) recommendations, get a few good readings on fresh plugs and keep an eye on ring/cylinder wear; changing piston/rings more frequently if necessary.
I also would suggest (and I can't believe I'm saying this) getting the 4$. You sound like you are attempting to become an AMA Pro rider. Unless you are willing to be a martyr to the 2T cause (and you'll be all our hero if you do), you'll need the thumper experience at the pro level.
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And I'll disagree. The OEM's will force him to switch when and if he is a ProAMA rider, either through being good enough to get a factory ride, or by ProAMA rules. Not one of the current ProAMA riders have had a problem adapting to the 250F. Plus he would be at a disadvantage at Loretta Lynns. Those rules are still 250cc vs 250cc. Why bring a stick to a gun fight.
Have your father or mother call Miedoso Racing today 214-316-3055. I'd like to speak to them, and I'm not trying to gain your business or anything like that. I'm really worried you are being taken advantage of. My first red flag is telling you to buy a new cylinder. No I mean NO reputable race shop buys new cylinders, they send away to one of 3-4 recoating companies for $100. Cost to client, about $150-200 usually. No $700 cylinder. Period. Then the whole dirt took out a reed etc BS. please tell them to call me. Thanks
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Curious.. would a broken carbon fiber reed be more prone to invoke damage vs a fiberglass/resin/plastic/whatever one?
Miedoso - props for looking out for this guy..
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"trick 114 with 927 premix, at 44:1 sometimes 50:1
If you are on a 125, this is a big part of your longevity problem. "
Agreed XInf.
I also agree with miedosoracing. You are getting screwed!!!!!
Find a new mechanic, start running 32:1, 36:1 premix, Drop that 927 crap, and use klotz or Lucas. The lucas seems to burn cleaner and is not as gummy, But the Klotz is the best stuff out there. Change the rings every 3 races, the piston every 6, and the lower end every 12.
Then punch that guy that's been doing your engine work in the mouth.
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Not that I am piling on, but I agree with Miedos and Myck. I think your mechanic is taking advantage of you. And if you are racing as hard as it sounds, I think your jetting and the fact that you may not be keeping the top end fresh is the cause of your problems. Just because the bike seems to run fine doesn't mean it is jetted properly. I don't know how many races you run, but Myck's guidelines are pretty spot on. Other than the Klotz comment, I hate that stuff... :D :D :P
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so here is what happened at the track...
i was going out for the 4th practice of the day, i warmed up the bike good then took a site lap around the track (check lines and continue to warm bike up) i did one hard lap and as im coming to the finish line section the bike bogs i would say 3 or 4 times, so i pulled to the side of the track to try and keep it running but it bogs out bad. i tried starting it, check compression with my hand, everything seem good. i pushed it back to the truck, we then took spark plug out to see how it looked and to check spark, the plug looked black, we put a new plug in. it fired up 2nd kick. i warmed it up listening to the motor sounded fine until you got to about 1/2 to 3/4 throttle and then it had a big bog. the bike kinda sounded like if you were to start your bike with no air filter. i rode it in the pits to see if i could feel anything and listen to it. it didnt want to run all that great so i put it on the stand and got undressed and took it to the guy who builds my engines.
now the thing that gets me is. if it ran when i took it to him, how does something claimed to have that big of damage run? now im not bagging on my engine builder (family friend and he has always been there to help me) at all im just confused.
i talked to my dad this morning, i have a friend who has a 07 ktm 250 (same bike) and we are going to try and barrow his for the weekend and have mine rebuilt, just with how money sits we might get a newer 250 sometime in the summer.
i would love to be the guy who trys to qualify on a smoker for some of the nationals, but as it being my first time trying to qualify i want to do good and i know as long as im not paying for all the entrys with my own money my mom and dad will want me on the 4stroke. now sometime in the near future when my mom and dad stop helping out, i will definitely try on the smoker. but just knowing my mom and dad i know it wont happen if they are paying for it.
Josh
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Ok, so it sounds like it wasn't running fine. Let's start there. Ask to see the engine apart. The piston should be scratched up and the top of the piston should have pings in it from metal hitting it and the head. The cylinder, you will be able to look at it and see scratches. Have him show you exactly what he is talking about. This should be a much cheaper thing, even if it is complete bottom up to top bad. Cranks, coating the cylinder and the new piston with seals and gaskets. You should be able to see everything and he can explain why he says what he says. The question I guess i'm having, is when is the last time you did a crank? You had mentioned 3 motors now completely rebuilt. So that should be a new crank. It sounds also like a previous poster may have been right about the reeds leaning out the mixture and running you lean to have your crank seize. I can't tell from posts on here, but more info after you see it will tell the truth. Maybe take some pics of the motor apart. The cylinder, the piston and even the crank.
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As for your parents wanting a 4 stroke, they had to have someone tell them that. Parents just don't know about 4 strokes and 2 strokes. There has to be someone else who is telling them they are better. Tell them any day, we can compare complete rebuilds and prices and see if they still like those. A 250 2 stroke should last 3 times as long as a 250F piston and crank wise.
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the only reason i say my parents is because my dad races to. so he races a 4stroke and he cant ride 2strokes and wont. it also doesnt help im 195 pounds and a 125 is going to be hard to carry my weight and they both just want the best for me. and the only reason i would get a 250f is to race the national. and i would probably still race my 250 2stroke locally and for loretta's.
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Parents just don't know about 4 strokes and 2 strokes.
Sorry I have to disagree with this, it is too broad a generalization. Just because you are a parent doesn't mean you don't ride or know about bikes :D . I know many guys who ride and have kids that ride and they really know their stuff.
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That's wierd man, maybe it's those first year of that body style KTM's. I know the first 144's had crank problems that they later addressed.
I've got an 09 250sx that I ride at tracks pretty frequently, and race now and again. I like to wring it out too. I'm still on the stock top end and clutch! it's getting tired though.
I mix it 60:1, following the manual, while using fully synthetic pre-mix and 92octane.
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That's wierd man, maybe it's those first year of that body style KTM's. I know the first 144's had crank problems that they later addressed.
I've got an 09 250sx that I ride at tracks pretty frequently, and race now and again. I like to wring it out too. I'm still on the stock top end and clutch! it's getting tired though.
I mix it 60:1, following the manual, while using fully synthetic pre-mix and 92octane.
ive actually been starting to wonder the same thing. maybe its just that year.
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Oh, you are on a 125. Sorry, I didn't read that if it was typed. So when was the last crank and piston done?
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no no.. the bike that blew up is a 07 250sx. i was saying if i was to try and qualify on a 125 for the washougal national it would be hard because im a bigger kid. (195 pounds)
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i think we did the crank/ top end in like late august, took the winter off. then we replaced the topend in February.
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i think we did the crank/ top end in like late august, took the winter off. then we replaced the topend in February.
Yeah, somethings wrong. I'm gonna post a "how to jet soon" when I have time. I will also try as much as I can to help you. That motor is a good motor. Same bottom end as a 300 even. Same as my 250xcw and am putting on a 300 cylinder that I just got from ebay. There is something wrong. Either jetting or lean from something else. Or he didn't put the seals or something in right from when he rebuild the crank, and the air is leaking in somewhere. That crank should last 5 to 10 years seriously. The piston should be a once a year if that changed. I rode a lot and could go a full season when racing pro.
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just wondering. in the last year i have noticed it being hard to shift out of 2nd when in the high revs. i have to completely shut off the gas and let the revs come down before it lets me shift. it seems to only do it in 2nd gear when revving hard. what do you think could do that or cause that.
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just wondering. in the last year i have noticed it being hard to shift out of 2nd when in the high revs. i have to completely shut off the gas and let the revs come down before it lets me shift. it seems to only do it in 2nd gear when revving hard. what do you think could do that or cause that.
Well, could be a shift fork or wear on a gear where it catches. It would be a perfect time to change that out. Have the guy check all parts inside the gearbox when he splits it. But it also could be the oil you use. I have found Mobile One fully synthetic 20/50 to work the best. That has nothing to do with the motor going though. I don't buy any of the expensive oils and never will. Our only use is gears and clutch and the Mobile one does wonders. ATF is terrible, I burned clutches up in a day, so don't do that. It's slick, but too slick.
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LOL Coop, on the Klotz thing. I love the way it smells(the green label Benol) and got almost 80 hours out of a topend on my old YZ, but it's was a PITA to clean up.
On the rebuilds, did you re-torqued the jug, head bolts,and reed block mounting bolts after the break in heat cycles??
This is an often over looked and very important step in break in procedure, as the aluminum jug and head expand when heated up, and contract when they cool. I check/re-torque the bolts after each heat cycle and ride in intervals.
It also sounds like you might have forgotten to turn off the choke ???
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ATF is terrible, I burned clutches up in a day, so don't do that. It's slick, but too slick.
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I have always ran ATF in my bikes. Never had a single problem as long as I keep it fresh. My 05 is only on its 2nd or maybe 3rd set of frictions ever.
As far as the motor failure goes I duno what else to add. I am gonna have to agree with what everyone else has said for the most part. Maybe a lean problem which led to other problems. Although if I remember right I blew a bike up last time I was at Burnt Ridge too...... maybe that track just has a curse on it!
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i think we did the crank/ top end in like late august, took the winter off. then we replaced the topend in February.
Sounds like your either sucking dirt, mixing your gas wrong, running crappy oil, jetted to lean, air leak somewere, not doing maintinence, something....no way that thing should blow up that much.
I used to practice/race the same 125 for 2 seasons and hardly ever blew one up. Thats with me riding atleast 3 days a week and racing atleast 4-6 motos on any given weekend. I wasnt small or slow either but I worked on bikes every night....maybe them YZs are just tough ;D
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i've been running Golden spectro10/40 in my tranny since I got bought my 07 kx250 new in 07, It still has the stock clutch in it, I got a new one for the rebuild but the stocker was still waaay in spec. I only change the oil when it's visibly dark or after a ride that involve water crossing.
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I have always ran ATF in my bikes. Never had a single problem as long as I keep it fresh. My 05 is only on its 2nd or maybe 3rd set of frictions ever.
As far as the motor failure goes I duno what else to add. I am gonna have to agree with what everyone else has said for the most part. Maybe a lean problem which led to other problems. Although if I remember right I blew a bike up last time I was at Burnt Ridge too...... maybe that track just has a curse on it!
what bike and what type of riding and class. I raced pro 125cc so I was all over the clutch. It did not like ATF. Whatever works for you, I guess that's cool. But depending on how much you ride and what type, 3 sets in 6 years could be good or bad? Not enough info... ;D
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I'm sorry, but you don't blow up a motor by sucking in a reed, unless of course your testing out new solid titanium reeds. What destroys cranks, cases, and cylinders is a piston failure, and the majority of piston failures are fuel related. Go look at the motor take pics and post them here, this thread stinks of BS. As for your dad wanting to buy the 4 stroke, fine, its his money. Become the moocher your dad wants you to be... ;D Wish my dad would go buy me a $10,000 clunker ha.
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Factoryx you're right about the reed thing... but I don't think he's bs'ing us. Something is just off.
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I race pro and I ride a few days a week, a lot in the woods. ATF has just always worked for me and I guess I have just learned to not use the clutch........ momentum momentum momentum! Everyone has their own likes and dislikes. What works for one might be total sh*t for another. :-)
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Maybe he's not, but maybe his dad is? At this point there are 3 possibilities:
1. He truly blew up the bike, but not from the reeds breaking.
2. The mechanic is screwing him over.
3. His dad is trying to convince him to move on to 4 strokes.
???
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It's a game of clue. Someone is framing the reeds. It's up to us to find out who the real culprit is.
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Have broken reed petals while the engine is turning over at 12,500 rpm, back of the piston munches the reed to carbon powder and disappears out the exhaust. But for the missing reed you will never know.
Maxima 927 is good oil , no problems with that.On a hard ridden 125 25:1 would be the very minimum of oil I would run. Remember "Nobody killed a 2 stroke with too much oil" (sic 'Spanky')
I see this as a straight mantenance issue, a 125 will usualy need 2 rings to every piston and a new piston would be needed after 15-20 hours on a track as a general rule.If your lifting the top end after season end your asking for trouble.
I would seek a reputable tuner rather than the one your persisting with.
Cranks and big end bearing failures are caused soley by the lack of lubrication.
Learn how to do a plug chop and how to read a plug(you will find you don need your 'tuner' then)
As mentioned cylinders can be replated for about $200 +piston no need to buy a new cylinder.
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it happened to his 250, not his 125...
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Remember "Nobody killed a 2 stroke with too much oil"
I get your point and I am not flaming you but actually, too much oil in the fuel causes a lean situation and generates heat in a 2 stroke.
You may also want to check your intake manifold real good. Maybe the carb was not put on correctly and well seated or the manifold is cracked? That would cause it to lean out as well and might even generate the sucking noise that you heard.
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Yes, if you add more oil it will run leaner, so you jet accordingly - hence the talk of checking the jetting with a plug chop etc.
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Remember "Nobody killed a 2 stroke with too much oil"
I get your point and I am not flaming you but actually, too much oil in the fuel causes a lean situation and generates heat in a 2 stroke.
You may also want to check your intake manifold real good. Maybe the carb was not put on correctly and well seated or the manifold is cracked? That would cause it to lean out as well and might even generate the sucking noise that you heard.
Ah well 250 my mistake.
At 50:1 your running 2% oil and 25:1 4% oil how many engines are jetted within 2% of a seizure? To little fuel causes seizure faster than anything, without oil a engine will go for half a lap.
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Well, any updates?
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Remember "Nobody killed a 2 stroke with too much oil"
I get your point and I am not flaming you but actually, too much oil in the fuel causes a lean situation and generates heat in a 2 stroke.
You may also want to check your intake manifold real good. Maybe the carb was not put on correctly and well seated or the manifold is cracked? That would cause it to lean out as well and might even generate the sucking noise that you heard.
The lean situation you talk about is still a jetting issue, as always.
Jet to suit the mix.
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Too Lean, chamfer cylinder wrong, for replating I would only use Milenium technologys , I used another plater and it costed me a riding season. A 1,000 bucks on a engine is a bummer, but it,s 25-28,000 for engine rebuild on a big truck engine. :o
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You can send your motor to Eric Gorr and they will diagnose the problem and recommend changes
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Looks like Gorr will save you money:
http://www.eric-gorr.com/cylinder%20repairs.html (http://www.eric-gorr.com/cylinder%20repairs.html)
We offer 4 types of repairs;
1) Honing of plated cylinders to clean-up minor seizures $20
2) Boring and honing to the next oversized piston for cast-iron sleeved cylinders $50
3) Replating with nickel silicon-carbide composite plating to stock size and up to 2mm oversize $250
[snip]
FAQs on 2-Stroke Cylinder Repairs
If the piston breaks can I just powerwash the crankcase and change the oil to get out the broken pieces?
The crankcase on 2-stroke engines is sealed so draining the transmission oil won't help. Most likely the metal particles will contaminate the bottom end to the extreme that you'll need to rebuild the bottom end with a new crankshaft, bearings, and seals. We offer that service and it averages $500 parts and labor. Additionally you'll need to powerwash the exhaust pipe (not silencer) because metal may be trapped in there and re-enter the cylinder once you restart the freshly rebuilt engine.
If I send my old piston with the cylinder can you tell me what the original failure was caused from and recommend repairs to keep it from happening again?
Yes, we recommend that you send any and all damaged parts, especially if you've had repeated failures. Also you should check out the tech article (PDF format) from Eric's book titled Piston Diagnostic Guide (on our home page). We'll diagnose your mechanical problem and recommend action solutions.
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Guys, on the first page he says his mechanic found dirt - right there is the start of the problem. Take any newer 2 stroke (or 4 stroke if your really brave) and throw some dirt down the intake and see how it works out for you!! You can say he needs to run X brand of oil or Y jetting with Z fuel , add some dirt and nothing matters LOL.....
2nd if your bike is trying to sieze, bog, and sounding wierd - quit riding it until you can properly investigate the problem