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HELP! When should i do a top end?!!!!!!!

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Hey Guys! Im 14 and have a 2008 ktm 200xc, bought it new 6 months ago or so. i was just wondering when i should do a top end on my bike? I've asked a bunch of Ktm shop owners and they all said different things:banghead: 1 said 120hours, another said 45, another said 80-100? The bike has been crazy reliable, i mean nothing has needed to be replace except for regular maint. i see its very easy to take off the jug. remove plastics, seat, gas tank, and 4 bolts.. but i just dont want to do it if i dont have too. the bike has 70.1 hours and has 160psi of compression, i take off the exhaust pipe and get a flash light and look through the port and see some wear (up and down lines normal.. and some polish) but nothing to bad it still has good power but i dont want to wait to long until it blows and having to have the cylinder replate, if i do rebuild it im going to hone the cylinder.. thanks for the help and sorry for the long paragraph:bonk:

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160 psi is still good. As far as when??it depends on how you ride. I'd start worring about it at about 120psi and before 100psi. I also will re-ring a piston first then next time I'd replace piston & ring....

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my 05 300 got a top end at 200+ hrs and was still compressing well at the time. they go really long between top ends if you are not mx racing it and in the higher rev range all the time.

Joe

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I don't know if there is a good answer to this question, as there are so many variables. Do you ride everyday after school, or is this a weekend toy? Is the bike use on trails, or on tracks where the throttle is often pinned? I don't keep track of hours, but here is what has worked for me--assuming the bike is ridden most every weekend, I do a top-end on 125s about every 9 months, and I do 250s once per year. My bikes are used for HS racing, and trail riding, with only occasional MX. At those intervals, I have never found anything to measure "out of spec", and there is no performance decrement that I can detect. Also, I normally don't bother with hones and such. I once came across some glaze on a cylinder from a CR 125 that I bought used, but a scotch-brite pad cleaned it up. Normally I just swap out pistons and go--it's a one-evening job.

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I have an 04 125 sx, that has 135 psi. The previous owner said the bike only has about 20 hours on the new top end. 135 is a little low but if I'm not racing I'm going to run it until it is at about 115psi and has trouble starting, my dealer concurs.

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there is a recent thread on this same subject in the last few days. A 200 can go a loonngg time. I would not do anything till 100 hrs, then I would take the cyl off, clean the power valve and inspect the piston/rings. I would not replace the piston/rings unless damaged. But many guys would not do even this at 100 hrs, they go 200 hrs. When comp gets down to 130 or so then its time for a piston.

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there is a recent thread on this same subject in the last few days. A 200 can go a loonngg time. I would not do anything till 100 hrs, then I would take the cyl off, clean the power valve and inspect the piston/rings. I would not replace the piston/rings unless damaged. But many guys would not do even this at 100 hrs, they go 200 hrs. When comp gets down to 130 or so then its time for a piston.

Good advice here.

i wouldn't do anything til 100 hrs unless you rev the living crap out of it, which most people don't.

I have a 2008 200. I did top ends at 230 and 430 hrs. I'll do another one at 600 hrs in a couple months. I would generally say 100-150 hrs. Towards the short end if you rev alot and/or are racing alot, towards the long end if you rev less. I tend to short-shift and lug and i'm pretty easy on bikes, so i feel comfortable going a little longer, esp for just trailriding.

I personally wouldn't bother taking it apart unless i was going to change the piston and rings. If you use a clean oil like maxima super-m or amsoil interceptor, you may not even have to clean the powervalve... ever.... I don't.

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wow Thanks guys! i ride EVERY weekend, about 5 hours on pure ridding time is on the bike. i ride it rather hard, but i never pin it or rev the hell out of it, i like to stay in a lower gear because it sounds better lol, and i do mx and trails, i never new my bike could go that long! please more answers tho like to see other peoples opinions:worthy::banana::worthy::lol:

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just do a search on the subject and you will see that hundreds of people go pretty long before changing top ends ( IF it is not revved to death).

Joe

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I don't know if there is a good answer to this question, as there are so many variables. Do you ride everyday after school, or is this a weekend toy? Is the bike use on trails, or on tracks where the throttle is often pinned? I don't keep track of hours, but here is what has worked for me--assuming the bike is ridden most every weekend, I do a top-end on 125s about every 9 months, and I do 250s once per year. My bikes are used for HS racing, and trail riding, with only occasional MX. At those intervals, I have never found anything to measure "out of spec", and there is no performance decrement that I can detect. Also, I normally don't bother with hones and such. I once came across some glaze on a cylinder from a CR 125 that I bought used, but a scotch-brite pad cleaned it up. Normally I just swap out pistons and go--it's a one-evening job.

why dont you hone it? and what do you do with the scotch guard?

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So I have a 2002 MXC 300. Never has had the top end off. Runs perfect for me. A friend that has a machine shops says that the pistons get fatiged and sometimes come apart or the pin that holds the rings from spinning comes loose and the ring end get caught in the intake or exhaust port. Now he has me scared. I dont need anymore power but want the engine to last. Any suggestions on this question?

Jon T

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i would never thing a pin would come out of the cylinder if the circlips installed right. never ever ever heard of anyones bike doing that??

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i would never thing a pin would come out of the cylinder if the circlips installed right. never ever ever heard of anyones bike doing that??

I'm talking about the very little pin that holds the rings from turning in the lands. They can work loose after time.

Also a side note. the circlips should be installed with the open end eather facing up or down. The force of the piston going up and down and compress them if they are in with the opening sideways.

Jon T

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I have a 2003 200exc. I'm third owner. It had never been apart. Not sure of PO hours but I had put 80+ in the last 15months. Single track. I decided to open it up last weekend and replace piston/rings. I was surprised how good it looked. Really no blowby. Reeds looked great too. The power valve was a different story, pretty darn crusty.

I measured things as best I could and swapped the #1 with a #2 since I had it apart. Cleaned up the PV and put it back together. Only did two thermal cycles in the backyard(4 acers). After I ride it this coming weekend I'll do a base comp test. Old piston measured 192 psi on my gauge with 7 kicks, so no hint there that anything was wrong. I don't really believe my gauge(sears best) but it's a relative number.

Anyway.. $140 for peace of mind for the next 2-3 years.

db

Edited by dan-oh

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My son had a Yamaha 125 that would grenade pistons on a far too often frequency. After the third shattered piston skirt, we switched to Wiseco and got a couple seasons on a piston. Revs kill pistons and rings, and Yamaha makes brittle pistons.

My KTM 125 went more than 5 years without needing a piston. Would have gone longer if it didn't get submerged while running. The water and probably grit was detrimental to the rings and compression dropped thereafter.

This happened another time a year afterward and I completely lost compression. The bike did start on a push and I drove it home (as I was many, many miles from home). The bike would run fine, but not idle, had to keep on the throttle. It turned out I had broken the ring and risked snagging a piece in a port. Luckily it didn't but be aware of this.

This past couple summers my 125 was pretty much my main ride. KZ1000, Ninja750 and the car sat in the driveway while I explored the environs with my little screamer. I even went on group bike tours with larger bikes, at highways speeds. This put the poor little 125 running at 3/4 max rpm for hours on end, for 1000s of kms. It has no problem keeping up. It finally "wore" out a ring, with compression now only measuring 90psi. It still starts, runs, but has low torque at low RPMs. Top speed is still the same at over 130kph but top end power is slightly diminished. Going to replace the ring some evening when I am free, but still riding it in the meantime...

Tough bikes, KTMs. Keep the RPM down and they will run forever, or enjoy the revs and power and realize you may need a ring every so often. Nice to have options.

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My son had a Yamaha 125 that would grenade pistons on a far too often frequency. After the third shattered piston skirt, we switched to Wiseco and got a couple seasons on a piston. Revs kill pistons and rings, and Yamaha makes brittle pistons.

My KTM 125 went more than 5 years without needing a piston. Would have gone longer if it didn't get submerged while running. The water and probably grit was detrimental to the rings and compression dropped thereafter.

This happened another time a year afterward and I completely lost compression. The bike did start on a push and I drove it home (as I was many, many miles from home). The bike would run fine, but not idle, had to keep on the throttle. It turned out I had broken the ring and risked snagging a piece in a port. Luckily it didn't but be aware of this.

This past couple summers my 125 was pretty much my main ride. KZ1000, Ninja750 and the car sat in the driveway while I explored the environs with my little screamer. I even went on group bike tours with larger bikes, at highways speeds. This put the poor little 125 running at 3/4 max rpm for hours on end, for 1000s of kms. It has no problem keeping up. It finally "wore" out a ring, with compression now only measuring 90psi. It still starts, runs, but has low torque at low RPMs. Top speed is still the same at over 130kph but top end power is slightly diminished. Going to replace the ring some evening when I am free, but still riding it in the meantime...

Tough bikes, KTMs. Keep the RPM down and they will run forever, or enjoy the revs and power and realize you may need a ring every so often. Nice to have options.

I can't believe you guys can ride a 2 stroke legally on the street over there. It must be a blast. I have but not legally.

Going to put a piston, rings and little bearing in. KTM piston would be nice but to rich for my blood. My friends going to get me one from this company. I can't remeber the name but he said the wisco are forged so they make them a little small so they can expand and they rattle a little in the bore. I'll update when I find the name out. He has done the machine work on bikes that have run during Daytona week so I trust him.

Jon

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I can't believe you guys can ride a 2 stroke legally on the street over there. It must be a blast. I have but not legally.

Going to put a piston, rings and little bearing in. KTM piston would be nice but to rich for my blood. My friends going to get me one from this company. I can't remeber the name but he said the wisco are forged so they make them a little small so they can expand and they rattle a little in the bore. I'll update when I find the name out. He has done the machine work on bikes that have run during Daytona week so I trust him.

Jon

It is a blast. Clicking through the gears and screaming through the powerband with six gears to play with, yet still at street legal speeds. Highway driving requires more precise jetting so it is excellent for sorting out jetting issues. Knobbies are treacherous on the pavement, but I have extra rims so I can switch to dual sport tires, which are terrible in mud. Nothing serves both well.

I have seized a couple Wiseco pistons in my KTM 125. My fault, leaned out in one instance and too hard too soon on the throttle in another. Just the same, the KTM piston was more tolerant of these conditions. The lighter Wisco piston did work better, rev freer, so it is give and take.

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