Jump to content

Engine tear down. Pics inside. Broken reed and piston!!

Recommended Posts

 

Hey guys. Doing a top end. I've put 62 hard hours on it and bought it used. Here's some pics. Few things of concern

 

Piston chipped. Wtf. Bike still runs great. Cylinder is fine. Bottom end is fine

 

 

Looks like piston hits power valve?

 

One reed corner is barely broken... Is this ok? What's the best fix/replacement. I've NEVER done reeds in my life.

 

When spinning the bottom end. It seems like the crank gets coated in oil which smells badly of gas... Why is this? Is that normal?

 

Otherwise everything seems ok. Gonna give the power valve and light cleaning and start to reassemble it

 

 

Thoughts? Tips? Advice? Anything??? Thanks

 

IMG_1963.JPG

IMG_1960.jpg

IMG_1964.jpg

IMG_1966.jpg

IMG_1967.jpg

IMG_1969.jpg

IMG_1970.jpg

IMG_1971.jpg

IMG_1973.jpg

IMG_1977.jpg

IMG_1979.jpg

IMG_1983.jpg

IMG_1984.jpg

 

 

Edited by cdf450

Share this post


Link to post
Share on other sites

You got lucky. The piston most likely has a fair amount of hours on it. The skirt is first place you'll see breakage, a few more hours and you'd be pouring skirt pieces out of the exhaust pipe. Ask me how I know..

Order a new set of reeds or buy a V-force cage. 

The bottom end should smell like gas since that is what is passing through. Any up and down play in the rod?

Are you putting that piston back in, and if so, will you please get lots pictures of the broken piston/scarred cylinder when it explodes?

  • Like 2

Share this post


Link to post
Share on other sites

Some piece or pieces of metal were bouncing around in your engine.

You might have lost a circlip holding the piston pin into the top con rod bearing. If it were mine, I'd pull the engine, and get the crank totally rebuilt, check the cylinder for wear/egg shape/barrel shape, etc. and plan on new piston, rings, clips, bearings, etc.

  • Like 1

Share this post


Link to post
Share on other sites

The skirt looks thinner on the one side. Is that normal?

What exactly do I need for reeds? Are just the reed pedals replaceable?   these ?  http://www.ebay.com/itm/vforce-4-reeds-replacement-petals-2011-2013-KTM-250-300-EXC-SX-XC-XCW-SIX-4P672H-/261697542665?fits=Make%3AKTM&epid=631237398&hash=item3cee639a09:g:YQYAAOSwax5YqWs7&vxp=mtr

No up and down play. Crank felt super good. Thank god.

I definitely did not lose a circlip lol. They were both fully intact. Ez clips actually!

Crank is staying. Cylinder looked perfect. No scoring. Nothing. I did not check it with a micrometer

New vertex piston in her and fired it up. Idled high at the start but settled down after 10-15 seconds. I'll start again. Idle it for a bit. Let cool

Then I'll ride it lightly. Let cool

Then I'm riding it like normal for the week

New reeds are gonna get ordered. And plug chops to perfect my lectron adjustments

 

IMG_1944.jpg

IMG_1945.jpg

IMG_1954.jpg

IMG_1989.jpg

IMG_1990.jpg

IMG_1991.jpg

IMG_1994.jpg

IMG_1996.jpg

IMG_1997.jpg

IMG_1998.jpg

IMG_1999.jpg

IMG_2001.jpg

IMG_2002.jpg

Edited by cdf450
  • Like 2

Share this post


Link to post
Share on other sites
17 hours ago, cdf450 said:

The skirt looks thinner on the one side. Is that normal?

What exactly do I need for reeds? Are just the reed pedals replaceable?   these ?  http://www.ebay.com/itm/vforce-4-reeds-replacement-petals-2011-2013-KTM-250-300-EXC-SX-XC-XCW-SIX-4P672H-/261697542665?fits=Make%3AKTM&epid=631237398&hash=item3cee639a09:g:YQYAAOSwax5YqWs7&vxp=mtr

No up and down play. Crank felt super good. Thank god.

I definitely did not lose a circlip lol. They were both fully intact. Ez clips actually!

Crank is staying. Cylinder looked perfect. No scoring. Nothing. I did not check it with a micrometer

New vertex piston in her and fired it up. Idled high at the start but settled down after 10-15 seconds. I'll start again. Idle it for a bit. Let cool

Then I'll ride it lightly. Let cool

Then I'm riding it like normal for the week

New reeds are gonna get ordered. And plug chops to perfect my lectron adjustments

 

IMG_1944.jpg

IMG_1945.jpg

IMG_1954.jpg

IMG_1989.jpg

IMG_1990.jpg

IMG_1991.jpg

IMG_1994.jpg

IMG_1996.jpg

IMG_1997.jpg

IMG_1998.jpg

IMG_1999.jpg

IMG_2001.jpg

IMG_2002.jpg

You purchased a used KTM?  Good stuff!  I did the same and I am completely happy with it.

About your situation:

This is what I would have done before I put a new piston in.

Clean out the crank shaft area to get all the pieces of broken piston skirt out of it.   That is, wipe the oil off the crank about 10 times as you rotate it until it comes up from the bottom perfect clean.  If you have to, put a 1/2 teaspoon of premix on the surface of the crank to help gather up debris off the bottom.

(Years ago, I had a riding buddy who turned his Yamaha two stroke upside down (handlebars and seat on the ground) and used a garden hose to clean out the crankcase/connecting rod.  Didn't cause any harm.  He MADE SURE to put a half teaspoon of premix down each of the two holes you will see beside the piston AND put some more on the crank/connecting rod directly and then rotated it by hand another 10 times.  So much premix oil that it smoked like crazy when it started up.  But, hey, it worked.)

You also needed to check to see if the power valve was protruding into the cylinder, making unwanted contact with the piston.  If it is, you need to adjust the vertical rod coming out of the crankcase up to the power valve mechanism.  This vertical adjuster is THE key to keeping the valve out of the cylinder.  I tell you all this because it is possible the previous owner might have tinkered around with the adjuster, not realizing what he was doing.  If you decide to do that, let me know and I can walk you thru the entire process of adjusting the power valve.  There is a digital outside micrometer for about $15 (?) you can buy at Harbor Freight that works perfectly for this.

About the chipped off piston skirt...never saw that before.  But the first question is:  Is the cylinder worn out allowing the piston to "slap" around in the cylinder, causing the piston skirt to chip off?  Well, the easiest way (and cheapest) to check this is to squarely insert one of the new rings you bought into cylinder.  To put it in squarely, gently push the ring down the cylinder about 10mm with an upside piston.  The using a feeler gauge, check the ring gap.  Look at your manual (or the internet) to see what the ring gap should be. Make sure the gap is within tolerance. Then do the same thing further down the cylinder.  I think it is fair to say that if piston slap caused the broken skirt, the ring gap would have to be WAY too much, indicating a worn out cylinder.  Hopefully, you will be pleased to find that KTM cylinders are really great and there will probably not be a great ring gap.  But you never know until you check.  And being that the bike could possibly have been horribly maintained...who knows?

When it comes to replacing the reeds, the most important thing is to use the right phillips head screwdriver.  Phillips head screwdrivers come in three sizes, 1, 2 and 3.  The number one is for the smaller screw heads and the 2 is used for "normal sized" heads.  Don't think I have ever the number 3.  Try both the 1 and 2 sizes to see which one fits SNUGLY into the screw head.  You don't want to used the wrong head and end up gouging out the screw head.  (If you do gouge it out, firmly grasp the screw head with a small vise grip on the screw head to get it out.  Then, of course, replace it with a new screw.)

 

 

 

 

 

  • Like 1

Share this post


Link to post
Share on other sites

awesome post. thank you very much for all the advice.

 

purchased a used 2012 250sx, sight unseen, and its been the best purchase ive ever made.  good riddance 05 crf450r.  ive put 64 hours on it since september, and nearly $10,000!!!

 

the crank shaft area is fine... those chunks are longgggg gone.  the bike ran great, ive never heard clunking or chipping of any sort. bottom end came out clean.   my magnetic drain plug was a bit dirty the last few times though.

 

I totally did not check if the powervalve was sticking out... I dont think it was. I mean it ran great last time I rode it. and it rode great today.  I put 3 engine hours on it today. runs very good. I could not hear if it was hitting the powervalve... but I highly doubt it.    I also did not check the roundness of the cylinder.... I was kind of rushed and just slapped er back together.   risky, I know.  

 

I idled it for 20 seconds. turned off for a few hours.

idled hard for 2 mins, turned off for a few hours

rode lightly for 2 mins, turned off for a few hours

loaded up and went to the riding area, rode lightly for the first 10-15 mins, then slowly progressed to medium throttle due to being on single track, then it turned to double track and I could really open it up and make it scream. even did some highmark hill climbs today. I think its safe to say its broken in!!

 

the reeds though... I would like to order those tonight, but im unsure of what I need/have.  is it just the plain ol V-force 1?  those reeds I linked earlier is what I need?  I imagine the replacing of them is easy (if its even possible... ive now learned that it is) so now I just need to find the exact reeds I need!

 

 

I did a plug chop... I dont think I did it right.   I rode all day. then on my way back I drove a bit passed the vehicle.  turned bike off, installed a BRAND NEW plug, fired bike up, banged through the gears, 5th gear screaming, then kill switch.   coast to vehicle.  remove plug, and this is what I got.... clean still.  also, pics of my old plug.

 

overall... was a damn good ride, and the bike runs awesome!!

 

IMG_2012.jpg

IMG_2029.jpg

IMG_2034.jpg

IMG_2035.jpg

IMG_2038.jpg

IMG_2043.jpg

IMG_2044.jpg

IMG_2067.jpg

IMG_2068.jpg

Share this post


Link to post
Share on other sites

When it comes to reeds, the truth is V-Force or stock...most people can't tell the difference.  I know I can't and I have been riding for over 30 years.

Buy whatever is easier to get your hands or which ever is cheaper.

In the first years when 4 strokes first came out, I remember the earlier CR450s would lock up due to a poorly designed lubrication system.

Then I heard of the nightmare repair bills.  I swore off 4 strokes.  

I will ride someone else's but I will buy one. :-)

Two strokes are GREAT.  You can replace the top end in an afternoon by yourself.

Four strokes?  I know their structure from older 4 strokes.  But the new ones?  They are a stranger to me.  And far more parts.  Cam chain.  Valves and valve seats.  Camshafts.  LOL, who needs 'em?

Looks like you might be up in elevation where you ride.  Looks like the plug is fine.  

Here is a link to Pro Circuit's jetting recommendations for various bikes including your 2012 250 SX.  I am sure they are providing jetting specs for sea level.

https://www.procircuit.com/jettingspecs2.htm

If you rid up in elevation, you will almost surely need to go to the next size (or maybe two sizes) smaller on the main jet.  My advice?  Run it as rich as you can without it sputtering and/or sluggish on the top end.  If it runs fine now, I'd leave it alone, assuming it has sea level jetting in it(?)

Side note: when I bought my 2005 KTM, the power valve was not adjusted right.  So "closed" it looked like it was rubbing on the piston!  Adjusted according to the service manual and, my God, what a difference.  Before it would take forever to rev out because the valve simply wasn't opening all the way.  Afterwards?  It makes great power thru the rev range and tops off with an absolutely stunning top end.  

Share this post


Link to post
Share on other sites

I have a lectron. So jets don't apply

Next time in in there I will 100% set the power valve now that I'm a bit more familiar with it all now. It seems easy.

We are at 2000-2400m elevation

So so you mean that any reeds will fit my reed box?

Share this post


Link to post
Share on other sites
25 minutes ago, cdf450 said:

I have a lectron. So jets don't apply

Next time in in there I will 100% set the power valve now that I'm a bit more familiar with it all now. It seems easy.

We are at 2000-2400m elevation

So so you mean that any reeds will fit my reed box?

Glad you asked the question about the reeds.  There is a STRONG possibility that the V-Force cage will require V-Force reeds.

Sorry, I don't know the answer.

Share this post


Link to post
Share on other sites

awesome. thank you very much for that.  I do have a paper manual, and 2 calipers... but was too lazy to go get it from the storage shed.  Slavens has an awesome youtube video showing how to check the Z dimension.    I will download that manual though... Ive always got the laptop in the shop. thats good to have. thanks for finding that!  otherwise I basically did everything those instructions you posted show except the Z dimension. the rebuild went very smooth.  it took a long time, but well worth it.  the power valve assembly got the royal teatment (minus z dimension adjust.. oops)

 

went on 2 solo rides in a row.   60km in 5 hours yesterday. single track.   51km today in 2 hours.  faster double track.  barely any breaks.  put 4.5 hours on the new piston in 2 days... it runs awesome!!!  (as much as my slipping clutch will allow).   rekluse is getting rebuilt tomorrow.

 

heres todays ride since ya like my pics so much hehe... as well as a few others ive done this year.   life behind bars aint so bad ;)

20258050_10159142032230008_5296565661264

and yeah... alberta has some pretty damn nice views/riding areas!!!

 

18766845_10158821464475008_5088928323412

 

333_4.jpg

IMG_0493.jpg

IMG_0586.jpg

IMG_1456.jpg

IMG_1778.jpg

IMG_1783.jpg

IMG_2008.jpg

IMG_2012.jpg

IMG_2029.jpg

IMG_2035.jpg

IMG_9802.jpg

IMG_9803.jpg

IMG_9949.jpg

17426273_10158466863775008_4314130086503

18700331_10158816876355008_1555611899439

19030661_10158887845690008_2801072874120

19400112_10158959775580008_3011163856443

19554954_10159004428680008_5936728841673

19598934_10159012406675008_6804675504216

19884054_10159046299465008_1871288675309

19894542_10159040779495008_6648648520416

20046544_10159106986805008_1872814175832

20155994_10159118888005008_3457373950146

 

Edited by cdf450
  • Like 3

Share this post


Link to post
Share on other sites

when you installed the odi lock ons with the lectron did the normal throttle cam for a 2 stroke ktm 250 work? 

I just ordered a set for my bike (2017 250xc) but wasn't sure if the lectron throttle cable was going to end up giving me a headache...I love the lock on's wife get's us the hook up through odi for being fast on her pedally bike.

Share this post


Link to post
Share on other sites

The odi lock ons that I got (emig half waffle) which I believe are the only ones you can get with the twist throttle, came with their own throttle cam built in. All in one. I loveeeeeeee them. Best grips ever made. New throttle tube every time. And they're only like $25. Otherwise all the other odi lock ons are only 7/8" and won't fit in the throttle side. On the plus side, those 7/8 mtb odi lock ons have two lock screws (one on each end). The Dirtbike emig ones only have one screw to tighten them down. And no, it's not to accommodate bark busters. Bark busters work fine with the double locked 7/8 mountain bike versions. My single lock emig lock ons have never moved on me though.

 

The lectron throttle end is the exact same as oem. Pretty sure the other end is too. But yeah, it'll all work The odi emig throttle tubes are basically a brand new throttle tube with a grip 100% fused and moulded to it. No screw clamp needed. They're amazing. Grip glue and tie wire is a joke.

 

  • Like 1

Share this post


Link to post
Share on other sites

ok thanks, I've long been a fan of the odi lock ons, ran a few sets on my 450xcf, but it didn't have a lectron so I was concerned that might give me a headache....first set I bought for my 450 off the shelf had the 125 2 stroke cam for yamahas lol.... I never even looked and realized they have so many different cams, had to order the right ones, which is why I was concerned. I also didn't put my lectron on my bike so wasn't sure what I was going to find under there when I swapped the odi tube on. I ordered them anyway and they should be here today. 

Edited by kickstand_ktm
  • Like 1

Share this post


Link to post
Share on other sites

on my rebuilds, to help avoid piston skirt contact and cylinder scorring, before installation i've always taken emery cloth or any fine grit sandpaper and sanded smooth any sharp edges of the skirt and wrist pin.  Your piston and cylinder otherwise all look great in my opinion.

What part of Alberta do you ride in?  Your pictures are incredible!

  • Like 1

Share this post


Link to post
Share on other sites

Thanks. Good to know the cylinder looks good. I thought so too. That's always nice!

 

Those pics are all in the crowsnest pass. Thanks for the compliment!

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×