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TexasDualler

300 Top End Advice

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My ‘15 KTM 300xcw absolutely refuses to start anymore, unless someone tows it to the top of a big hill and it gets going about 20mph and you bump start it then keep it pinned otherwise it’ll sputter out and die. After checking everything else (spark, carb clean, fuel getting to carb, reed valves) decided to inspect the power valve thinking maybe it was stuck open. Checked it out and it moves freely. So since I had the pipe off I did a little inspection of the cylinder and to my dismay found some pretty heavy scoring. 

D3D3A9A2-A284-43C8-9A58-084D990A2FE6.thumb.jpeg.2ddb27e3e95156ada4a45dab6003959b.jpeg

So if I’m not mistaken this is the cause of the failure to start and without a doubt not a good thing in general. 

Now my question is does anyone have any advice on where to get the cylinder machined? If it’s even possible to correct it. Then assuming it’s not too far gone and I get it machined, where’s the best place to get a top end kit? Thanks in advance for any input. 

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Try messaging spaugh on here see if he's still doing work on bikes if you don't wanna do yourself, he's awesome with 2 stroke

For parts check with these guys

://www.cookseycrank.com

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Your cylinder is Nikasil coated, it can't be bored out.  You'll need to replace it or get it re-coated.  I have used a few places, Millennium Technologies is one that has worked out well for me.  

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I've heard those nikasil cylinders are pretty tough. Looks like you stuck a ring and that's why its so hard to start. Might be able to just acid wash the cylinder? Not sure who could do that.

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That looks pretty bad. Very likely that scoring is thru the Nikasil plating. Either of Thes guys can fix you up with either new, exchange, or replated cylinder, piston, and rings.

http://www.powersealusa.com/

or Millennium Technologies http://www.mt-llc.com/

There are only a few places that do Nikasil plating. Some will say they do it, but really they just send it to these guys.

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dont get ahead of yourself you need to disassemble first get a thorough inspection, than decide what needs to be done. Piston and rings are sacrificial ( engineered with the harder material being the cylinder plating).  If you need to redo the cylinder there are a few top tier replaters, Millenium Technologies is one, and the prices are very affordable and will save over a new cylinder. There is also the sleev option from LA Sleeve but If needed I would replate. Millenium will even match up a piston for the cylinder.  I did a one of my 4 strokes with them.

 

http://www.millennium-tech.net/serviceInfo.php?id=1  

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I have had some aluminum deposits on cylinders before without scoring them, used muriatic acid to remove the aluminum.  You can Google search it, plenty of videos.  That's only if you got lucky and the piston didn't score the cylinder.  

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Cylinder is possibly beyond repair. Heavily scored and a sizable chip in one of the transfer ports. See for yourself:

428E1750-110C-4CB5-B2FD-698FDFF9EA18.thumb.jpeg.2ef7fb3f9de8eb7f7eba77d0ffca4200.jpeg

E044CED8-C219-49B8-BCDB-5CBBFA2AACB7.thumb.jpeg.c5a1039ab9e511690857b3179e3bd21b.jpeg

3AFEAA54-A33A-4D9E-AF0A-39B996FD3469.thumb.jpeg.a8844ea704cfed9f614cfcdb774b3075.jpeg

One of the piston rings is broke but it’s hard to say what started the terrible chain of events. Clearly some piece of metal made its way to the combustion chamber and was banging around in there for awhile. 

E49F35EA-57E7-42EF-8BF6-9A11E596BF80.thumb.jpeg.1f2dbfc5f94b5add0708757cad70c8cf.jpeg

50BC5A52-0B64-4231-904B-70E29B7722E8.thumb.jpeg.dd27e93e5acdcc992ea33620cd02a329.jpeg

26E40EB4-334D-4FAD-BEB4-F01F7A52BFA1.thumb.jpeg.a00a3be1c0a57751cbb86115ef1d3ead.jpeg

37774D66-D176-492A-A3E8-A6D7F36AC75E.thumb.jpeg.1bec850a65c85ffc8183ad5126b23d51.jpeg

Aside from potentially needing a new cylinder if the original is beyond repair, my consern is there a bunch of shrapnel rattling around in the case. I couldn’t see any signs of damage to the crank or rod and everything is still tight and smooth but I can’t say for certain nothing is down there. 

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Upon further inspection of piston found the top ring wasn’t broken, the retaining pin was missing (fell out, came lose?) causing ring to rotate and resulting damage. 

8DB4D1A6-BF55-4AAE-A7E1-77033F7CD0E4.thumb.jpeg.a47d41e9cb72fd722db5ed2116864ab0.jpeg

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I guess that explains why it wouldn't run!  Guess it's time to look for a replacement cylinder? 

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Hours,   Operating conditions??  Something in your use failed.  You do not want to repeat this.Dirty filter, Oil ratio,  you two stroke guys help us here. 

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Wow... that's pretty bad. I think it's time for a new top end, cylinder and cylinder head. Don't even waste your time trying to repair the cylinder or head... Drop the coin, maybe a big bore kit, and get back to riding.

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165hrs. 50:1 VP race gas and Redline oil. Cleaned air filter religiously, virtually after every ride. Used a few different filter oils (KTM brand Twin Air, No Toil, Uni) but I want to say I used Uni the most. Oiled the filter very thoroughly on both sides each time. Carb was always jetted per factory manual for conditions. Rode this bike everywhere. Single track, desert, couple dune trips, D37/38 races, rocky technical. Some days barely above idle. Other days wide open pinned. My best guess is the pin that’s supposed to keep the top ring from rotating came loose somehow and caused all the damage. Guess it just vibrated loose after all those hours. Not sure there’s anyway to prevent that other than changing out the piston more frequently. I’ve heard of people easily going over 150hrs with no problems but I guess they don’t ride as hard as me. 

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7 hours ago, Oracle said:

Wow... that's pretty bad. I think it's time for a new top end, cylinder and cylinder head. Don't even waste your time trying to repair the cylinder or head... Drop the coin, maybe a big bore kit, and get back to riding.

Agreed minus big bore kit its already a 300. I would personally throw new cylinder and piston kit and upgrade to rktek head saw big gains and cooler temps on my 300xc from it

Edit: or just do this complete kit and try and sell back ur cdi on eBay since wont need 2

 https://slavensracing.com/shop/slavens-mule-250300-cylinder-kits/

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Just now, TexasDualler said:

My best guess is the pin that’s supposed to keep the top ring from rotating came loose somehow and caused all the damage. 

That was my first thought as well after you mentioned it.

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15 hours ago, TexasDualler said:

Aside from potentially needing a new cylinder if the original is beyond repair, my consern is there a bunch of shrapnel rattling around in the case. I couldn’t see any signs of damage to the crank or rod and everything is still tight and smooth but I can’t say for certain nothing is down there.

Solvent or kerosene sloshed around in the bottom end and drained a few times may reveal tiny pieces of metal.

For peace of mind I would suggest a thorough inspection of the bottom end before you put new parts on top. A good motorcycle machine shop could check things out. I have used Racers Machine for this type of stuff. There are other good shops out there too. A machine shop can check the crank, bearings, etc. with precision tools that can find things we can't feel with our hands. Hopefully it is all good.

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pull the engine. solvent flush the bottom end use air to blow it out--engine turned upside down. Get a new cylinder and piston kit. keep a magnet around as you clean to see if you can the pin stuck to it for insurance

That is what was needed a disassembly and inspection.

You can also contact LA Sleeve they can most likely install a sleeve with matching piston to save some $$ and get you going again. Installing a sleeve may cover you for the port damage as the cylinder will be overbored to accept the sleeve. 

Also I hope You have been paying attention to your jet spec for altitude and temp, you fuel and oil choice sounds perfect  And Yes it looks like a ring pin was liberated and bounced around in the chamber and possibly it got wedged between the piston and port, and or with out it the ring spun out of index and got stuck on the port and tore up the bore etc. etc. . This issue is identified. Now for corrective action.  Looks Like La Sleeve does not have a sleeve for the 3 hundo, but I would call and talk to them

..but here again is Millennium Tech

FAKK I cant put links here go to Millennium technologies- you can send your cylinder to them for a free inspection/EVAL before you scrap it. They can weld repair and replate do a high degree from stuff that looks beyond repair.

They have fully kitted Wiseco 330cc kit for @ 600 bucks  box and send cylinder. They call their kits M-Spec big bore kits

 

OR I will come to your house and buy your exploded machine for 1000 bucks and take her off your hands..........

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16 hours ago, Bp619 said:

Edit: or just do this complete kit and try and sell back ur cdi on eBay since wont need 2

 https://slavensracing.com/shop/slavens-mule-250300-cylinder-kits/

I was looking at that earlier and seriously considering that kit now. Not a bad deal. Plus I was reading through Millennium Technology’s site and apparently they’ll buy junk cylinders so maybe I can get a little bit money out of it. 

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looks like the OEM replacement is @ 900 bucks.

 

Jeff's kit is a good price at 900 bucks lock stock and barrel as well. and you have Jeff as your tech rep. he's sometime cranky but he is very very very on point for knowledge at the professional level.

 

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Do you have full coverage insurance?

Time for a new ride. 

Kidding 

I just spent more on a recluse and going tubliss than your repair cost. 

Fix it and ride it like it’s stolen. 

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I have had that happen- the ring locating pin coming loose and doing a bunch of damage.  I had the cylinder repaired, probably by Milennium.  It was a while ago.

At least get a repair evaluation on the cylinder.  Knock the high spots off the head and you should be fine there.  If you wanted to be a maniac, you could get the head resurfaced, but I'm not sure you would be able to tell the difference.

As for the bottom end, split the cases and take a look.  There is a good chance there is nothing down there, but it isn't that much more of a job if you are able to pull the top end off, and you need something to do anyway while the cylinder is away.  At this point, it isn't worth the risk of damaging another cylinder+piston to avoid the couple of hours it would take to pull it apart and take a look.

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Any suggestions on what kind of solvent to use for flushing bottom end? Preferably something that won’t damage the crank seals. 

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11 hours ago, isde97 said:

I have had that happen- the ring locating pin coming loose and doing a bunch of damage.  I had the cylinder repaired, probably by Milennium.  It was a while ago.

Spoke with Millennium. About $300 for the repair plus round trip shipping but it’s a gamble if it’s repairable, the chip in the port being the concern. Then I would still need a new head and main power valve (also damaged). So roughly by my estimate somewhere between  $700-750 if I go that route. 

Slavens kit that contains everything I would need and a new CDI for $900. And then I could sell my old CDI on eBay for a steal at $100 (I see several other used CDIs going for $170). Plus maybe sell my old cylinder to Millennium and come out the same or maybe a little ahead if I go this route. Or at the very least only 100ish bucks more for a power gain over the stock set up. 

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6 minutes ago, TexasDualler said:

Any suggestions on what kind of solvent to use for flushing bottom end? Preferably something that won’t damage the crank seals. 

Kerosene is safe on the seals. You can buy a gallon at Home Depot for a few bucks.

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