Ktm 150 rings replacement

six10
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5/28/2017 2:23pm Edited Date/Time 8/5/2018 9:25am
Hello,

I bought a used 14 ktm 150. The person I bought it from claims the piston had been changed 25 hours ago. At this point i would like to change the piston rings and just visualy inspect the condition of the piston, cylinder and whether the crank has any play (i do not have a lot of experince, but i will be able to see if there is anything alarming going on).

I have never dissasembled a 2 stroke, so my question is, can just pull the cylinder off, replace the rings and inspect the piston and cylinder, put new cylinder gasket and be done with it (assuming there is nothing alarming going on).

Or do i have to mess with power valve and exhaust control system also, just because I will be removing the cylinder?

Thanks
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Paw Paw
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5/28/2017 4:47pm
Yes you will have to deal with the exhaust valves hoot up as well as draining the coolant. With the piston already having at least 25 hours on it, I would suggest replacing it with the rings while you are in there. Having a service manual for your ride would be your best bet at this time.

Paw Paw
zeikei
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5/29/2017 8:59am
At 25 hours I recommend get original piston kit it comes with all you need except exhaust o-rings. Remove also cylinder head so that you can confirm correct base gasket thickness. Piston kit comes with different ones, use them so that piston is flush or 0.1 mm below cylinder wall at TDC. When installing cylinder make sure the power valve arm goes correctly in its 'hook'. Cylinder nuts torque 30 Nm, head 18 tighten criss cross very little at a time.
six10
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5/29/2017 9:22am
Thanks for the answers...

well the bike has a total of 132 working hours, but it is supposed to be 25 hours from the piston change as i stated.
I cannot find the service manual for the 2014 150 sx, but i do have it for 2012 125 sx, i assume it is somewhat similar.

The thing is, as i watched some youtube videos, the guy just unbolts and takes the cylinder off the engine, the exhaust control assembly does not seem to 'fall apart'...so I assume the problem is when everything is put back together?

Will report back how it went...
T-Fish
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5/29/2017 9:26am
Paw Paw wrote:
Yes you will have to deal with the exhaust valves hoot up as well as draining the coolant. With the piston already having at least 25...
Yes you will have to deal with the exhaust valves hoot up as well as draining the coolant. With the piston already having at least 25 hours on it, I would suggest replacing it with the rings while you are in there. Having a service manual for your ride would be your best bet at this time.

Paw Paw
A 125/150/200 cylinder will just come off. On a 250, you have to worry about a little more.

If I remember right, you just have to make sure you put the fork for the power valve in correctly when you're reinstalling the cylinder, which is very easy.

The Shop

zeikei
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5/29/2017 9:34am
Yes the power valve arm one end is shaped like -C and the other end like o- and you just need to make sure you slide the o in the C when installing Smile
six10
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5/29/2017 10:54am Edited Date/Time 5/29/2017 10:56am
So i am looking at the piston kit for the bike:

http://www.ebay.co.uk/itm/KTM-SX-XC144-150-2007-2015-Vertex-Piston-Bear…

In the description it says:

We reccommend when fitting a new piston kit to a used cylinder that you have the bore honed.
This honing method leaves a functional cross hatched effect on the cylinder to help retain 2 stroke oil in the bore which aids the piston and bore life.
Oversize pistons are available for certain models with boreable liners fitted.

I have heard on multiple occasions, the cylinder should not be honed, because it removes the Nikasil layer. Is that true?

zeikei
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5/29/2017 12:02pm
You will get different opinions on that, the guys that I trust over here do perform light deglaze after couple of piston changes.
chump6784
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5/29/2017 10:11pm
132 hours ? Crank is probably on borrowed time.
I second this. On my 125's I do 12-15 hours on rings, 25-30 hours on pistons and every 4 pistons I do a bottom end. If I were you, I'd be doing a full rebuild. At least then you know that everything inside the motor is good and you reduce the chance of having the bike lock up
six10
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6/28/2017 9:16am Edited Date/Time 6/28/2017 9:52am
i had a little time to pull just the haed off, this is how it looks:



I guess it looks ok, there are three 'straps' of about 5 mm width of surface down the cylinder, that seem a bit more worn out (barely seen on picture below)



all three straps are identical, any idea what is the cause of this?



Also when i pulled the head, i noticed a bit of liquid on the top of the piston. Was that coolant that maybe was still in the head and leaked (i didnt really noticed, as the head was dry), or was that gas? It went away fast and i could not smell it to determine.


EDIT

sorry, a bit dumb of me to not put the piston in BDC, below are pictures, it can be seen a bit better:






bigger pics:

http://shrani.si/f/8/Hg/1j7PSYQ2/1/dsc06122.jpg

http://shrani.si/f/2k/3T/1KTMHLHk/1/dsc0611.jpg

http://shrani.si/f/3Q/k5/3nNxQsgT/dsc0610.jpg
r.sal923
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6/28/2017 10:20am
six10 wrote:
Hello, I bought a used 14 ktm 150. The person I bought it from claims the piston had been changed 25 hours ago. At this point...
Hello,

I bought a used 14 ktm 150. The person I bought it from claims the piston had been changed 25 hours ago. At this point i would like to change the piston rings and just visualy inspect the condition of the piston, cylinder and whether the crank has any play (i do not have a lot of experince, but i will be able to see if there is anything alarming going on).

I have never dissasembled a 2 stroke, so my question is, can just pull the cylinder off, replace the rings and inspect the piston and cylinder, put new cylinder gasket and be done with it (assuming there is nothing alarming going on).

Or do i have to mess with power valve and exhaust control system also, just because I will be removing the cylinder?

Thanks
My wife's 2014 150xc just came apart at 39.9 hrs. Lower connecting rod Bearing. I would replace the whole works.

zeikei
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6/28/2017 10:24am
Looks like normal wear at 100+ hours, it is hard to see but are those marks aligned with edges of ports? How do those marks feel with your fingernail?

The part of the cylinder that presses against head seems a bit wet and dirty, you may have a slight head leak. Can you take a picture of the head, especially the 'ring' that goes against the cylinder? If that is discolored then I suggest you get it checked that it's straight. It is cheap and easy to get it fixed now if needed.

The carbon on piston looks like either the bike has not been ridden very hard or low quality oil has been used.
six10
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6/28/2017 11:27am Edited Date/Time 6/28/2017 11:33am
marks are excatly beetween the ports on both sides (red line on pic1). Nothing can be felt with with a fingernail, there is no depth yet, but i am wondering what is the reason for them. On the pictures they are really hard to notice, on pic 2 you can see maybe:

pic1
http://shrani.si/f/3c/Fu/3XlOD4ol/dsc0619.jpg

pic2
http://shrani.si/f/15/ot/4XOmNc9O/dsc0620.jpg

Here is a picture of the head. It looks wet because i spilled a bit of leftover collant that was still in the head when i removed it from cylinder (pic3)...

pic3
http://shrani.si/f/2/pc/15io9OA1/dsc0621.jpg

Well, cant say how hard its been ridden for 130 hours, but its been ridden pretty hard for the last 12 heh. It has still very good copmression thou.

I got a couple of questions:

a) as i wrote, i spilled a bit of coolant in the cylinder. Would it be best to change the engine oil before starting the bike?
b) can i use the same o rings, or do they have to be new (and btw, what is this green stuff of them (pic3 right side))
c)why are there no dowels for the head and cylinder? Older models and EXC have them.
d)marks/scrathes beetween ports-the ports do seem to have a small chamfer on them

thanks for the answers everbody!


zeikei
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6/28/2017 12:00pm
In two stroke the "engine" oil is in gearbox and separated from cylinder. If it was just a drop or two don't worry about it. Rotate engine couple of times and wipe the cylinder walls from coolant if there is any and put a thin layer of 2 stroke oil instead.

Those o-rings are green, made of Viton I guess. If they look good I guess you can reuse them but I replace them always since they are cheap and shop is nearby. One thing to keep in mind is that there is coolant behind the head bolts so if you reuse the copper crush washers you may start dripping coolant from there.

If 150 is like 125 the head is not flat and kinda goes in the cylinder, that centers it by itself without dowels.
six10
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8/9/2017 10:52am
Hello,

so i measured the diameter of the cylinder, and it was only 0.01 to 0.02 out of spec...replaced the piston of 56.95 diameter so the clearence to the cylinder is by the book, measured the x dimension and choose the right thickness of gaskets so it is 0,1 mm...

The bike fired right up, but it runs very poorly and a lot of smoke coming out of exhaust. Even with the choke on, it dies on its own after a while, does not want to idle at all....

I am 99% sure i messed something with the the z distance, ie control flap. I measured the z-distance while i had the cylinder off, but i have not checked it when i assembled the cylinder on the engine....I am thinking maybe the arm is not even hooked to the control flap assembly on the cylinder....oh well, ill check it tomorrow with the cylinder on and the piston at the bottom...hopefully i'll be able to measure it.
Paw Paw
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8/9/2017 11:50am
Sounds like a plugged up pilot jet to me.

Paw Paw
six10
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8/9/2017 1:41pm
i took it apart again....it was the control flap, the arm from the engine was not hooked at all on the cylinder....so the exhaust control couldnt wotk at all...happy it works now
six10
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1/7/2018 12:35pm
Can somebody please make one thing clear to me regarding the Z distance.

If I set the Z distance by the book, there is no way i can hook the male arm of the control flap on the cylinder to the 'female' arm (the hook) on the engine, when i am assembling the cylinder on the engine.

I have to put the control flap all the way down, so that i am able to even hook it.

I dont understand really why checking the z distance is even necessary on the cylinder, because the height of the control flap is determined by the position of the 'female' hook on lower engine, ie this female hook doesnt move at all when assembling the engine (the 'male' arm of the control flap adjusts to the position of the female arm when hooked).

Hopefully what i've written makes sense and somebody can explain it to me.
zeikei
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1/7/2018 2:57pm
I think you have misunderstood something. You choose base gasket thickness so that you get correct piston height (squish, X-distance). Then after you have installed cylinder you check Z-distance to see that with those base gaskets that you used the position of the power valve flap is still in spec. If not, turn the adjuster until it is. Here is pic from service manual.



six10
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1/8/2018 8:37am Edited Date/Time 1/8/2018 8:43am
Thanks, but how can the measurement be made, when the piston is in the way?
Or maybe it is not when the piston is BDC (i have to check), but i would imagine it is very difficult to measure this wihout some special measurement tool (i'd imagine it would be very difficult to see), some special caliper?
zeikei
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1/8/2018 11:24am
At BDC exhaust port is of course wide open. To measure you can use a regular caliper or make a tool from something that you have in garage. It is not that critical to be exactly within 0.1 mm there is slack here and there but as long as it is close.

A tool by Nihilo looks like this:



six10
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2/13/2018 12:28pm
Hello,

I am doing a bottom end rebuild on this KTM 150.

I am gonna swap the crank (proX) and get it balanced, and both main bearings (OEM). Should I change any other part, now that i have everything apart? Bearings on the transmission maybe? Upon inspection, everything seem in good condition, but I know for a fact, the crank has minimum 100 hours, of which i did 50 hours of hard riding on the track. So i'm doing this as a preventative measure.

Thanks for advice



How to get this roller bearing out thou? Do i have to basically destroy it - grind it out and pry it with a screw driver?







2/13/2018 12:42pm
six10 wrote:
Hello, I am doing a bottom end rebuild on this KTM 150. I am gonna swap the crank (proX) and get it balanced, and both main...
Hello,

I am doing a bottom end rebuild on this KTM 150.

I am gonna swap the crank (proX) and get it balanced, and both main bearings (OEM). Should I change any other part, now that i have everything apart? Bearings on the transmission maybe? Upon inspection, everything seem in good condition, but I know for a fact, the crank has minimum 100 hours, of which i did 50 hours of hard riding on the track. So i'm doing this as a preventative measure.

Thanks for advice



How to get this roller bearing out thou? Do i have to basically destroy it - grind it out and pry it with a screw driver?







Blind bearing puller would probably get that bearing out.

I wouldn’t bother with any tranny bearings unless you can either hear them making noise when you spin them, or you can feel roughness. They don’t move a whole lot compared to the main bearings, some don’t even make a full turn.

Replace crank seals when you are in the lower end. Make sure you do them correctly by following the manual and don’t damage them.
six10
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2/16/2018 12:45pm
When I was loosening the nut on the clutch basket, the tool that I was using to hold the inner hub slipped, so I damaged the aluminium inner hub (outside notches (or ribs) of this inner hub). I damaged 1 notch or rib (dont know how to say it, sorry), but i am thinking this is not really a problem, because there are these notches all around the hub, so the plates are still held plenty by all the other nothes.

Or do you think i should still buy the new inner hub of the clutch basket? The picture below does not show the damage, cant find that pisture right now...


Shrani.si
zeikei
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2/17/2018 2:53am
Good old trick which is also the official procedure in KTM service manual: heat the case in oven to 150C and bearings fall out when you knock the case on wooden table.

As for the clutch inner hub as it has visible notches from plates in addition to the damage you made I would replace it so that the plates can move freely and not cause clutch drag or slip.

I usually replace the tranny axle bearings when splitting cases unless there is just some tens of hours from last time. They don't cost that much. I mean the 4 bearings on each end of main shaft and countershaft. Usually no need to replace other bearings. Check also waterpump bearings / seals while you have engine on table.
six10
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2/20/2018 8:01am Edited Date/Time 2/20/2018 8:08am
Thanks for the answer.

As far as the inner hub goes, below is a picture that shows the damage. I dont think i really need to replace it, but if its necessary i will, it costs around 80 EUR. The outer hub has little a bit of notching, but the clutch works perfect, there is no drag or slip whatsoever, plust the OEM costs more than 300 EUR, so I wont be replacing that.

http://shrani.si/f/3f/kM/e5iefKk/dsc0816.jpg



Shrani.si

I'll check the prices on the tranyy bearings and replace them as you suggested, might as well do it now that the cases are split.

As far as getting a bearings out, I've wathed some YT videos and I ordered IR thermometer. I'll heat the area around the bearing to 180 C, and than i'll try to punch them out with the bearing puller. I dont have a spare oven. I am just not sure how to get the bite with the puller on the roller bearing. That bearing doesnt have an inner ring.
zeikei
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2/20/2018 9:01am
I am sure there are several tricks for that roller bearing, a low tech one is to first pry the roller pins out then find large washer that just fits inside the outer ring. Drop that in there and then put the roller pins back, then you have a way to apply pressure from the other side.

As for the clutch you can always try with old parts first and then decide.
six10
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3/25/2018 9:24am
thanks for the tip, thats exactly the way I got the bearing out...

it is a bit silly, but for the life of me i cannot find the sealing for the main shifting shaft (the big sealing on the right side of the case) on KTM's spare parts finder...it is not under any of the shafts category under egine, any idea where am i supposed to look for the part number, it has to be listed somewhere...

http://shrani.si/f/3h/Th/4qKKnmc2/dsc0897.jpg



CarlinoJoeVideo
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3/25/2018 1:42pm
six10 wrote:
thanks for the tip, thats exactly the way I got the bearing out... it is a bit silly, but for the life of me i cannot...
thanks for the tip, thats exactly the way I got the bearing out...

it is a bit silly, but for the life of me i cannot find the sealing for the main shifting shaft (the big sealing on the right side of the case) on KTM's spare parts finder...it is not under any of the shafts category under egine, any idea where am i supposed to look for the part number, it has to be listed somewhere...

http://shrani.si/f/3h/Th/4qKKnmc2/dsc0897.jpg



I believe it’s #17 on the countershaft diagram. Not sure what year bike you have. This is 2016 125.



zeikei
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3/25/2018 1:53pm
I think it is #33 in OP bike's countershaft diagram. Check the surface of the bushing that goes inside the seal and if it has worn then buy the repair kit #99.

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