Posts
52
Joined
8/6/2016
Location
SI
six10
5/28/2017 2:23pm
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
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
Paw Paw
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...
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
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?
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
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.
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!
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.
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
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.
Pit Row
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?
A tool by Nihilo looks like this:
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?
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.
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...
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.
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
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.
As for the clutch you can always try with old parts first and then decide.
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
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