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Taking your nitro engine apart


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#1 alex199020

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Posted 02 January 2007 - 07:54 PM

Heres a small guide to how to take your engine apart for cleaning. Hope its usefull :)

Start by taking the clutch assembly off. Once you have all the shoes etc off take the nut holding the flywheel on off. (You may need to hydro lock the engine to do this. Move the piston till it's just under top dead centre, take the glow plug out and fill the engine with after run oil and then replace the glow plug. Now turn the flywheel towards TDC and it should lock and not go any further)

Once the nut is off take the flywheel off. If it is stuck use a flywheel removing tool or take a flat headed screwdriver, place it between the back of the flywheel and the crank case and gently turn it so it pushes the flywheel off. When doing this push the flywheel from different points (I.E do a small bit in one place the move to the opposite side and push the flywheel there)

Now take the exhaust and manifold off followed by the carburettor and then the heat sink. (If the engine is still in its mount take it out of the mount now)

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Now take the pull start/roto-start and one way bearings out{if the engine has one}. Next put the piston to TDC and remove the back plate. (Make sure the back plate stays at TDC while removing back plate as the piston usually goes lower that the back plate at the bottom of its stroke and there is a grove in the back plate to allow this. If you have the piston at the bottom of the stroke and force the back plate off you will snap the back of the piston and have to replace both piston and liner)

Once the back plate is off move the piston to the bottom of its stroke and put something like a zip tie into the exhaust port. Slowly move the piston up and the liner should start to slide out. {You may need to heat the crankcase with a head dryer to allow this to happen. Alternatively you can get some string and feed it through the exhaust port so that you have both ends, one from inside the line and the other from the exhaust, and pull on the string which causes the liner to come out as well. Remember to be careful while doing this}

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Next you need to take the piston out. First look at the bottom of the inside of your crankcase. If there is a grove in it for the conrod to pass through put your piston to TDC, if not move the piston to BDC. Now take a piece of string and put it round the back of the conrod and back round the other side so that it "hooks" the conrod. (Make sure you use soft string that won't scratch the conrod. Don't use wire!) Now pull the string. Start of gently and slowly apply more force. If the conrod does not come off the crankshaft pull it as far out as it will go and while keeping pressure on it use your figure to push the back of the crankshaft towards the front of the crankcase (In the opposite direction to the direction you are pulling the conrod). {Make sure that you check which way the piston and conrod where so they go back in the same way)

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Once the conrod is off simply push the piston up the crankcase and take it out of the top. Now it's a simple case of pull the crankshaft out of the engine and your done.

Now clean it up, drown it in ARO/WD40 etc and rebuild it (this in reverse) :good:


(If anyone thinks something should be done differently or notices any mistakes please tell me :) )

#2 JamesChatz

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Posted 02 January 2007 - 07:55 PM

Good guide, needs some pics though. With them it will be really useful,

:good:

#3 alex199020

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Posted 02 January 2007 - 07:56 PM

Ye i'll get some pics when i put my engine back together..couldnt get them while i was striping it :( :good:

#4 alex199020

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Posted 13 January 2007 - 08:42 PM

A couple of pics added :good:

#5 chris52

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Posted 13 January 2007 - 09:00 PM

exellent guide pictures help a lot

one point to mention

i always mark the outer face of the conrod with a permanent marker so when reasembling you can put the piston and conrod back in as it came out and not 180 degrees out

chris

#6 Ziggy122

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Posted 13 January 2007 - 09:38 PM

exellent guide pictures help a lot

one point to mention

i always mark the outer face of the conrod with a permanent marker so when reasembling you can put the piston and conrod back in as it came out and not 180 degrees out

chris


Dont make a difference really mate :)

But the liner has a notch to tell which way to goes back in - and all yah gotta do it note sumet on the piston to tell which way it was before hand :)

But if i have enough money after bike and builiding my simple discharger :) and batteries and stuff - i'll get my old t-15 rebuilt like i have been saying i would do for months on end :) and get a guide up on HOW TO REBUILD :)


Ziggy

#7 chris52

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Posted 13 January 2007 - 09:50 PM

Dont make a difference really mate :)

But the liner has a notch to tell which way to goes back in - and all yah gotta do it note sumet on the piston to tell which way it was before hand :)

Ziggy



i agree is doen't make that much difference but for the sake of a 5 second mark on the conrod before you take the piston and conrod out, you guarentee to put the engine back together exactly as is was origionally. the piston beds itself to the sleave and if you alter that it can't be good :D

chris :D

#8 alex199020

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Posted 13 January 2007 - 10:37 PM

It does matter which way the conrod goes as there is a "oil hole" in them and if you put them in the wrong way then the engine won't get lubricated properly and get damaged. :good:

#9 sea118

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Posted 13 January 2007 - 11:51 PM

eiher way, top guide :good: :P

#10 chris52

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Posted 13 January 2007 - 11:54 PM

It does matter which way the conrod goes as there is a "oil hole" in them and if you put them in the wrong way then the engine won't get lubricated properly and get damaged. :good:


i know there is an oilway in the conrod but i didnt realise it was sided?? you would have thought that if it mattered which way way round the the conrod went it would have some sort of marking on it??.the point i was trying to make about marking the conrod before removeing it was so the piston was put back in the same position :unsure:

#11 alex199020

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Posted 14 January 2007 - 11:02 AM

i know there is an oilway in the conrod but i didnt realise it was sided?? you would have thought that if it mattered which way way round the the conrod went it would have some sort of marking on it??.the point i was trying to make about marking the conrod before removeing it was so the piston was put back in the same position :unsure:


Ye there is..i nearly put mine in wrong but saw that one side of the conrod had a long oil well and the other had 2 small short oil wells (thats on a k4.6) But its definatley something you need to check :)

#12 allan1010

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Posted 14 January 2007 - 11:17 AM

Also remember that if you put the piston back in "back to front" compared to how it was before you'll have none of the benefits of your break-in period. The piston (or ring) and liner will have to bed in together again.
On a microscopic level, the wear marks won't match between the 2 moving parts.

#13 Samari

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Posted 14 January 2007 - 11:30 AM

Excellent guide. I've linked to it from the Nitro tips sticky. :good:

#14 Schumach3r

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Posted 14 January 2007 - 12:25 PM

Funny you posted this, i took mine apart last night, never done an engine this small before, but its still pretty much straight forward.

Only complication i had was getting the flywheel off the collet taper, but once i heated it up with a burner it dropped straight off :D

#15 Ziggy122

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Posted 15 January 2007 - 11:06 AM

Funny you posted this, i took mine apart last night, never done an engine this small before, but its still pretty much straight forward.

Only complication i had was getting the flywheel off the collet taper, but once i heated it up with a burner it dropped straight off :D


getting that dam flywheel off is a pain in the bum.... i ended using a screwdriver in via the carb hole on the crankcase to help me remove mine :|

its a bugger todo...

Its off those with heat and some perswasion :)

Ziggy




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