|
|
Post by JerryScript on Mar 14, 2015 1:30:44 GMT -5
The main thing is to have them offset, no gaps on top of each other. I personally do the oil rings at 120 degrees, others may call this over kill.
|
|
Sophomore Rider
Currently Offline
Posts: 128
Likes: 3
Joined: Jun 1, 2013 5:11:09 GMT -5
|
Post by gingel on Mar 14, 2015 2:46:23 GMT -5
Is it also important not to have gaps over the piston pin?
Also, regarding the pin circlips, is it important where to have their gaps?
do you need to put the gap up, down, or is doesn't matter?
|
|
|
|
Post by JerryScript on Mar 14, 2015 17:20:30 GMT -5
It really doesn't matter where they are in relation to the circlips (some may argue with me), so long as the gaps are spaced well you are fine.
|
|
Sophomore Rider
Currently Offline
Posts: 128
Likes: 3
Joined: Jun 1, 2013 5:11:09 GMT -5
|
Post by gingel on Mar 17, 2015 12:41:26 GMT -5
Update: Good news, i assembled the engine and it started. Engine is working.  Here are some pictures from during the rebuild: The engine is out of the frame:  The variator side:  Taking out the megneto using a puller:  The stator:  Revealing the starter clutch. I used the special socket to remove it. It's a reverse thread nut.  The right cover that goes over the starter clutch:  The engine head after removing the head bolts and nuts:  The head after rocker arms and camshaft removed:  Now you can see the cylinder and piston:  The old piston:  The old cylinder:  The engine head before replacing valves, springs and valves oil seals:  Engine Head after doing valves lapping:  I did a water test to the head, to see if there is a leak from the new valves. (sorry the picture came out unfocused):  After removing the starter clutch:  The right crankcase:  I replaced the crank bearings, including the connecting rod needle bearing. (I'm not sure if this picture is before or after replacing the bearings)  The right crankcase is installed with a new gasket and the starter clutch:  The cover is installed over the starter clutch and the stator is installed:  The new piston installed on the connecting rod, and a new gasket:  The new cylinder installed:  The engine head on the cylinder:  I also replaced the timing chain and the chain tensioner. The gear after removing bearings:  I used this puller set to remove the bearings:  Gear after installing new bearings. i also replaced the bearing on the driving gear.  Gear cover after installing new bearings and oil seal:  New oil seal on the driving gear from the variator side:  Ofcourse i also replaced the crankshaft oil seals. I started the engine, and it's working.  I do have a question about tuning the carburetor. When you pull the throttle quickly and then release it, the rpm goes down more than it should and after a few seconds goes back to the correct idle. Is that mean i have lean or rich mixture? Thank you all for helping me during this rebuild. :-) |
|
|
|
Post by lain on Mar 17, 2015 12:59:17 GMT -5
gingel Great work man! The carb question you have, if it drops down low after letting the throttle go and letting it idle and it drops below idle then cleans up and idles smooth after a few seconds or so that means your idle circuit is rich. Try out Alley's carb tuning guide to tune your carb to be leaner.
|
|
|
|
Post by scooter on Mar 17, 2015 19:01:35 GMT -5
Update: Good news, i assembled the engine and it started. Engine is working. Thank you all for helping me during this rebuild. :-) Great work gingel! Have a bone for a job well done! |
|
|
|
Post by JerryScript on Mar 17, 2015 19:58:32 GMT -5
Good Job! Nothing better than riding on a motor you rebuilt yourself, and the peace of mind that comes from knowing it was done right. Enjoy the ride!
|
|
|
|
Post by onewheeldrive on Mar 17, 2015 20:42:17 GMT -5
What did you use for replacing/pulling the crank bearings and pulling apart the crank?
Good job!
|
|
Sophomore Rider
Currently Offline
Posts: 128
Likes: 3
Joined: Jun 1, 2013 5:11:09 GMT -5
|
Post by gingel on Mar 18, 2015 8:36:04 GMT -5
Thank you all  Hopefully the engine will keep working. I will try to lean the mixture a little, see if that help. Regarding the crankshaft, i took it to a workshop, cost around 40$ for the labor (not including the cost of bearings). You need a press and a dial gauge to balance the crankshaft. I don't have these tools. A new SYM crankshaft is around 200$ + shipping (it's heavy so shipping will not be cheap), so i prefered to rebuild the crank that i have. Btw, the old bearings from the crankshaft are still ok, even though they made more than 100K km. |
|
|
|
Post by onewheeldrive on Mar 18, 2015 9:13:23 GMT -5
Ok cool. I know for the 139qmb engine it averages between $59-69 for a new crank. I'm guessing I wouldn't be saving much after parts and labor at a shop, depending on how much they charge. Thanks for the reply. Hopefully I won't have to worry about it any time soon, lol.
|
|
Sophomore Rider
Currently Offline
Posts: 128
Likes: 3
Joined: Jun 1, 2013 5:11:09 GMT -5
|
Post by gingel on Mar 26, 2015 18:30:03 GMT -5
Yes, you are right. For 59-69$, it's better to buy a new crank.
I have a question about what i need to do after i'll end the engine break in.
Do i need to recheck the torque on the engine head nuts?
|
|
|
|
Post by dmartin95 on Mar 27, 2015 9:34:16 GMT -5
Yes, you are right. For 59-69$, it's better to buy a new crank. I have a question about what i need to do after i'll end the engine break in. Do i need to recheck the torque on the engine head nuts? I found this thread to be most informative. That's awesome you kept us updated. You showed a pic of the puller you used on the bearings to remove them, but what about install? Did they fit right in or did they have be pressed in? Also I'd like to say Job well done! You did a good job. |
|
Sophomore Rider
Currently Offline
Posts: 128
Likes: 3
Joined: Jun 1, 2013 5:11:09 GMT -5
|
Post by gingel on Mar 28, 2015 5:00:22 GMT -5
I had to use a heat gun to warm the bearings seat so i can get them out with the puller. When i installed the new bearings i also used the heat gun to heat the bearing seat, and i put the bearings in the freezer for a few hours. Still, they didn't go in so easy like you see in this video. Only the final axle bearing dropped straight in, and also the driving gear (with the bearing on it) just slid in without any force (after it was in the freezer also). The small bearings (number 6301C3 i think), were a tight fit, and even after heating the bearings seat, and putting the bearings in the freezer, i still had to use a socket which have about the same outer diameter and use a hammer to get them inside. To replace the bearing on the driving gear, i asked someone with a manual press to help me with that. |
|
Sophomore Rider
Currently Offline
Posts: 128
Likes: 3
Joined: Jun 1, 2013 5:11:09 GMT -5
|
Post by gingel on Mar 30, 2015 18:58:07 GMT -5
Any one knows if i need to recheck the torque on the engine head nuts, after i'll end the engine break in?
|
|
|
|
Post by JerryScript on Mar 31, 2015 0:59:17 GMT -5
Any one knows if i need to recheck the torque on the engine head nuts, after i'll end the engine break in? I don't, but it couldn't hurt to do it when you check your valve lash. |
|
