ScootDawg Forums - PST150 Build

Well folks here it is; what you have been waiting for. The procedure and pictures of Lefty’s Ice Bear 150cc motor build.
To start off I found it better to remove the rear fender assembly, seat and all the rear body panels to give more room to work with. Remember when removing panels off an Ice Bear Trike you have to start at the rear of the trike and work forward. This is because Ice Bear interlocks their panels together. Once all this is removed, disconnect the wiring harness, reverse cable, if equipped, remove the exhaust, carb and intake, rear drive chain and sprocket. Now place a jack under the motor and remove the nuts and bolts holding the motor in place:
http://i609.photobucket.com/albums/t...m/DSC00894.jpg
Lower the motor down and remove it. Place it on a bench where you will have room to work and keep the parts in order along with their retaining hardware so they don’t get mixed up and makes reassembly easier.
http://i609.photobucket.com/albums/t...m/DSC00891.jpg
Next remove the pull start and the CTV cover exposing the clutch and variator.
http://i609.photobucket.com/albums/t...m/DSC00890.jpg
Now remove the nut holding the variator outer shell on. An impact wrench will make this a lot easier, if you do not have one, you will need a strap wrench or similar to hold the variator from moving while you remove the nut. Once the nut is off you can slide the belt off.
http://i609.photobucket.com/albums/t...m/DSC00889.jpg
Now you can remove the rear portion of the variator by reaching behind it and pulling it off. Be careful not to allow the rear plate to fall off and drop your rollers (sliders) all over the floor. Now you can remove the nut holding the clutch bell in place. Once again, an impact wrench makes this an easy task.
http://i609.photobucket.com/albums/t...m/DSC00885.jpg
This will expose the clutch which can now be taken off.
http://i609.photobucket.com/albums/t...m/DSC00884.jpg
The next two pictures show the differences between the OEM clutch and the Performance clutch. The first picture you will notice how much longer the friction pads are. More material to engage the bell
http://i609.photobucket.com/albums/t...m/DSC00883.jpg
This picture shows the differences in the bells. Notice how much larger and the different shape the cooling holes are on the performance bell.
http://i609.photobucket.com/albums/t...m/DSC00881.jpg
This is one area we had some problems with after reassembly and testing. The performance clutch required a lot more RPMs to engage due to the contra spring that was used. I wound up taking the performance clutch off and using the OEM clutch for break in. If I am not mistaken, Lefty has gotten the clutch issues taken care of.
Next we removed the final drive cover and the drive gears.
http://i609.photobucket.com/albums/t...m/DSC00880.jpg
http://i609.photobucket.com/albums/t...m/DSC00879.jpg
http://i609.photobucket.com/albums/t...m/DSC00878.jpg
http://i609.photobucket.com/albums/t...m/DSC00877.jpg
This pictures below shows the old gears and the new. The pilot shaft has to be pressed off the old gear and pressed on the new. You will need a press for this. Most local garages should have one and not charge but a couple bucks to do this. Do not attempt to use a torch and a vise to do this. You will damage the gear or shaft.
http://i609.photobucket.com/albums/t...m/DSC00865.jpg
http://i609.photobucket.com/albums/t...m/DSC00876.jpg
Next I removed the transmission cover and gears. Make sure you keep the bolts in the right order in the cover. They must go in the right holes when reassembling. Make sure you lay the disassembled parts in order of removal.
http://i609.photobucket.com/albums/t...m/DSC00875.jpg
http://i609.photobucket.com/albums/t...m/DSC00874.jpg
http://i609.photobucket.com/albums/t...m/DSC00873.jpg
http://i609.photobucket.com/albums/t...m/DSC00872.jpg
http://i609.photobucket.com/albums/t...m/DSC00871.jpg
http://i609.photobucket.com/albums/t...m/DSC00869.jpg
http://i609.photobucket.com/albums/t...m/DSC00868.jpg
http://i609.photobucket.com/albums/t...m/DSC00867.jpg
http://i609.photobucket.com/albums/t...m/DSC00866.jpg
This picture shows the missing 6004 radial bearing installed.
http://i609.photobucket.com/albums/t...m/DSC00870.jpg
Next we start disassembling the motor itself and split the cases. Remove all the plastic covers. Then remove the screw covering the timing chain adjuster. Then remove the chain tensioner. Lay these in a safe place.
http://i609.photobucket.com/albums/t...m/DSC00854.jpg
When reassembling the tensioner, it will be necessary to retract the tensioner by using a small screwdriver inside the hole that was created when removing the above screw.
http://i609.photobucket.com/albums/t...m/DSC00855.jpg
Now remove the valve cover and then the four nuts holding the cam rocker assembly. Remove the rocker assembly, then gently slide the bearing side of the cam up to allow room to remove the cam off the timing chain. If the chain drops in the case don’t worry about it, the cases are coming apart anyways.
http://i609.photobucket.com/albums/t...m/DSC00857.jpg
Now remove the 2 bolts on the side of the head. Remove the head, the gasket, and the upper chain slide. Now you can remove the cylinder.
Now it is time to work on the stator side to finish the disassembly. You will need a flywheel puller to remove the flywheel. Also an impact wrench will help in pulling the nut. Make sure you don’t allow the crankshaft to spin while removing the flywheel nut.
http://i609.photobucket.com/albums/t...m/DSC00852.jpg
Once the flywheel is off you can remove the stator and pickup assembly.
http://i609.photobucket.com/albums/t...m/DSC00851.jpg
Now remove the left side case cover.
http://i609.photobucket.com/albums/t...m/DSC00850.jpg
Remove the tin cover covering the oil pump
http://i609.photobucket.com/albums/t...m/DSC00849.jpg
Next we remove the starter clutch assembly. Now the nut holding the starter clutch assembly is REVERSED thread. You will either need a special 4 post socket to remove it or make one. You can take a 12 point 15/16 deep socket and make your own by grinding sections out of it. You will need an impact for this. Once again make sure the crank does not turn. Again, this is REVERSED thread, you turn clockwise to remove it.
http://i609.photobucket.com/albums/t...m/DSC00848.jpg
Once the nut is off, carefully remove the starter clutch by reaching behind it with your fingers and pulling it off as an assembly. It is also a very wise idea to replace it with a new one when reassembling. Starter clutch takes a lot of abuse. Since it is freewheeling with the motor running, it rides directly on the nut and wears down the center. For the cost it is just a good idea to change it while the motor is apart. A pain to change later.
http://i609.photobucket.com/albums/t...m/DSC00845.jpg
Now you can remove the oil pump and the chain. Pay attention to where the arrow points on the oil pump for reassembly.
http://i609.photobucket.com/albums/t...m/DSC00844.jpg
Now remove the remaining case bolts and split the cases and remove the crankshaft. Strip all the seals from the cases and the remove the cylinder/head studs. Make sure you note which stud goes in which hole.
http://i609.photobucket.com/albums/t...m/DSC00823.jpg
Now if you are using your old cases, they need to be taken to a machine shop to be machined to accept the new 62mm jug. An alternative is to buy new cases already machined. I had the cases machined, I wanted a perfect match between the jug we were using and the case. The only way this could be done was to provide the machinist with the new jug and the cases. Using cases already machined there could be a tolerance difference. Make sure you clean, clean and clean again, the cases before reassembly.
Parts List
62mm Big Bore Kit with head
60mm Stroker Crank
16/37 Taller Tranny Gears to replace the 13/40 Gears
NCY Performance Clutch
NCY Performance Bell
24mm carb, 38 pilot, 122.5 main
New starter clutch
Seals and Gasket Set
Assembly Notes.
Reassembly is the reverse of disassembly. You can use a hose clamp to fit the jug over the assembled piston and rings. Hose clamp holds the rings tight to the piston so the piston can slide into the jug. then simply unscrew to remove it and finish installing the jug. Make sure you oil the rings up before installing the jug.
http://i609.photobucket.com/albums/t...m/DSC00843.jpg
Make sure piston is at top dead center before installing the head, double check flywheel markings. When installing the cam make sure the alignment holes on the cam are as in the picture.
http://i609.photobucket.com/albums/t...m/DSC00858.jpg
Once the motor is assembled, rotate the crank by hand several times and recheck timing marks. Also I use .004 inch valve clearance on both intake and exhaust.
Remember that the nut that holds the starter clutch is REVERSED thread.
Piston Pics.
http://i609.photobucket.com/albums/t...m/DSC00825.jpg
http://i609.photobucket.com/albums/t...m/DSC00826.jpg
I also did a bench compression check before installing the motor back in the trike.
http://i609.photobucket.com/albums/t...m/DSC00861.jpg