Strokers PDI

[speedy1125]

I will be upgrading/assembling a 2011 50cc QT3 identical to this one:




Remove the cardboard and unbolt the metal frame 'crate'. Save the nuts and bolts, they are identical to many on the bike so you can use them should you lose any




This bike will have the following upgrades:

High Performance:
50mm Big Bore Kit (specifically 82cc but engine sizes are always rounded up to whole numbers for the most part. I will be referring to 47mm bore as 80cc, 50mm as 90cc, 52mm as 100cc.)
95/32 Carb Jets
Free Flow Air Filter
Timing Advance, No-Rev Limit Ignition
Tuned Transmission (5.5g rollers, Increases operating RPM into Max HP and Torque Range)

Reliability:
Replace stock drain plugs with magnetic drain plugs (Engine and Gearbox. Prolongs bearing life.)
Replace stock fuel lines, vacuum lines and fuel filter with high quality lines, filter and band clamps.
Replace stock tire valve stems with racing 3/4 inch metal valve stems with metal caps
Replace stock drive belt with genuine Gates Premium belt
Replace stock spark plug with genuine NGK plug
Replace stock glass fuse with automotive type blade fuse and water resistant holder
Exhaust painted with 3 coats high temp automotive paint to prevent rust
Better hardware used in areas where factory fastening has proven to be insufficient.



Step 1:


Lay out some cardboard the crate came wrapped in to use as a place to lay bodywork. Appoint a good friend to stand guard




Disassemble down to the frame. Be patient with the body panels! they are thin and fragile. Use 3-in-1 household oil on places where they are hard to separate. This helps when reinstalling as well. every component you remove put the screw/nut/bolt back in its journal after you remove the component. This way you will not have the fasteners laying everywhere getting mixed up and lost . Another method is to use baggies and label them with masking tape tags ect..
Remove wiring harness for inspection and modifications. Inspect frame for rust. Use sandpaper or wire brush on any rust and spray with black paint. Remove engine (if you are installing a Big Bore Kit).

[speedy1125]

Step 2

Cut out old glass fuse holder and wire in a water resistant automotive blade type holder and 'EZ ID' 10a LED fuse:




This fuse glows when blown:




The factory has 2 locations for CDI mounting on this model. They always install the CDI under the floorboard beside the battery box (1). This location is difficult to access. I always relocate the CDI to the other mounting tab that is welded on the frame at the factory on the frame rail beside the starter relay (2).. This location makes testing and replacing the CDI in the future much easier.




The CDI wiring is a few inches short for the new location. Remove tape on the harness and isolate the wires to be lenghtened. Splice in a few inches of wire using butt splices and cover with heat shrink tubing or tape. Then re-wrap the harness.




Inspect all connectors for loose wires. When re-installing the harness use dielectric grease in all connectors.




Tomorrow:
Reinstall fuel tank and install new fuel/vac lines. Reinstall wiring harness.

[speedy1125]

Use plenty of zip-ties when reinstalling the wiring harness (in the photos below the ties are black so they are hard to see) And use the dielectric grease in all connectors:




When you have all the body panels off and are putting the dielectric grease in the connectors make sure the wires are in the connectors snugly and in the right position.....colors matching.

Recently I found this situation on 2 new crated bikes:

red and white reversed on the rectifier plug
kill switch wires reversed making 'kill'=run and 'run'=kill
fuel gauge wires reversed making a full tank read empty and an empty tank read full.





As you see above, I reinstalled the fuel tank before the engine. it was raining yesterday and I needed something to do so I carried the entire frame to a dry indoor location. Its easier to reinstall the engine first, access to the top shock mounts is easier. you could always take the shocks off at the bottom in the first place but it depends on the model as to which is easier.

Depending on where you live and the time of year and/or time of day you are doing your PDI, you may want to go ahead and fill the tank as soon as possible. In central NC this time of year, it can get quite cool at night then warm up rapidly in the morning. this can cause the steel gas tank to 'sweat' on the inside. if you fill the tank when it has condensation built up on the inside, you will have a no start condition and will have the drain the fuel, remove the carb and tank to clean them out. I filled the tank as soon as I connected it the the fuel valve to replace the air in the tank with fuel thus eliminating the possibility of moisture buildup.

Of course be sure the new line is connected to the shut off valve BEFORE filling with gas




If you did it at the stage of the above pictures put the front wheel on temporarily to counterbalance the weight of the fuel or the bike will fall off the stand.
Again I only did it because conditions were right for the threat of moisture in the tank. This is a rare thing and if you are doing your assembly in summer you will not have to worry about it. This build was done in fall.



At this stage it is best to install your big bore kit then reinstall everything in the reverse order of which you took it apart. The engine came out last so it will be first to go back in. Rather than do a whole documentary on the bbk installation, refer to this procedure:
49ccscoot.proboards.com/index.cgi?board=4ttech&action=display&thread=350

Also While your engine is on the bench, it is a good time to install your previously ordered Enki 3/4 metal racing valve stems.




You will need a valve core tool, access to an air compressor, 10mm and 12mm wrenches (the wrench in your factory toolkit works perfectly for this), an air blower and some sort of clamp or vise.

First remove the core from the stock stem to let the air out of the tire.



Use pliers to remove the old stem.



disassemble the new valve stem completely.



I use a big clamp to squeeze the tire together and hold it out of the way as much as possible.



First insert the valve stem.



Then the inside rubber seal.



Then the retaining washer



put on the first 12mm nut and tighten down snug. it does not have to be gorilla tight, just tight enough to compress the rubber making a good seal.



then the second 12mm nut which locks down the first one



you will have to lift the tire bead over the end of the stem with a big screwdriver or something similar. careful not to gouge up the bead.

I use a Blue Point air blower from Snap-On Tools.



It has a rubber tip that you can insert into the valve to blow in a hard shot of air to set the tire bead. You then install the core, inflate to proper psi then put on the 10mm metal cap.


While you have the engine on the work table, pop out this little screen on the CVT cover. It restricts airflow into the CVT cover and your belt will cook, shortening its life:




Always drain the oil AFTER installing your BBK. This is easy now since the engine is on the bench. Now is a good time for draining and replacing the gear lube also.

[speedy1125]

The factory paint on the exhaust merely keeps it from rusting during shipping. the first time it gets wet it will rust. Repaint with Rust-o-leum Auto high temp flat black. At least 3 coats.

[speedy1125]

HEY!! No sleeping on the Job!

[speedy1125]

Use great care and patience in reinstalling the body panels. I use a dewalt 18v drill with the clutch set to '2' to run the screws in, it snugs each screw down evenly without breaking the journals.



Then install the front wheel using red loctite on the front axle nut and front brake caliper mounting bolts.




By this point the exhaust is now dry and ready to install.
It is very common for me to see these bikes sold from local dealers with missing and/or broken exhaust bolts after a few thousand miles if not sooner
. They thread into the engine case and have no locking hardware on them. I use longer grade 8 bolts that thread all the way through to the other side of the mounting point then use flat and lock washers to secure them. These will never fall out.

[speedy1125]

Since this bike now has a Uni performance 2 stage air filter, the stock airbox has been removed. The crankcase vent from the valve cover that went to the stock airbox will now have go to an oil catch can

Here is a catch can system from a popular vendor:

49ccscoot.proboards.com/index.cgi?board=4perfrom&action=display&thread=1819

If you prefer to make your own you can use a camp stove fuel bottle, a little air filter, some fittings and big band clamps. This type of catch will allow you to check your oil easier but will have to be periodically removed and cleaned out:

49ccscoot.proboards.com/index.cgi?board=4ttech&action=display&thread=1542

Personally I prefer the 'homemade' can above. If your engine is running right there will be very little oil in the can. If you start to see more and more oil in the can this would indicate you are starting to have engine issues.

I tested a 'decompression tube kit' intended to relieve crankcase pressure like the catch can and capped off the vent on the valve cover.





This will NOT work. At least it didnt on this 139qmb motor. This morning when cranked up it blew oil out of the tube. cleaned it up then added oil to proper level. Started it up and oil started coming up the tube. Took the cap off the vent on the valve cover and heard an audible 'woooosh'. Left the cap off and no more oil up the tube. Apparently these engines were designed to relieve crankcase pressure only through the valve cover so this type of 'decompression tube' will not work.


After you reinstall your exhaust with a new exhaust gasket you are now ready for a test run.

CHECK YOUR OIL!!! NO HARD REVVING!!



Run the engine for a minute to let the oil circulate then switch the engine off and add oil, it will need it because the oil galleys were empty.

After your initial engine start and carb adjustments you can then finish reinstalling the rest of the bodywork, trunk and mirrors. It is best to do the first startup and adjustments while the rear bodywork is still off though. Adjustments are easier and if there is a problem the motor is easier to work on with the panels still off. You can even put the front panel (the one that goes in front of the seat bucket, it helps support the seat) and seat bucket on and take a little test drive to evaluate things. Any adjustments to be made will show themselves pretty soon on a short test ride.

Some cleaning and waxing and this bike will then be ready for many many reliable miles of peppy scooter fun!!




some notes..

NO WIDE OPEN RUNS!! NO PROLONGED CONSTANT RPM RUNNING!!
A proper break-in is VERY important on a new scooter engine and even moreso on a Big Bore install.
Oil and gear lube change at 300 miles. This first oil change is very important. Not so much on this engine since it now has magnetic drain plugs but still should be done on schedule. Run for another 300 miles then adjust the valves and change the engine oil again. (600 total miles)
Keep heavy weights in the transmission to keep RPMs down. Once you are done with the break-in period you can install lighter weights to raise RPMs into the peak horsepower/torque range.
The longer you allow the engine to break-in the longer it will last and the better it will run in the long term. I recommend no WOT runs for the first 1000 miles. Always use conventional oil during break-in then at 1000 miles adjust the valves again and switch to Mobil-1 synthetic or Amsoil. I let the bike you see in the background break-in for 2000 miles. I could feel when it was ready for some WOT running and its a strong little scoot now .

Have Fun!!