Check out my video series on getting a non-running moped running
I just bought a QT50 that has sat for years (or an undetermined amount of time), what should I do before I try to start it?
1. Remove the carburetor and thoroughly clean it. Check and make sure the idle jet isn’t clogged by using a flashlight (see below);
2. Check condition of inside of gas tank and determine if rust needs to be removed (empty any old fuel; here is an excellent article on removing rust from an old gas tank);
3. Replace fuel line and fuel filter (fuel filter with paper element is recommended);
4. Install a new (and correct) spark plug, NGK BP4HS, with the correct spark plug gap (0.024-0.028 inches);
5. Drain and refill transmission with 10W/30 oil (11 ounces only);
6. Check condition of air filter and clean or replace;
7. You may want to add premixed fuel to the gas tank for the first start as the oil line may need bled or cleared of gunk or the oil pump may need to be checked for proper function;
8. Check condition of battery and for presence/absence of a regulator. Dead battery and absence of regulator will lead to blowing headlight and/or tail-light. Headlight can be expensive fix.
9. Change the left and right crank seals. Although an intimidating repair for the newbie, replacing these seals will save you a lot of heartache and pain later, especially if you put on a 60cc or bigger top end. Go to my qt50 links page and you will see a link to a description on how to do this.
10. The charge coil in the stator was defective on 1979 models but I’ve found that replacing the charge coil on all models leads to much improved starting. You can find a PW50 stator for cheap (less than $20 on ebay or amazon). Take the charge coil off and use it to replace the old charge coil on your qt50. You will want to install it with the ground facing down (at least that was my experience). If you install it and your hopper is hard to start or runs lousy then take it out and flip it upside down. The lighting coil is not compatible. I’ll have to check and see about the pulse coil.
11. If your qt has sat in the weather for years then you will want to check the bearings. I’ve had several people ask me about a seized rear tire. This is most likely caused by rusted pinion bearings. You can find the pinion bearings with removal tool for sale on ebay. As with many parts, if you search for PW50 pinion bearings instead of qt50 pinion bearings, you may find cheaper options. I believe the bearing part no. is 62022RS.
12. If 2 stroke oil was left in the oil tank while it sat, chances are it drained into the carb, intake and cylinder over the years. If you manage to start it, it will smoke for quite a while until that oil is burned out of the cylinder.
13. You will need to lubricate all cables. One way to do this is to take the cable off at the handlebar. You can make a little funnel out of duct tape and wire. Attach the duct tape so that it goes around the cable end and the cable wire. I also take a small wire and cinch up the duct tape around the cable end to prevent leaks. Leave some space around the cable wire so you can shoot some lubricant into your “funnel” formed by the duct tape. Place some cardboard under the other end of the cable. Gradually shoot your preferred lube into the “funnel” and wait for it to drain. Repeat until you see drips on the cardboard at the other end. Work the cable back and forth and check for proper lubrication. Basic WD-40 is probably too thin a lubricant to last over time. They do make a silicon based lube that is probably better.
I learned the hard way on my first qt as my throttle cable broke during some of the initial rides.
14. Check and replace light bulbs as needed. Instrument panel bulbs are usually not all working. Early models had 4 bulbs. Later models with 3 position switch had 5 bulbs. Flasher relay is usually the culprit if turn signals do not function properly.
15. Do a visual inspection of the wiring; checking for missing insulation; loose/unattached wires and dirty or unattached grounds.
If you succeed in starting it and want to ride it, then do the following:
1. Check the condition of the tires. Cracking, missing tread, or other damage may require replacement of tires;
2. Check for missing or loose spokes;
3. Check condition of brakes and adjust or replace as needed;
4. Check throttle for proper function;
5. Check handlebars for play/looseness;
6. Check for possible leaks in gas tank, petcock, fuel line, carburetor