These engines were originally made to haul around people for a tiny sip of fuel, low operating costs, and ease of MAINTENANCE....kinda like the old V-Dub beetle. Or the early Honda step through. Or the model T.
Top performance for these engines then should be defined as great fuel mileage, ease of operation and low overall cost.
Some are treating these engines like they should do something other than putt around on a litre of fuel all day and get you where you are going with a minimum of drama.
You aren't going to make one of these engines haul you down the coast @ 40+ MPH or win any stop light drags with that blue haired lady in the Volvo. (although, you may)
You aren't going to find any magic fuel or "performance" add-on that is going to do anything you can't do for pretty much free with the exception being your time. Coleman fuel? nah...super duper spark plug thingy? nah....NOS or turbos? Are you serious? You aren't really serious, are you?
100+ MPG? Yes. Easy running, and easy maintenance? Yes. Lots of tinkering and learning to do maintenence and repairs? Yes, if you want to keep riding it. Fun? Of course, why else would you want to own one?
Buy a good plug, and a good replacement sparkplug wire cap from Pep Boys or other favorite large auto outlet.
Never remove a sparkplug from a hot engine, you may remove the threads from the head as well.
Here's a list of replacement plugs- do it today!
NGK B5HS (preferred)
Champion L86C
Champion CJ7Y low profile or CJ-8
Autolite 4093 or 425
Mix your fuel/oil mixture @ 20:1 for break-in and 36:1 after.
Buy some good gasket paper DON'T MAKE ONE FROM A CEREAL BOx! (really cheap) and make a couple intake gaskets, and install one, even if you think yours is fine. You can make gaskets really easily by drawing the new gasket by using the old gasket as a pattern, and no, it doesn't have to be PERFECT. Use an exacto knife and take your time, finish the rough stuff with some 220 sandpaper. Some of you (me) old-timers will use the "good old ball peen hammer method" to make the gaskets.
Make sure your carb is set right and that means check where the needle clip is, start at the second from the bottom in most cases. One slot lower near sea level. I have two bikes and they are both set up diferently due to poor tolerances in manufacturing FIND THE ONE THAT WORKS FOR YOU- it just depends on your carb and your elevation. (I'm @ 1000' here)
Clean out your tank before you mount it...at least look in there and see if it's full of rust or crud. You can use a shop vac ONLY IF THERE HAS NEVER BEEN ONE DROP OF FUEL...otherwise you'll blow your shop vac to smithereens.
While your in a cleaning mood, pop off the mag side cover and clean all the metal shavings out of there with some spray can brake cleaner and compressed air. Check the area around the sprocket too- full of metal dust!
To save yourself a lot of hassle, buy a length of M6X1.00 pitch threaded rod and REPLACE ALL THE STUDS. Or make them outta bolts like I did. Those would be the intake, exhaust and also the four mounting studs. The originals are made of "anti-metal" and will strip at the first inopportune moment.
Secure all wires with zip ties or electricians tape so none are pulling at the ends or connections. Seal up any ends/connections that are in doubt with liquid electricians tape...READ THE DIRECTIONS ON THE CAN!
Grease your gears with some wheel bearing grease or lithium grease before you ever fire the engine up, then again after about 50 miles. USE ONLY A TINY AMOUNT OR YOU'LL BE CLEANING THE CLUTCH SOON. (a dab about the size of a pencil eraser is PLENTY. Clean them first with some brake cleaner, or carb cleaner, then lube.
Don't spray brake or carb cleaner in your eyes, you won't be doing anything else on the bike for awhile afterwards, if ever.
While you are greasing stuff remove, clean and grease all your wheel bearings, or YOU WILL BE SORRY. Bicycles are not really made to haul a 200+ pound guy over the road and all the bumps/potholes/ect @ 25-35 mph. The bearings take a massive beating. Use red grease because it starts to turn black when it needs servicing.
Make sure your chain is aligned and lubed. Same goes for the pulley/tensioner. Don't make the chain TOO TIGHT. 3/4-1" play.
Always clip on your masterlink so the opened end faces toward the rear when it's at the top of the chain run and going forward.
Zip tie your spokes where they cross while you are installing your sprocket.
Balance your wheels- I used solder wrapped around the spokes at the rim. You can buy stick on weights at the sporting goods store...in the golf aisle.
Don't try to use your clutch to take off.
Use loctite on every bolt you put a wrench on, and don't OVERTIGHTEN the head bolts, or any bolt that goes into aluminum. 15-20 ft/lbs. is enough, and that goes for the spark plug too! While we're on the subject, you do use anti-seize compound on the plug threads, don't you? Never remove a sparkplug from a hot engine, you may remove the threads from the head as well.
Make sure your brakes are up to par. Stuff hurts more @ 35MPH than it does @ 10MPH, especially if it stops you before your brakes do.
Ride defensively, because the only drivers that will see you are the ones you DON'T want to see you- aka "da fuzz".
If you have a problem with dogs chasing you- eventually they get old and bored and leave you alone...if they are smart.
