Borrowed and updated:
1. Remove the head when dead cold. Ease off the head nuts each one a little at a time to help prevent warpage. Remove studs (replace if possible) On most bikes now the threads are 8.0mm x 1.0mm(fine pitch), but some will be coarse M8X1.25 or M6X1 When reinstalling it may be wise to Loctite (red, not blue) the portion that goes in the block. On the top threads, do not re-use acorn nuts they have no place in a cylinder head application. Use good washers and good beefy 8.0mm x 1.0mm(fine pitch)nuts (see #3 below). Torque to 12-14 ft-lbs (8mm) in a criss cross pattern a little at a time, re-torque when cold each time after 2-3 runs, but do NOT over tighten. Some rationale: studs vibrate loose and stock threaded parts are very weak.
2. IF you need to pull the cylinder ensure the little pin on piston that prevents rings from rotating cannot be pulled out. NOTE: Not all engines have this pin. If it can be pulled out, replace it or the piston. Some have JB welded it in – but everything on paper says these temps are very high and a bonding agent may not help. Perhaps a high temp bonding agent or other means will work. Rationale: While quite rare, the pin can fall out, causing piston ring to rotate and catch on a port causing lots of engine damage.
3. If you choose to only replace the head nuts, use HD nuts (several varieties available) and new USA made washers on the head. Again do not use those blind "acorn" nuts on the head. In addition to new lock nuts, you can JB weld (blue) the head bolt/nut interface after you tighten them to the correct torque setting - Torque to 12-14 ft-lbs (8mm). Also certain types of lockwashers can be used, but again due to heat a Nylock may not be effective.
4. Intake, exhaust, all engine mounting studs - 6mmX1.0. Replace with US made metric all thread and cut to size or purchase studs at a supplier. Rationale: Chinese factory studs will fail and leave you stranded.
5. Nuts for intake, exhaust, all engine mounting studs. Use metric nuts with lock washers and (and optionally) Loctite to mount all of these. Nuts really don't cost much but whatever they cost, it's cheap compared to a broken engine mount or losing a muffler 20 miles from home. Get tend to get extras and use Nylock nuts all all applications that don't get really hot.
6. Carb: Some folks take it apart and loctite (red) the main jet (full throttle jet)Most folks never seen one come loose – be careful with getting Loctite in the carb and jet – although it doesn't cure until it's anaerobic, you still don't want it in your fuel. . Locktite (blue) the screws holding it together if you like, but this usually isn't necessary. Ensure float is properly set too – occasionally the float will have a hole in it from the factory! Leave the needle clip where it is for now – as the bike breaks in and the fuel flow improves with a new fuel valve it maybe be necessary to move the clip up to the top (lean position). Assure that the needle has a nice real taper to it.
7. Intake gasket: throw away factory intake gasket. It will eventually blow. Cut new one from gasket material bought from the autoparts store. There is a pattern if necessary that will be posted. Use gasket sealer/tack for gasket prior to install. Permagasket blue works very well for this.
8. Exhaust: Heat elbow cherry red to bend it as necessary to clear pedals. Don't bend while installed on engine. Some won't need bending, and remember sooner, rather than later you will find out an expansion chamber can be used to radically improve engine performance without going broke.
9. You can Loctite the bolts to engine covers if you like. Some folks even replace all cover bolts with USA bolts (Using hex head bolts). Nothing worse than losing your clutch cover bolts and not being able to disengage bolt. Do this only after you are 100% sure clutch is properly adjusted – but you will still need access later for lube.
10. Relube the clutch engagement pin and ball. Use a lot of HD grease.
11. Touch of very sticky lube on gears on clutch.
12. Carefully Loctite the small screw/bolt on the clutch assembly that prevents the clutch adjustment from rotating. Rationale: it can loosen and fall out making a mess and possibly damaging the gear assembly and/or clutch. But be careful – that small screw is quite soft and if Loctited too strongly even a good screwdriver will ruin the head.
12a. You can Loctite the bolt on the small drive gear in the clutch assembly. While rare folks have had this bolt fall out before.
13. Engine wiring: do not install the kill switch wire until you get engine running, unless you are competent at electrical work and have assure (with a meter ) the switch and wiring are a-OK. I prefer to solder and shrink sleeve the connections. Rationale: eliminate a source of potential no start condition.
14. All wiring connectors: cut and throw out stock connectors and use covered blade connectors. Solder and crimp and then use shrink tubing on everything along with conduit for a nice clean and professional install. Rationale: stock connectors will get loose causing wiring to come apart or intermittent connections.
15. Lube all cables with a good cable lube Rationale: some cables are dry and some are frayed. Pulling cable wire out of sheath and inspecting and lubing is a good idea. If in doubt, replace cables. Lubing the clutch cable will make a big difference.
16. More on the kill switch: The older style separate kill switches are JUNK and fail causing a no start condition. The build in ones are quite trouble free, to the point if your engine ever starts in an over rev condition – placing and holding the switch with your thumb is quite necessary until the engine quits turning.
17. Chain tensioner roller: get a bearing one from a good supplier such as DAX, research and build your own tensioner, or lose the whole chain sprocket affair. Rationale: stock ones don't have bearings and will fail.
17a. Chain install: 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.
18. Chain tension: chain will stretch by an inch or two during first 50 miles. Keep eye out and don't use bike for transpo to/from work until you do multiple test ride and shorten chain and adjust tension with roller bearing. It shouldn't be said, but you need a chain breaker for install. On a new chain, make chain tension fairly tight but once chain as stretched, make sure that is about 3/4 of an inch play/slack.
19. Rear sprocket: replace all nuts and bolts and lock washers with US made ones. Rationale: The chinese bolts threads strip when you need to tighten down that donut. Use locknuts in addition to lock washers. Nuts will need frequent adjustment during first 100 miles as the donuts settle onto the sprockets and routine tightening for course of ownership. Alternative is to spend money for livefastmotors clamshell mount for rear sprocket which will save lots of install hassle, allow you not to worry about broken spokes. Ensure sprocket is mounted so it runs true. It can be done but takes a while. Have rear tire checked for balance before installing. Clamping donuts onto sprockets can cause wheel to be out of round.
19A. And there are ways to totally avoid the hassle of the chain and bolt on sprocket.
20. Clutch lever and throttle assembly: if kit doesn't have a push button locking clutch lever, buy one.
21. Spark plug: Some have had good luck with the stock plug, but most throw it away and replace with an NGK B5HS or B6HS, or equivalent Champion plug. Rationale: very common for plug to fail internally. It will always fail at the farthest point away from home requiring uphill pedaling the entire way back home.
21. Spark plug wire and boot: throw away and replace with a good automotive plug wire and boot. Rationale: stock plug boot has a small clip that keeps it mounted to plug. It often falls out during ride causing intermittent connecting to plug.
22. Despite the instruction drilling through the frame is not the best thing. There are just so many better options or engine mounts. If you are brave (foolish?) enough to drill through frame don't use factory bolt for front engine mount install. It may shear.
23. Gas tank fuel petcock. Basically throw it away – if you use the stock one, don't use the little build in screen. Get a HD or at the very least different fuel valve. Rationale: The cheesy screen will clog, the stock petcock will break and the basically the valve is a piece of junk that impedes flow significantly making consistent tuning and performance impossible.
24 Fuel line: Always install in-line fuel filter – there are a number of sizes that work perfectly with our bikes. Rationale: needed or crud in fuel tank may clog fuel line.
25. Fuel mixing: Use a dry clean gallon gasoline container. Add some fuel (¼ gallon) then the oil to container, mix and then fill with gas and shake well. Don't add oil to all your fuel at once because it will be a bit more difficult to mix without time and shaking well. Don't pour oil into the dry container for the same reason. Unless it's an emergency don't try to mix it in the tank.
26. 2 stroke oil and oil ratios: The 16-20:1 ratios are unnecessary in well broken in bearing street engines. Run engines at 30:1 - 40:1 when broken in. Follow the instructions while breaking in, but 20:1-25:1 are generally fine and quite oily. You really don't need to keep this up for more than a tank or two – but it does take time to break the engine in. Most kits now recommend synthetic oil.
Some prefer good racing oils because they use castor bean oil. If you wish, buy a gallon or quart of castor from a RC hobby store and blend it with a quality synthetic 2 stroke oil. The ultimate blend would be 1 oz of castor oil with 2-3 oz of Amsoil or other oil of your choice per gallon fuel for the ultimate in engine protection. Castor bean oil does the temperature stability to survive ultimate temperature excursions, but it's unlikely your engine will see this. Castor bean oil does have some drawbacks.
27. Check plug gap on that new US or Japanese sparkplug before install .018-.024 works well.
28. Bike wheel bearings: repack all of them before engine kit install.
29. Bike general stuff: engine vibrates and can loosen many bolts. Including pedals! Brake assemblies fall apart etc...etc..check frequently
30. Fuel tank: put clean bb's or ball bearings (don't use gravel unless it's semi-polished and very clean) in tank before install and shake too loosen rust. Rinse and repeat as necessary. There is lots of rust and crud in many new tanks. Blow a bunch of PB Blaster and allow to soak. Rinse 3 times with gasoline. Some folks will seal the inside of tank...a good idea.
30a. Fuel tank studs: sand paint around studs coming out of tank. JB weld the area. Rationale: some studs leak fuel out of where studs are mounted to fuel tank.
31. Double sided tape: Put double sided tape on bottom of fuel tank. This will prevent scratching of bicycle frame, keep tank from falling off when you are using both hands to mount the frame clamps and nuts. Also allows less torque on tank studs to prevent tank from rotating around the frame. Don't forget to use locknuts and lockwashers and even Loctite. Chain roller bracket: Put doublesided tape on anything that is clamped onto the bike frame. This will prevent scratching paint as you do the necessary sliding back/forward to get correct chain tension and setup. Some often make a new chain as tight as possible by moving bracket as close to rear as possible. Then use the adjustment on the BEARING roller to tighten chain as it loosens from use.
