I thought this would be a good time to bring the Bible back now that it├óÔé¼Ôäós springtime and people are going to have a TON of problems breaking out their mopeds. This tackles everything from minor performance upgrades to basic rebuilds and troubleshooting techniques. These are taken from MopedArmy.com, MopedRiders.org, TomosMopeds.org and my own experiences. Hope this helps someone.
JETTING, JETTING, JETTING:
Jetting is the only sure-fire way to ensure your motor├óÔé¼Ôäós getting the proper mix of fuel and air and plug-chops should be done for many reasons. Season changes, humidity changes, altitude changes, new or different types of spark-plugs and after performance-part installation.
NO REPLACEMENT FOR DISPLACEMENT:
Granted, boost-bottles and Nitrous Oxide have been used to hop-up small weed-whacker motors. HOWEVER, they are not a proven (or practical) method of adding performance. Sure, if you plan to race your ped├óÔé¼┬ª or blow yourself up├óÔé¼┬ª you can do whatever you want. However, from what I├óÔé¼Ôäóve found 1) boost bottles are used on larger ATV├óÔé¼Ôäós to ensure equalization in mix and pressure between carburetors. They can create an increase on HIGHLY MODIFIED mopeds. I.E. Max Payne├óÔé¼Ôäós Tomos.
Therefore there are minimal, if any, performance gains with a boost bottle on a stock 50cc ped. Sorry. 2) Nitrous Oxide is a fools├óÔé¼Ôäó fuel. Your ped will require HEAVY modifications in order to accept Nitrous, and even then, it may not work correctly. Nitrous Oxide will work best in the CLEANEST Air/Fuel environment├óÔé¼┬ª Throwing the mix-oil in really gums-up the works of the Nitrous Plumbing and can cause problems down the road. Nitrous is mainly made for 4-stroke motors├óÔé¼┬ª nuf-said.
EXPANSION CHAMBERS MAKE THE POWER:
Simply removing baffles and drilling holes in your stock exhaust restrictors may work for most 4-stroke motors. However, 2 strokes need a bit more of a technical approach when it comes to expelling fumes. Expansion Chambers create a variation of sound waves that help to regulate the flow of exhaust through the chamber├óÔé¼┬ª This creates a mini-vacuum which actually facilitates "sucking" exhaust out of the motor├óÔé¼┬ª The back-pressure is normally aided by a sharp bend in the pipe or a series of baffles in the silencer. Some guys may gain a few MPH out of their stock exhaust by removing the silencer or drilling holes. However the most efficient way is with the expansion chamber.
LET IT BREATHE:
Drill holes in your air box, add a K&N filter, use the classic "pantyhose" filter├óÔé¼┬ªIt will not only get you some power gains, but also sound much better than the stock "mosquito" buzzing.
GEARING:
On most models├óÔé¼┬ª the more torque you want, the smaller sprocket you want on the MOTOR end. The more speed you want, the larger you want the sprocket on the motor end. This is opposite for the rear. Finding a good balance of speed and torque is where you need to get. A stock Tomos A35 will go 30 off the show-room floor. It will be a little rough on steep hills however. Solution├óÔé¼┬ª 25 tooth sprocket on the front (rather than the stock 26). Boom├óÔé¼┬ª Goes up hills fine├óÔé¼┬ª however, you now only go 26-28mph. Thus, balance.
Using this setup with a 70cc kit, 16mm carburetor, performance exhaust and all the other bells and whistles you could do to your motor├óÔé¼┬ª. You will FLY from a dead stop, however the sprocket will restrict a lot of the speed you should be making. Throwing a 32 tooth sprocket on the front may just balance things out to where you had near-stock acceleration from a stop, but end up going upwards of 45+mph.
SPARKPLUGS & PLUG-CHOPPS:
Ok├óÔé¼┬ª Plug-Chops may be done at any time to determine what is really going on inside of that motor of yours. Install a BRAND-NEW plug in your motor EVERY time you do a plug-chop, otherwise you won├óÔé¼Ôäót be able to determine the exact color of the chop.
This step mainly consists of making sure you have the new plug in correctly and starting your moped. Leave it sitting at an idle for a couple minutes to warm up. 5-10 minutes should do. Take the bike out and run it at FULL THROTTLE for about 1 mile. At the end of a mile CHOP the ignition (cut it). Roll to a complete stop, pull over, and take out the spark-plug. If your plug is WET or black, you├óÔé¼Ôäóre running rich, time to down-jet.. If you├óÔé¼Ôäóre running white or pitting the plug, you├óÔé¼Ôäóre running lean, time to up-jet. This chart gives an example:
OIL-FUEL MIXTURE:
In most-all moped manuals they recommend you use 50:1 mixtures with 1 part being 2-stroke oil and 50 parts being 90+ octane gasoline. This ratio is even printed on many gas-tanks as a reminder to the owner that they simply can├óÔé¼Ôäót pull up to the pump and go.
Even though 50:1 is the recommended ratio by the manufacturer, many owners and even dealers will tell you differently, especially for brand-new break-ins. It is recommended that for the first 300 miles you PRE-MIX your fuel (DONT USE YOUR EQUIPED OIL INJECTION) to 35:1 with an "industrial" grade non-synthetic 2 stroke oil. This will typically be any kind of boat-motor, chain-saw, or weed-whacker type oil. (I personally used STHIL chain-saw oil for mine). After the 300 miles run regular AMS-OIL or the equivalent synthetic-based oil at a mixture of 40-45:1. This will ensure all of your parts are getting properly lubricated and won├óÔé¼Ôäót have any ill-effects on your motor or performance. If you have oil-injection, simply add a cap-full of mix-oil to your gas tank at each fill-up and swash it around really well IN CONJUNCTION with your oil-injection. (or simply disconnect it and run the pre-mix)
NOT RUNNING?
There are a few basic things you need to get a motor running; air, fuel, compression and spark. Missing one or more of these things will cause a motor not to run. Here is a 2 hour breakdown of what you need to get running. (3 or more if this is your first time).
1.Make sure the gas-tank is CLEAN and all lines, petcocks, and filters flow nice, clean gas. If you├óÔé¼Ôäóre getting drips, leakage, or blockage, your moped will not run properly. Even if your hoses attach with friction nipples, use hose-clamps and CLEAR fuel hose, this will help you see what├óÔé¼Ôäós going on in-between your tank and your carburetor. BE SURE to use a new fuel filter (motorcycle grade) when re-installing the hose and lines.
2.Clean your carburetor. Take apart the carburetor as far as possible. This includes, bowl, float, float needle, jet, jet tube, throttle slide, throttle spring, choke slide, fuel intake banjo, intake filter, and needle valve. EVERY HOLE ON A CARBURATOR DOES SOMETHING. Make sure all holes are clear of debris! Use a small needle, or thin piece of wire to poke through holes. (Taking the paper off of half of a baggy-tie works best, that way you have a small handle to work with.) Use carburetor cleaner on all parts inside the carb. Use GOGGLES and GLOVES. Carb cleaner is NASTY stuff and can cause blindness if it gets in your eye. Be sure to re-assemble the carb in the same order you took it apart. Go slow, take your time, you want to be sure everything goes together properly.
3.Clean the air box. If you have a steel-mesh air box, soak it in gasoline or carburetor cleaner over-night. Shake it out or use compressed air to blow out the excess dirt. If you have a foam filter, soak it in gasoline.. allow it to dry.. and then re-install it. Paper filters and K&N filters are normally aftermarket and come with their own directions.
4.Clean the exhaust. Bake it in a BBQ to dry the built up oil and carbon inside the pipe, then simply bang it all out. Either that or use carburetor cleaner and penetrating oil to dislodge the sludge inside of your pipe. Allow it to soak for an hour, then re-apply the cleaner. After another hour, knock it around and flush it out with fresh gasoline. When the gasoline comes out clear, it├óÔé¼Ôäós pretty clean.
5.Carbon buildup. Check the inside of the exhaust port on your cylinder and be sure there├óÔé¼Ôäós no black-hard carbon buildup around the opening. If you have the time/skill, take the head off of your moped and check to see if there├óÔé¼Ôäós any buildup on the top of your piston or around the spark-plug hole in the head. This needs to be cleaned and taken care of.
6.Change the spark-plug. Most Tomos mopeds use a B6HS NGK plug, some Puchs run B7HS NGK plugs, it all depends on your chops and what you need specifically for your motor. Your best bet is to get a couple of each, you can never have too many spark-plugs.
7.Checking the spark. Take the plug out of the head and attach the plug wire to the top. Place the threads of the plug against the head of the motor and have a friend crank the motor over for you. BE SURE not to have your hand on the motor or on the metal end of the plug-wire. No one likes to get shocked. Anyway your spark should be BRIGHT white and flitter with ever revolution of the motor. If not, you have a bad magneto, capacitor, or plug wire.
8.Compression: (you need a compression tester for this) and points (you├óÔé¼Ôäóll need feeler gauges for this). Take the plug out of the head, and put the compression tester in its place.. Crank the motor over and check to see how much compression you have. All motors run at different compression rates. Your points are located under your stator plate of your moped. These points open and close in correlation to the advance and retard of your timing. The gap set between these points is imperative to having proper spark. Check this site for your bike and it├óÔé¼Ôäós rated compression and points gap: http://mopedriders.org/article_cat.php? ... 2ea0313129
9.CHECK ALL SWITCHES AND WIRES. Be sure there are no frayed wires, cut wires, loose wires, or disconnected wires. Be sure all switches are working properly and that there is no rust or corrosion in the connections or switches.
After all these steps have been completed, be sure everything is put back together properly, all nuts and bolts are tight, and there are no fuel leaks, add some mix gas and kick it over. It should start├óÔé¼┬ª If not, some of your parts like points, and other electrical parts may be damaged or malfunctioning and may need to be replaced.
TIRES:
Check your tires for dry-rot every now and again. To maintain the quality of the rubber, keep your moped in a fairly climate controlled area. Dry rot is caused by moisture, and changing temperature, causing the expansion and contraction of the air inside of the tire. This can cause stress cracks and splits within the rubber and may cause shredding, uneven wear, and even blow-outs at traveling speed.
BRAKES:
Brakes can easily be checked from the two plugs in the side of the drum housing. If you notice the pads are getting worn down past half way, it├óÔé¼Ôäós about time to think about changing the pads. When changing the pads, be sure you clean the wheel drum with brake-clean and lightly sand the contact surface on a 45degree angle. For re-installing old pads, you may want to do the same to get rid of any old dust or residue. You may not need to do this for new brake pads, but it is recommended. When re-installing be sure all areas (OTHER THAN THE PADS) have been cleaned with brake-clean and hot-soap and water, and have had enough time to dry thoroughly. When the wheels and brakes are back on the bike, be sure your cables are not frayed and are working properly. You may want to remove the cable from the sheath and oil it down with some light oil. Reinstall the cable with the handle end completely loosen the adjustment. Pull the lever on the brake housing until the brake grabs, then back it off a tad and attach the cable to the pinch-nut. Now, all your adjustment will be made up at the handle.
(TOMOS brakes are notorious for being spongy and not gripping properly. It has been found that if you adjust them to be tight and then run them for a while, they will wear in and begin to grab properly. If this doesn├óÔé¼Ôäót happen, you may want to contact your dealer.)
CABLES AND CHAINS:
Be sure your chains are tight and dont have a whole lot of ├óÔé¼┼ôsnake play├óÔé¼┬Ø in them. To check for snake play, take the chain off of the ped and bend it from side to side. If you├óÔé¼Ôäóre finding the chain can almost be bent into a U, then you need a new chain. There should be BARELY any bend in the chain. Be sure to use a good chain or gear oil on your chain before riding.
Cables should be checked for frays and for stretching. If your cables are spongy you may need new ones.
BASIC 2 STROKE OPERATION:
In order for you to completely understand everything about your moped you need to read up on it. Your moped is unique in that no two mopeds are the same in the way they operate with YOU as the rider. You have to think of your 2 stroke from a couple different angles├óÔé¼┬ª How the air├óÔé¼Ôäós getting in├óÔé¼┬ª How the fuel├óÔé¼Ôäós burning├óÔé¼┬ª How the exhaust is getting out├óÔé¼┬ª and how the power gets to the ground. The more air and fuel means you├óÔé¼Ôäóll need a larger place to make it all combust evenly means you├óÔé¼Ôäóll need more spark to make it combust properly means you├óÔé¼Ôäóll need the most effective way of getting the exhaust out of the motor.. All this power means you├óÔé¼Ôäóll need a good set of gears to get the power to the ground (and a good set of tires). And even after all of this modification├óÔé¼┬ª the only way to ensure everything├óÔé¼Ôäós working properly is through plug-chops and re-jetting.
SOURCES:
http://www.mopedarmy.com
http://www.tomosmopeds.org
http://www.mopedriders.org
http://mopedriders.org/article_view.php?faq=2&fldAuto=8
http://mopedriders.org/html/manuals/tom ... 35p017.jpg
http://Hondaspree.net
Amen├óÔé¼┬ª
Darat
PS: If you have any COMPLAINTS or AMENDMENTS to this post, please add them in a courtious and informative way. Thank you.
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