Been wrenching a lot this past week and thought I’d share a few things that came back to me with whoever is interested. I hope others add more tips to the thread.
Two Stroke Base Gaskets: They often protrude into the cases and cause an area of turbulence for the air trying to get up into the transfer ports. May not be a big deal on a stock engine that has a number of mismatched spots in this area, but this particular engine has had the cases matched to the cylinder, so any obstruction by the gasket defeats the purpose. The fix is to firmly hold the gasket in place and trim the excess with a razor. Just be careful you don’t cut though, or get off track if the gasket shifts. Best have a spare handy the first time you try it.
Intake Manifolds: Big carbs and ported intakes are great, but a stock intake boot between the two usually ends up choking the path of air. The best way to fix this is to open them up with a wood cutting bit on a drill or die grinder. If the head is off the engine it is really easy, but if it is on the engine you can stuff a rag deep into the intake tract to keep the rubber and any aluminum out of the engine. It seems a lot of people skip this either because the builders don’t have the intake boots when they do the head, or they don’t want to spend the time. This mod makes a huge difference to top end HP. If the boot looks rough after you finish you can remove it and polish it up with a sanding drum, but don’t do this while it is on an assembled engine. A little rubber and aluminum won’t anything, but sand particles will.
Exhaust Pipes: For whatever reason (cost?) some pipes come with unpolished welds where the mounting collar is welded on. Take a minute and smooth them out with a die grinder before you mount the pipe.
Spark Plug Indexing: This one is a stretch, but why not try it. The theory is that you scratch the base of the plug, or mark it with a Sharpie to indicate where the open side of the electrode ground is. You then try to tighten it to have the open side facing either towards the center of the combustion chamber, or in the case of a HEMI, into the path of the intake charge. You need to start with a new plug so that the washer has some life in it, otherwise you’ll be too loose, or too tight when you hit your mark. Pro-Stock guys swore by this at one time, not sure if it is still practiced.
Carb Leveling: Some carb/manifold combos, especially aftermarket, don’t have an alignment mark, or groove. This makes it difficult to tell if the carb is level. Even worse if it’s a two wheeler resting on the side-stand, or the intake is offset to the side. To make sure the carb is as level as it can be remove the cap and rest a 12 inch machinist’s level across the top of the carb. The level should be as close to parallel to the crankshaft as possible. Then loosen the manifold boot and have a buddy balance the bike from the rear while you twist the carb until the bubble shows level and snug the carb up. If you are doing this on a trike make sure the rear tires have equal air pressure in them before you start.
Chain Alignment: Picked this up about a year ago after seeing it on a Motion Pro “Tool of the month” email. It is fantastic! Alignment marks are iffy at best and measuring from swing-arm pivot to axle is a PITA, neither will get you as lined up as this thing. I just wish the rod was a little longer. You’ll get your investment back in extended chain life and rear wheel HP in no time at all. If you aren’t sure you’re using it right invite a buddy over that shoots rifles, plays pool, or lays bricks for a living and he’ll figure it out for you.
Chain Tension: Raise the trike or bike. Disconnect the rear shock(s). Raise and support the swing-arm until the rear axle, swing-arm pivot and counter sprocket line up. Unless you have some sort of weird geometry going on this should represent the furthest distance that your rear sprocket will ever be from your front sprocket. Find the tight spot on your chain (they all have one) and with the chain in that position adjust the axle until the chain has about ½” inch of play in it. Double check it after you tighten the axle as it may get tighter. Repeat until its right, and then put your suspension back on.
Front Axle/Fork alignment: Don’t obsess over the difference in height between the two fork tubes as they sit in the tree. Try to get them close, but don’t worry if they are off by say a couple mm. What is critical to a supple fork action is the distance between the two lower axle mounts, especially on inverts, and long travel forks. Typically your axle will thread into and tighten up against the inside of one of your forks , the furthest one from the head of the axle, usually the brake side. Start by raising the front wheel. Now install the axle and tighten it fully. Make sure the pinch bolts are torqued on the side the axle threads into. Now make sure the pinch bolts on the other fork are loose and using a flat tipped screw driver pry it open a little. Grab the fork leg and make sure it can move laterally on the axle. Now spin the wheel with your hand and slam the front brake on. This will jar the suspension and cause the loose fork leg to align itself parallel to the tightened fork. Do it at least three times, the harder the better. Tighten the pinch bolts and try it out. This adjustment makes a huge difference to the first few inches of travel and saves your seals and bushings. If you want to get really obsessive you can loosen the tree clamps on the fork you just aligned and repeat the spinning wheel/front brake lock so that the spring pre-load balances between the two forks. If you do decide to do this I recommend you repeat the axle alignment steps afterwards to be certain nothing changed.
Throttle Cable Adjustment: While free play from lock to lock is critical in the cable it’s always a good idea to pull the carb off, or get a good look inside after you’ve changed, or adjusted the cable to make sure that the slider is opening all the way when the throttle is wide open.
Clutch Cable: The best way to make sure you’re getting all the release you can, but not holding the clutch pack open when you ride is (if possible) pull the oil filler cap and get your pinky finger onto the pressure plate of the clutch. With your other hand gently pull the clutch lever in until you feel the pressure plate release. Now slowly release the lever until you feel the pressure plate stop moving. Repeat until you are sure when the clutch pack is free and when it is closed. You can adjust the cable accordingly until there is almost immediate movement of the pressure plate when you pull the lever. Now screw the adjuster at the lever in one full turn and check once more that you can move the lever a little before the pressure plate starts to move. If all seems fine snug your jamb nut and you are safe to ride while still getting as much opening of the clutch pack as possible. Makes finding neutral a lot easier and has no adverse effect on the life of the clutch. As the clutch wears the lever will have more free play and you will have to repeat the process.
Reply With Quote
Originally Posted by 3wheelrider
