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Technical Re-Port Stalking tbewild Suzuki TM/TS Suzuki 400 re-po rt d iagra m 43m m _ _- - L This article is intended for the person wh o either owns or is considering the purchase of a 1973 or 1974 Suzuki TM 400. The . information contained here will help obtain the maximum amount of useable horsepower and, thereby, provide a more controllable machine. Notice I said useable horsepower, not maximum horsepower. Most riders prefer lots of low-end power, super mid-range power and good top-end power to the actual peak horsepower capable of being produced by the engine. The following paragraphs provide a detailed procedure that actually works for obtaining these results. If you do not already own a TM 400, but are getting one, you might try to get the dealer to trade your TM cylinder for a TS cylinder. The first thing to do, and the most time consuming, is to make the necessary port modifications as shown in the accompanying diagram . Bevel the lower edge of the transfer passage and rad ius the divider in the port base (next to the base gasket area) . Next, ma t ch th e rubber inlet mainfo ld with the cy linder to eli minate the sh arp edges. Th e cy linder is now ready to b e installed. If yo u wou ld like to ma ke t he b ike easier t o kick sta rt , ins t all a st ock TS 40 0 co m pression rel ease abo ve th e exhaust port. Otherw ise, plug the h o le at this ti me. Remember , however , th at if y o u loc k up th e r ear wh eel an d th e co m press io n release is install ed, a simple flick of the release lever will ge t th e engine running again. The next st ep to be p er formed is to d ean th e h ead an d polish the chamber. Polishin g the ch amber help s retard the build-up of carbon in th is area. You can no w install the cylinder an d head usi ng the stock gaskets, piston and rings . There are th ree methods of ch an ging th e rotating mass of the crankshaft to obtain more even power pulses and th ereby ma ke the engine more tractable. Th e firs t, and mo st expensive and time-co ns umi ng, is to replace the TM crankshaft with one from a TS. This places the mass between the main bearings ; which is, technically, where it should be pl aced. The second choice is also ex pensive, b ut not near ly as much as replacing the crankshaft. This choice invol ves installing the co m plete magneto assembly fr o m th e T S onto the Tl\l crankshaft . ' Th e third option, an d th e on e I use for th e desert, is to install a brass fly wh eel weighin g two and three qu arters pounds. I have been usin g this method for o ver a year an d find th at it is not only the least expensive o f th e three meth od s, bu t also wor ks very well. Th e next step to be pe rfo rmed in volve s the carburetor. The parts listed be low are used to mod ify th e stock 34 mm carb that co mes with the bike. Howeve r, since these modifications are designed to be used in my area (altitude approximately 2000 feet), you should pr o ceed with caution while trying to 1 OC] Ex By Nile Downe r, Manage r, Mesa Suzuki, Mesa, Arizon a r Stock Stock In Base Major porting is confi ned to radiusing the bottom of the inlet port. determine the proper jet size for your altitude. Just remember to stay on the rich side until you get some time on the engine . Slide : 2'1.. cutaway Needle: 6FJ6 with the clip posit io ned in the second notch fr om the t op. Needle jet : P3 35 Pilot jet: Main jet: 260 If you are going to use a 1973 TM 400 pipe, start by removing the baffles inside. An easy way to do this is to locate th e spot welds on the back side of the pipe and drill them out with a 5/1 6 drill . These welds hol d the baffles in p lace an d also indicat e where the pipe should be cut apart. Cu t the pipe and remove the baffles. Reweld the sections back to geth er . Next, trim the rear section t o o b tain th e proper di ame ter and weld on so me kind o f muffler with an inside diameter of 1-3 / 8 " . If y o u are goi ng t o u se the 19 74 pipe, all that is necessary is to remove the o ne screw holdin g th e cen ter sec ti on in th e bolt-on m uffler . . Now th at th e exhaust pipe an d muffl er ar e inst all ed, th e en gine is ready to start. Warm the engine up an d finish zeroing in o n the carburetor settings. Remem ber th at th e mi x tu re should be a little rich at first until you h ave some time on the engi ne . The engine will lean down a little by itself after being run in, due to the increased compression obtai ned from the rings properly seating. Here are a few more things to do th at will make the bike a little nicer to ride : • Change the rear sprocket to an aluminum 45 tooth sprocket. This will permit you 10 use stoc k Suzuki countershaft sprockets 10 obtain an overall gear ratio that will fit most occasions and with minimum effort and co st re quired: • .Ro u t e the air vent line from the o il ta nk down the left side of the fram e to the area just above the chain. This ma kes it easier to clean and also permits any oil that escapes to drip onto the chain. Install one of those 10 d o llar fork ki ts up fro nt. Ad di ng 30 weight oil seems to work just abo ut right . • Add solid a luminum bars, sin ce they don't bend as easily. They also absorb some of the vib ration . Install a skid plate to pro tect the pipe a nd clutch actuator. • Replace the rear shock units only if you've tried the original o nes and don 't like them. Resu lt : more t orque th rough t he range for controlled slides like this. Mesa Su zu ki modifications have been done on a number of cu st o me rs' TM 4005. 1 5