TM400 Manuals

[TIKI]

TM400 Manuals



Starting to work on the TM400R engine and these manuals I have lack  detail compared to my Yamaha and Kawasaki manuals I have, are these all that’s available for this bike? I want to pressure and vacuum check the crankcase for leaks and replace all seals if needed what position should the piston be in to do this test? If I need to replace the right side crank seal I assume I am splitting the cases as the seal is behind the crank bearing? This is all new to me and I appreciate any advice. Thanks

[pokey]

I havnt bothered with doing a leak test since I learnt how to do them 40+ years ago.
if you think it may be leaky just replace the seals and you will know they are okay. if you dont know the engine history change all the seals anyway as they could be 45 years old sp they will be hard and perished.
Left seal can be done externally, right seal that rarely goes , engine must be split.
takes longer to do the test than it does to change the left seal.

if you want to be perfect, change the seals and then do a leak test

[TIKI]

The main issue with this engine is the kick start lever is not returning which makes it a pain to try to get it running so I assume it is the return spring, can this spring be accessed by removing the clutch cover or am I back to splitting the cases?. It did run a few years ago when I bought it but not long enough to really determine its condition. I am now trying to make it a rider.

[pokey]

just drop the side cover off and you should see it.

[TIKI]

I got the pressure/vacuum test done, the left crank seal leaked so bad that I had to use gasket sealer on it to get any pressure built up at all but after the sealer I pumped it up to 7lbs. it lost ½ lb. in 10 minutes so it passed but I will change all seals except for the right crank as I do not want to split the cases. The 1/2lb was lost at the carburetor manifold to head connection, the metal plate on the manifold has a slight bow in it as you can see in the photos the leak was so slight that the soapy water foamed like shaving cream rather than the larger bubbles that happened at the leaking crank seal.





The kick start return spring is fine and has good return tension so I am not positive as to why is was not returning when it was together and in the bike but it is difficult to really test it on the bench. A few things I did notice it had no clutch cover gasket  only gasket sealer, the kick start shaft seal garter spring was off of the seal and the seal deformed, and there was no thrust washer on the shaft between the kick start gear and the clutch cover as shown in the manual and the parts guide. The thrust washer is an obsolete part but I think I found one on line. I could get this back together and have the same problem of the lever not returning but I will correct what I found and hope for the best. Could a dry deformed kick start shaft seal cause enough friction on the shaft to keep it from returning?