I have the reed block aqdapted to the ts 400 cylinder im raising the export to with in 4* of the tms duration and also raisng the transfers to the same level as the tms and adding in the rear boost port .i also machined the heavyer ts crank to acept a 88 yamaha yz 250 ignition i should be able to make 45 hp eazly and over 32 #s of torque.Im building a new set of forks using the tm lowers with cut down rm 125 tubes with better dampning rods and using emulators for husqy fork s.i will get some pics.

I remember the TM-400 having awsome power but....I'm glad you're working on the handling too.

the original TM400 made all of its power at the time when you didn't really need or expect it

Another TM400 Survivor! Any progress, Ron?

i got a piston for the reed valve cylinder i built and it did not clean up i have to get another from horvac.i have the new forks done except for the springs that i need to get from race tech.im undoing my tm 400 that was set for the ice and getting it ready also for mx i found a good swing arm from a early dr 400  nice steel rectangular about 2" longer the shocks are the same position i had to make bronze bushings to fit the arm and used the tm inner bushings the rear axle is biger so i have to fit larger bearings and make asleeve to fit the axle .time and money.

Ron being a TM guru can you expound on the old suzuzki ad's that inferred the TS series were bred from the winning class Motocrossers of the time ™ that is what simularities if any did they really share with the TM's.

the ts cranks that are porked cchop actually have more mass and is a good thing the ts cylinder is around .050 taller lowering the comprsion the intake port is not as wide as the tms and the exhaust port i beleive is 5 mm taller i have acuratley measured but the specs are in the shop the trans gear all seem to be the same ratios.The ts can eazly be made into a good mx engine .

I now own three TS250's a 71 and 2 72's love the old bikes. I had a 73 XL250 back in the day and although reliable as a rock it was no match for TS250J Savage. I am also working up a 72 TS400J Apache, got the piston from Ron Horvat. Yesterday I installed my freshly rebuilt PE250B engine into the frame, man what a tight fit in the mounts. The PE250 should prove to be a fun woods playbike. :-)

I remember watching a salesman back in 72 "demostrating" a TS250 in the back of Everett Suzuki here in Washington, the parking lot in the back was all pea gravel and that bike broke the rear end loose in every gear!  I asked if I could ride it, and he let me, I thought it was the fastest bike on the planet at the time. The TM's I imagined as just scary fast and only for the likes of professional racers and of course My hero as was everyone elses then The man,  Roger DeCoster.

I did get to ride a TM125 in 73 and it was fast!

Sorry for medandering this thread off topic.....

i kind of have the same feelings about the old bikes we are probally trying to relive some of our past but if thats what it takes too feel good than do it right.

I am in the process of rebuilding another MX bike and I came across a 74 tm400, I like the bike, shift a lot better than my husky. It need a lot of work but looks like a solid project. I was going over all the stuff I will most likely need before I start. the first thing is a piston, I have spent several day looking and cannot seem to find one. anyone got any suggestions? I know when I needed one for my 73 Husky cr250, I got a modifed honda cr250 one. Anyone have an idea if I can mod another one to fit? Also I have been looking at Ron's post and I want to change out the ignition, I cannot find a PVL to fit. I dont mine turning down the crank a little to fit a better igniton, Ron, if you have time can you explain what type of ignition you used? Also where did you get the cool swing arm? I was just sitting out in the shop looking at the bike and photos of Decoster RN73, i think with a little cutting and welding i can make it look like that. I better put the beer down. thanks and if I can get the parts i will start the project and post some photos.. thanks again TGreen