1971 TM 400 resto

[Davey Crocket]

Frosty, do you walk with a limp?....that's what TM400's do to people, take the good people's advice on here....nobody can see what's behind the mag cover.

[frostype400]

It is one of those things I know that no one can see what it is running but I'd know and then that would bother me because it would be as if I actually wasn't riding a tm.

It is probably silly to say that because the modifications that every one is suggesting would improve the bike but it wouldn't be the same bike.

If you read the tm400 brochure it says that the pei ignition delivers perfect timing at any engine speed they wouldn't lie would they.

[EML]

Here's a tip: fit the std ignition for your mates and put the TS unit on so you don't kill yourself.
A US mag stated that the powerband was variable and was prone to change from lap to lap.
 

[SON]

What a load of 8()LLs#!t
Decent tyres, decent shocks, progressive fork springs,
And a tuned pipe and your fine
TM 400s were dangerous in the 70s
Tame by today's standards.

[80-85 husky]

A mate had a TS 400 and I spent some time on it. brakes were pooh, suspension was ordinary, forks unresponsive and shockers a tad boingy.

The power was sensational, just awesome but the lack of flywheel saw it stall at the drop of a hat.

Just thinking about rear braking would stall the motor and then the compression of that big lung and short stroke would see a lock up into the scrub.

Despite putting some time on the bike, I never got around that issue.

When I read about the flywheel weights, I thought yes, that will do it...

It also shook itself to bits, cracking all the engine mounts..... that motor!

So watch out Frosty, the TS was bad enough with the lock up, the TM will be worse.

so I could see the TM's taking scalps regularly with a lock up and high side being pretty much a first corner event.

[SON]

A mate had a TS 400 and I spent some time on it. brakes were pooh, suspension was ordinary, forks unresponsive and shockers a tad boingy.

The power was sensational, just awesome but the lack of flywheel saw it stall at the drop of a hat.

Just thinking about rear braking would stall the motor and then the compression of that big lung and short stroke would see a lock up into the scrub.

Despite putting some time on the bike, I never got around that issue.

When I read about the flywheel weights, I thought yes, that will do it...

It also shook itself to bits, cracking all the engine mounts..... that motor!

So watch out Frosty, the TS was bad enough with the lock up, the TM will be worse.

so I could see the TM's taking scalps regularly with a lock up and high side being pretty much a first corner event.

Thanks John I forgot to add EBC Watergrooved Brake shoes
And Decent Fuel with a correctly adjusted Carb
TM/TS 400s are fun

[frostype400]

Yes I have one broken engine mount to attend to just needs a quick weld and grind off and it will be ok.

What bikes do you have in mind as dangerous by today's standards because I can't think of any maybe a cr500.

[80-85 husky]

some of the later husky wr 360's were pretty snappy in the power for the uneducated and the ktm 380 had plenty as well and all the big 500's were just that.... big... but compared to those older bikes, the engines are still very useable and the range of difference between different models is much smaller now c/w a tm 400 and say a husky 400.

I found the earlier crf 450's to be very snappy and a handful compared to the other 450' but again, its not that much different in overall feel across the range.

interesting concept though, I haven't heard anyone describe any recent (10 years) models as dangerous ..just different.

[firko]

I found this article on flywheel weights for the TM400.


A BOLT-ON SOLUTION for TM400 sweaty palms?

Some people have this healthy fear of snakes. Others cringe inwardly when they find themselves alone in a dark room. Yet others can’t stand being up high, or even worse-flying in an airplane. All of these fears pale by comparison to the fear-inducing potential of a stock 400 Suzuki MXer. This is one of the truly Frightening Machines Of All Time.

What makes it increase your pueker power? Part of the problem lies with the frame. another part with the suspension—but the bulk of the guilt lies with the power band of the engine.

There is no such thing as “just a little more” from the twist grip on the TM 400. Nosirree. You either get a giant handful or the engine stalls. This phenomenon is, of course. caused by the lack of flywheel weight. A logical cure, then, would be to bolt on some weight to slow the rev buildup down to a more usable level. Remember, power that does not get to the ground is wasted power. And slower building revs mean that the bike will be easier to ride. At least in theory.

And that’s why DIRT BIKE decided to test S0me of the bolt-on flywheels currently on the market. Woodland Hills SportCycle supplied the bikes and the equipment for our controlled testing. Along with our intended test of the 400, a flywheel was also bolted on the 250 MX. Even though this model doesn`t have the jolly gruesome of the larger machine, Woodland Hills SportCycle claimed that it makes the 250 into an easy to-ride trailbike.
 
The bikes were ridden in standard trim first, to get the feel of the stockers. If you read the test in the October “72 DIRT BIKE, you’ll remember that we were favorably impressed with the power band of the 250, so we really couldn’t see why SportCycle offered heavier wheels for this bike. Their reasoning was that some people might want to take the 250 trail riding or something of that nature. They claimed that the addition ol their flywheels would allow the rider to bog the engine down to very low r’s. Would we test the 250 also? Sure. Why not?

Our other machine was a brand-new, totally stock 400 Cyclone MX. For this machine, we had two separate flywheels to try. A 2-pounder and a 4·pounder. We chose the heavier item.

Off to the trails went the DIRT BIKE Wrecking Crew, with two Suzukis in tow. Both, as previously stated, were first ridden stock. The 250 was as we remembered it—decent power and very rideable. It could be ridden at very low revs for a racing machine low gear would let the machine move forward at a walking pace with the clutch out, just above idle. Any slower than this and it was necessary to slip the clutch to keep the engine from stalling.

A 2-pound flywheel was then bolted on the 250 (after a trip back to the shop). The 250 will not accept the 4-pounder—2 is the maximum.

An immediate difference was felt in the engine performance characteristics. Not all of it desirable. While the engine would lug down lower and smoother, engine response was sluggish. Not only did it take too long for the revs to build, but it also took a great deal of time for the engine to return to idle when the throttle was shut off. Much like a trials machine.

One additional factor made itself felt: The rear brake was less effective and had difficulty slowing the bike down. This will always be the case where heavy flywheels are working against brake shoe efficiency. In the case of the 250 Suzuki, however, it never had a giant reserve of brakes for starters, so this cannot come under the category of a Good Thing. No way. A rider who installs a heavier flywheel on the 250 will find his lap times on the motocross course getting slower. For trail riding? Even though we feel it makes the engine more tractable, the undesirable side effect on the rear brake makes us hesitate to recommend its use on the 250. Unless the rider modifies the rear brake to be more efficient.

Our attention turned to the 400. First a ride on the bike in standard trim. Culp. The merest tweak on the throttle produced a spinning rear wheel. Or if there was a modicum of traction available, the front end would leap for the nearest cloud. If contact was made with a series of harsh bumps, the machine would slither and hop sideways in an instant. Coming out of a corner under heavy power was a true adventure, indeed.

Back to the shop and zip-bam-boom—there we were with a heavy wheel bolted on. This one a 4 pounder. Back to the riding area, and a pleasant surprise. That 4—pound slab of steel did astounding things for the 400 racer. No kidding. Without taking a single iota away from the top end of the Cyclone, it made the power band almost pleasant. Additionally, much of thc tendency for the rear wheel to lock up under braking was eliminated. Unlike the 250, the 400 had an overly sensitive rear brake.

This is the best thing, the single best thing a rider could possibly do to a stock 400 Suzuki. In Fact, there really ought to he a law requiring the installation of the 4-pound wheel before the bike can be sold.

Much of the sideways hop disappears and the machine is infinitely more tractable. The bad handling is still there, but even this is helped considerably because of the more predictable throttle reaction. One can almost trail ride the bike—but not quite. We would recommend that the rider go for the 4-pound flywheel rather than the 2 on the 400.

Woodland Hills SportCycle offers these wheels either mail order or at their high-rolling shop. The address is 22726 Ventura Boulevard, Woodland Hills, California 9136-1. Phone number (213) 340-2191. Tab for the items is $19.95 For the 2-pound wheels and $23.95 for the 4-pounders. They pop for the postage if prepaid and you get burned For the tab on COD stuff. If you stop by the shop, they’ll install the wheel For Free. Providing, of course, you bought it there. Don’t expect much more than a nice smile if you bought yours in Wilmington, Delaware. Oh yes. They have all manner of trick items for the Suzuki line of dirt hikes and will send you a free brochure if you want to gamble a stamp. It’s your stamp
                                                      


The "Skunkworks" brand 4lb flywheel weights on my own TM400 .

[Simo63]

The "Skunkworks" brand 4lb flywheel weights on my own TM400 .

Great article Firko, thanks for posting it.

Just a question.  Does the modified flywheel (such as your skunkworks one) fit under the standard sidecover with the weight attached to the rotor?  Just looks a bit too wide?

[firko]

 

Just a question.  Does the modified flywheel (such as your skunkworks one) fit under the standard side cover with the weight attached to the rotor?  Just looks a bit too wide?

It fits fine Simo.

[80-85 husky]

I rekon that alone would transform that bike to something very enjoyable.

[SlideRulz]

As mentioned previously there is a great article on this Beastie in the latest VMX mag.
Considering it's an OZ publication I'm disapointed they didn't mention that a Hazel & Moore entered TM400 won the 6 hour race at Nepean in 71.
Suspension isn't as important on DT nut they must've been pretty quick, might be the first of those disgusting oil burners to win the 6 hour.
I'd own one.

[yamaico]

As mentioned previously there is a great article on this Beastie in the latest VMX mag.
Considering it's an OZ publication I'm disapointed they didn't mention that a Hazel & Moore entered TM400 won the 6 hour race at Nepean in 71.
Suspension isn't as important on DT nut they must've been pretty quick, might be the first of those disgusting oil burners to win the 6 hour.
I'd own one.

Do you remember who was riding it Steve?

[SlideRulz]

Sure do Pete, 3 Legends, well 2.5.
Brian Martin (Kiwi), Brian Clarkson & brother Carlos.