1979 RM400 info please!

[DRH]

Any of you guys own a RM400N or T? I've heard they are nosedivers. Mine is getting a nice treatment, nut and bolt restore with 82' RM465 frontend and works perf. rear shocks. I am still looking for a few parts, like a correct 79 rear fender and and airbox lid and cage, and a good shift shaft. I have a old malcom smith racing skid plate for this bike (very cool little extra) and I am looking for a stick on type of material to go on the frame and clutch cover to keep my boots off the paint. I have seen it before but can't find it anywhere. I would also appreciate any cool tips, tricks and modifications for this bike. Thanks!

 

[SFO]

the stock pipe had a washer in the belly of the expansion schamber if I remember right, that if removed will make this bike a little harder hitting. I also think this was one of those frames that people were cutting the frame backbone, sucking the front wheel in and welding a strap around a 1/2 gap that was created. This made the bike turn better.
It was all in dirtbike magazine with a pic of Kenny Zarht(sp?) on the cover flying the bike over a big trench.

 

[DRH]

Yes, I have already removed the restrictor plate and internal baffles from inside the pipe as they were loose and clanking around. I have never heard of cutting a section from the backbone. I'd love to know more about this one. I'm sure it was probably in some old magazine somewhere. The sad thing is I have never actually ridden the bike, only had it running. How are these bikes powerwise and how do they handle?

 

[docgonzo]

Stock, with the restricter plate, they are fairly mellow but still fast. I only rode the one I had stock, but I've read that with the plate removed, they are very hard hitting and very fast when there is traction. It's been awhile since I had mine but I seem to remember it felt top heavy compared to newer bikes but it was still easy to ride fast. It was also the most reliable bike I have ever owned, for the three years I owned it I put it through hell and it held up very well. It was a great bike and I wish I still had it.

There is a dedicated Suzuki site that has a scan of the original Dirt Bike test on it. If you do a search you should come across it. They gave it a favorable review and tested it with the modified pipe as well as the stock one.

 

[Britt Boyette]

My 79 RM400N was a decent bike to jump but you did have to keep your weight back a little. It wasn't that big of a deal and overall, it never bothered me.
I wouldn't recomend cutting the frame, the bike handles nice. I've read the Dirt Bike review and they didn't mention that mod in that article. They did say that for the CR125 the were testing. Could that be what your thinking about?
The pipe mod was interesting at best. It did hit hard but, my lap times went up. It would snap the tire loose right away. You my friend, will learn respect for the throttle.
The one mod that was worth it's weight in gold was to run the carb bowl vent line straight down in front of the front sprocket instead of over the top of the rear of the case. You will be able to start your bike dead cold in three kicks! When you route it like the book says, fuel will collect in the low side and screw with your float level.
If you have a choice, go with the 80 RM250/400 airbox. It has extra clearence to run larger styles of shocks like Olins. The lid for the top is a mud guard and nobody ever uses them as they have a restrictor plate on the underside. It does use a different airfilter than the 79 though. UNI still makes both.
My favorite bolt on was using foot pegs from a 2001 model DRZ400. Wide pegs made a huge difference. It's hard to keep all of your boot on the stock one because of the way side panels stick out.
Another thing was adding the Clarke stock replacement tank. It's the smaller version of the two styles that Suzuki had back then and it makes the bike feel much slimmer.
The last mod you can do is to add aftermarket bar mounts to the top clamp. Most of these clamps have an offset meaning that you can open up the cockpit by rotating the clamps to move your bars forward. They also have different heights so you can tune the handlebars to your liking.
One really interesting thing I found amazing was how many parts you can still get thur Suzuki. They may still have NOS front number plates for under $30.

<a href="http://photobucket.com" target="_blank"><img src="http://i93.photobucket.com/albums/l50/MotoBrittB/RM40001.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>

 

[Britt Boyette]

Another veiw.

<a href="http://photobucket.com" target="_blank"><img src="http://i93.photobucket.com/albums/l50/MotoBrittB/RM40003.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>

 

[DRH]

Thanks Everyone and thank you britt I was hoping to hear from you as I saw some old posts from you about your 79 RM400. I will definitely be using the DRZ400 footpegs and I have already removed the restrictor plate from the pipe so I'll be in good shape. Why did these bikes tend to be nose heavy? Was it something with the suspension or just the way the weight was distributed throughout the bike? Which peg return springs did you use for the peg swap? I've ridden some real handling nightmares in my day, Like hondas extra flexible late 70's elsinore 250's and and always thought suzuki had the handling department down over them all.

 

[Britt Boyette]

I'm not sure about why they were a little nose heavy but it's really a small matter that you won't notice after you try a few easy jumps. The spring are the stockers. I did have to rebend them slightly to make them work. Again, it's really easy to do. These bike handle very well and respond to air and oil adjustments in the forks. Don't be afraid to try different things.
Another mod you may want to look at is the swingarm chain guard. I went to the 80 T version. You will have to modify the swingarm and the guide a little but it works a lot better than the 79 N version.
Two areas that you want to watch for is the lower frame tubes and the left side peg mount. Some were know to develop cracks in the tubing down in the lower rear area of the frame. Also, after every race day, check the engine mount bolts and the spokes on the rear. They do come loose. And last but not least, blue Locktite is your friend. Buy the big bottle and use it everywhere.

 

[Britt Boyette]

Here's a picture of how I ran the carb vent lines. You can also see the foot peg and the chain guide in this picture.

<a href="http://photobucket.com" target="_blank"><img src="http://i93.photobucket.com/albums/l50/MotoBrittB/RM40004.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>

 

[Britt Boyette]

In this picture, you can see the bar mounts that was talking about.

<a href="http://photobucket.com" target="_blank"><img src="http://i93.photobucket.com/albums/l50/MotoBrittB/RM04.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>

 

[Britt Boyette]

Here's another view.

<a href="http://photobucket.com" target="_blank"><img src="http://i93.photobucket.com/albums/l50/MotoBrittB/RM02.jpg" border="0" alt="Photobucket - Video and Image Hosting"></a>

 

[wirefryer#85]

Chris, that bike is flat-out WOW! :cool:

THAT old girl is how it's supposed to be done!

Bravo!

 

[Britt Boyette]

You should have seen it when I got it. Scrapyard ready! I took it all the way down to a bare metal frame and did it piece by piece. It was a lot of fun and I'm doing it again on a RM370 which is almost done, just got to put the engine back together.
Britt

 

[Flat Track Pete]

I don't know about the nose diving.(Never jumped a bike in my life, well maybe my KTM every now and then). Cutting the frame and pulling the bottom of the steering head in will make it turn tighter (common practice on modified stock frames in the flat track community), but it'll make the bike a little unstable (head shake). I'd look more in to the spring rates and shock valving. Power wise, I've got a 79 RM400N in a Champion Flat Track frame, on most half mile tracks it never runs out of power. Of course mine has a little modification, but the power delivery is more like a 4 stroke. They're a fun bike if you like to do 0 to 100 mph in 4th gear in about 200 yards. (i've never used any more than two gears on a half mile 3rd to start 4th when at speed. I usually shift in the first 100 feet) Well, that bike only weighs about 200 lbs. Good luck

 

[Britt Boyette]

While suspension setup is very important, the thing that one needs to do to make the most out of this bike in jumping is to practice. Sure, it jumps a little different than some bikes but it's not something that you can't learn in an hour of testing. As far as handling goes, it truly is suspension setup. You can dial these bikes in without any problem to turn how you wish.

Just remember, one MUST respect this bike throttle which is the key to getting low lap times.