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Old 12-02-2008, 12:15 PM   #1
tbirdsp OP
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1976 RM370A Project

Here is the RM370 I just bought (seat is off of a 250). Needs work but runs well. PO said it was a '77 but it's a '76. I'm not going to do a full resto or anything, just make it mechanically sound and clean it up a bit. Lots of cool stuff available here http://www.vintage-suzuki.com/
This is the first 2-stroke bike I have ever owned After my short test ride I think the first thing I need to fix is the kill switch



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Old 12-02-2008, 10:21 PM   #2
ADV8
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Nice score and handy link.



Model Frame Number Engine Number
1975 RM125M RM125-10001 - 30000 RM125-10001 - Not Applicable (Notes)
This is a mid-year model identified by downpipe
1975 RM125S RM125-19800 - ? RM125-19800 - ?Not Applicable (Notes)
This bike is very rare in the "states" to learn more about it buy VMX Magazine issue #20 2003' . The article is entitled " The Day the TM Died". Here's your link to order the issue: www.vmxmag.com.au . We also sell a RM100-125 Service Manual on CD that has the specs on this little bullet, check our Manuals page for more info.


I still have (in boxs) the 1976 RM125S i bought new (Factory hotted up with porting and 34mm VM Mikuni)

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Old 12-03-2008, 05:22 AM   #3
Yossarian™
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Nice snag, Mike. This reminds me of the DT250 I used to own way back when.

I'm sure you will have a lot of fun getting the sucker into modest shape, and then letting it whoop your rear end!
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Old 12-04-2008, 07:54 PM   #4
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Any RM370 gurus here?
I e-mailed these questions to Vintage Suzuki, but if any of you guys can help it would be great. All I have now is the Clymer manual which covers many bikes. I should have a reprint of the factory manual on the way soon though. I have attached some pics to help clarify my questions.

1) The forks on this bike have unusual thick caps with air valves which face horizontally to the rear. From what I've found the 370 didn't have air forks. Also any of the RM's *with* air forks don't look like this as far as I know. Is it possible that this was a modification? Is there any way to tell if these are the original forks? They appear stock otherwise.

2) Other than the lower chain guide roller on the swingarm (mine is missing) I can't find any forward roller(s) or chain sliders on my bike or any provision for mounting them. Nothing in the fiche that I can see either. Is this correct or am I missing something?

3) I know the 370A and 370B have differences in the swingarm and rear wheel. However I have seen several references which suggest both the '76 A and '77 B use the same rear brake shoes. Is this correct?

4) My bike has a seat from an RM250 on it. Mounting points match up perfectly. The pan is made out of plastic (370 was metal?). There seems to be a pretty big gap between the front of the seat and the back of the tank but I looked at several other bikes and this appears normal. Is this seat the same as the 370 seat?

5) (Vintage 2-stroke noob alert) This bike runs pretty well. I figured that it wouldn't idle because the carb was dirty. However from the Clymer I gather they weren't supposed to idle, you just have to keep blipping it to keep it running. Is this correct?

6) There's a small hose fitting on the left side of the crankcase. On the fiche it just has a "hose" connected to it. Is this just a breather?





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Old 12-05-2008, 08:33 AM   #5
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not much help, but...

those look like aftermarket air caps. was pretty common back then as a mod, even though it also meant a lot of people prematurely killed their fork seals by pumping too much pressure into them then bottoming off the first jump.

if i recall, "goki" was one of the main brands for those.

i would *guess* that the seats would be about the same, but don't recall for sure. not much idea bout the rest of things, except i recall all our old 125 and 250 mx bikes not idling back then. some mikuni carbs from that era maybe didn't have idle screws, but man, i dunno.
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Old 12-06-2008, 05:04 AM   #6
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Answers from Tony at Vintage Suzuki:

Bike looks like a 1976' RM370 with 77' RM370 reserivior shocks.

1- air caps are aftermarket, front forks are correct for 1976'

2- has rubber chain defence at swingarm pivot bolt.

3- brake shoes are the same

4- 76' bikes came with metal pans, plastic is the same and prefered. Foams would be the same.

5- stock carb has no idle screw, not designed to idle

6- crankcase breather hose
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Old 12-06-2008, 07:03 PM   #7
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Started tearing it down some. Fork seals bad, front brake shoes worn and soaked with fork oil. Head bearings loose, probably bad. Swingarm bearings marginal, I'll probably leave them for now. Shocks both leaking at the rod seals and right one has a bad hose. All control cables bad and will be replaced.
Ordered about 50 bucks of bits and pieces that are still available from Suzuki. Was able to find a NOS chain guide online, roller and bushing still available from Suzuki. Frame, tank, and body work (and bars-WTF?) have rattle can paint jobs (note overspray). Side covers and front fender are in pretty good shape though, no cracks at all.
Amazingly simple machine. Hard to believe it was state of the art in it's day.



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Old 12-10-2008, 09:06 AM   #8
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Got the forks taken apart today. The aftermarket air caps are a pain in the ass They are too big around to fit down through the triples. OK, so take them off - except it's a giant wrench (32mm was too small) and then the air valves hit the bar clamps on the top triple. Tried to slide the tube up to get it to clear but there's enough minor corrosion on the tube (just the part that's in between the upper and lower triples) to make that difficult. Finally had to just rotate the fork tube a bunch of times until the cap unscrewed. (edit: duh, you can just unscrew the air valves from the caps to get room to turn them.)
Lots of corrosion under the dust cap where the oil seal is. Gonna be hard to get the circlip out. I have them soaking in PB Blaster now.
Also discovered why the forks seemed kinda "saggy" - there's no preload spacer installed even though the book shows one.
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tbirdsp screwed with this post 12-13-2008 at 11:30 AM
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Old 12-12-2008, 08:35 PM   #9
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When you get her all ship shape, I'll buy it for $299.99. Deal?
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Old 12-13-2008, 10:49 AM   #10
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You gotta get an exhaust like the one in the stock Suzuki pic. I love it.

Looks like a fun project.
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Old 12-13-2008, 11:17 AM   #11
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Quote:
Originally Posted by crazydrummerdude
You gotta get an exhaust like the one in the stock Suzuki pic. I love it.

Looks like a fun project.
The 370 never had an exhast like that though.
Here's what a '76 370 is supposed to look like. I couldn't get the images to link direct for some reason
http://www.vintageworksbikes.com/1976SuzukiRM370.html
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tbirdsp screwed with this post 12-13-2008 at 11:25 AM
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Old 12-13-2008, 11:25 AM   #12
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Quote:
Originally Posted by fifthcircle
When you get her all ship shape, I'll buy it for $299.99. Deal?
To make it even safe to ride is gonna take the cost of the bike + about $700.
All new control cables, brake shoes, front sprocket, handlebars, shifter, brake pedal, air filter, fork seals, new shocks, bunch of little odds and ends too.

To make it semi-pretty is gonna be about $500 more
All new repro plastic, Clarke fuel tank, new seat foam and cover.

I'm just doing a little at a time...
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Old 12-13-2008, 12:25 PM   #13
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Quote:
Originally Posted by tbirdsp
To make it even safe to ride is gonna take the cost of the bike + about $700.
All new control cables, brake shoes, front sprocket, handlebars, shifter, brake pedal, air filter, fork seals, new shocks, bunch of little odds and ends too.

To make it semi-pretty is gonna be about $500 more
All new repro plastic, Clarke fuel tank, new seat foam and cover.

I'm just doing a little at a time...
So is that a NO?
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Old 01-13-2009, 03:58 PM   #14
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Hey Mike how is that RM coming along?
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Old 01-14-2009, 06:44 AM   #15
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At a standstill. Couldn't do anything over the holidays, went out of town plus kid was off of school. Then our sewer drain backed up and flooded the basement, still cleaning that up.
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