1978 rm250C2 restoration

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11/30/2016 4:54 AM

I recently had an opportunity to purchase a 1979 Suzuki rm250 for practically nothing. I am wondering if there is anything I need to lookout for on these bikes, as far as I know it is stock, I had it running and it sounds good but I am planning on a total tear down of the entire bike as it needs some serious tlc everywhere lol. It's been a 1 owner bike for the last 34 years or so and only really been ridden the last few years by the previous owners kid who just beat the death out of it. Here are some pictures of it.





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11/30/2016 5:07 AM

There is already a really good thread on the 79 rm 250... Although you may want to start a new thread on "78" rm 250"s......

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11/30/2016 5:35 AM

Or, more correctly, a "78 RM250C2" thread.

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11/30/2016 6:02 AM

Ha ha, I knew someone would pick that up! A great bike to restore, nice find! Kęep us updated with progress & photos!

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11/30/2016 11:40 AM

back in 78.5 u didn't see to many around in my local, bought mine when they first arrived at dealer . mine was missing big spacer / washer on swingarm, rearend felt loose . they were back ordered according to dealer, so I don't know if there were a lot of them missing or just mine. had good powerband compared to 76 -77 rm250s

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11/30/2016 2:25 PM

Somebody correct me if I'm wrong, but according to what I read and remember, this bike was released shortly after the original 1978 RM250 C.
The 'C' had a steel swingarm, aluminum tank, and was lacking power compared to the other 78' OEM's.
The 'C2' was released later (kind of like KTM's factory editions) and was a step in the right direction, with more motor, plastic tank, and aluminum swingarm. But the other Jap bikes of 78 were still slightly better.
Still a cool bike, and a big part of Suzuki's history.

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11/30/2016 4:07 PM

Can you take a close up picture of the countershaft cover

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12/1/2016 4:07 AM

Thanks for the replies! I'm sorry, I didn't know it was a 78, I was just going off a what I was told. Yes I can take a close up of the counter shaft cover when I get home from work. I apologize for the late response also as I'm only online during the early am hours before I go to work. I must say that I am happy it is the better of the 78s, nuggets of knowledge like that are interesting and I'm sure will help when getting parts.

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12/1/2016 10:22 AM

Yes, the 78.5 C2 was a big impovement over the 78 C model and was considered by many "back-in-the-day"that it was at the top of the class (me included) . dumped my YZ back then for one. Picked up a super clean C2 last year and its as cool as i remember them. I have some extra pieces that I may be able to help u with as you do your rebuild,but Tony at Vintage-Suzuki can be extremely helpful with just about anything you need for that bike,and a ton of OEM pieces still available on Partzilla as well. Good luck and great find.

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12/8/2016 5:06 AM

Parris wrote:

Can you take a close up picture of the countershaft cover

Looks like the cover is missing.

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12/8/2016 8:48 AM

Some things to watch for with the 1978-1/2 RM250C2:

1) Swingarm pivot, left side: (a) bearing not being maintained -> pivot bore deteriorates (b) chain defense no. 1 not maintained -> chain saws through swingarm (b) outboard weld cracks where left side joins pivot tube.

2) Swingarm, left side: somone puts on longer shocks, leaves kickstand installed -> kickstand rubs on bottom, outboard, left side of swingarm -> metal gets worn away.

3) Swingarm shock mounts: cracks in welds

4) bottom motor mount bolt: bike is run with loose bolt -> cracks develop in bottom frame tubes near motor mount

5) expansion chamber, belly section: pipe gets dented, fatigue cracks develop along edges of dents

6) rear hub, sprocket side: bike run with loose bolts -> lugs crack

Good luck!

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12/8/2016 9:25 AM

rcmshop wrote:

Some things to watch for with the 1978-1/2 RM250C2:

1) Swingarm pivot, left side: (a) bearing not being maintained -> pivot bore deteriorates (b) chain defense no. 1 not maintained -> chain saws through swingarm (b) outboard weld cracks where left side joins pivot tube.

2) Swingarm, left side: somone puts on longer shocks, leaves kickstand installed -> kickstand rubs on bottom, outboard, left side of swingarm -> metal gets worn away.

3) Swingarm shock mounts: cracks in welds

4) bottom motor mount bolt: bike is run with loose bolt -> cracks develop in bottom frame tubes near motor mount

5) expansion chamber, belly section: pipe gets dented, fatigue cracks develop along edges of dents

6) rear hub, sprocket side: bike run with loose bolts -> lugs crack

Good luck!

Well Phil, those are all good points ,lol. And Tomm55x, this guy has some crazy super-trick parts for those bikes. Craftsmanship beyond reproach. Do yourself a favor and look into it.

And btw Phil,did u get my email ? , I need another set of the RM125C engine mounts ,since Ive seemed to have misplaced one of my sets !!

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12/9/2016 2:52 AM

rcmshop wrote:

Some things to watch for with the 1978-1/2 RM250C2:

1) Swingarm pivot, left side: (a) bearing not being maintained -> pivot bore deteriorates (b) chain defense no. 1 not maintained -> chain saws through swingarm (b) outboard weld cracks where left side joins pivot tube.

2) Swingarm, left side: somone puts on longer shocks, leaves kickstand installed -> kickstand rubs on bottom, outboard, left side of swingarm -> metal gets worn away.

3) Swingarm shock mounts: cracks in welds

4) bottom motor mount bolt: bike is run with loose bolt -> cracks develop in bottom frame tubes near motor mount

5) expansion chamber, belly section: pipe gets dented, fatigue cracks develop along edges of dents

6) rear hub, sprocket side: bike run with loose bolts -> lugs crack

Good luck!

Thank you for the information and what to look out for!!

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12/9/2016 5:45 AM

I have restored a couple for racing, engines can be pretty easily modified for more power, lower the intake port, carefull widening and cleanup of the exhaust port, reeds or reed block.

83/84 front forks duel pull brakes, I still have a complete setup available. I like to install the metal RM125 tank, pretty simple mod to make it fit.

Strip the frame have all weld adressed

I have a post showing cylinder mods and tank on this site.

Good luck

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12/21/2016 4:35 AM

do these shocks look familiar to anyone?



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12/21/2016 9:47 AM

The 77B, 78C, and the C2 have the same engines

changes are Exhaust, cdi boxes

The 77mid, top end ripper
C,C2 mid range, torque engine( pipe , cdi)
Run the 77 pipe, huge difference

weak spot's - 2nd, 3rd gears- teeth fracture, break off
main seals, bearings wear fast, ( crank on right left hand threads)
replace all the small springs, detents, shoes in the shift
mechanism
buy a Suzuki manual( original)

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12/22/2016 4:36 AM

I figured it out thanks to someone's sweet old tool box pictures, Koni , I can't say I've ever heard of that brand.

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12/22/2016 9:05 AM
Edited Date/Time: 12/22/2016 9:06 AM

tomm55x wrote:

I figured it out thanks to someone's sweet old tool box pictures, Koni , I can't say I've ever heard of that brand.

Koni was an inexpensive aftermarket brand of shocks.
I think this brand of shock was used with a little success in the early 70's, but by the late 70's they were outdated.
The stock shocks with the remote res' were probably better.

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12/22/2016 10:03 AM

tomm55x wrote:

I figured it out thanks to someone's sweet old tool box pictures, Koni , I can't say I've ever heard of that brand.

mxrose3 wrote:

Koni was an inexpensive aftermarket brand of shocks.
I think this brand of shock was used with a little success in the early 70's, but by the late 70's they were outdated.
The stock shocks with the remote res' were probably better.

Thanks for the info!! I'm deciding what I'm gonna do for shocks and would hate to throw something out that is good because I didn't know what it was.

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12/22/2016 11:35 AM

tomm55x wrote:

Thanks for the info!! I'm deciding what I'm gonna do for shocks and would hate to throw something out that is good because I didn't know what it was.

Dont throw them out! They are going for 200 bucks on evil bay. But yeah if your going to do any vintage racing, i would go with a better set of shocks.

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12/22/2016 12:24 PM

KONI is a German brand of shocks, big in auto market

What length are they? (eye to eye)
I have Ohlins with remote reservoir that might fit, just have to dig them out and see if they can be brought back to life..

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12/23/2016 8:58 AM

Just curious on these shocks - are there any suitable replacements that don't cost big bucks? I'm working on a 76 RM 125, looks to be a very similar setup.

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12/26/2016 6:50 AM

mark_swart wrote:

Just curious on these shocks - are there any suitable replacements that don't cost big bucks? I'm working on a 76 RM 125, looks to be a very similar setup.

Progressive Shocks... DC Plastics will get you a set with your spring rate needs shipped to your door for around $300

They will work great up to a fast MX pace on a modern track. If you're a front runner in MX you would need to spend more $$$.

I ran them on a few builds and they are way safer that worn out stockers!

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1/3/2017 5:53 PM

tomm55x, another couple of things to watch are the motor mount bolts which can break and the footpegs. Mine would falloff at the worst possible moments. Get rid of the footpeg pins and use bolts with nylock nuts and some Loctite for an extra measure. If you spend some time getting the jetting correct, it will make a world of difference. I ended up changing the slide cutaway and it really helped the midrange but I can't remember what cutaway I changed it to but maybe a 1.5?

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1/4/2017 7:19 AM

Not sure what size the 78 forks are but, I have an excellent condition 79 front end complete including wheel, brake plate, nos brake cable & rebuilt forks for a very good price. The 79 forks are 38 mm"s, seeing how you need shocks, longer travel shocks would balance out chassis.

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1/4/2017 9:41 PM

The 77 RM250B and 78 RM250C only had a few changes, you have a mid year release 1978 1/2 "C2" model as previously stated.

My 77B:



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"Welcome to Southern California......the mecca of motocross racing." ~ Jason Wiegant

1/8/2017 1:40 PM

thanks again for the comments and advice, all is appreciated ! I have been slow at making progress, I appreciate the patience! OW38B, the 78 you have pictured is perfect as far as I'm concerned, nice work!!! I have completed tearing my 78 c2 down and taking note of what I'm going to need to make this race ready, well somewhat race ready lol. by the looks of things this bike hasn't had a ton of use, a lot of the hardware is original which to me, is a surprise to say the least. It looks as if it hasn't been washed good in a number of years. I only had issue with 2 bolts being seized in tearing it down, minus the motor in which I have it out but have not touched it. I included pics of the frame and will also include more pictures as I go.







pics are not the best, ill try to take better ones as I go!

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1/8/2017 2:20 PM

A few fork pics, everything has not been cleaned yet, I would figure some before pics would be good. The forks obviously have blown seals but under all that oil there is still warning stickers!!













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1/8/2017 11:33 PM

Keep us posted on the progress, just love seeing these things come back to life.

I have quite a bit of info on the 76,77,78 RM250's and hopefully can answer some question you might have. Plus many other in here are very knowledgable on these type of things also. Have fun!

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"Welcome to Southern California......the mecca of motocross racing." ~ Jason Wiegant

1/9/2017 4:54 PM

looks like its in great shape to start with!

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