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i have a few questions about the 1982 RM 250

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if you have seen my posts on here before you might like to know the bike-in-a-box project is ridable once again. this was the worst restore project ever, everything had to be repaired or replaced.

questions

so does anyone know where i can buy a new DG or answer(or anthing besides stock) seilencer? i just ordered a new DG front pipe. but have no luck on seilencers.

Timing= i read the timing is soposed to be 16 0r 18 degrees i don't remember wich, but does anyone know what it is in mm before TDC?

and if i was to rebuild the rear shock i have, did they fill them with nitrogen back then????

mainjet= for some reason my bike has a 230 in it but in TT OEM they show 270 -330, mine is deffinately way lean, but perfect everywhere else. what is the stock main jet. i need some where to start from.

here is a rundown of what ive done so far

bought used= cylinder, head, crank shaft, a rear shock(that didn't fit on this bike wasted money)

bought new= main bearings, connecting rod, rod bearings, piston, all seel and gaskets, new read valve assymbly, new intake boot, swing arm bearings, twist throttle, clutch perch/lever, pad

repaired= welded cracked swing arm, welded hole in case by chain

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I had an 82 and 2 83s, great bikes. On mine the 82 had a piston in the reservior of the shock and the 83 had a bladder. You had to put the piston in the middle of the reservior the add oil to the oil side , have the shock

assembled and bleed then hook up the hose and charge with nitrogen to 145 PSI. It was hard ot no get air in it but I did it a few times.

The stock main jet was 300 and I ran 270s.

Ed

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The timing is specified as 16 degrees BTDC, +- 2 degrees - so you could set it anywhere between 14 and 18 degrees BTDC.

Here's a link to a degree/mm conversion utility - you'll need the stroke (64mm) and the center-to-center con rod length:

www.scooterhelp.com/tips/timing/timing.calc.html

Can you let me know what your con rod measures? I've been meaning to check my timing for, like, years.

The jetting on my bike is as follows:

270 main, 55 pilot, 6FJ40 needle @ #2, air screw 1.5 turns out, 4.0 throttle valve

I've been meaning to try a 280 main, but the 270 works fine. It's a standard Mikuni 4/042 hex jet, common as dirt. The 55 pilot is a little rich, so a 52 is waiting to go in.

The RM manual describes the shock rebuild process; it doesn't look too bad. When you're done, you can bring it to a dealer for nitrogen recharge. If your shock is toast now, it can't hurt to depressurize and disassemble it to see what's going on inside, what parts are needed, etc.

I've been very happy with my FMF Turbine Core II universal silencer. It took a little work to make it look and fit exactly as I wanted, but it was initially up and running within 15 minutes. You want the larger 1.25" size.

http://www.motorcycle-superstore.com/2/9/187/4160/ITEM/FMF-Turbinecore-II-Universal-Spark-Arrestor.aspx?SiteID=CSE_GBase_187&WT.mc_ID=80003&zmam=88421133&zmas=1&zmac=2&zmap=4160

Don't worry, all the hard work will pay off and you'll be scaring yourself in no time. :)

Ray

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Check out Circle F racing in Texas. They can build up one for you. I was quoted $45 shipped for a 77 RM250 silencer.

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0305091639.jpg

notice the freshly painted frame and engine. oh it scares me in mid throttle. would be even worse when i put a good back tire on it and get the jetting straightened out.

i think i might be pretty lean on the pilot too (won't idle) but i am waiting on the new pipe. i don't know what pipe came with it but it wasn't the right one. was for an older bike without radiators( notice mine is unbolted and cocked forward for the pipe to fit) i'll get the connecting rod length in a minute, but the link you posted only works up to a stroke of 62mm. we need 64mm. new plastic soon. i sent an email to circle F for a quote thanks guys

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measured my old connecting rod at 120mm center to center with a caliper so it should be accurate. 30mm big hole,23mm small hole, and 146.5 between outer most of the two.

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i think i might be pretty lean on the pilot too (won't idle)

if it has the original 82-83 carb.. it doesn't have an idle screw.... RM250s didn't idle till 1988 if memory serves

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i was adjusting the cable at the twist throttle for idle. so your saying it shouldn't idle?

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0304091456.jpg

just got done with the new swing arm bearings and putting the engine and fork back on.

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heykenny is right, there is no idle screw on these carbs and no these did not idle.

Ed

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Thanks very much for the con rod length! Much appreciated.

Sorry about the conversion page - it's mainly for use with smaller short-stroke motors. Here's the formula:

Piston Travel vs. Crank Rotation: d = ((S/2) + L) - (S/2 cos X) - L sin[cos-1 (S/2L sin X)]

Using a 62mm stroke and 116mm con rod length should get you results extremely close to the correct 64mm/120mm - probably within .1 degree. I came up with the following (all in mm BTDC):

14 deg: 1.164mm 15 deg: 1.334mm 16 deg: 1.516mm 17 deg: 1.709mm 18 deg: 1.913mm

My bike idles fine using the cable adjuster, although the idle speed changes a bit when the bars are moved. I picked up all the parts needed to convert the carb to the somewhat strange top-adjust idle screw setup (later carbs have the more normal side-adjust screw) but I've never gotten around to putting them in, as the cable-adjust method has worked fine for a while now.

The stock pipe looks to me like one of the first 'fatty' pipes - the center section is pretty big (it doesn't look that way in this pic so much, but directly from the side it does). Notice how the vertical pipe section slants rearward.

P1010007.jpg

Your pipe looks more like a '79 RM250 pipe (here's the link, I can't get it to display) with a smaller body and nearly-vertical center section:

http://www.suzukicycles.org/RM-RMX-series/index.html?RM465_brochures.shtml~isoraami

Ray

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wow if i can get mine to look like yours. new plastic should help, but that pic of mine was when i was just getting done putting it together. it's already been through the mud a couple times now :) ya circle F pretty much told me to look on ebay for a universal. i think they specialize in 70s models.

whats a good way to make my airfilter box look good, in the pic it's so dull it sticks out. i guess use the same plastic polish as for the other plastic?

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For the airbox, I'd first try Armor All; if that didn't work well enough, I'd try plastic polish and/or wet sanding followed by Armor All. If that didn't do it, I'd clean the box with straight gas to remove all traces of polish and Armor All, then paint it with a semi-gloss black enamel Like Dupli-Color DE1634 engine enamel or similar. This will cover most scratches and scuffing, and should look pretty good.

Look on the bright side - your airbox doesn't have the usual sh*tload of giant holes randomly drilled in it. :)

You've probably already committed to a plastic purchase, but if not I've got unopened DC Plastics fenders / shrouds / side covers that I'd be willing to take a loss on (sorry if I mentioned this before).

Ray

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ya i remember you saying that. i will get in touch with you on the plastic. i gotta find out what this lawyer is gonna charge me to get my license back. then i'll be in a position to buy the plastic off you. i thought i remember you saying you were missing a peice or something like it wasn't complete? let me know what you want for it. and i'll budget it in soon. ya i didn't buy that head off you because i found i needed a cylinder and ended up getting a good deal for cylinder and head.

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i will get in touch with you on the plastic.

Absolutely - take your time, nothing's going anywhere. I have both side panels, both radiator shrouds, and both fenders - I don't have the number plate, but it's available for $20 from the place I bought all this stuff from (www.reproductiondecals.com). I paid something like $175 plus shipping, but $100 + shipping is all I want for it. I also have a tank, but it may be in about the same condition as yours, I'm not sure (I can take pics if you need 'em).

Reproduction Decals is an excellent source for vintage graphics too, and they're great to deal with.

Ray

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I was wondering if you could send me a picture of your clutch cable on the engine side. I am restoring an 82 rm 250 and it basically came in a couple of boxes. I just got the swing arm back on with new bearings and new rear wheel bearings. Now I dont know where the clutch cable goes? It has the arm on the engine, but thats it. Is there a bracket that bolts to the engine to hold the cable in place? If there is can you take a picture of it and e-mail it to me at seth_hamre@hotmail.com.

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their should be a hole going through the case at the base of the jug, look at the water pump and look up and to the left. the cable goes through that hole to the arm.

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Thanks to everyone that replied. Ray sent me a couple pictures of the cable placement. That helped so much. Thanks everyone! I am definitely going to use this site more offen..

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Anyone know where to get a cylinder for an 80 RM 250?(air-cooled)

I'm having no luck.

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