'89-'92 RM pipe on '93+ RMX? placelast?

[little Loopie]

Just curious if a exhuast pipe off a '89-'92 RM will fit my '93 RMX? I know the plastic fits, but what about the engine stuff? Is the engine(ie. headgasket)/susp.(ie.springs) a carry over as well? The reason I ask is 'cause I'm looking for used and can prolly open up my search a little w/ RM parts if they'll work?

Thanks for anybody's help in advance.............
Cheers,
Mike

 

[placelast]

Nope - no fit-'um. The exhaust port on (all) the RMs are too large for '93-up RMXes, although the early RMXes & RMs could interchange ('89 & '90 for sure), although they did away with that as the RM evolved as did the RMX; the RMX exhaust port was updated in '93 to a smaller sized port for off-road favorable low-end response and perhasps scavenging via a higher velocity discharge rate.

You could use up to a '95 RM cylinder, head, pipe and exhaust valve cover (as a whole interchanged group; not independently) Eric (the one good Gorr I know and respect) used to recomemend the a '94 RM top end as the hot setup and Suzuki off road (when they raced RMXes) used to likewise swap the above group, but post '93 the team stopped doing so and started to massage RMX components instead, and Eric took the recommendation out of his book.

The suspension and components between the two are interchangeable. You could spend some time in the White Brothers' catalog to get an idea of what fork/shock internals intermix, down to the part numbers, even with other brands like - heaven forbid - Honda (j/k on the Honda part, but it's true that Honda and Suzuki Showa suspension from the early '90s did share a lot more than a supplier. Thing is, only one of the two brands got the valving right for the production runs and team bikes, and the other's race team eventually copied the competition's. Hint: you'd be surprised to know the copier was the one with the largest R&D budget in the world!)

Sorry for the ramblings, bit is is intriguing, no? Feel free to ask more...

 

[little Loopie]

rambling..not at all. Extra info is great as long as it's something I'm intrested, truth is, I've thaught about getting all the power out of it as possible, but would like to get a NEW bike next spring. So, knowing this I'm trying to basically get 5th to pull harder w/o spending a S-load of cash. The bike had a recent top-end done to it just when I got, so I figure a pipe, silencer and RM gasket would make me a little happier for the next riding season, but I'd prefer to buy used parts because the bike will only prolly be around one more year till I can afford something lighter. Any of your buddies(or you) have used performance parts for one of these things?

 

[placelast]

My situation was somewhat simlar to yours at one time.

Six years ago I started doing enduros again, after a two-decade layoff. After settling on the right bike, and after becoming a bit better at using the newfound power of a modern machine (well, at least designed in the late '80s), I thought there could be some room improvement. In particular, when zooming through sand washes, my RMX would not pull the gap to 5th as well as thought, and uphill washes were iffy in 4th. I tried regearing (52T rear) to minimal improvementl. So I called Eric Gorr and told him my delima. For $100 he did a more-better port job and head squish reshaping. Bamb! That did it! Now don't you go thinking it will turn it into an RM, but it could pull almost any gear any time I dare. Do it; you will not regret it one bit.

What brand pipe/muffler do you have now? Certainly lose the stock head gasket and go with a '89 RM or Cometic (hi-po) equal, unless you have Eric machine the head height instead.

Another thing you can do is buy a used 39mm Keihin PWK or 38mm and have it bored to 39.5mm, but that would cost more and bring less gain than Eric's work.

I have an FMF Gnarly w/E-Line guard & S/A, V-Force (original version) you are welcome try (I was going to put them on that auction site soon) but all those are for bottom to mid, not top. Same goes for my spare '93 barrel/head, which I had Eric port for low to mid response (I will sell that soon also.) Though all these parts are collectively going in the opposite direction you intend.

In light of what you are looking for I don't believe there's much to be gained from using RM parts primaily because the RMX has a ligher crank and wider gears. My suggestion is to have Eric port your existing cylinder to your preference. It will be was less $ than pipes, etc.

 

[little Loopie]

Currently, my bike is BONE stock w/ the exception of a gear change the older guy I baught the bike from did to enhance tight woods riding, and basically, all my riding is steeper type hills/terrain with 5th gear being used slighly, but when I do use it I want it to PULL! More bottom-mid would be great AS-LONG as 5th was more usable, to me, it seems like going from full throttle 4th to 5th the bike just STOPS pulling, it's like an overdrive in a 4cyl car, just makes cruising a little less wound out :( .

What would you want for the above mentioned parts you were going to be selling anyways? If the price is right I might/will strongly consider trying them first for my riding areas, I figure they HAVE to be an improvement over stock, and how much of a hinderance could they be if I get MY current head ported later? The way I look at it, anything I do to this bike, will help me decide what I WANT when it comes to buying an NEW bike later, not ot mention the supposed weight savings from the pipe swap? NO?

I always run 94 octane fuel w/ bartol mix so the extra compression from an RM gasket will be a def. asset. I'm paying for the fuel anyways, might as well bump the comp. ratio. Whats a top-end gasket kit worth? $40?

BTW, thanks, you have been a great help :worship:

 

[placelast]

Oh: no wonder - any pipe other than stock would give it a whole new personality, not resembling the old whatsoever - though I never rode mine at all with the stock pipe, just started it at the dealer, nothing more; didn't want to waste my time. Yes, there is some weight savings but don't think it will become as light as an MXer.

(Yes, I would like my RMX to be lighter and am tempted to get something lighter like the new MXers, but I've found there's tradeoffs, and if my only complaint is this bike being heavier than all other 250s then I'm still ahead as it has a wide-ratio trans, kickstand, lights, slim big tank, comfy suspension, enduro power, reliable, easy to work on, blah blah blah...)

From what I'm told/read, w/the stock exhaust it will barely outrun an XR/KDX as this "choking mechanism" limits free flow; with aftermarket it leave them for dead! There would be no doubt in anyones mind a new exhaust would fulfill your wants and then some. So let's start there:

I suggest you certainly redo the exhaust, head gasket ($10 US; I'll throw that in for you), remove the lid off of the airbox, and rejet first. Leave your stock cylinder on as the top end was recently done. Then if that's not enough (it may very well be more than plenty - let's do it a stage at a time), go the top end route, either redoing yours or buy mine - but only if you discover (you will) this is the direction you want to go in and then decide to perfect/fine tune it.

I figure $150 US max for the pipe, CF guard, S/A, and head gasket, richer jets & needles; you pay shipping/insurance as I have no idea what the customs, ect. would do. Fair? Email me at hit-n-miss @ dslextreme.com.

 

[little Loopie]

Hey I sent you an email, so instead of going to a different bike did you just go w/ the RM engine route? The snorkel has already been removed by the previous owner. These RMX's weigh roughly what?, 250ish lbs? And new 2 stroke MX'ers are around 210lbs. Can you no longer buy a OFF-ROAD 2 stroke other than a K#M? What do they weigh? I know the new off-road 4 strokes are like 230ish if memory serves correctly, but I prefer the hot start ability of the 2-strokes myself. But I hear ya about the "if my only complaint is" remark, I've just never really thaught about it that way as I've only been on a dirtbike for this last season since I was 13(....now 25), but frankly I got sick of doing shuttle runs to the top of a hill to ride down it on my MTB, now I have a motor :)

Also, just out of curiosity, whats your KX/KDX hybrid deally?

 

[placelast]

Loop: no RM engine here, though many parts interchange, there are better ways to extract performance from the RMX. I do have RM plastic - the tank, shrouds (same) and rear UFO enduro fender (no longer available so I bought up the warehouse's stock!)

The RMX weighs more than any modern MXer, even the strokers - but perhaps less than the enduro versions of the latter except the (hearsay) well-suspended yet adequately-powered Honda CRF250X. The advantage the RMX brings is being a smoker the CG is way lower, and as a Zook it has a good turning heritage; which was a problem with the older Yamahas (and CanAm) I had - I'll take a heavier bike which turns well over one that is "stable", although I'm sure Yamaha has come a ways. For the record I briefly owned a XR250R, TT350, and DR350R; may as well cover the others: Qualifier 250, IT175, MR250. All were kept for a year or three; the RMX going on seven.

If there were one thing I would change about the RMX it would be the weight, although I have no complaints about anything else, nor do I want to remove those things whch distiguish it (lights, kickstand, etc.) For that weight reason alone my next bike if ever would likely be a new(er) RM250, but my wife for some reason disagrees...imagine that? A man has to dream, and that's mine, unless K#M can slim up the 200s and improve their suspension. Another favorite of mine is the Gas Gas 250 in XC or DE trim; like that red plastic. CPTJack's is one fine ride.

The latter-day K#M 250 E/XC or XC-W is lighter by virtue of its evolution/modern materials and linkless suspension. I'd like one of those too although I'm truly a high-performance 200 rider, barely a 250 guy at 5'-9", 160 lbs, 32" inseam. Heck, I can hardly crank my 250 over. When considering a '99 Gas Gas EC250 way back, I coun't turn the motor over! What a lightweight, here! Beach weakling.

Yes: the RMX was the last of the true Japanese off-road 2 strk enduro produced. The current ones are all Euro. (You KDX guys can argue with me, and how Jeff Fredette races one - he can go fast on anything - even a KXF! Well, now I've offended most everyone, so there.)

I like the performance of the 250fs, though I am just not ready for subsequent higher maintenance costs; Eric was saying thery are 10x a smoker! Today I can do top ends myself for $100 - once a year if it needs it or not - in a couple of hours if I take my time - no machining nor special tools/skills (I'm proof) required.

My KDX/KX hybrid is just that. It is a '98 KX125 chassis (RMX forks) with a 200 engine in it. I had Jeff Fredette go through the engine, RB do the carb, and I did all kind$ of thing$ to it to make it a tight woods/enduro bike. It's good looking too, and has more mods and $ into it than my RMX. I was hoping it would become a Japanese 200 E/XC but it just doesn't have near the same snap, even after all the $ I put into mods; the power is still electric-motor like. In theory it should be THE ride. Don't get me wrong - it's an excellent bike when the trails are tight and sloppy - it's when the trails open up and you go into the upper gears it loses site of the RMX. It's been a good bike for my younger sons, though - I just won't be keeping it long term like my 250. The latter is easier and less $ to get performance out of, and less work in more ways than one.

 

[apb]

I'm truly a high-performance 200 rider, barely a 250 guy at 5'-9", 160 lbs, 32" inseam. Heck, I can hardly crank my 250 over. When considering a '99 Gas Gas EC250 way back, I coun't turn the motor over! What a lightweight, here!

You think you're a lightweight, huh? I'm definitely borderline 250 material at 5'6 135 lbs ;)
Placelast, I gotta agree with you though, the bike is really hard to beat for performance and reliability and economy. With my grad-student budget, I can only dream about any of the newer machinery, but I really doubt I'd have any more fun than I do on the RMX. And I feel like it'll run forever. But when I drop it on a hillside and gotta pick it up, I do wonder if it'd be easier on a newer bike! My bike is actually devoid of nearly all the enduro stuff -- no kickstand, lights, odo/cable, wiring for lights.. Just handguards, disk guards, and pipe guard is all I'm running. Assuming the frame is pretty close to the '89 RM frame, my bike should weigh pretty much what the RM weighed, do you think? Would you guess my bike is down around the 230 lb mark? I don't know what the late 80's rm's weighed, but I guess the rmx motor would add some weight, with the flywheel difference.. :think: What do you think?

 

[placelast]

That stuff adds very little weight. It's mostly in the engine bottom and some frame reinforcing, if the frames are in fact different. The reast is a little here and there like what you were thinking.