Vintage MX Help Please


Well-Known Member
So I came across a not quite vintage, but older bike yesterday for free, so I took it.
It is a 88 Yamaha 250. It's all there and in really goos shape for how old it is. I mainly picked it up as a project, and plan to just tool around on it a bit if I can get it running. I also wanted to get some experience working on bikes since I have never owned one. So yes, I know it's old, outdated suspension, and not running (some valve blew a hole in the bottom of the case), but it was free. Here are my questions. Any help would be great.

1. Is there such a thing as used donor motors for dirtbikes. How much aprox.
2. Can I put a newer than 88 motor in it.
3. Where would I find a donor motor.
4. What would you do?

1.Where do I get parts for a bike this old. (I searched online last night, couldn't find much. Most places only stock parts for newer bikes.)

1. The plastics are in pretty good shape but pretty dirty. Any tips on getting older beat plastic looking like new? They are white and have a brownish haze kind of embedded into them.

Thanks in advance.

It's never too late to be what you might have been....


Krittro Campbell
carb cleaner works good on white plastic and amkes it look new...but watch out for the will eat them right off.

I know down here there a few cycle salvage yards where you can pick up complete engines, but they are not cheap...

<A target="_blank" HREF=> Fab Parts</A>


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I can't remember the name of the box I bought, but pick up a plastics refinisher kit. It comes with sandpaper (which you'll need to buy more of if it's as beat as the Metal Mulisha bike), cleaner, and a solution you wipe onto the plastics a couple times. The coarse paper gets the big scratches out, the fine makes it smooth, and that solution really makes them all shiny and new. It does wonders for white plastics, and it helps colored plastics out quite a bit. Old Honda Orange/Red that's been faded by sun is such an awful color anyway, but the blue should look nice!

<font color=red>Heaven Doesn't want me, and hell is afraid I'll take over</font color=red>


Well-Known Member
Alright, cool, I am covered regarding the plastics. Thanks. What about the motor and parts in general for older bikes. How much can I expect to pay for a replacement motor and where. Can I put a newer motor in it. What years are compatible with a 88 YZ 250. Any URLs for replacement parts?

It's never too late to be what you might have been....

John Bitting

Map, I dont think Vintage Yamahas came with blue plastics? They are either white or yellow. I dont think blue was until later in the 90's.. But I could be wrong.


Well-Known Member
you're right about the blue plastics, I'm pretty sure that didn't happen til late 90's. I think that all the plastics were white, and the seats were blue, but who knows... White plastics are great on old bikes, they clean up really nice.

Try these places for some used motors, they should probably know what years will work for your bike too... All these places are located in California.

Good luck! I'll race ya on the Hodaka when you're done! lol, j/k

<font color=red>Heaven Doesn't want me, and hell is afraid I'll take over</font color=red>
for cleaning your plastics, you might want to try wd40.
<A target="_blank" HREF=></A> is great for finding oem parts
and you can check ebay, just type in *88 yz 250


Well-Known Member

Another resource that might point you in the right direction:

Hy-Tech ATV (formerly known as Hy-Tech ATV Salvage)
31933 Outer Hwy 10 So.
Yucaipa, CA
<A target="_blank" HREF=></A>

Good luck!

Tony B.

"Get Creative!"


The Yamaha "IT 250/465" model had light blue plastics for couple of years in the 80's. It was almost like a powder blue. Fugly!



Well-Known Member
you can put any motor you want in the bike but it wont be worth it, just get a used motor, what about chaparrel for the parts?

"Everything you do is triggered by an emotion of either desire or fear."


Well-Known Member

That is what I want to do. Get a used motor or fix this one. As inexpensive route as possible. I am just not familiar with MX so I have no idea which other Yamaha engines (years and models) will bolt right up.

I talked to a guy today who said he might be able to weld up the hole in the case. Oh well, either way, I am tearing the bike apart tonight.

Not famiar with chaparrel, but I will check it out. Like I said, I have zero experience with MX, so all this stuff is new to me. Thanks, J_

It's never too late to be what you might have been....


Well-Known Member
i had an 86 yz 250 had red and white plastics... was a good bike...this is where id start, first wheres the hole in the case and what caused it...i had a rock fly up from my front tire and cracked the case...what i ended up doin was using good ole JB weld, it wouldnt be worth it to fully rebuild it in my eyes, i would have it welded if it isnt on the split in the case do a top end and maybe a clucth thats if everything in the transmission works fine and your lower end is in good shape, as for the plastics u can get fenders really cheap and for the side plates go down to any motox shop and get a couple sheets of the universal number plate background comes in different colors to suit ur needs. theye simple to work on if u wana do the forks let me know ill come buy and pick them up for ya...j

the faster i go the smother it is
if youre going to take your engine apart youre not going to be able to get very far. 2 stroke engines, imo, are the easiest motors to work on...until you get to splitting the cases, then youre in for a treat. If this is your first time doing this, i would recommed you get as far as you can taking it apart and then take it to a mechanic. He'll appreciate that you've done some of the work and knock some $$ off labor.

To get to the rod/crank/bearings you need to do the splitting and not only do you need to split them exactly straight apart but you then need to place the cases in an oven to take the main bearings out (if they need replacement, which the probably should), of yeah, and you also need to split the crank to get to the rod, so youll need a hefty press.

Last time i did this work the rod was about $90something and the main bearings where in the upper $200's. Since your engine should be taken apart by then, you might want to measure the bore and the ring clearance/piston/etc. and consider changing them aswell (less then 100 for piston/ring/gasket kit). And hope you dont need to spend an extre 20-30 $'s to bore/hone the cylinder.

...was i being too honest?

After all is said and done, you should be able to enjoy a fairly reliable and fun bike.

good luck


Well-Known Member
The problem with older mx bikes that aren't popular vintage racers is parts availability. If this is just a bike to learn on and have a little fun with then do the least possible to get it to run. If you end up splitting cases, swapping rods, bearings etc., your great deal "free" dirtbike just turned into a $1000 bike that's not worth a penny to anybody but you so you're stuck with it. You might want to think about offing the bike to a neighborhood kid, and buying a running bike that you can ride a bit for a few hundred $$.

Of course if you're in it for the education....then have a great time with it. The great thing about 2-strokes is you learn the same operational basics on a 78 that you would on a '03. So have fun!


Well-Known Member
The only way to make an engine swap possible is if the swing arm mount to the chassis and not the rear of the transmission, if it does mount to the engine then you must use a motor from that years design, if it mounts to the chassis then you could put a differtent chassis mount motor in it. Chaparrell(sp) is like the hub of MX, your best bet, if it is going to be a costly rebuild is to find a used motor from hytech or similar places, call Chap though they will hook you up with the necessary numbers to call.

"Everything you do is triggered by an emotion of either desire or fear."