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Don,t forget the 92027-1445 collar, the 92055-022 o-ring and the 92033-1079 circlip. You can switch to the 1991 countershaft layout with a different collar, and two o-rings to prevent gear oil seepage. Kawasaki had the simplest and easiest to understand parts numbering system of any mfgr. The first # sequence designated the type of part and the second # sequence denoted specifics.
I found a Japanese equiv to the link above: https://www.ebay.com/itm/165954276059
Could I get a second opinion on the cylinder? Could this not be honed and run? I could feel zero imperfections with my finger, but at the same time it does look like some of the lining has worn down. Just not sure if this is still somewhat serviceable.
If I have to I will but I'm wanting to pull back from dumping a ton of money in this bike, as I will never see any of it when it eventually comes time to sell. I don't like doing random work for the next owner for free if that makes sense. I'd much rather use some of this money for wheelset for the KX327 later this year.
The crank is being rebuilt by Millennium Technologies since I saw some grit/dirt in the intake side.. new piston and bearings throughout bottom end. Had no choice to do that. But if this cylinder can be safely run a while longer I'd rather defer some of the costs on to the next owner.
What plating that looks like a sleeve to me even has what looks like surface rust. Check it with a magnet. It sticks then it's sleeved. Bore it out go to next size up possibly.
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
A magnet does not stick. I was able to wipe down some of the crud/carbon you see at the bottom in some of the photos using WD40 + light use of scotch pad.
I understand not wanted to stick more money than you have to, are you actually planning to ride and race this? If not, run it. If so, you are going through the trouble of rebuilding the crank, to me that cylinder doesn’t look great, I would replate if I was planning to ride it
That cylinder doesn't look great, but none of those late 80s/early 90s early Nikasil cylinder did IMO. I don't think running it would cause anything catastrophic.
I remember hearing that Kawasaki's electrofusion, although it was the first, did not hold up as well as the other mnfgrs. nikasil plating.
Truly hate pissing more money away on this bike. I'm not building this for the $, but realistically... a functionally rebuild 1990 KX125, new crank, bearings throughout, seals, plastic, seat foam and cover, rebuilt forks and shock with gold valves.. what could I realistically expect for this? It's not a showroom resto with new parts, but it will have OEM kawasaki everywhere I can find new bits for it.
I may have to cut my losses at some point.. if this thing is only worth $2500-3000 in a fully (functionally) rebuilt state.. I'd pass on a cylinder replate.
I think you answered your own question. Unless someone has a deep connection to the bike you will be hard pressed to get more than $2500-3000 when done. I’m in the same boat as you and am struggling with the decision to stick a bunch of dead money into my RM or just get it good enough
If your original plan was to use the bike, it would seem like replate is in order.
If your original plan was to resell the bike, hold off on the replate.
queen of spodes :
I have to say, that barrel looks absolutely f*****ed!
I first saw it on my phone, without my glasses.
Then saw a fellow say the surface looked like an iron liner.
The, just now, got to my 'puter, with my glasses.
Bloody Hell!
It just looks trashed - unless somehow it was say, just some dirt that got all over it while you took pictures, and you didn't notice that , that bore surface will Eat any piston and rings in a near instant.
Any pictures after you done a basic scotchbrite to the surface, or a hone?
If you were originally hoping to a rebuild to then sell on, or keep as an EVO era racer, you appear to have an expensive, probable near loss bike on your hands.
I feel for you on this - I've been caught out on this sort of thing, but thankfully, it was a Long time ago.
Hang in there with it all!
You've already spent money on a new crank. It would be a shame to skip replating the cylinder now. That's a bit like spending a fortune renovating a house and then leaving the old leaky roof as it is.
The electrofusion back then was lucky to outlast the first piston…
I did the opposite once, fresh replate and top end on an unknown hours bottom (kx250) all in spec and looked great on a full restoration. 10 hours later I was doing the crank. Once you’re in…you’re in.
Making money on old bikes? 😂 it’s literally the fun way to burn your money by the wheelbarrow full.
If you ain’t keeping it for life and doing it right, why even bother in the first place.
I was dumb and should have just bought a little more expensive and running bike. Hey I could have even bought a 1990 KX125 with freshly rebuilt engine with OEM parts for next to nothing!
Wanted something to play on until the 327 comes out. Here we are. Did not realize the engine was dusted until I got it home and pulled off the air filter, saw the grit/dirt in the air boot..
This was a fantastic time in motocross history for many of us and it would be a cryin' shame to not restore this bike back to it's original glory. Keep it in the collection.
I am hating this but will pack it up for plating. Even the post-scotchbright areas still looked a bit worn down.. did read about Kawie's electroplating quality before.
Porting is another 265 on top of.. it's nother wheelbarrow of cash in the incinerator, but maybe a much faster 125 to play on? Maybe a selling point later?
Somebody talk me out of doing porting on top of plating. It will have a new PSI pipe and RAD valve to boot. Not sure if porting a bike this old will even make a huge difference
Dont port it. Not worth it. Your not trying to win pro vintage races are you?
Pit Row
Nope, not going to race (lol or think of winning) pro vintage races.. if there was big bang for buck return I'd do it, but only for enjoyment not for racing
A simple polishing of the exhaust port and slightly enlarge the upper windows with a dremel and a craytex bit will make a huge difference. Combine that with any Team Green issued jetting changes and it should sing on the top end like a soprano.
Agreed, had Eric Gorr port one of my RM125s back in the day. Always did better on a stock one with pipe. Waste of money IMO
Don't port that cylinder. The sub exhaust ports right above A transfers are notorious for cracking.
It takes someone who really knows what they are doing with those cylinders. Just leave it.
They are also tricky to replate. If plater gets crazy with chamfers it' super easy to ruin those cylinders
thanks for that info.
Who would you recommend do the plating (and chamfer work)? Was about to box up and send to millennium...
Millennium is great.
But I would put a note in there to please use minimal chamfers on ports.
They chamfer ports before plating. It's easy to make them too big
Minor update:
There's a local SEVMX race coming up Oct 17, so my hope is that I have the bike ready for that. I'm not sure I'll be ready, haven't raced since 2021, but hopefully I can give it a try.
Its nice having you around here Queen!
Talked with a couple guys from Millennium as well as chatted with Eric Gorr. MT recommended the 130cc big bore package. It was a few hundred more, but there are some reliability benefits.
Tom from MT said with the bore kit I am getting that they additionally add a little material to the A Transfer/Sub Exhaust port bridge.. it also is thickened a bit from enlarging the cylinder bore in the first place. They aren't doing aggressive porting to that area, but will do some light porting as well as decking cylinder 0.5mm as well as taking some material off the head to compensate.
Eric is very familiar with this model's cylinder, he used to port for TUF racing back in the day. It wasn't clarified whether he personally would be working on it, or one of his trainees.
The entire kit was around 780 or so, it is reportedly on sale and normally more towards 1100.
Think I am gonna grab a '91 KX125 CDI from the online flea markets.. I hear that is another way to get a meatier mid range powerband.
"You only live once" they say...
This is becoming an expensive step through to the 327, hopefully worth it in the end!
What the heck, skip going out to eat at fancy restaurants for a while!!
The sickness claims another one.
From budget to big bore. Atta girl!
Hi Queen, I was at a similar crossroads a couple of years back with a 94 KX 250.I decided to buy one that was running and in half decent condition. I rode it once and had to rebuild from the frame up fixing other people’s crap repairs.You have inspired me to put it up in the builds, it will make you feel better about your 125.Keep up the great work.
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