KDX80 woes

Picked up a 1987 KDX80 to fix up for my son by christmas. Bike is in good shape and even has a Works Performance rear shock. Well it would not start as it only had 30psi in the cylinder. Today I removed the cylinder only to discover it had a stuck ring and it put some nasty grooves into the cylinder. The piston in the bike is a 514P2 Wiseco and it is 48.50mm. I see there is a 49.00mm piston available but I think the gouge is too deep. Been looking for a used cylinder but they seem rather hard to come by. There is one for a 1980 KDX80 on Ebay. Will this work? If not any ideas as to where to find a cylinder?

just checked out the pics and both are air cooled..so thats promising

you can go back to 1984 on that cylinder p#1005-1229

the 1980 p# is 1005-1071 so its a no go I believe

According to the Fische:

1983 through 1987: 11005-1129

1982: 11005-1184

1980 through 1981: 11005-1071

I have no idea, at all, what the differences are.

I guess I could just get the 1980 cyl and see what the differences are

Is the current cylinder in stock condition, with the factory Electrofusion coating?

Has someone in the past had a sleeve installed? If it has not been sleeved, then if you are thinking of boring it out larger to install an oversize piston and rings, that is not going to work. Stock cylinders are coated / plated and must be replated (best idea) or sleeved (it's a free country) to repair the cylinder.

If you go shopping for a used cylinder, it might need to be repaired and replated as well. Look for one from the same model years that had the same part number. I think the different part number cylinders will not work. If the base gasket part number is different, then I suggest you skip it.

I am slowly rebuilding a 1985 KDX80 for myself and have done some research on them. I had one as a young kid and it was a lot of fun. Parts do turn up on eBay from time to time, but if you are wanting it rebuilt by Christmas, you need to send te cylinder off for repair and replating ASAP. Millenium Technologies or some other company can help you.

the cylinder has a liner in it from what I can tell. It currently has a 48.50 piston and the only other oiston available is a 49mm. I will see if it can be bored and still be used.

Let us know how it turns out.

brought the cylinder to a mechanic and he said the score marks should come out no problem with a bore job. I ordered the top end kit and will be done in a few days.

good job next just install the piston with arrow pionting to exhuast and before anything scrub the cylinder down with soap and hot water till clean

and don't forget order some new grips and cables for a nice touch on the Christmas gift to your son

Hey, allright! That is good that you can get the top end sorted out.

DO INDEED spend a lot of time on washing the cylinder in warm, soapy water to get all the metal dust out of the cylinder passages.

Some new grips and cables would be a great toch. Cool idea, basketcasebill.

I will be doing a very thorough cleaning of the cylinder before it all goes together. I am also looking at the following items





and a major detailing job as it is dirty. Already has a new clutch cable and the front brake cable is good.

I plan on installing a KX80 front end on it in the future to gain the disc brake set up.

I also noticed the bike has a works performance rear shock installed. :thumbsup: This was great news to me as I was thinking of installing a KX80 shock but no need to so now.

Look on eBay for brake shoes, as I very often see EBC, Vesrah or OEM KDX80 brake shoes on there.

www.denniskirk.com has some parts you can find by looking for 1987 KDX80 on their site.

Doing the same things we type this on an 86,just got chain guide front and rear as they are now unavalible.For the price of that flebay cylinder we will get ours replated and the exhaust welded and new piston-rings-wristpin-clips.Frame to be painted this week,and all bushing replaced.

Got to take a few pics soon,good luck on your build !

Bet i spend more in parts than it was new.

kinda old post but i just saw it. i just started rebuilding my childhood bike (86 kdx 80). anyone know were to get aftermarket performance parts (exhaust ect). i know its asking alot on a 25yr old bike but hey its worth a shot. i still need to find new plastice and chain guide, tires, and front brake pads.



Keep up the good work. That is a 1987 seat, in case you were not aware.

Maier plastic f/r fenders,they are on clearence. Side panels no longer in stock,just scored a brand new nos set fle-bay 30$ !!! You can still get a fmf pipe. Chain guide is out of stock,flebay but you going to pay.Works will do you a shock. We are going to relace a 17in rim to the front,better tire selection.Brakes can be had new.

Have you purchased an FMF pipe, or are you reading that in a catalog? I have seen it on a catalog or on their website, but it shows for 2002 or 2003 maybe, something like that? The last year for a KDX80 was 1988.

you can still get nos pipes or fmf,buch of new fmf on fle-bay.

http://www.nwvintagecycleparts.com/ other hard to find parts,good prices GREAT service.

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