1989 kx 250 tear down / build finished! I"m a Tool...

Thanks for the kind words guys!..I Learned a lot on this build....Hope to get a video of it running sometime this week...

Bike fired up on the 3 rd kick! But, have an issue....head & cylinder are getting very hot for just ideling & putting around the yard.. Coolant is flowing into radiator nice, bled coolant system, radiators are warm but no where near as hot as the head & cylinder.. Cooling system is not building pressure... After a few minutes the engine starts getting very hot & acts like its leaning out, surging.... Thinking a bad head? Not enough fuel flow? I did have a slight coolant leak at one of the head studs but after retightening the head nuts it stopped... Any thoughts?

Well, found the air leak.....splitting cases again to replace seals again....thanks Kawasaki....for putting the seals inboard so cases have to be split....I have 1 more Suzuki to build next, after that, I"m done! These things are sucking the life out of me!

Pulled top end & engine out, piston looks fine, slight blowby on head gasket at edge of combustion chamber, not sure if coolant was getting into the chamber, but definitely ran outward toward center head stud, I did notice seepage there while running the engine, I retorqued the head nuts & it stopped, but at this point I will have a qualified bike machine shop inspected head & cylinder top surfaces for warpage...

Had some coolant seepage at the center rear head stud, same spot where there is black residue in the head dome...assume this is the warpage?

That looks like a solid foundation for a restore. mine was purchased not to far away from Boston ....one 89 kx is enough for me! Currently in a holding pattern waiting on head & cylinder to get machined....sometimes these restores can suck the life out of you....luckily I"m dumb enough to get right back at it after a few weeks of modern bike riding...

Mine started as a roach to......everything was there but it all needed to be replaced......the 500, 88- until discontinued shared a lot of the chassis parts. Just about everything else can be bought new or aftermarket. The trans gears & kips power valves are NLA....I bought an eBay tranny before I even split my cases, between the 2 I made a decent tranny. The KIPS valves are 88-89 only & made from aluminum, if not serviced regularly, they will stick & the splines break or incur heavy wear. Like mine, I"m sure the PO"s never serviced them. I was searching Craigslist one nite & found a complete cylinder located in Ca. The Kips valves were better than mine...I"ve had the valves out of my cylinder so many times, I can do it with my eyes closed! Bring it back to life!

The plating is called "yellow zinc" but yes, it looks gold. Much of the Kawasaki hardware was plated this color, but not all of it. I had everything done in the yellow zinc, the platers charge per batch, 2 colors would have been 2 batches. The "yellow zinc" against the kx green looks great. I believe early model Honda cr"s used the same color...

Well seeing how the rain just won't stop here in the northeast, figured I would get back to this bike....I"ve had the engine & parts for a while now just getting back to it....I had the main seals replaced again, with Oem seals, all case mating surfaces have been redone, head, base, center cases...everything that could have been surfaced got it...I also carefully ground back the center exhaust valve flap edge, as it was very close to piston due to some play in the valve parts, clearance is better now.



Hopefully all the air leaks & head gasket leaks will be cured....

Well, I thought I would post this up as I can laugh at myself....Remember, I never claimed to be a factory mechanic....I finished this bike last summer, had problems upon initial startup, mainly, after a few minutes the head & clylinder would get extremely hot while the radiators were only warm. After getting super hot the engine was dieseling & sounded like it was leaning out bad. I did have a slight coolant leak at the center head stud & an air leak at the mag seal, the bottom end had been rebuilt by a very well know & good mechanic. So I pulled engine out & had mechanic redo bottom end & replace seals with Oem, as I had used aftermarket seals before. He also surfaced cases, base, head, cylinder...everything to prevent air leaks. I get around to reassembling engine yesterday & finished installing in bike this morning. My mechanic said he did not find anything really that bad when he redid the engine...I fire it up....same F&@$$@ thing! Starts right up, sounds great a then head & cylinder get super hot, starts running like its leaning out/ overheating. WTF? So I double check everything, jetting... Stock...plug... Brand new, stock heat range...no air leaks found....I have service manual out.... Maybe bad CDI..? But I noticed when I fill the radiators they take a long time to burp, & when the engine is running super hot, the radiators are barely warm....ok, I have a cooling issue...water pump is all new, bearings seals ect. At this point I"m starting to think of all kinds of shit....Is piston to tight in bore ? I measured everything several times, ring end gap, piston to cylinder clearance....I remove coolant drain plug from water pump cover, on'y a little coolant comes out, I can still see coolant on the radiator...WTF? Pull bottom hose from water pump cover, more coolant...and........this....

Of course after removing the paper towels I had stuffed into the water pump spigot, she runs like a champ & does not run hot...mind you, I had the whole bottom end redone because of this! I did have an air leak at the mag seal, but my mechanic told me I likely over pressurized the engine while testing it with my homemade pressure tester and he did not feel the mag seal was compromised. Looks like he was right.... So.......I just had bottom end redone, all new gaskets, had to strip cylinder of studs & powervale assy to have surfaced.... Never mind the time & labor involved...all because I had to plug the end of the water pump spigot with a paper towel.....complete jackass.....but It"s DONE...

Looks like post to wrong build.....but I"m all about new Oem carb hoses on my builds! Nothing but the pink stuff bro.....

Yep....so glad I found my screwup, bike looks & sounds so awesome...the combination of green/black/yellow zinc look great, the late 80"s early 90"s bikes are so great looking..... It will be ridden....Thanks JWACK....

I grew up working in a body shop.... The shit I"ve seen guys, including myself screw up is unreal....in the grand scheme of things, it was no big deal.... i"m Just glad I found it before I brought it to a REAL mechanic....thanks for sharing your story Slosh 112...,,live & learn.....

I"ve left a rag stuffed in the airbox boot once also....maybe I should just not worry about stuffing shit everywhere....

I believe the 88 & 89 cylinders & powervalve parts all interchange the 88 & 89"s share many engine & chassis parts....how bad is your cylinder? Companies like Millenium & Powersealusa can work wonders on damaged cylinders. I have a spare 89 cylinder that is ported, needs to be sent out for repairs, the companies that repair the cylinders also can match a new piston while they repair/replate them. Powervalve parts are very hard to come by & nos powervalve parts & tranny gears are almost non existent. Get that 88 posted posted in the build section!