Z250 Single

Sweet you are secondarily getting there as for mine I have decided the jetting has been messed with seeing as how it is carbon fouling the plug after 20 miles but I have decided to be lazy found a guy will rebuild and tune the carb for $35 followed by a paint job for $40 plus paint hee hee

Nice, that's a pretty good price from where I am. I've found a mobile mechanic who will help with the engine for $100, but I'm not sure if he does honing.

Managed to replace the fuel tap gasket and "rebuild" the petcock. The leak was from a dodgy strainer, which had come off from the O ring and mangled that as well. For future reference, the fuel tap gasket which fitted my Z250 C gas tank cap ended up being the 51059-008, the same one for Z900/1000's.





Even got new washers!


The crankcase vent.

So its the cam chain tensioner and engine work next. I think I will get a new spring just in case, though reasons for it breaking may have been because I installed it incorrectly resulting in the cam chain being over tightened. Not sure how this may have been as I thought I installed the tensioner in the loosest position.

Can anyone confirm which spring tensioner part I should be using for my kz250?
After thinking that I had ordered the wrong part, as the one that arrived in the mail was 5mm longer than the service limit, I believe that my part number is correct and I was either sent the wrong part, or the microfiches have the wrong part number one them.

The part I believe I should be using is 92081-1105 Spring Tensioner.

See link in my signature for help with using kawasaki.com to determine part numbers.

Good Fortune!

Hmm my VIN doesn't work for the site. Maybe its an Australian thing?

Here's the reply from Z1's Rob:

The 92081-1005 spring was originally used as a throttle stop screw spring on KL250-A and KZ400-A, D and S models. On the 81 KZ250-D2 however, the spring was used as a tensioner spring.

Reviewing the 80 KZ250-D1 and 81 D2 cam tensioners on fiche, the tensioner components, except the tensioner spring, are the same between both models. I suspect, Kawasaki was experiencing issues with the 92081-1105 tensioner spring on the D1 model and found the characteristics it was looking for in the 92081-1005 throttle stop screw spring. Hence the change.

Unfortunately, I’m unaware of any documentation providing specifics of the 92081-1005 or 1105 springs. As the 92081-1005 spring is not available through Kawasaki or our network of dealerships, you’ll have to locate the spring through other channels, Ebay, craigslist.org, online parts search of the OEM part number, etc. Once you locate the spring ask the holder if he can provide whatever specs he can of the spring.

If the manual in hand covers the 81 model. The information may be indicating details for the 1005 spring rather than the earlier 1105 spring.


My manual definitely covers 80-82. If its the case that the specs detailed is for the 1005 spring, yet the 1105 spring was used before hand, then perhaps the 2mm excess isn't that big a deal? But my cam chain tensioner did break...

Have looked at the 1005 part for sale on ebay - the number of coils are different from the picture shown in the manual, but I have emailed for confirmation of free length.

If anyone has any additional information that would be much appreciated.

Ok think I have got to the bottom of this cam chain tensioner business.
Looked into putting the new cam chain tensioner on yesterday, and, after a big struggle to remove the tensioner collar (had to sand down a side before tapping it out) managed to put the new one on.

That's when I realised the adjusting bolt was again not fitting properly - this had happened on the original one, but seeing as the hole was kinda messed up, I attributed it to that. Turns out my "adjusting bolt" is just a random bolt which has been cut down to size, with similar threads but not quiet...

So I believe that's the main culprit to the cam chain tensioner splitting, seeing as it wouldn't have been capable of handling the same loads.

Took off the top end and cylinder block today, which was quiet fun. I've gone through the manual looking at the various tools I'd need to disassemble and reassemble, trying to gauge whether to get a mobile mechanic to come do the job or if I could do it myself. It costs about the same to get the tools, but the different procedures for removing and checking the valves seem to suggest that a pro should do it. Also will have trouble tightening the cylinder base and head bolts to the right torque as the torque wrench won't fit...

Regardless, wanted to take the top off to get it to the machinist, to get it honed and leveled. The state of the gaskets and O rings weren't fantastic, and I think that is definitely related to the low compression I'm getting. Found one of the O rings from the cylinder head chewed up and lodged in the bolt passage. The large O ring around the cylinder also had holes through it, though I assume I can check with my new one (I assume I have one in the gasket/o ring set) to see if that's normal. The gaskets between the cylinder head and block, and block to crankcase were also a mess - flaky and breaking off immediately upon removal.

So lots to do in terms of going through the maintenance section and doing as much as possible, getting the block honed head leveled if necessary, and getting a pro to do the rest. Will start by cleaning the carbon off the combustion chamber.

Don't want to get into the crankcase if possible, hopefully the mechanic will look at it.






ps. used the Y shaped attachment from the paddock stand to push out the piston pin. Fit perfectly.

Looks you are mmaking preaty good progress I finally got mine running right and after about 50 miles it stoped smoking after burning out all the carbon build up even though after discovering why it ran so rich I felt kinda stupid not realizing it sooner it turned out to just be pluged up air bleeds so after good cleaning new points condensor and adjusting everything just the differance in acceleration is amazing however in the process got talked into a cbx 1000 but for it I am gonna cheat and picked up a brand new crate motor from a guy with a stash of nos parts lol but meh thats all a different forum keep the updates coming and best of luck ta ya

Thanks Jo - getting it on the road definitely isn't cheating. I kinda wish I could do that right now. Cleaned the carbon build up off the combustion chamber and piston head a bit, and did some of the maintenance tests on the cylinder head and block. The head is pretty level and meets the service limits, but definitely have issues with the piston and cylinder. The gap between the cylinder and piston is over the .058 limit, which supposedly means I might need to rebore and get a new piston?

Hoping not. Will talk to a machinist soon.

Well it's been a while.

I ended up taking the cylinder head and bore to the machinist at MMT, who was a really cool guy, showed me around the workshop and let me watch him work a bit. I asked for them to remeasure the clearance and told them about the discontinued piston. They tried to do a very light hone but in the end, the clearance went to .10. I also left new alive seats with him and he replaced and reseated them - that seems fine.

So all of this is now ready, it cost 275. It seems reasonable but i was expecting less. A hone was only going to cost $10 a hole, but i understand more time would have gone into this. I believe 110 was for the new piston and rings. But for around 80 I could have got a valve spring compressor, rotor puller and holder...

I guess my question now is having spent so much on the top half, is it worth just letting him check out my crankcase just incase? I don't feel like having the top ruined by some random debris that might have fallen in, even though I've covered it with a cloth and glad wrap...there are also the seals I want to replace.

Will call and get a quote. I guess the annoying part of this is that they're only open weekdays so I don't actually get to learn.

Well if its not broke.... But that being said with it already apart maybe better safe than sry oh and on mine carb kept acting funny after awhile so after 3 trys the mechanic just went out back to another 80 kz250 he had by chance long story short mi jet towers was a bit eroded so got new used carb and best part factory muffler and ended up rejetting down to a 93.5 main mostly due to lawn mower filter in filter box lol but berm bout 600 miles now and other than some hesitation at wot (got a dirty gas tank still needs a relining) can't complain but I digress all in all if top end was worn bad enough to rebuild better to do bottom now aswell seen many people do a top end then bottom then top again better to get.it all nice and right all at once but thats just mi 2 cents

Yeh, I asked about getting the bottom looked at, but he's too busy. But he was willing to have a quick look at it for me when I pick up the top end. So that's nice of him. But the problem is getting the bottom end off seems to be a lot harder than what people make it sound - mainly because of these stripped screws I keep encountering...


Here's a pic of the stripped screw over the chain cover, before I tried angle grinding a slot into it to fit a flat screwdriver into it...might have to look into using a screw extractor, but I have a feeling its too stripped for that? Might have to get a friend to weld a nut onto it? Any ideas?


Also how do I detach these? I thought it would be like the 6 pin connector on the CDI, but I can't seem to pull it apart? Is it just a housing and I should be pulling on the wires instead?

G'day mate, I know it's a very old thread but I was looking at an issue with my bike fouling it's plug and noticed the inspiration photos you posted of the Kz250 from Australia. Just to let you know, I purchased that exact bike 6 months ago, It came to me as a non runner and was in pretty bad condition, I had to do a full resto on it, its almost perfect now except for my fouled plug on cold start. Thought you might be interested in some photos on how it look today.

How did yours end up?