The Great KR makeover

[Racey Rider]

So I's got me a cheap Kawasaki KR150 with a ticking noise in the motor. Had my first forray into streetstock racing last winter and are keen to get this KR sorted and do the full Vic series. I brought this bike because it was cheap, and it matched my leathers!
(What other reason do you need?)

Being a little mechanical, and on a tight budget, I'm diving into fixing the bike up myself. Stripping all the unnecessary stuff off the bike is always fun, and helps to be able to see exactly what you've bought.

The main fix would be that ticking in the motor. A "somethings definitely wrong" sort of ticking. Bought the bike knowing that it may need a new piston kit or something so, was expecting to spend another $300 odd dollars on that, and end up with a fresh motor to go racing with.
Unfortunately the budget doesn't allow to get the shop mechanics to do the job, so it's me and ... the dedicated advice givers at KiwiBiker, to attack the project.
( Yes, yes ,,, I'll mention your name when I get on the podium!)

So, a 99 KR150, Single cyclinder two stroke ... how hard can it be?!

After a compression test, (130psi), I started dismantling everything around the motor. Have layed the radiator down and filled with water, as read somewhere they shouldn't be left to dry inside, as it allows the air to develop rust in them. (Any thoughts?)

Thought I should get the flywheel off before removing the motor from the frame. What a mission getting that flywheel nut off! Had to use a rattle gun in the end, which took about 2 seconds. Then had to get a special puller to remove the flywheel. Once done I could undo the last bolts and remove the motor from the frame. Stage 1 complete!
(well ... a coffee anyway!)

Today was the "take the motor apart" Day.
Pouring with rain outside, noisy kids inside! New flood lights in the garage.
What shall I do today? SEE YA! (Don't worry, She had the morning in town to herself!)
Set up a table in the middle of the garage ... plonk motor on said table ... and start to dissect it! Out come the reeds first. They look fine, but a little bit of metal filings around the area. Not a good sign.
I decided to leave the head on, and expose the piston by removing the cyclinder. The cyclinder showed quite an area of scratching around the intake side. The 2 rings were still in one piece, but the piston had a chunk missing from it's skirt. The top of the piston had a flattened top edge in one spot.
I presume, as the piston travelled up the cyclinder, not perfectly square due to the broken skirt, it was hitting the top of an exhaust port, thus making the ticking noise.
So new piston and rings it is!
What else should be changed while am there? Top end bearing? con rod pin?
Should honing the cyclinder remove the light scratching, or does it sound worse than that? Re the metal fileing, was thinking of spraying some deisel around inside the crank case to help wash this away. Thou I can't see anything much in there. Is there a better way? :spudwhat:

So stage 2 is well under way.

What else needs doing.
Have taken the triple clamps and forks off as the streering bearings are a bit notchy. There seems to be two of the bearing races left in the frame stem. Do you just beat these out with a screwdriver pushed through from the opposite side or what?

Brakes: have got the pots out of the brake calipars to clean them up. Is fine sandpaper alright to clean these up? Should the O rings that seal the pots in the calipars be replaced or just leave as is?

Anyone know if I'm required to have an air filter on the bike for Streetstock racing?

I'm gonna try the "ride it like you stole it" run-in approach, so will let you know if it develops any immediate problems.

Wish me luck in getting it all back together!
Racey.

[Andrew]

Talk to Dave. I've seen him do this sort of thing each time he does a re-build of his 125's. He'll know for sure!

[speedpro]

That piston is well used, check the brown stains below the rings. It's just about definite you will need to rebore. If you have metal filings floating round inside and you don't want to dissamble the crankcases which you should, you could slosh some engine degreaser inside the crankcases. This will dissolve all the oil and free any debris. Then jam the garden hose in and flush the whole lot out. Drain the water as best as possible and give it a good dose of WD40 or CRC. Oil it good before reassembly. If you are thinking of doing more of this work yourself get a torque wrench, it'll save all sorts of dramas later like stripped threads or blown gaskets. For getting old gaskets off rather than use a scraper and risk garking up the alloy give it a dab of oven cleaner first. Spray it into an ice cream container first and then put it on the gasket with a little paint brush. It'll bubble away and make the gasket easy to remove. You must wash it good afterwards. DON'T get it on paint.
Keep anything with grit away from the brakes. Spotless attention to detail is required here, if you have any doubts just remember the situations where you'll need your brakes the most and then imagine them failing.
Ask lots of questions , , , oh , , you're already doing that.

[Dave]

Replace piston,rings,clips,pin and small end bearing. Check the manual and see what milage the crank needs changing at.
If its a plated bore then DO NOT HONE it. If it has aluminium stuck too it anywhere, use some wet and dry 800 grit and polish it off, (could take hours).
New reeds,check the clutch.
if you do the crank,then fit new main bearings as well.
If it all turns to shit-package it up and send it too me. Yes i will charge you, but it will be done properly!

[FzerozeroT]

one thing to remember, the ring pins that stop the rings rotating, had a mate rebuild an RM 125 and not check this, "bit tight to kick start and doesn't make the same power", whoops, ANOTHER rebore and rings

[Racey Rider]

Have been told by two mechanics that the barrell is stuffed. Doesn't seem that bad to me, but what do I know!
Has some slight scratching around the bore, and apparently, as it's "plated" can't be honed or rebored.
So options are:
Get it re-sleaved and bored to the orginal size - about $400.
Send it overseas to get re-plated - $530
Find a secondhand one - $???

But as I say, It doesn't look that bad. What would happen if I just took to it with some sandpaper and then chucked new rings/piston in it?
Sure it may not be 100%,,, But wouldn't it still be 99% !?
Motors still run when ther're in bad condition, wouldn't the new rings just wear to the wear off the cylinder?
Of course a real mechanics go'na say it shouldn't be done,, It can't be done!
cause the've got a reputation to protect.
But I'm a man of "No Reputation"! 99% is good enough for me!

What I want to know is,,,, How badly are you laughing?!

Little laughing,,, yer, it might work.

Lot of laughing. Should be good for ONE LAP!

[Kwaka-Kid]

I Personally would just do it :P but i know NOTHING and my advice shoud not really be taken but a big thumbs up to you RR for doing it all yourself! im the same only have no mechanical knowledge

[Motu]

Take a look in Bike Mart(inside Kiwi Rider) there is an add for Electrosil,they replate barrels - 18 day turnaround,looks like it's something to do with Te Puke Farm and Trail.With an 18day turnaround I'd say it's going to OZ.

[Dave]

Just clean it up with wet and dry, like you say, it will be down on power slightly-but will still run o.k.

[Racey Rider]

I Personally would just do it :P but i know NOTHING

Just clean it up with wet and dry, like you say, it will be down on power slightly-but will still run o.k.

Well there you go then! I've been given the go ahead by two titans, at totally different ends of the mechanical reputantion line!
Sounds good enough for me. Maybe i"ll change the barrel next time.

Take a look in Bike Mart(inside Kiwi Rider) there is an add for Electrosil,they replate barrels - 18 day turnaround,looks like it's something to do with Te Puke Farm and Trail.With an 18day turnaround I'd say it's going to OZ.

I rang that guy. he's an agent for a Oz firm as you say. $530 back on my door step. Thanks.

[Racey Rider]

Finally I got some spare money to get on with this project.
I ordered a Piston kit, with the idea of useing this slightly worn looking barrel for the mean time. But about the sixth time I looked at this old cylinder barrel, I noticed a broken port bridge, of a size you can fit your finger in. Trouble is, I can't find a secondhand barrell for the bike.
As it wasn't in the buget, and the motor was running fine before, (other than the ticking noise), I thought let's just stick it back together and see how it runs till I can find a replacement.
So in went the new piston with the old rings on, old pin and bearing. At least if it all turns to custard It's only a $109 piston I loose not the whole $230 kit.
So motor goes in, bits go on,,, comes the big moment.
Fuel on. Key on... For your own saftey, take one step back from your computer before I throw a boot at this thing!

RRrrinnnnng ding ding ding ding ding!
"KK would be proud" I thought as the little motor setteled into a calm idle.
So she goes! Yes it sounds a little ruff as the rings ajust to the half sanded barrell. Yes it still may only make it round half a lap of the track. Yes the broken port must be affecting the power output. But I'll be there at the first round of the Manfield winter series (17th April). I'll be trying to pick up that valueable 1 point for comeing second-to-last in the last race of the day!
Who knows,,, That 1 point may be all it takes to finish in front of the next guy at the end of the season (by which time I should have my motor sorted properly!).
Racey

[pete376403]

Which port was the bridge broken? The bridge prevents the rings from bulging out into the port, so its not really optional, especially if its the exhaust port.
However it sounds like you're doing fine so far, and learning, which is the main thing.

[Kwaka-Kid]

Good stuff racey! and heck yeah im proud! thats great news, with a bit of luck shell hold out yeah!

[F5 Dave]

If the plating is worn through then you will be running on Ally & that is just begging for a seizure. The broken bridge may also expand out, get a good yank & cause some real damage. 2nd hand rings will lose power as well.

Most places that do replating also do barrel repairs if they aren’t too far gone.

[Kickaha]

I rang that guy. he's an agent for a Oz firm as you say. $530 back on my door step. Thanks.

Ther are two firms at least in OZ that do this work,one of these firms rooted a 99 TZ250 kit barrel that was sent to then,it was so bad it had to be scrapped.

A guy down here deals with a UK crowd time around time is slower but they do a top job,he's a aircraft engineer so is a fussy prick and for a replate without any repairs was a bit less expensive.