KR-1S.co.uk Forum

didn't get around to anything other than checking the water level and it's not moved, so i guess head gasket is ok. So confident it can seit now without water corroding the internals until i get a chance to do something with it

it's only taken me 16 months to get back on this!
Well the bike has sat since Aug last year. When I used it then there was white spoke and sparks coming out the RH exhaust. Fuel dripping from that carb over flow too.
The bike's been holed up on stands at the back of the garage under a cover. One of the things I also wanted to do was do something with the top yoke. It was pretty marked on the top from keys this seems to be the only picture I had of it, not a great picture, a little out of focus



I picked up a nice stock [mostly] ZXR750H1 in the summer and did a light restore/clean/service on that. The top yoke on that was in a similar state. I used a stock celly lacquer on that bike. I gave it a good soak in celly thinners, then used an abrasive pad on it going in one direction only. Holding it in a vice with a block of wood as a guide one side helps. then clean with celly thinners again and then lacquer. There's a build thread here http://www.400greybike.com/forum/viewto ... 62&t=43013 I should get the two together really for a picture



So I did the KR the same way, only this time I used some 2k lacquer. It sets harder and is more durable. I know that because I was in process of trying to pain the front mudguard of the NC30 and screwed it up. It's a swine to get off! So KR one done is below. It's probably 30mins work. Of course the bolts holding the clipons onto the yoke were damn tight and one rounded off and the other sheared off. I spent an hour on the lathe messing making some new collars to go onto st/st button heads. Then decided to buy the proper ones from Cradley for £7/pair. At least they won't go rusty, like my mild steel ones.




So of course while I had the bike out I thought I'd have a little play. Coolant has dropped a little in the rad, maybe 1" lower than the neck. I kicked it over about 10 times, no joy, then once the fuel cock was on Prime it fired after 2 kicks. Seemed to run ok, no excessive smoke from either cyl. I did notice that one oil line was dry, but within a minute of running it bled up to the reed block [?]. The exhaust had enough blue smoke to not give me any concerns about lack of oil. There wasn't any fuel dripping from the carb either. So took it for a gentle run, about 2 miles. Probably didn't go over 5k.
When I got back exhausts were running clear. But the fuel leak had returned to the RH carb again. you can see how clean the carbs were when they went through the ultrasonic tank last year.




But I will pull them out and check them again, with fuel in them to check the fuel level
The plugs were well oily, both looked similar tho. I have a feeling it maybe running rich on the oil pump, so want to check that. Then I'll pull the pipes off for a look at the pistons. Most likely top end off for a look-see, but they maybe a while, I have the 851 in bits. The main bearing was mullered. It's not complicated as such, just everything has to be shimmed and checked. It wouldn't be unheard of to assemble and disassemble the cases a dozen to 20 times to get everything right. And the two mains are £150, gulp!

I've managed some more work on the bike.
I stripped the carb's again, the needles were on 2nd ring from top and mixture screw was 1.5 turns out.
2nd ring from top means it's pretty weak. I have a feeling I thought the stock setting was no 3 and I leaned it off a one notch.

The stock 1S settings are 4th ring from the top and 1 & 1/8th out for the mixture. So I set the carbs to this.
Despite the float height both being set to 19mm I clamped them up in the vice and checked the fuel level. The RH carbs which is the one that keeps overflowing crept up to above the gasket line. The spec is different for the 1 and 1S manuals. The KR1 being 1 +or-1mm below the gasket face [ref factory manual 2-8]. The KR1-S is 1 +or-1mm above the gasket face [ref factory manual KR1-S supplement 2-5]. I couldn't quite see the float needle seat but in the leaky carb but the used a drill bit to clean up what looked like a rough edge and after that it's didn't appear to leak.
I set the tickover using a infrared thermometer on the headers, balance was good.

I finally managed to give her a quick run out. Seemed to go ok, but not so quick as I'd like. As soon as I got back I checked the headers temps and had about 155degC on the LH cyl and about 130degC on the right. Plugs for both looked ok, possibly the RH cyl [lower running temp and maybe a little down on power?] was a little more oily.

So today I pulled the barrells off, complete with the head attached. here are the pics. the crank/insides looked ok, no sign of rust or anything which was good.

RH bore, no damage. I fitted the top ring square in the bore and there's a ring gap of 0.7mm.


LH bore, no damage tho' the head shows some marks. maybe a ring broke at some stage.


Pistons, RH one is on the LHS in this picture


RH piston






LH piston






both pistons seem to show more blow-by at the sides, ie by the gudgeon pin. Can anyone identify the pistons?
also there seems to be the signs of slight detonation on the sides of the pistons near the rings. Does anyone agree with my slightly basic knowledge of 2 strokes?

Well the new pistons came from PJ Engineering, they're the Mitaka and claim to be Japanese. They're stamped with Made in Japan underneath, along with 1KT250. 2 x pistons, complete with rings and small ends was £130 inc del.
Pictured alongside the pistons that were in the bike, which I now understand to be genuine Kawasaki pistons of 'ART' manufacture.
The pistons came complete with RIK rings.
You can see clearly that the side of the piston is the same height as the stock one, as is the centre height. I put all four pistons together, joined at the pins and with a steel rule across the top it's easy to see. It looks as thought the stock pistons have a larger radius to the crown than the Mitaka. Which will increase the squish.
Interestingly I think I found the culprit for the lower temperature on the RH pot. The exhaust KIPS was in the wrong way round. They should be flats to the front when you assemble them.
See pics below

I did a dry build first to check the squish. I'd welcome any comments.
One thing I've read a lot is to bolt the head to the barrels first, then fit the whole lot. I have to disagree with this. I believe the correct way is to fit the barrels losely, do the nuts up but so they can still move sideways slightly. There's only one dowel for orientation, so the barrel can rotate around this point to a degree. Then fit the head and torque it up, then the barrels. As it was my head seemed flat and the barrels were very close to the same height
I did the dry build with the original genuine gaskets. I used solder approx 1mm dia.

Right pot


Left pot


Results


What I'd like to know is at what point to you consider the squish, right at the cyl wall or in a little. You can see that the outside of the RH pot is 0.36mm right at the cyl wall, but 5mm inside and it's 0.62mm

While I was playing the top end I had the side stand off to try and sort the sloppy gear linkage.
There's a bush in the side stand bracket and it develops slop. So I machined a new one from Oilite
It's so much better, knock the old bush out and new one in, sorted!

More top end stuff. When I replaced the KIPS linkages the thread in the one was stripped. I swear by this Plastex stuff for fairings [more to follow], but I thought I'd try the claims it could be drilled and tapped, so filled the offending stripped thread with the stuff, left it over night to cure and then drilled and tapped it to M3. Looks good and tried a screw in it and could tighten it enough


One thing that bothers me is the wear to the KIPS valves and the oil seals. You can see the bushes out of the head casting below. They're available from a dealer for 17pence and to be honest if I'd known they were that cheap I wouldn't have bothered f****g around making some brass ones, which I failed to do due to the thin wall that kept breaking up! But. . . .the problem is they wear the shafts of the KIPS. The oil seals also wear and then leak, spraying oil over the insides of the fairing



I had an idea to replace the oil seals with bearings. My thoughts are that the KIPS are then held more centrally, the bearings knock into the head easily but are an interference fit, and as they're sealed bearings they also act a little like the oil seals. I did a forum search and it seems I wasn't the first to think about bearings, however I could only find discussions and not anyone who had run them. I heated the head up on the woodburner, the bearings almost drop in then. The KIPS shaft still fit quite snug in the bearings. I tried it all out on the dry build, before I tried with a new head gasket and had problems. They're all really free turning, and so long as the bearings don't seize then the shafts shouldn't wear where they do with oil seals


These are the linkage ends I used before, but I've replaced the old stock M3 bar with stainless threaded bar. Just looks better!


Here's most of the bits before it all got reassembled!


Not run it yet, and despite the old pistons being in reasonable condition there's a lot more compression with the new top end all back in one piece. Hopefully will have it running this afternoon!

I wouldn't say your old piston's are in a reasonable condition, I'd say they are only good for the bin, especialy the left one.

Curious about the results of the bearrings for the KIPS
did you have to heat the head much to get the bearrings in ? 'cause when running the engine the head heats up to, hope they will stay in place.

your squish is too small, shouldn't go below 0.65-0.7mm on a 125cc cylnder, and if it's just for a roadbike not squeezing out the last HP, I'd go for 0.8mm

I agree about less than .8 on the squish being a problem. If you leave it that way it might pay to check for contact between piston and head fairly soon after the rebuild.

I'm still not sure what constitutes piston life these days except that early pistons used to lose their pins so this was the limiting factor. If this is no longer an issue and damage is not the problem it may come down to the shape changing or so many heat cycles before the metal weakens?

Perhaps someone can clarify this one.

I am with jan bros on this one regarding squish. what base and head gaskets did you try it with. 0.7-0.8 being what I would be wanting

some good pics there

I presume you know 1KT is code for the first model TZR (2ma) etc

did you spot that your kwak pistons were also different clearance size/tolerance A vs B

for the Kips stems to fit thru the bearing there is clearance and will this be a path for splouge ?

Making nice progress there,

Any of the books I have read give a min squish of .7 mm.
As the lads have said - rectification needed. Interestingly, my engine's squish is about the .8 mark and I believe it is standard.

Just throwing an idea out, seeing as the squish is ok past .05mm in -- could you take slight skim off the circumference of the piston? slightly chamfer the crown maybe? this shouldn't interfere with the compressed volume too much.

Like the gearchange bush , it things like sloppy gearchange that ruin nice bikes. I sometimes re-rivet the balljoints in the linkage if they have become sloppy.

Looking forward to seeing how you get on with this.

hi,can you tell me the size of the bearing you are using for the kips valves,thanks brian

Thanks guys for the informative comments.
I did have the bike running yesterday, had it ticking over for about 20mins. road it 50 yds up the road and back, maybe reving to 4k, it seemed to have so much more bottom end now the one KIPS is thr right way around. It's been 22 years since I rode a KR1 other than this one, hard to remember that they're like after years of 1000cc V twins! I am intending to pull the head off again to see if there's any contact.
Using stock gaskets top and bottom. Am I right that squish is measured right at the cyl wall?
So I either need to add about 0.4mm to the base gasket or as Dmac suggested I had considered taking this off the very edge of the piston, 5mm inside from the edge the squish is ok. Not sure the piston will go in the lathe easily.
What thickness are stock bases gaskets, I seem to remember 0.4mm? I could use the old ones as well? Or would I be better making one out of thicker 0.8mm paper?
Yes I was aware of the A and B pistons. The one barrel is stamped B. I did lots of measurements of the pistons and couldn't really see any difference between them, but I should check.

Brian- bearings for the KIPS http://www.ebay.co.uk/itm/350795511558? ... 1439.l2649 10pcs Silver Tone Metal 8mm x 14mm x 4mm Shield Ball Bearing
£3.50 for 10 delivered! FYI the stock bushes are 14p each and oil seals £5.75 each from Cradley. If I'd known the stock bushes were so cheap I'd have replaced them
No idea how hot the head was Jan, I picked it off with my bare hands and dropped it into my workshop coat to keep it warm to knock the bushes and bearings in. Maybe 100degC, probably only held it for 0.5 sec!
It's common to use heat to fit bearings. You're dropping cold bearings into a hot head, when they're both at working temperature they will have both expanded. It's the same for the Ducati mains, you leave the crankcase in the oven at 150C, drop the cases onto newspaper and drop the bearings in.
There's a small gap around the KIPS spindle. With my old seals in, even ticking over you'd see the oil spitting out. With the new bearings in, nothing yet, tho I can see the blue grease starting to ooze out of the bearings a little
At £3.50 for 10 the bearings aren't worth not trying! you can always go back to seals

One issue I did have was there was a leak of 2st oil from the pump area. Turns out the oil line [to cyls] union was cracked and dribbling and is now broken. This explains why the oil from that line had drained out when the bike sat for 16 months!
I see the oil lines come complete but are NLA now anywy. Is there a cheap alternative to replace them, or do I have to make one?

philfingers wrote:when they're both at working temperature they will have both expanded.

correct, didn't thinck about that


I wouldn't change the psiton to correct the squish, it's not the right way.

I would bold the head on the right cylinder only and redo the squish test by putting it on the right AND on the left crank. if your squish turns out to be quit even on the left one and still more uneven on the right, my guess is you have a bent conrod.