KR-1S.co.uk Forum

Well, after what seems to be a hugely protracted period of inactivity, eyes finally returned to project ditch salvage. I’ve just read back through the thread and decided to start a new thread as I had clearly been on the sauce whilst posting in the old one.

Anyway, without this thread turning onto a monologue (I do go on a bit), we last left it with me deciding that I had got to do something with the engine. Well, I did, but it was with a different engine, on a different bike, so the KR1-S sat forlornly in the back of my shed watching it’s battery go flat.
However, the other bike has know been completed, so back to the KR1-S



All of this is a total aside, but got me thinking, more importantly it got me thinking of what I should do to keep the space between the KR1’s spars warm whilst the motor was out for rebuild.
It’s got to be a two stroke, and I can’t have less power, which led to the same conclusion as many others have come to. Either a CR500 or KX500.

CR’s defiantly have that animal image, but I think KX’s are actually more refined, hey they even have a power valve! Plus it’s going in a Kawasaki, so it should really be a Kawasaki.

A large level of “hens teeth” and “rocking horse poo” type responses from moto-X breakers meant countless evenings on ebay – which resulted in this:

Wow – what a peach, someone even helpfully stamped a new engine number on it at some point!

An evening’s Kronenburg fuelled spannering in my shed has culminated in this, top give me an idea of where to go with it.


Quite a lot of work to do I think – and that’s just to tidy the shed!
Jan – have you finished yours yet? – I may need some advice.

R1-DAZ has done a CX500 conversion might be worth having a look at that for info if required

Glad to see you back at it there Abel.
I like the idea of the conversion, but don't kid yourself that it's just something to put in there while you rebuild the KR's old heart. I think you must realise that if you do this, you'll never end up taking it out again unless it's for a rebuild.
Not to mention the fact that it's going to cost a lot more to do the conversion than to rebuild the origional motor.
Now, after I've said all that, if you can commit yourself to the long build ahead, I say GO FOR IT!!!!!!!
Now I have to stop looking at the pics you posted, as it's giving me evil thoughts of stuffing something similar in my Tandem Twin, and I know I just don't have the budget for that after buying a house.

Seriously though, it will make an insane piece of kit to ride, and I'm looking forward to seeing the build progress pics.

Good luck.
Scott.

Abel wrote: Jan – have you finished yours yet? – I may need some advice.

no, all the parts are waiting for me to put them together , which I didn't want to do before the KR1-SV was on the road...

... and now it is

got to do some other small things first on other bikes, but somewhere this summer it'll kick off. bought a frame that already has been prepared for the KX500 though, so can't give you lot's off idea's as the "do's" and "dont's" , but if you want me to measure up some things, let me know

Jan - I must admit I've got a fairly relaxed attitude to it, I don't mind making a few mistakes along the way, but the first of the problems I have noticed is getting the output shaft of the KX motor to be in the same place as that of the old KR1S motor.
That is that you can't, unless you want to hide the kick start shaft behind the frame rail!
I think I've got a solution, but would certainly be interested to know where the engine sits in the frame you have. That is can you measure the mounting bolt and centres of the "extra" peice of frame you have? -the double cradle.
Also, I saw in you post that you got it of ebay - do you know who did the work? They may have been as dim as me and got it a bit wrong!?

I've got some photo's of the geometry of where I've managed to place the motor. I'll post them tonight.

Abel wrote:I've got some photo's of the geometry of where I've managed to place the motor. I'll post them tonight.

No I won't becuase I've moved it to a better position.

Jan - I've been looking at the pictures in your thread. Infact I should probaly be posting this there.
However, I've noticed a few things.
Firstly your motor doesn't have a head mount - I don't know if that means it's earlier or later than mine. Mine's a '92.
Secondly your additional peice of chassis - the twin cradle - only mounts on two of the three engine mounting points. The big one at the back seems to have been left free. Is there more to be added to your frame that you haven't photographed or do you think two mounts is enough?

took some pictures :



at the back off the engine, there is a thick plate welded onto the frame. you can also see there are 2 holes in it : a bracket is bolted on there that fits onto the big engine mount.

you can also see the shaft for the kick. it just passes under the frame, but there is nothing yet to brace it. I don't know yet if I'm gonna put a kick on it, since it will only be a trackbike. might be I just make a "professionel starter thing that makes the rear wheel spin" to start the bike will it's on the stand .




no engine mount on the cylinderhead. I have no idea what year mine is.

Been moving the engine around trying to get everything in the right place, which has been no mean feat.
At last I think I’ve got something acceptable. I’d been struggling to get the output shaft high enough so as not to effect the anti-squat characteristics. The problem was whenever I raised the motor the kick start shaft tried to disappear behind the ring side frame spar. Jan’s cunning and therefore will of cheat this by having a roller starter, but I’m intending on using mine on the road and you can guarantee that if I don’t have a kick start I’ll stall it just as I go to pull that one handed 5th gear minger past the girls school!!
It’s ended up output shaft being further forward than before, but the motors not too far forward so I not bothered.
Oh, yeah, and I forgot to mention I don’t want to chop a hole in the spar because I want to be able to go back to original (whether I do or not is another issue, but I want the ability.) Oh, and the other thing is whatever I do can only be made from steel as I can’t weld ally. Ok, I know steel is a dirty word, especially as I’m trying to get the thing as light a possible, but if it all turns out working then I’ll I ask someone to copy my steel work in ally.

Anyway, I finally found a position which seems suitable, and won’t required use of an offset sprocket or anything nasty like that.

The bit of blue chopping board was cut up to mark where the KR1S output shaft was. That socket head cap screw wound down to touch the end of the shaft on its axis before the old motor was pulled out. The bit of orange string shows a line from rear spindle through swing arm spindle and on at full rear extension. If anyone thinks this is in the wrong place TELL ME NOW PLEASE!

This time the orange string is the centre axis of the chassis. The motor is offset what looks like 12mm from the central axis of the bike, 12mm to the left, but I don’t know that the centre of gravity was on the crankcase split line anyway so I’m happy with it. If it proves a problem then I’ll have to come up with a solution, like the fuel tank holding more fuel on one side than the other or something?

Anyway , like Jans pictures he posted, the engine is going to be housed in a double cradle, but I’m going to use all four of the engine mounts (three on the crankcase and one on e the head) as apart from anything else I don’t trust my welding!
The front end of the cradles is going to be welded to a thick plate which will be bolted onto the front frame brace (that the regulator/rectified bracket bolts to). This looks a bit scrawny to me (confirmed but the extra bracing on Jans chassis), so I’m going to bolt through it to another plate which will be on the other side.
I’m going to go off this plate onto the head steady mount but that is for another day.
The rear ends of each cradle are going to be welded to vertical plate which will mount onto the bottom frame mount, and the rear big motor mount (16mm bolt!)



SO with the motor in it proposed position I used card to see where the cradles would go.

Card board turned to hardboard, which was used as a template to bend 25mm seamless tube as you can see. Tubes were left long so I could have got it a bit wrong.


Since then a lot of standing, looking, thinking and tea drinking has gone on – slow progress but progress all the same - there’s no turning back!

Jan – from the photo’s you posted it looks like someone has chopped your head steady off and filed it flat. This is what’s on the back of the head on mine– 10mm diameter - meaty!

I like the plate you’ve got bracing the rear chassis mount. Very good idea.

Abel wrote:Jan – from the photo’s you posted it looks like someone has chopped your head steady off and filed it flat. This is what’s on the back of the head on mine– 10mm diameter - meaty!

well, no you mention that, the engine I bought came out off a KX250 frame, maybe that's why

FWIW I would do a couple of things.I would not solidly mount the engine I would be making some form of isolating engine mounts.Next(ties in with No 1) would be to check the balance factor on the crank/rod/piston assembly and see if it is suitable for the higher rpm the engine will now spend it's life at.Lastly would be to retune the engine for a more linear power delivery.Instaed of having 75% of torque at 2500 rpm shift the power up the band so more throttle = more torque in proportion. Most 5 hundies have a power curve that drops away with rpm.
Looks like fun though.

does look like loads of fun, I'm green with envy. =D> =D>

SHimmer45 wrote:R1-DAZ has done a CX500 conversion might be worth having a look at that for info if required

I've built one with a CR500 motor.I can guide you through all the pit falls,do's and don'ts.
I offset the motor 10mm to line the sprockets up and made an outrigger on the frame to support an extended shaft for the kick start.
Exhaust was my biggest headache because i went underseat.
ABEL,PM me and i'll give you my phone number if you want a chat.
Daz
PS It's up for sale if anyone is interested.

JanBros wrote:

Abel wrote:Jan – from the photo’s you posted it looks like someone has chopped your head steady off and filed it flat. This is what’s on the back of the head on mine– 10mm diameter - meaty!

well, no you mention that, the engine I bought came out off a KX250 frame, maybe that's why

The reason there is no head steady is that the engine has probably some time in its life been in a sidecar outfit.
All water-cooled motocrossers,80cc,125cc,250cc,500cc to my knowledge use a head steady but the sidecar guys cut them off because they don't use them.
Hope that helps you out.
PS. I did a lot of motocross in my youth until the bones kept breaking!!!

SHimmer45 wrote:R1-DAZ has done a CX500 conversion might be worth having a look at that for info if required

Really ?!

Ah, you mean CR500. That's a relief...