New Build Project - KR-1 with 421 Athena Banshee motor.

[pookie]

Pics are fine, as Sp.Bott says it's nice to have some quality content on this forum, I'm not on social media which seems to be the go to place nowadays and unfortunately I've owned my bog standard Kr-1 for over 36 years now so apart from the odd ride out and polish there's not much content I can provide.

[JanBros]

pictures are back.

[RickNC30]

Final Drive -

I always knew that this would involve some juggling to get the chain run correct as the stock YPVS front and NC30 rear sprockets were around half an inch out of line.

This special front sprocket from an outfit called Fast from the Past in the States deals with most of it - it has an offset of 10mm and I managed to squeeze another 1mm by putting a shim in behind it without losing the engagement of the lock washer on the end of the shaft -



Talon engineering in the UK actually make a similar sprocket but they haven`t been replying to calls or emails for the last four months so I have to assume that they have gone out of business which left me the choice of buying one from a European supplier for about £80 or an American one for half that price.

I have regained another 2mm of the offset with some subtle machining of a Talon 520 rear (luckily Dennis Trollope had one on the shelf) -



I don`t think that the gold sprocket really suits this build but I`m stuck with the compromises of limited choice -



This is a workable solution but something I may have to revisit later. I have fitted a heavy duty non O-ring race chain with a clip link for now as I will need to check the chain clearance when we re-route that left side exhaust tail pipe.

Stock gearing on a 350 YPVS is 17/39 but that`s a bike which makes 60 bhp, weighs 145kg and has an 18" rear wheel - this bike will potentially make 80bhp, weigh 120kg and has a 17" wheel, each of those factors would warrant higher gearing in it`s own right so all three together certainly will.

I have no choice with the front sprocket which is only available in 17t from any source - 38t is the smallest `off the peg` NC30 rear so that`s what I`m going with for now but I fully expect to be needing a smaller, custom made rear further down the line.

Putting the chain and sprockets on has enabled me properly to test the gear selection with the Chinese `uprated` cam and detent arm and I have to report that it is so bad that I am going to strip the right side of the motor and put the stock parts back in - yes the location in each gear is positive, so positive that the force required to shift is nearly enough to bend the gear lever, also the neutral detent position is so tenuous that it takes half a dozen attempts to find it and as soon as you turn the rear wheel of touch the kickstart it drops straight back into first.

We live and learn...

[RickNC30]

Finally some more progress to report - I collected the bike today after having the exhaust custom fitted around the modified chassis parts.

My friend Chris is that rare thing, a proper old school bike engineer with great machining and fabrication skills who will turn his hand to any job a special builder might need and do it well - here are the results of his work -

Extra bend in the left stinger pipe to clear the single side swingarm -



Stand mods and extended mounting bracket so nothing touches when the stand is up -



-and an elegant bit of bracketry to fix the chambers together under the engine and mount them to the underside of the frame -



The brackets are staggered so each chamber is individually rubber mounted and the tubular nut on the bottom will double as the mounting point for the fairing belly pan.

Overall a very tidy job - the whole exhaust is well tucked away and completely stable...

[pookie]

Welcome back! good to see you're not rushing this project I like the way the downpipes cross over each other like the Yamaha tdr 250, shame that they will be hidden when the bellypan goes on, keep up the good work.

[JanBros]

I don't like the way the springs that keep the exhusts on the cylinders are touching the pipes and make an angle .
I think they'll make noise and wear quickly at the touching point.
everything else is top.

[RickNC30]

Good point regarding the springs, Jan - I will fix that when I do the final fitting of the exhausts.

Next thing to work on is getting all the major components mounted satisfactorily so that I can test fit the KR-1 race bodywork, trim anywhere that needs extra clearance for the non-standard bits and get that over to the painter so he can work on it while I am building the wiring loom and sorting out control cables, hoses etc.

The carbs and filters fit with plenty of space to spare - I have made up a bracket to position the rear shock reservoir in the gap left by the absence of the stock KR airbox -



I will be using the same YFZ450 radiator which is a popular upgrade for the KR-1 -



- but with one small addition - the RZ350/Banshee motor has that small bypass hose at the top rear of the cylinder head which has to be connected back to the radiator on the pressurised side of the lower filler cap seal so I have turned up an extra spigot and fitted it to the upper end of the right side tank -



I plan to get the cooling system plumbing done this weekend using a selection of appropriate bends and reducers together with a h***a thermostat housing and a Yamaha 50 degree stat -

[RickNC30]

One for you, Jan -

I can`t change the way that the exhaust springs fit so I have given them Akrapovic-style heat proof rubber sleeves...

[RickNC30]

The cooling system is mostly complete now, I may have to shuffle and tweak here and there but essentially it`s done.

The radiator is the YFZ450 race version with the double thickness core, rubber mounted top and bottom -



The cut and shut plumbing is a tight fit but nothing actually snags anywhere -

[pookie]

Always seems a shame with these builds that after the fairing goes on it covers all the effort and detail work that goes into it, at least you know that it has been done properly, great work

[RickNC30]

As you say, shame to cover it all up but `function over form` demands it and the fully clothed version should be not bad looking, I think...

I`ve had to take a break while I had a bit of service work done on myself but after some minor heart surgery I`m firing on all cylinders and back to it now!

I sent the carbs, twistgrip and choke control away to Venhill so they could make me a set of custom cables, meanwhile I have made made a start on building the wiring loom - this is just the charging and ignition circuits done so far -



Next job was to get all the modifications done to the KR-1S race body kit. The RD350 engine is wider than the KR-1 unit and sits lower in the frame, also there`s a lot more exhaust plumbing ahead of the engine with the crossover pipes so a fair bit of cutting away was required -





- but the end result doesn`t look too butchered -





I have also installed the headlamp and Koso tach/temp gauge - the speedo will be a small GPS unit mounted on the top yoke just inboard of the brake reservoir on a bracket which will also hold the indicator, main beam and oil level warning lights (the Koso tach includes a neutral light).



The project is not as near to completion as it looks but the big stuff is all done with only plumbing and wiring type jobs left to complete. The bodywork will go away for painting this week, that will probably take a month but I hope to get to the point of running the bike up on the bench in the meantime...

[pookie]

Looking good, keep the final colour scheme a secret until the end hope you have a good paint guy, they seem to have no concept of time, my Suzuki Katana took two months to finish and i'm just having a bike partially wrapped and have been told it will take two weeks

[RickNC30]

I had the colour scheme visualised in my head before I even started the build so the paint and graphics are already here but I will save that for the final reveal...

[RickNC30]

Today I did the thing which I usually forget and bolted the bike together in full road trim with battery, indicators, mirrors etc all fitted but no fluids so that I could accurately measure its dry weight.

I was hoping to hit 125kg dry but the actual figure is 129kg, split 49%Front / 51% Rear.

The weight of the engine oil sits about central, fuel and coolant are both more forward so when all the tanks are filled the bike should weigh about 150kg and have a slightly front heavy weight bias.

[RickNC30]

Here`s my first stab at a speedo/warning light assembly - I could (and may yet) use a Koso XR-01S unit but that would involve a bunch of extra wiring and the need to fit magnets to the wheel and set up a sensor on the fork leg, all of which is a bit of a pain, so at the moment I have gone with the most compact GPS speedo that I can find and some generic warning lamps on an alloy bracket -