Shrinking a 300 to a 250

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mellorp
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Shrinking a 300 to a 250

Post by mellorp » Wed Feb 14, 2018 5:11 pm

The 300 arrived along with the assorted boxes of bits. A quick inventory check showed a pretty good record of all the bits and pieces.
1st job to store the big bits, fairings & pipes and make the bike move able with a dry fit.
Wheels came off and the various spacers found and then reinstalled. No major probs. Brakes on and calipers positioned. As expected the calipers have seized up. A refresh is on the way
On the shelf (well the loft) I had a freshly built crank and some 250 wosner pistons. The 250cc barrels are a bit sloppy so they have gone off for a replate
Plan is
Dry build everything before I drop the engine. That should highlight what bits I have spare/missing/broken.
Once the replated 250cc barrels are back I will drop the engine and rebuild it with the new crank. I might pop a BDK F3 Kips system in whilst it's apart. With the engine out I can get the frame welded.
Then the existing crank and 300 kit will be up for sale.
Rebuild it, MOT it, Thrash it :-)
Pics (maybe) to follow

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Binetta Steve
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Re: Shrinking a 300 to a 250

Post by Binetta Steve » Wed Feb 14, 2018 7:23 pm

Rebuild it, MOT it, Thrash it :-)

Thats the spirit, good man!

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Re: Shrinking a 300 to a 250

Post by mellorp » Fri Feb 16, 2018 11:58 am

1st parts arrived from Venhill. New throttle cable and some KIPS cables. A massive thanx to RickNC30

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Re: Shrinking a 300 to a 250

Post by mellorp » Thu Mar 15, 2018 4:27 pm

The dry build is going a bit slow as I have damaged my hand (binned one of the NSR's at Oulton; Idiot). Anyway new brake lines fitted along with reconditioned calipers front and rear. An order from Cradley Heath for some missing bits, springs, grommets, odd nuts, carb rubbers (why not) and some new gaskets ready for the rebuild once the barrels are returned. Found a fuse box on eBay so I can check out the electrics once that turns up. The RGV250 VJ23 uses a 55A starting current battery that fits in the KR1s battery tray. One of them is going in as they are only slightly more expensive that a std gel battery (from TheTuningWorks).

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Binetta Steve
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Re: Shrinking a 300 to a 250

Post by Binetta Steve » Thu Mar 15, 2018 7:18 pm

Good decision on carb rubbers. Lots of folk on here , myself included have had running issues, binned the cracked rubbers and clean throttle response abounds. Please get some photos of the bike up when you get a chance
Steve

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Re: Shrinking a 300 to a 250

Post by mellorp » Thu Apr 05, 2018 5:36 pm

No excuses why we can't get started now I have a few important new bits

https://www.flickr.com/photos/156864217 ... ed-public/

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Re: Shrinking a 300 to a 250

Post by mellorp » Sun Apr 29, 2018 2:21 pm

Finally had some spare time today
2 hours later the engine is out.
https://www.flickr.com/photos/156864217 ... 2182914232

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Re: Shrinking a 300 to a 250

Post by mellorp » Sun Apr 29, 2018 9:18 pm

And another 2 hours and it's in bits

Having never taken a KR1s apart before it was pretty straight forward. As usual the engine had been put together with a couple of badly chewed up screws here and there, a few were finger tight and others took a bit of heat to remove them.

The 300 bores and pistons are in excellent condition, ditto the heads with no damage. Someone had the good sense to fill the cases with 2T oil so the crank and seals are in great condition. I've not checked clearances but the mains seem like new. The KIPS valves were not brilliant, 4 std valves, with one solid on the actuator. It snapped so I have 3 std ones. The little screws in the adjuster arms were a bit tight but everything came apart once I figured out where the cir-clips and retaining bolts were. Flywheel was a pig to shift but it came off without too much drama.

So it's all out ready for a rebuild. Well almost. The rear engine mount has a very large crack in it. Should get that welded this week (work permitting)

I've ordered the full F3 KIPS kit from BDK. I'm not @rsing about with the motor. It has Wossner pistons, new ceramic plating and a new crank going in. It would be pointless bodging the KIPS valves together.

Once the frame is welded I can swap the swing arm to a nice powder coated one. In the mean time I can clean everything up, put the new crank in and build it as far as fitting the barrels, then once the KIPS valves turn up I can bolt the top end together.

I'll take some pics of the rebuild as we go.

I might even put a zeeltronic on it :-)

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Re: Shrinking a 300 to a 250

Post by JanBros » Sun Apr 29, 2018 9:45 pm

if you do not change the KIPS links and control wheels, you should only use 2 F3 KIPS valves. if you want to use 4, they should turn in opposite directions in each cylinder.
You know it's cold outside when you trip over dog shit instead of standing in it.

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Re: Shrinking a 300 to a 250

Post by mellorp » Sun Apr 29, 2018 11:31 pm

Cheers for the info. The bdk kit has two F3 and two std valves

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Re: Shrinking a 300 to a 250

Post by SP_BOTT » Mon Apr 30, 2018 1:20 pm

I must admit, like yourself, have a few strokers in the shed, and these engines are really nice to work on, nearly as simple as an Rd engine.

Why aren't you using the 300 kit, are they a bit of a 'hand grenade' or is it due to racing rules??

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Re: Shrinking a 300 to a 250

Post by scooble » Mon Apr 30, 2018 1:54 pm

I'd be interested in the 300 kit for racing

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Re: Shrinking a 300 to a 250

Post by podman » Mon Apr 30, 2018 3:08 pm

Sounds good mate, pop some pics up when you get chance, would be interested in seeing them..

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Re: Shrinking a 300 to a 250

Post by mellorp » Mon Apr 30, 2018 3:24 pm

Pics are on Flikr https://www.flickr.com/photos/156864217@N06/albums

I read the history of this bike before I bought it. For a road bike I'd prefer to not have the high maintenance the 300 requires. If I was racing I would probably go the 300 route

As for selling the 300 kit Jarno has had 1st dibs since February. I'll be selling 1 x head, 2 x std KIPS valves (I'm keeping 1 as a souvenir) 3 x KIPS arms, 4 x KIPS wheels, 2 x barrels, 2 x KIPS covers, 1 x crank, 2 x pistons with 2 x rings, gudgeon pins and little ends.

Details to follow once I have the 250 built

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Re: Shrinking a 300 to a 250

Post by JanBros » Mon Apr 30, 2018 8:20 pm

scooble wrote:
Mon Apr 30, 2018 1:54 pm
I'd be interested in the 300 kit for racing

A KR is already oversquare. going even bigger on the bore means you will have even less time-area to fill the cylinder. in cc, the increase of the bore is squared (Pi*D^2) ; but on your port-real-esate-side, the bore increase is only single (Pi*D) -> the ports area increase is lower than the cc-increase and can't keep up and will run out of breath sooner : you might gain some bottom end but you'll loose top end.
and it makes the cylinders weaker and the piston's heavier so your crank will be a little out of balance.

so if it is for racing, it won't make your bike faster Tricia ;-)
You know it's cold outside when you trip over dog shit instead of standing in it.

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