May 24, 20251 yr Author I machined a keihin to 32.30mm to fit it into a remanufactured pipe. The original dellorto is 31mm. It fits without forcing. A quick dremel work to pop the pipe lug and remove the shoulder due to the original 26 diameter. I will test Josep Banyeres' sleeve to adapt the airbox. Otherwise I will install a TRS sleeve. Edited May 25, 20251 yr by ahell
May 28, 20251 yr Author On 5/26/2025 at 5:23 PM, Tr1AL said: @ahell https://www.agbikes.co.uk/products/jitsie-keihin-carburettor-adaptor-pwk28 There is no more space to fit adaptator like this.
June 13, 20251 yr Author Replacing the intake manifold to install the Keihin carburetor requires removing the engine. A screw is inaccessible... A quick stroke with the Dremel to adjust the manifold diameter to the white plastic part that fits into the reed valve. This gave me the opportunity to add an extra 0.5mm base gasket, following J. Banyeres' advice. The Italkit S3 piston and connecting rod are perfect. This was a good opportunity to check the previous work. 45/125 jets. It seems like a good base. New footpegs, more in line with Lampkin's bike. 48 idle jet (adaptable), 3/4 open air screw. I'll try a Keihin 48 jet to see if my adaptable jets are properly calibrated because I thought I'd see more difference between a 45 and a 48. I made three 3.5mm shims to shift the airbox further back because the carburetor and adapter piece assembly are longer than the Dellorto's. The engine is soft at the bottom. I didn't lighten the flywheel on this one. The extension seems better... test on the flat. We'll see on the climbs. Edited December 11, 2025Dec 11 by ahell
October 8, 2025Oct 8 Author keihin settings update 48/120 Rotor -10mm (around -500grs) Alloy footrest Xlight tyres Resurfacing the brake discs Dry weight : 72.9kg (stock : 76.5kg dry) Better handling, brakes, clutch, reving ... this 315R is way easier and fun ! Edited December 19, 2025Dec 19 by ahell
December 9, 2025Dec 9 Author Restoration of a pair of original 4RT 32-spoke wheels. Sandblasting, painting, and polishing of the hubs, SKF bearings. Cleaning and treatment of the spokes. Deglazing of the discs. The weight saving on the front wheel is 700 grams less than 315R wheel! Spokes nipples are aluminum, brake disc, different hub, and four fewer spokes... a significant weight reduction. Edited December 9, 2025Dec 9 by ahell
December 10, 2025Dec 10 Author 32 spokes rear wheel, 750grs less than 36 spokes wheel. Dry weight : 71.5kg (- 5kg) Edited December 19, 2025Dec 19 by ahell
January 27Jan 27 Author New Ollé shock save 571grs (showa with stock spring 1820gr. heavy spring 1903grs) New Ti exhaust save 260grs New dry weight: 70.7 kg Edited February 13Feb 13 by ahell
February 22Feb 22 Author Now, the bike is very nice. Crisp engine sound and light feeling. What a bike !
April 28Apr 28 Author I'm waiting for a used 4RT top triple clamp for 22mm handlebars. It's lighter and also moves the handlebars forward, which is what I'm looking for to modernize the stock, slightly chopper-like geometry without compromising the look. I have a few other bits and pieces to add to save even more weight (I expect to save around 400-500 grams). I'm going to machine an alloy swingarm pivot. I'll take this opportunity to remove the engine and take off the extra base gasket.
May 6May 6 Author Machining of a 7075 aluminum (Zicral or Ergal) swingarm pivot. The nuts are grade 5 titanium, M14x1.50. Around 110 grams lighter and a beautiful finish. Edited May 7May 7 by ahell
May 7May 7 Author Iris chain instead of the DID, saving 130g. S3 T41 sprocket for the look, replacing the solid red T42, and titanium bolts. 250g lighter today. We're getting closer to 70kg...
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