February 21st, 2020
For your viewing pleasure, a specially prepared, bespoke Allens Mikuni VM28-57 carburettor with a custom made, radiused air entry.
A generous radius helps to guide air into the carburettor entry, massively reducing turbulence and allowing the pressure drop caused by the engine to draw more air than it otherwise could. Due to production practicalities the carb manufacturers rarely put a particularly nice shape on the rear of the carb. This can be rectified, but a new piece has to be made, pressed on, holes filled, then turned, shaped and blended in. A lot of lumps and bumps that disturb airflow have been removed. In this case, the air hole for the cold start fast idle has been blocked up and smoothed over. A little compromise in the name of high performance.
An extra difficulty with modifying this type of carburettor is that the inside diameter of the carb is not concentric with the outside. This means more metal is removed from the top than the bottom. It’s very tricky to make sure there is still enough metal left in order to avoid the whole thing falling apart.
The front spigot has also been modified to fit a rubber that the customer provided.
A picture of the standard carb below is a great comparison:
June 12th, 2019
The latest off my bench: A set of specially built Benelli Sei Keihin CRS26 26mm racing Smoothbore carbs. Built to order, replacing three standard Dellortos, special spigots made to fit individual manifolds, imagine the sound!
December 6th, 2018
We do aim to please Lewis Ranger!
December 4th, 2018
Next time you’re rebuilding carbs with repair kits, bear this in mind.
Pattern (Left) vs Genuine Float valves under the microscope. Hmmm!
November 28th, 2018
Another nice home for an Allens Performance carburettor!
A Mikuni VM26 looking pretty on a Moto Guzzi Falcone 500cc.
July 26th, 2018
The most recent carb build, shaft made at Allens. The next time you see these, they should be racing around the Isle of Man at the Classic TT!
July 10th, 2018
Meet VM32-0407-K, Mikuni VM32’s for the big Guzzi Twins. Including Allens Performance specially cast and machined manifolds! Smoothest tickover ever.
March 7th, 2018
Just finished! One lucky lad will be able to replace those nasty CV’s with a set of beautiful Keihin smoothbore CR29’s. Complete with specailly made airbox adaptors by Allens.
May 25th, 2017
Some powerjet conversions are more work than others… The TM24 really isn’t designed to be used this way. But nevermind, we have a milling machine and we can be stubborn at Allens Performance!
April 19th, 2017
Here we go!
Replica Yamaha Race Kit Exhaust Flange Castings ready to be machined at Allens Performance.
Many possible applications include RD350LC2 YPVS, TZR250 RD500, RD350LC.