This is a budget build 74 XL350 rat racer built by Andrew Robertson. The main objective was to get the bike into better shape for VMX duties, a number of things were required to achieve this task, update the suspension to the maximum allowed for the pre 75 class, slim down the weight of the bike and add a bit more reliability to the package. And all of this was to be done on a constrained budget.
So the forks have been upgraded with a XL 350/XL250S damper rod combo and NJB gas oil shocks fitted. This is reasonable combo; while it possible to strip some weight out of the front end by using period 35mm Husky fork tubes and CR 250 triple clamps these are not so easy to find but would be a future option should the bits pop up on ebay. The NJBs are pretty much just like Gas Girlings, nice and light and suitable for basic racing.
To remove further weight and to get a slim profile happening, a CR 125 tank, XL 175 seat with alloy seat pan, an XR 200 rear hub and a total loss ignition system fitted. The XR 200 hub is considerably smaller and lighter than the XL hub and also has a cush drive which is essential for the XL 350 to soften the load on the gear box. Likewise fitting a total loss ignition allowed the removal of the entire magneto and to run a lightweight 6.2V RC 4500 mha battery. Two batteries are all that is required for race day – this provides sufficient spark for up to 8 races.
The pipe was built by Cycleworks to replicate something between a Bassani and Hooker – another masterpiece by Damon Gruenwald.
The engine is bigbored to 399cc which also meant the fitting of a heavier duty clutch is by Tusk with Barnett springs. The clutch is an XL 600 unit that slots straight into the XL 350 clutch basket without modification. The springs from Barnett though were an overkill though – way to strong unless you have a Gorilla grip. A slight preload on the standard springs is all that is required.
Last but not least, with a grinder and sander, remove all the old tabs and brackets no longer required on the frame and forks. And a few light weightening holes were drilled in components that can take it.
The total weight savings have been around 11kg savings over the standard XL350 in what Honda called the MX trim (instruments, battery, indictors and lights removed). Total weight with oil in the bike and helium in the tyres is 114Kg.
Future mods for the bike include a better carb and fitting a period plastic tank. Other than that the bike in its current form is being raced both in the pre 75 and pre 78 classes and has proved reliable and lots of fun to ride.