Layshaft Needle Bearing Installation Tool: TBS-0041 By David Porter, Customer and Technical Support at The Bonneville Shop           When using our TBS-0041 layshaft bearing drift tool, be sure to place the 57-1607 thrust washer on the locating peg in the gearbox housing, as it sets the depth of the closed-end 57-1606 layshaft needle bearing. I like to freeze the bearing for an hour and then heat…

Carburetor Mounting O-rings: 622/101 Thin vs 70-9711 Thick By David Porter, Customer and Technical Support at The Bonneville Shop Frequently, confusion arises over which carburetor flange mounting O-ring should be used when fitting Amal Concentric carburetors to Triumph twin-cylinder engines, or whether an O-ring should be used at all. We offer 3 different carburetor O-rings: the 244/1048, as used on the Amal Monobloc carburetors, and the 622/101 and 70-9711 O-rings,…

Creating a Custom Made Cable By David Porter, Customer and Technical Support at The Bonneville Shop From time to time we encounter an inquiry for a throttle or choke cable that is not available as pre-manufactured by our suppliers. There can be a number of reasons for non-standard fitment of cables, such as a change in handlebar height or width, the use of an aftermarket throttle twist-grip, or when a…

Piston Ring Replacement By David Porter, Customer and Technical Support at The Bonneville Shop From time to time, we receive reports from customers replacing piston rings on their Triumph engines, that the measured ring end-gaps appear to be out of specification. There can be several reasons for this perception. Sometimes, the technician performing the job simply doesn’t know the size of the pistons presently in service in the engine. Usually…

Fettling with your Vintage Brit Bike By David Porter, Customer and Technical Support at The Bonneville Shop This interesting Triumph Service Bulletin, issued on 11/9/1973, seems to confirm what many of us have known all along- sometimes you have to massage parts to make them fit correctly, or slightly modify them to improve fitment. Pattern parts originate from all over the globe, and are manufactured to varying tolerances. We find…

Amal Concentric Carburetors Service Bulletin 10-69 By David Porter, Customer and Technical Support at The Bonneville Shop On May 1, 1969, Triumph published Service Bulletin Number 10-69, pertaining to the Amal Concentric carburetors. The bulletin, which appears to have been influenced by the West Coast Triumph distributor, Johnson Motors, explains the changes made to the late 1968 and 1969 Triumph models to enhance engine performance in the 1968 models which…

Why do you offer 2 Different Wiring Harnesses for my Bike, and What is the Difference? We get a lot of calls from customers fed up chasing electrical gremlins and, upon questioning, we realize that they are troubleshooting an old, brittle and potentially hacked on original wiring harness. Deciding to replace the wiring harness is an easy choice in such situations and we stock a vast inventory of wiring harnesses…

Wear Limits on Measured Parts & the “Nicholson’s Specifications” By David Porter, Customer and Technical Support at The Bonneville Shop   One of many considerations the restorer or engine builder is faced with is whether a part or assembly is rubbish, or can be put back into service. Factors include a preference to retain originality, taking advantage of modern upgraded parts manufacturing processes, and perhaps most importantly, holding to an…