One idea at a time in focus mode
Top-end planning figures, and the failures the sources actually tie to jetting and to cheap reeds.
Before you start
Your own risk. Wrong jetting or timing can seize the engine. This is information, not advice.
How many steps: 2
Step 1 of 2
MCN’s mileages are planning figures, not a tuned interval.
MCN, via the research brief: rings around every 5,500 miles, piston and barrel around every 10,000 miles. Those are planning figures. They are not a measured wear limit, and they are not a revised interval for a bike with a 34 mm carb and an expansion chamber. Haynes wear limits for pistons, rings and bores are on the engine spec page. Use those when the parts are in your hand. A shorter interval after tuning is To verify. A mileage with the spec of the engine, and a source, is how that line gets filled.
Step 2 of 2
A lean mixture seizes these engines.
Licence, MOT, insurance or a seizure.
The derestriction notes and Hartrusion’s carb page agree on the failure, even where they disagree on jets: a mixture that is too lean seizes the engine, and a larger carb or a different pipe makes that mixture your job. Hartrusion’s extra point is that the 34 mm carb is harder to set up at low rpm, and that the effort is regularly underestimated. Cheap carbon reeds that break are the other sourced failure, on the reed page: debris in the crank, the rod or the bore. A top-end life after a named pipe and a named carb, in miles, is To verify.
This guide is done. Your place stays on this device.
MCN, via the research brief: rings around every 5,500 miles, piston and barrel around every 10,000 miles. Those are planning figures. They are not a measured wear limit, and they are not a revised interval for a bike with a 34 mm carb and an expansion chamber.
Haynes wear limits for pistons, rings and bores are on the engine spec page. Use those when the parts are in your hand. A shorter interval after tuning is To verify. A mileage with the spec of the engine, and a source, is how that line gets filled.
Source: MCN, via the research brief
The derestriction notes and Hartrusion’s carb page agree on the failure, even where they disagree on jets: a mixture that is too lean seizes the engine, and a larger carb or a different pipe makes that mixture your job. Hartrusion’s extra point is that the 34 mm carb is harder to set up at low rpm, and that the effort is regularly underestimated.
Cheap carbon reeds that break are the other sourced failure, on the reed page: debris in the crank, the rod or the bore.
A top-end life after a named pipe and a named carb, in miles, is To verify.
Legal and safety. If the engine is tight, hot, or the plug is pale after a hard run, stop. Do not “see if it clears”.
Source: Derestriction guide, and Hartrusion’s carburettor tuning page
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