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[purplefox]

I think I have a problem in the gearbox bike starts and runs at first then I get this noise grunts I throttle back It goes away when I go up an hill and I drop gear it starts again I go into top gear it disappears I thought it could maybe a faulty third gear needing replaced If it is would I have to take gearbox out is there any way I could do a test I originaly thought it was the clutch or clutch chain thanks for any ideas

[PeteF]

Are we talking about a 4 speed box? If so, is the noise in 1st, 2nd, and 3rd but not in top? If so it sounds like a problem with the layshaft (this doesn't carry any load in top gear but does in the others. Could be bearings, as the offside layshaft is only formed by the kickstart shaft. Pretty quick job to check this. There's a tech note on here about how to change the kickstart pawl. This procedure gives access to the kickstart shaft.

[purplefox]

Thanks Petef
Noise only seems to be from third gear would this be a complicated replacement

[purplefox]

Sorry I should said its a 1961 royal enfield bullet 350cc owned it since 1978

[Alan R]

Hi guys---------my 2005 Classic 500 does a similar thing...1st,2nd run ok.........3rd has a "rumble" and 4th is normal.. My feeling is it's the 3rd speed gear teeth that are showing signs of wear ??..I believe it can be changed with the box in place ---NORM is that true ???

[Norm]

Owned it since 1978 and never had the box apart, it has done well. Box comes apart easily in the frame, pull it down, fit a set of sealed bearings, have a look at the gears and decide from there

[PeteF]

Like Norm says, just be very methodical and lay everything out in order on a board. If you're stripping the gears out you might as well change the bearings while you're in there for sealed ones. There are tech notes here which cover everything you'll be doing.