750 SOHC Gearbox

[flamethrower]

Got a problem with the gearbox on my 750sohc. After building the unit up I have found that there is a noise from the gearbox when in neutral when running. Its as if there is a dog on one of the shafts that is to close to the corresponding cog that it mates to. When I press the selector drum in the noise gets worse and when I pull it out it seems to clear the noise. When I say pull it out there is only a few thou end float but it does make a difference. I have now stripped the engine and looking at the gearbox find it hard to see anything wrong(all the circlips and washers are present. The only thing I can think of is that maybe one of the selector forks could be slightly bent and not clearing the cogs enough. Any thoughts anyone? Also does anyone have a set of selector forks(3) they can sell me then I can compare with mine
CHEERS  KEN

[Bryanj]

Depends on the age of the 750, there was a modified selector drum from a certain engine number but i think it was madified to help stay in gear not keep it out.

The drum end float is governed by the neutral switch, if this is not in quite right it can cause a problem otherwise it has to be something in wrong or,as you say, a bent selector. If it has only done this since being stripped it would suggest more of incorrect than bent

[flamethrower]

The engine was in a bit of a sad state when I bought the bike so didnt ride it, just stripped it down. The end float on the selector drum is only a few thou so is proberbly ok, but as I say does anyone have any selector forks I can buy from so I can check if mine are bent slightly

[K2-K6]

Usually if a selector fork is bent then they can show a wear pattern on the tip of one side of the mating surface and diagonally the tail of the opposite surface as it will not meet the gear groove exactly flat (that's if it's been doing it a while).

They can be checked by putting the selector shaft with each selector fork on it into a pair of v-blocks on a surface plate and standing an engineer square up against the fork to see if it's at 90deg to the shaft as a quick check.

You should be able to see which one is close if you lay them into the crankcase half and look through the clearances carefully to find out which bit is touching and double check the assembly to give you more of an idea before spending on it though.

[kaceyk2]

when you have done as everyones suggested, if you still need a set of selector forks...give us a shout.
Or better if you want to borrow a set for comparison, I can lend you a set.
Kaceyk2