'77 370 Bully

[crankpin]

Went for a spin over the weekend. Love the handling of this bike, just need to sort out the jetting (rich).

Was having a good weekend until a strange noise from the primary forced me off track to investigate...

Can you guess what happened?

There's a split in the primary cover between the oil drain and the stand mount 

If you click on the pics they blow up quite large...

http://circa74.lefora.com/2011/08/15/bugger-2/#post4

[Oppet]

Too bad 
Something to do with transmission??

[crankpin]

Ate it's primary chain tensioner 

Made a fair mess while it was at it...

Does anyone run without one?

I tried when I first got the bike but the chain rattled on the bottom of the primary cover.

[coza778]

love your signature   crankpin 

[crankpin]

 

[Davy123]

should have kept yer  C&J YAM...!!!

[crankpin]

Doh!

Came here ta get away from ye 

[Moto]

This model Pursang was the only one with a different primary ratio.
The clutch basket has a bigger diameter, it uses a chain with a half link and even a tensioner.It always seemed to scrape on the sidecover.
It is a problem that is fixed by fitting a standard Pursang basket and primary drive sprocket and new standard length primary chain.(as they used in the previous and later models) Dont use the tensioner they can't handle the Pursang RPM.

[crankpin]

Cheers Moto.

Will the adjusted primary ratio require final drive ratio changes also?

[Moto]

 The secondary ratio's were not changed on the earlier or later models, they remained at 13 / 46. Your bike is listed as 12 / 46
 So the change in primary ratio doesn't seem to have had that big an effect.Changing up or down teeth on the countershaft is normal to adjust your gearing to a particular track.
 

[crankpin]

Changing up or down teeth on the countershaft is normal to adjust your gearing to a particular track.
 

Not for me 

Thanks for the info, been a great help.

[JC]

Std pursang primary ratio is 2.375 (16/38); 77 pursang 370 was 2.157 (19/41). Half-link in the primary chain was disastrous, as you found out.

[firko]

Another prodigal son returns...welcome back JC, I hope your health's on the improve matey.

[jerry]

Didn't know you were crook John. Wondering where you had been. Good to hear from you. Keep the knowledge coming..... please. Cheers Jerry

[crankpin]

Std pursang primary ratio is 2.375 (16/38); 77 pursang 370 was 2.157 (19/41). Half-link in the primary chain was disastrous, as you found out.

Thanks for the info, most useful.