Topic: Progressive front fork springs CB750K2sohc

[My k2]

Hi Im new to this so please bare with me. I am attempting to fit new progressive fork springs [Progressive Suspension units] to my CB750K2 the instructions say to use the spacer provided as my model is listed on the chart supplied, however this will give me a total preload of 2.25" which to me seems too much if i just use the fork cap the preload will be 15/16". The springs are flush with the fork tube at full extension. As the instructions list if your model is not listed a rough rule of thumb is most motorcycles need between 3/4" to 1" of preload. The spring or spring and spacer should be flush or [or above] the fork tube when fully extended. Has anyone out there installed progressive springs to their CB750sohc and can tell me spacer or no spacer is required.

Cheers,
Roy

[Jerry Rxman Griffin aka MuthaF'er]

Just built NOS forks for my 75 750F. The Progressive springs are shorter than my original springs and came with the spacer also. Didn't measure, just compared stock vs Progressive then installed with spacer and washer as listed on the Progressive model chart for my bike. It will be a while before I can ride the NOS forks.

[My k2]

Thanks for the feedback, my old springs are shorter than the progressive ones by 3/8" and 11/64"[progressive]diameter against 3/16"[original?]. Looks like i will have to do a bit more research. Had mine for 2 and a bit years, in the process of completing a full bare frame resto.

[bwaller]

For the street plan on that 3/4 to 1" preload as a starting point. In your case you don't need to use any spacer.
 
Don't be tempted to use too heavy an oil, a good 15 weight fork oil, or even ATF is the ticket.