Primary drive reduction ratios

[K2-K6]

Those figures for the 550. Give clutch reduction of 2.625  so there must be the other component on the primary chain to make total of 3.063.

If you work the 500  figures and assume 2 more teeth on the clutch,  then that's going to be 2.826  on the clutch alone,  so you still need the number of teeth for both primary chain sprockets to add to both of these illustrations to give total primary reduction.

May have found another error in Honda manual,  the one that states primary reduction of 2.0 it just can't be that figure.

[paulbaker1954]

The primary shaft gear, the very large one the primary chain runs on is the same for the 500 and 550, they share the same part number, the smaller one which sits inside the clutch casing is different, the 500 has a 23T gear and the 550 has a 24T gear. The 550 clutch basket has 63T but the 500 isn't shown in the parts book.

The 500 clutch basket has 64 teeth (just counted them on a spare I have) so what I am now missing is the number of teeth on the crank and the primary shaft where the primary chain runs.Anyone have these figures?

[K2-K6]

Without those primary sprocket figures you can't be accurate,  but if you try and just extrapolate the difference for that tooth change on clutch drive ( the others say it uses the same primary chain) then I've got something like 3.183 total primary reduction for the 500.

Worth running that figure to see what you get perhaps.

[paulbaker1954]

Without those primary sprocket figures you can't be accurate,  but if you try and just extrapolate the difference for that tooth change on clutch drive ( the others say it uses the same primary chain) then I've got something like 3.183 total primary reduction for the 500.

Worth running that figure to see what you get perhaps.

If we assume the quoted primary reduction of 3.063 for the 550 is correct with 24 and 63 teeth on the clutch reduction then the primary chain reduction works out at 1.167 ((3.063*24)/63)

This then gives a total primary reduction for the 500 of (1.167*(64/23))=3.247

So finally in 5th gear and standard 17/34 sprocket set I get a total reduction of 3.247*0.9*2=5.845

So with my Avon 4.0/18 rear with a circumference of 82.9” giving 0.0013 miles per rear wheel rev I get (60000/5.845)*0.0013) miles per hour per 1000 rpm = 13.34 mph

So finally at 5000 rpm I get 5*13.34=66.7 mph

Feels about right to me

Conclusion

Without accurate data on the 500 primary chain reduction I make the total primary reduction for the 500 as 3.247 NOT the 2.0 stated in the Honda tech specs I have!!!!

And finally just for fun for the 550 in 5th with a total reduction of (3.063*0.9*2)=5.513 and using  same Avon tyres you get 14.148 mph per 1000 rpm i.e. 70.74 mph at 5,000

[Seabeowner]

Been away a while so just catching up. Indeed it's one of the many Honda mistakes. The 2:1 for the 500 is the final drive ratio. 34 teeth on rear wheel sprocket and 17 at the motor end.
I did a little excel spreadsheet on the 500/550s a while ago.
Both share 24 teeth on the crankshaft and 28 on the driven primary shaft gear.
500 is 23:64 driving the clutch basket and 550 24/63. So primary reductions are 3.246 (as quoted the June 72 test in MM) for the 500 and 3.063 for the 550 from crank to rotation of clutch basket.

Interestingly as the 550 has a 17:37 teeth arrangement (rather than the 17:34) on the final drive chain sprockets, but also has a slightly larger rear tyre specified as standard (3.75 instead of 3.50..2% larger) all the differences just about cancel out with the stock arrangement so 500/550 all should rev about the same. (about 62 mph at 5000rpm or 100kph as Delta will proudly tell us)

[paulbaker1954]

Cheers Seabeowner at least it confirms my own calcs

Good to know I wasn’t  going crazy then!!!