The International CBX Owners Association

Running at 100km/h (60mph) the bike runs at 5500rpm which seems bit high. After reading a road test where they indicated it runs at just over 4000rpm at that speed I`m suspecting the previous owner changed sprocket sizes. Anybody know the standard sizes?

What size chain do you have?
630 chain-15/35.
530 chain-18/42.

No idea..how do I check? Didn't realise there are different chain sizes for this bike..which use different size sprockets.

630 was stock on 79 but a lot are converted to 530 chain
On a 80 the stock chain was 530.

mcferreira100 wrote:No idea..how do I check? Didn't realise there are different chain sizes for this bike..which use different size sprockets.

Measure between the pins, mate. A 630 chain will be 3/4 inch (.750); a 530 will be 5/8 inch (.625). That's pin-to-pin. Both chains are the same width.

That does seem high

its a 530 chain

SProcket sizes are correct with 18-42. SO what else could it be..screwy rev counter?

Not trying to be a jerk but are you in 5th when you are seeing 5500rpm?
Do you have stock gauges? Just thinking maybe you have CB900F front end or something not stock.

Valid question..yep made sure I`m in 5th and it does have original gauges..feels like it could use a 6th gear when cruising. Otherwise maybe just need to change sprocket ratios. 1tooth up in front and 1 down at the back (depending what's available).

Nah- I'm guessing that there's possibly something amiss with your rev counter. Do you have another similar rev counter to do a A/B comparison with? Alternatively go to an auto electrician or decent bike service shop and get them to put an electronic rev counter onto your motor & take a reading whilst the bike is idling- should match with your own rev counter. I'd have the calibration checked before fiddling with the sprockets. Boet- if I was still in Cape Town I'd be with you to help sort it out. Left the Mother City 13 years ago to settle in NZ. Feel free to email me privately for a yak if you wish...
Best
Dave

mcferreira100 wrote:Valid question..yep made sure I`m in 5th and it does have original gauges..feels like it could use a 6th gear when cruising. Otherwise maybe just need to change sprocket ratios. 1tooth up in front and 1 down at the back (depending what's available).

Should read between 5000 - 5500 for 70 something mph on the gages with the sprockets you have. Go with the advice to have someone do an electronic check of rpm before expending time and $$ chasing other butterflies. Assume you have stock size tires (or near stock). Check your speedo with a known mile and stop watch. Could it be a dragging dial there?

Oh..you mention tyres. This got me thinking as this bike has a wider wheel conversion at the back..takes a 160 tyre. Not sure what the conversion entails but maybe its having an influence.

What is the profile and diameter of the tire?

Its a Bridgestone Battlax 160/60 ZR18 M/C