In Search of the Lost Top End

[Brian G]

Good Day, eh?

I've had my stock '79 for a couple of years now and have enjoyed tooling around the backroads of the Island. She starts at the touch of the button, pulls smoothly from 1500 rpm in top gear up to speeds governed by comfort (stock high bars) and the limits of my aging body. She doesn't burn oil, attracts more attention on a sunny Sunday afternoon at the coffee shop than bikes costing four times what I paid for her and apart from a clatter from the clutch - which was minimized with a decent carb sync - I was a happy camper.

Then my step-son bought an '84 VF1000 Interceptor.

I soon found that to keep up with the exuberance of youth, I was going to have to ride considerably harder than usual and to my dismay, discovered that the engine had a hard time pushing past 7500 rpm in 4th! Dropping into fifth, she'd accelerate some more but again run out of breath around 7500 rpm. By this time, Shawn was disappearing into the distance and I was more than a little concerned. What could be wrong when she runs so well in the lower gears - up to redline if asked - but has such a hard time at high revs in 4th and 5th?

The P.O. had the engine apart at one time so I initially thought a cam sprocket might be one tooth out but she runs so well at 'normal' speeds. There's a good flow of fuel from the tank with the petcock hose disconnected. He had also fitted a pair of aftermarket mufflers of unknown origin which are welded to the stock header pipes and collector. They're looking more than a little shabby (and are a touch too quiet for my taste anyway) so I sprung for a set of Sankei replicas from Six Center in Holland. I'm thinking that perhaps the cheap aftermarkets are too restrictive and are choking the engine at high rpm and wide open throttle. Could I be right? Or do you suggest I look elsewhere for the lost top-end?

Thanks

[steve murdoch icoa #5322]

If it will hit redline in the first 3 gears i would not think the exhaust is restrictive.
Maybe the previous owner changed the sprockets/chain. Stock '79 is a 630 chain with a 15/35 sprocket ratio.
Can't have those punk kids running away from you.

[preston]

Brian, Remember back when, in the day the CBX was unsurpassable in speed or thchnology, now 5 yyears later you're trying to outrun a HONDA!!!

But, it casn be done.

[Brian G]

Well, I posted the first message in this thread a little over a year ago. Shortly afterwards, I took her off the road to have some dents knocked out of the tank, get some new paint, change the front brake rotors, install the Sankei exhaust I got from Six Center, fit a pair of sportkit footpeg brackets, slightly lower bars from a Prolink (thanks for the bushings, EMS!) and a Probe electronic ignition. I also replaced the foam air filter element with one from an '81-82.

Before


After


I'm happy to say that somewhere along the way, the lost performance was found! Shawn can still pull away when the going gets um.., competitive, but I'm not far behind now and it may be due more to older tires and a more developed sense of self-preservation on my part . She now has that surge of power starting at 6000 rpm about which I've read so much, redlines in 4th and presumably will in 5th, if I could find a road surface on PEI not strewn with potholes! What was already a great motorcycle to ride just got even better!

Brian

[spencer]

I'm happy you didn't just give up. Nice job!

[harvey]

Brian,

I rode across the Bridge to and from PEI last year and do not remember any potholes there!

I don't remember the speed limit but I do remember there were several police cars in the area. Actually as we rode around a little bit of the island, I don't remember that many potholes, but I do remember several roads turning from paved to gravel to mud.

Now for potholes I think of a road across New Brunswick which was one of the worst roads I have ever ridden for a bad surface. It showed on the maps as a good road but turned out to be very rough and just trees on the right and trees on the left.

By the way for those who have never been to PEI, they grow potatoes there and when the plants are blooming it is quite beautiful to see the fields in bloom.