Flat spot

Mine is the same - but there is a lurvely sweet spot 7000 upwards

Its not a tourquey bike, and the small 'spirited' engine needs a bit of work getting there. Up to 5500ish in 6th is about 60mph ish... 50-80 in 6th gear is a bit slowwwww and needs a bit of 4th gear drop down to pick up the pace in a more spirited manner...

Welcome to the club

Cheers

G-T

Welcome to the club Foggie!
As GT saya this is normal behaviour (assuming it isn't restricted!!).
You have to work the gears to get decent acceleration but once you've got the knack you can get some decent welly out of it! You could fit a K&N filter and a more free flowing pipe, this did make a difference to mine and it sounds much better!

Foggie15 wrote:flat spot i've just noticed, it's at it's worst when i try to roll on in top gear from around 4000rpm, it gets to about 5500-6000 and doesn't want to go any further unless i change down and cane it through the 5000-7000 area in a lower gear. Any thoughts?

Hi Foggie and welcome

I had the same flat spot ( although it would rev passed that, it just bogged down) and just assumed it was a charateristic of the bike but since a carb clean and sync, and valve clearences i dont have this anymore, its pulls smoothly right up to the redline in any gear...perhaps its worth checking if this has been done on yours?

Flat spots are not uncommon on any bike, normally got rid off or at least smoothed out by a service and or a bit of tinkering. Not being able to rev passed at a certain point sounds like something more fundemantal, but strange how you can get by it by dropping down a gear... ..I`d be inclined to strip and clean the carbs and synchronise the throttle bodies and take it from there..

Hello Foggie, and welcome to the club.
I get this flat spot as well, but it's not a big issue. Like yourself dropping a gear is sufficient. It's a bit like the engine bogging down when you're trying to cruise at 30 MPH in top gear. I think it's down to the tall gearing on the CB making any flat spots more evident quite frankly.
Very willing/reliable/bulletproof engine otherwise.

[quote="chromedome"] It's a bit like the engine bogging down when you're trying to cruise at 30 MPH in top gear. quote]

I think 30mph in 6th gear equates to less than 3K revs with the gearing the Cb has, to be honest a patallel twin of only 500cc with what torque there is available doesnt stand a chance of picking up smoothly form those revs, that`s asking too much of the bike.
If my bike is anything to go by, if I want to cruise around economicaly but still be able to get out of a tight spot or overtake the revs have to be above 4-4.5K, I`am guessing maximum torque is around 7.5K revs and max power between 8-9K revs so they have to be worked reasonably hard to get a move on.

But, having to drop down a gear to get passed 5-5.5K revs is not right though, Honda just would not be able to sell a bike like that.

Not sure if it's related but i've just noticed the vacuum pipe that's connected to my scottoiler, it wasn't connected so i'm thinking that air was getting in to the inlet manifold where it shouldn't have been, not sure if this was like it before or after i had the tank off the other day, oh well, let's go try it!
Oh yeah, gotta see if i can sort out my cam chain tensioner too, i have an annoying rattle from down there, maybe connected to the FS if it's affecting the timing??? , anyway, where's my socket set?!

An air leak would certainly have a big effect.

Good luck Foggie, I hope this is about to be a `eureka` moment!.. keep us posted..

ok, no air leak, and stripped everything down to take out the cam chain adjuster, took it out, cleaned it, made sure it was moving freely, turned the engine forwards at the crank to take up any slack in the chain and put everything back, IT'S WORSE!!! one big coughing wheezing flat spot everywhere above 4500 revs!!! is it possible i could have slipped a tooth on the cam chain? i'k going out of my mind!!!

Its unlikely to have slipped a tooth foggie, unless the tensioner didnt fully engage and you rotated the engine clockwise

Only one way to be sure, whip the tank off, cam cover off, undo the small timing plug on the left hand crank case and the bigger centre plug on the alternator cover..turn the engine anticlockwise using a socket on the rotor bolt untill the `T` lines up with the marks in the inspection cover. you should have the `EX` on the exhaust and the `IN` on the inlet camshafts aligned with the top face of the cylinder head..if it is then no problem with timing.

Do it when the engines cold, if youve got that far you might as well check the valve clearences while your there?

good luck mate....don`t panic, it will be something simple..

Enjoy some beers Foggie, you've earned them!!

well done foggie..

have one for me!..

Well done that man!