Ok, so having 2 CBRs, of approx the same age, (1990ish,), bike A, both very different in engine sound/riding feel.
The white one is super smooth, where as the red/black jobby, bike B, is not, or should I say, not as smooth.
So, other day I tried to adjust the balancer shaft, as per `How to write up`, and having managed to un seize the pinch bolt, then rotated the shaft, whilst running, to get the `whine`, then just eliminate it, it made no difference....None.
The plugs are all okay, air fiter new, and the inlet and exhaust valve gaps are spot on; the vacuum gauges read ossible timing issues, ie valves, or possible inlet leaks. We discussed this in a previous thread.
It has the odd stalling episode, when idling, and the running is not as smooth as bike A.
So, question is, where would you start? So starting from the lowest expenditure to eliminate possible causes, Im planning on cleaning the carbs in situ, (as per another How to... write up), and inspecting the free movement of the plungers in the carb. And to check the rubber diaphrams, and re seal them against the groove.
I think its carb issue, but one can have an iffy battery, and that can make running an issue.
So any thoughts? Thank you.

 

If you really think its carb related, it would only take a bit of your time to switch them out to tell for sure.

 

You say the battery may be marginal? Check that first along with electrical connections in the ignition circuit.

Second: you mentioned possible intake leaks - a little WD40 around the carb mounts will demonstrate yea or nay on that.

Third: have you balanced the carbs? If not, do that. Although if you feel the carbs are not in good shape they should be gone through first. Balancing is generally the final step in a thorough tuneup.

 

Hi DRam.
Thanks for that.
Im rather loathed to swap carbs from the good one, tempting fate that is ! (previous reply).
When I have a spare mo, I will test the battery, as they can be an issue. As for the wd40 , how will that tell me whats going on, as I realise that if its under pressure itll blow bubbles, even better would say, be spray soap, but if its drawing in air around the inlet rubbers how will I see the problem?
As for the carb balancing, they were all very close, certainly not far apart from each other as to warrant adjustment. Cheers.
Mike.

 

Have you considered a spark issue. Aged coils and wires could be a culprit. Maybe try swapping from bike to bike and see.

I know doing the CoP swap cured a whole lot of the MkI stumbles on my bike

 

If the intake is leaking it leans the mixture out, A spritz of WD40 enriches the mixture and causes an increase in RPM. If there is no leak, and the mixture is correct, the spritz causes an over-rich mixture and the RPM drops.

Take a look at the following:
Motorcycle Message Board - Motorcycle USA

 

Thats a very useful write up. Saved. Thank you.

 

And of course there's the stick-coil upgrade. Cheap and cheerful and nearly always makes the old girls run betterer!

https://cbrforum.com/forum/cbr-1000f...r1000f-138495/

Cheers, SB

 

Hi SB. Ive seen a few comments about this stick coil thingy. I have not read in depth about it, and have yet to see whats required, and understand its benefits, it seems the way to go. When winter stars to bite its northern chill, I will spend a bit of time on it in the workshop. In the meantime, a few basics will be at the fore, so once those are eliminated, then onto more complex tasks.
Thanks folks, from far and wide for your input. Mike.

 

Think about this?

One might not always serve two mistresses.

Which one is more likely to sit?

And which one is more likely to be ridden?

Therein. may lay the answer