So, i am in the middle of adjusting valves on my 1989 NC30 and i have quite a few intake and exhaust valves that are on the "tight" limit but still good per the Haynes manual (.21 exhaust and .12 intake) My question is what is anyone's opinion on getting these adjustments closer to the middle of the limit range, or leave as is?

I will be riding this bike primarily to learn how to ride (first bike ever), commuting and a bit of fun and maybe a track day or two for experience. Basically, i don't feel ill be beating on the drivetrain a whole lot. I would think the way people ride would make a difference, so that is why i threw that tin-bit in with the question. Thanks for all you inputs!

oh, bike only has 14,200 miles on the clock, if it matters and i have know idea if the valves have been adjusted previously. I am guessing "no" however...

I always adjust mine to as close to correct as possible, or if not then looser as they do tend to close up, The 1 thou shim increments allow adjustment to within 1/2 thou.
However, If within spec, then leave them as only when they close up to nil or less will you notice a problem, and if you are not that used to working on the bike yet there is a danger of dropping/loosing a shim down the engine or setting/measuring the clearances wrong.

No difference to how the bike is ridden, but hats off to you as a new rider getting stuck in with maintenance.

arsey30 wrote:I always adjust mine to as close to correct as possible, or if not then looser as they do tend to close up, The 1 thou shim increments allow adjustment to within 1/2 thou.
However, If within spec, then leave them as only when they close up to nil or less will you notice a problem, and if you are not that used to working on the bike yet there is a danger of dropping/loosing a shim down the engine or setting/measuring the clearances wrong.

No difference to how the bike is ridden, but hats off to you as a new rider getting stuck in with maintenance.

Thanks for the advice, i think i will only adjust the out of tolerance valves, and leave the rest. I am sure Honda has those specs for a reason, and if as long as within, they should be good to go until the next service mileage.

I aim for loose valves usually - but if in spec and not on the limit, then you'll be alright I reckon.

At least you checked 'em!

CMSMJ1 wrote:I aim for loose valves usually - but if in spec and not on the limit, then you'll be alright I reckon.

At least you checked 'em!

I always run mine at the loose end of the spec - they will only get tighter over time.

CMSMJ1 wrote:I aim for loose valves usually - but if in spec and not on the limit, then you'll be alright I reckon.

At least you checked 'em!

9000 ... Makes you wonder what we find to post about. Well usually the same stuff different day

Evilchicken0 wrote:

CMSMJ1 wrote:I aim for loose valves usually - but if in spec and not on the limit, then you'll be alright I reckon.

At least you checked 'em!

9000 ... Makes you wonder what we find to post about. Well usually the same stuff different day

soon to be over 9000!

If there inspec then they will be ok, but valves tend to tighten up overtime as the valve wears into the head so if you have a valve thats right near the tight zone its often less hassle to set the shim to a looser one then as you lessen the chance of forgetting one of your valves it tight and leaving it tight for a long time.

Also the sheer hassle of taking things apart to get to the shims means most people dont want to do it more often than necessary.

Thanks for the opinions all. I was able to get most of the valves closer to the middle of the spec range by getting 5 new shims and moving others around. some are still a bit on the "tight" side, but i am willing to live with it for now. Just have to get the carbs on and see how she goes!