Mixture screw direction

[Oddjob]

Dom I have a full set of brassware out of a bank of 69a carbs just lying around. I think I may be missing one emulsion tube. If you wish to borrow then to test if they make a difference just let me know. If they work and cure the problem we can discuss it.

As for listening to exhaust notes, oddly in one of the carb manuals Honda produced and is linked to on this thread it says specifically it’s not possible on muliti cylinder engines. Not my words, those are Honda engineers saying that. They do say it’s doable on twins but not fours. How you’d do it on a 4 into 1 system is another question entirely. Plus even with a genuine 4 into 4 system they are still linked between the pairs.

I also have some genuine orings from a genuine Honda gasket kit if you want to replace those Vesrah ones. No charge for you mate.

[DomP]

Thanks Ken, I'll have another look at it this weekend and get back to you, I really have to get it running right by the end of this summer.

[deltarider]

[...]As for listening to exhaust notes, oddly in one of the carb manuals Honda produced and is linked to on this thread it says specifically it’s not possible on muliti cylinder engines. Not my words, those are Honda engineers saying that. They do say it’s doable on twins but not fours. [...]

The balance tubes at the end of the exhausts could interfere. Could. But what if you slide the tube a little further inwards, passed those tubes? Worth trying imo.

[deltarider]

By the way...

As for listening to exhaust notes, oddly in one of the carb manuals Honda produced and is linked to on this thread [...]

Linked to on this thread... ? Are you sure? I haven't found it. I know only one Honda Carb manual and in there it is not mentioned...

[Oddjob]

It’s the link Scottly pasted. The Honda motorcycle carburettor service manual. Top post on page 2.

Look at page 12 and you can see what Honda says about trying to balance carbs by ear. 

iIf you’ve ever seen a 4 into 4 exhaust for the 500 dissected, eg with the chrome outer skin peeled off, then you would notice the balance pipes don’t connect to the central tube exiting the rear. They feed into a void which surrounds that tube, so it wouldn’t matter how far down the tube you went the balance pipes would still be affecting it. How much it would affect it I can’t say but the bike in question on this thread is a 550f which doesn’t have a 4 into 4 system anyway so the point is moot.

[deltarider]

Thanks. I've read p.12 in that carb manual. There it deals with syncing. My aim is to see if I can finetune the mixture (adjusting the airscrews) by listening to the pops and compare the 4 to determine which exhaust produces the thinner and which one the fatter sounds. It's an idea. I don't know if it will work. I guess I have to try myself.

[Sesman]

‘Fine tuning’ may be beyond practical reach as the metering system is pretty crude! Twist the screws for best effect and leave it at that😁

[McCabe-Thiele (Ted)]

I would add, sometimes it's worth holding your hand against the silencer exit pipe to feel if the exhaust is cooler or hotter with a small adjustment of the air screw. Obviously more difficult with 4 into1 systems than a 4 into 4 set up. Cooler is richer, hotter is weaker.

[DomP]

I would add, sometimes it's worth holding your hand against the silencer exit pipe to feel if the exhaust is cooler or hotter with a small adjustment of the air screw. Obviously more difficult with 4 into1 systems than a 4 into 4 set up. Cooler is richer, hotter is weaker.

The headers could be used with a temperature gun though?  What temps should I be getting when warmed up?

[Bryanj]

Kin ot!