idle: achieved

[Anonymous]

Managed to rig up a damping screw for my vacuum gauge, get the carbs synced and adjusted the idle mix. Plugs are clean aside from one which had some oil near the thread (otherwise clean). I did another compression test yesterday (wet and dry), is it possible this could be leftover oil in the cylinder from then? I didn't squirt in more than 5 ml or so but haven't ran it since. If it persists I'll assume it's a bad stem seal.

I've also just noticed there is quite a delay.... in throttle response if I snap it back real quick, like 0.7-1.2 seconds. I suppose that's just cv's being as they are but it seems a bit excessive to me. I've never noticed this before on bikes with cv's but I suppose I don't often slap the throttle like that. I've read another thread where this has been mentioned but can't seem to find it now. I haven't raised my needles yet but it happens even if I only slap it to around 2/5 throttle and I don't see how needle position would en-cite lag. If I open it up reasonably quickly there is no lag. Any suggestions?
Thanks

[Steve]

Are you saying that the lag is engine speed going up or going down?

Either way, that would be a lean-ish mixture.

I just looked through the first couple of posts to remind myself what bike we are talking about, and I see that it's a mix of '79 and '81. Did not read far enough to see which carbs you have, so here are both ways to richen the mix a bit:
If you have the VM carbs from the '79, turn the air screws (the ones on the sides of the carbs) in about 1/8 to 1/4 turn.
If you have the BS (CV-type) carbs from the '81, turn the pilot screws (mixture screws) out about 1/4 turn.

One method that is used by many to judge proper idle mixture is to snap the throttle to see how it returns to idle. If it hangs at the higher speed and returns slowly, you have a lean mixture. If it falls quickly, but goes below the set idle speed and comes back up, the mixture is too rich.

.

[GSX1000E]

He stated that he is currently running the '81 engine in his '79 frame so you can surmise that he is using the CV carbs besides the hint at using the 42.5 pilot jets
which are causing the hesitation down low due to being too fat (rich). He needs to go back to the stock 40 pilot jets and then jet from the main jets down.

[Anonymous]

He needs to go back to the stock 40 pilot jets and then jet from the main jets down.

Put the 40's back in, cylinder 3 isn't firing now and can't idle off choke. When I soaked the carbs (+8hrs each in engine cleaner), I checked all the passages with air. Was this not long enough a dip and #3's pilot circuit still is restricted somehow? Why does everything work fine when I put in the 42.5's? If the pilot circuit was blocked how would a richer jet change that? Maybe if it's not fully blocked...I don't know.

If the solution is a longer dip can I re-use my nearly new o-rings? They've been in for like 3 weeks. I couldn't find 'chem-dip' or similar products anywhere (except ebay for £50 plus £60 postage!). So I soaked in engine degreaser after a thorough spray down with carb cleaner. No good?

[Steve]

The "chem dip" that we commonly use (Berryman's) has directions on the can that say to dip parts for "15-30 minutes". However, we feel that the directions were written back when they actually had some decent chemicals in the can that would do the job in that amount of time. NOW, the contents of the can have changed, but not the directions. We feel that they should read "dip parts for 15-30 HOURS". Yeah most of us leave parts in the "dip" for about 24 hours. Not sure what your degreaser might require, as it's 'tuned' for grease, not crusted-up petrol remains.

Yamaha makes a carb cleaner concentrate that you mix with water. Is it available over there? It's about as good as Berryman's.

.

[Anonymous]

No joy so far in finding berryman's or any carb cleaner other than the spray sort. My 'gunk' engine degreaser is pretty strong stuff though (it eats rubber for tea), they came out spotless and all passages seemed clear.

I suppose my question is: If it were a blocked idle passage wouldn't the 42.5's be nearly as bad as the 40's?

It runs great with them (42.5's) in, other than the lag in increasing the rpm's when the throttle is slapped back. Settles back to idle nicely too. (and no black plugs)

Keep in mind I've got paired k&n's on. When I back the mixture screws right out the idle improves but not sufficiently.

[Anonymous]

Also if the idle circuit was blocked wouldn't it still run with the choke on (choke circuit)? I think my idle circuit is fine because with the up sized pilot jets I don't need choke to start (too rich, I know) and all cylinders run. I figure a blocked choke circuit could stop #3 from running and I'm not letting it heat up enough before trying to take off the choke.

Any quick way to check if the #3 choke circuit or do I need to strip them down again?

[Anonymous]

All sorted now, problem was the valve lash and a 'swiss cheese' exhaust header. New shims and a heat wrap now she runs great....As far as I can tell in the shed.
I gave it some Seafoam through the vacuum plugs while syncing (and in the cabs and tank), pistons look a lot better now. This probably helped reduce the lag too.
Nest step, raise those needles!

Oh yeah, I kept the 42.5's in.