Post by: AndyH on October 24, 2017, 11:11:54 AM
I selected carb #2 as master and calibrated the Motion Pro sync tool on this carb. The motor was previously warmed up and was running OK but somewhat "rough". The idle screw was adjusted out to get near 1000rpm.
Initial indications showed #4 out by quite a bit. Anyway, after some adjusting across #1,3 and 4 the idle could not be reduced below ~2200rpm (idle screw not contacting the throttle bar). I did not adjust #2 as it was the master.
As per the 3000 service .....timing, tappets and cam chain adjusts have been specced.
Jet needle is at 4th position from top, air screws at 2 turns out. (DeltaRider I'm setting this bike up to US specs! :P EDIT: DR knows this! )
What is my next troubleshooting step folks? :-\
Post by: K2-K6 on October 24, 2017, 02:01:05 PM
You probably need to go back to a bench sync start point though to make sure you are looking at the idle circuit in isolation.
I'd not sync them with a gauge until you understand if the idle circuits are functioning else you risk compensating for impaired idle circuit by raising a throttle slide, which is back to front logic wise.
Post by: Seabeowner on October 24, 2017, 02:56:29 PM
If you are confident of the idle circuits then you could try closing the slide on 2 a little and repeating.
Post by: deltarider on October 24, 2017, 03:30:30 PM
By individually adjusting the air screws, while it's running you can determine if all of the idle circuits are clear and working something close to correct.Although that method is OK to determine an individual idle circuit is clear or not*, I don't see how the airscrew can have an effect on the vacuum. It's the piston going down in combination with the almost closed slide that creates the underpressure, not the A/F mixture.
You probably need to go back to a bench sync start point though to make sure you are looking at the idle circuit in isolation.
I'd not sync them with a gauge until you understand if the idle circuits are functioning else you risk compensating for impaired idle circuit by raising a throttle slide, which is back to front logic wise.
* If idle RPM doesn't change when an airscrew is turned to fully closed or to say 2 turns out, that particular carb probably has its idle circuit blocked by dirt somewhere.
Post by: K2-K6 on October 24, 2017, 04:04:17 PM
I think carb syncing is viewed as a hopeful fix for many things on bikes when in reality it only fixes........out of sync carbs.
As they've been bench synced first then it does suggest something else is out of range which will need to be assessed and sorted anyway, synchronisation is just the icing on the cake after everything else checks out as good.
There are numerous examples on here of the idle circuit not being up to scratch regarding cleanliness and flow, so it would seem reasonable to establish that first prior to chasing information circles.
Post by: Bryanj on October 24, 2017, 04:16:31 PM
Post by: AndyH on October 25, 2017, 03:08:59 AM
I'll re-do the bench test as Bryan suggested and report back.
Post by: K2-K6 on October 25, 2017, 09:49:28 AM
I think the whole carb sync thing with gauges has been misaligned over the years as something that is part of tuning the engine.
I can't construct any competent case for altering the carb's slides away from mechanical parity to run the engine correctly under load.
Honda provide in their manuals the method for adjusting the air/idle screws at tickover to produce an even running engine. This is the correct device for equalising the cylinders at very very low engine speeds as they are effectively micrometer adjustment throttles for each cylinder..... Not the main throttle slides.
As Bryan has posted over the years on here, you need all the setup done, verified and complete before you put any gauges near them.
The gauges in my view are just a device for a workshop to get the carb's slides something close to parity without having to dismantle the bike. That assumes all other things are working correctly else it'll more likely put an error on the bike.
Bench setting should hold sway if done properly, the confidence should go with that as an engineering principle, not the other way round.
Post by: AndyH on October 25, 2017, 10:39:02 AM
Anyway I’ve pulled the carbs again, double-checked the idle ccts for cleanliness, and took a slightly different approach to the bench sync. Carb throttle valves now completely close off when I back the throttle stop (idle adjust) screw right out. As others have suggested, I may have initially set my “master” carb throttle valve too high which then gave me the issues.
On a separate note, I checked the static timing and discovered I didn’t read the document that came with the electronic ignition properly!! :-[ So I was a few degrees retarded which would not have helped matters.
All correct now.
I haven’t re-installed the carbs yet as I’m still mulling over some conflicting data from the various Honda manuals. In Europe it seems that the std needle clip setting is in the 3rd groove from the top, with idle mixture screw 1 ± 1/8. In the US it’s 4th groove down and 1½ ±½. In the genuine Honda Shop Manual it states 1±3/8 for the air screw. (No needle groove setting mentioned). I should mention that the needle settings on the jets I originally pulled were on the 2nd groove down and IMSs were 2½ turns out!!! And yes, close scrutiny shows the genuine Keihin needles have a slightly different profile to the aftermarket ones.
I realise that with a non-std exhaust the std settings may not be 100% but I should be close.
Stay tuned..... :)
Post by: deltarider on October 25, 2017, 12:13:30 PM
I think you can leave them set as Bryan explains, certainly won't be anything much away from ideal depending on how diligent they are set initially.Couldn't agree more. Honda did an excellent job to design the rack so that synchronisation is seldomly needed. Doing this with a 4 gauges set is only to save time (= labour costs) in the workshop. Yet a lot of us think they also need a set as if they also have to save on labour (=costs). But... from what I read, it's much more common they have the carbrack already removed and on the bench or kitchen table for that matter. Then you can do a bench sync. The way I do it, I've managed, on all occasions, to sync them within 2cm Hg when tested afterwards using the vacuum set.
I think the whole carb sync thing with gauges has been misaligned over the years as something that is part of tuning the engine.
I can't construct any competent case for altering the carb's slides away from mechanical parity to run the engine correctly under load.
Quote
Honda provide in their manuals the method for adjusting the air/idle screws at tickover to produce an even running engine. This is the correct device for equalising the cylinders at very very low engine speeds as they are effectively micrometer adjustment throttles for each cylinder..... Not the main throttle slides.Can you direct us to where we can find that? I remember having read something on this, but I doubt it will work on a 4 cylinder bike, each cylinder having its own carburetor. Let me put it this way: I myself have never managed.
Quote
As Bryan has posted over the years on here, you need all the setup done, verified and complete before you put any gauges near them.Again, couldn't agree more.
The gauges in my view are just a device for a workshop to get the carb's slides something close to parity without having to dismantle the bike. That assumes all other things are working correctly else it'll more likely put an error on the bike.
Bench setting should hold sway if done properly, the confidence should go with that as an engineering principle, not the other way round.
Post by: K2-K6 on October 25, 2017, 02:50:35 PM
It gets to idleness screw initial setting then a further setting on idle mixture that contains the fine tuning routine. ( this I find repeated in later manual for CV carbs with changes for type).
The thing is, it looks like a very benign little routine that is easily overlooked for application and ultimate effect as it doesn't lay out its aims for the reader to see.
I've come back to this from more modern petrol any diesel cars which are in effect using this routine on the fly to stabilise tickover. They use a flywheel sensor with a trigger for each cylinder, as the trigger passes the sensor the pulse time is checked by the ecu and if it has arrived late or early for each cylinder, then it alters mixture and /or timing of fuel injection pulse to accelerate or reduce speed for that one cylinder. It's why when you start them they just go into a flat rock stable idle with apparently no wandering or variation.
This I see as an extension of idle adjust screws, and with that information it's easier to see what the original Honda routine is aimed at achieving. That is each cylinder combusting as close as the same to each other that the design will allow. As previous post, you've effectively got a micrometer adjustment for each cylinder at tickover.
It appears to have become established for most people setting up multiple idle circuits to fix all of the screws at the same nominal mechanical position, that just discards a big part of their capability in facilitating a even and smooth idle speed.
Post by: deltarider on October 25, 2017, 04:54:28 PM
Post by: AndyH on October 28, 2017, 10:16:19 AM
#40 slow, #100 main, IMS 1½ turns out, jet needle 3rd groove as a starting point. My exhaust is a 4 into 1 (I think Delkevic, dunno how to confirm?) but I'm saving my shekels for a repro 4 into 4 from a bloke in Preston, VIC, Australia.
https://www.ebay.com.au/itm/Honda-CB500-Four-CB550-Four-Mufflers-Exhaust-System-Reproduction-/182588936538
Other commitments today have precluded me firing up the bike but I'll do so tomorrow.
Stay tuned....again!
Post by: deltarider on October 28, 2017, 11:38:09 AM
Post by: AndyH on October 28, 2017, 12:03:52 PM
Please stop steering topics sideways with specious comments which add nothing. Thanks.
Post by: deltarider on October 28, 2017, 02:14:46 PM
Quote
Thanks.Don't mention it.
https://www.4shared.com/office/jC4Zzkqhce/Honda_Motorcycle_Carburetor_In.html
Post by: K2-K6 on October 28, 2017, 04:09:19 PM
I know we can go on a bit here about apparently trivial stuff but often it shakes out some small piece of information that is not common knowledge, and helps move things forward in understanding some of these bikes.
Sure, I'm guilty of perhaps elaborating stuff that people may not really feel interested in but I think thing's should be posted and constructively examined in looking at problems. Ultimately there's alot to learn and some have not had the benefit of working on these long term so most discussions are valid.
Be interesting to see how the setup on this one progresses, having any additional number of them running well is what we're interested in.
Post by: Seabeowner on October 28, 2017, 05:27:26 PM
+ interesting carb document, from first principles.
But delta it refers to the air screw as an "air bleed screw for adjusting idle mixture" so IMS covers it.
Peace.
Hope all goes well with the start up.
Post by: deltarider on October 28, 2017, 06:04:21 PM
Quote
But delta it refers to the air screw as an "air bleed screw for adjusting idle mixture" so IMS covers it.No doubt Honda self is a bit strange in giving names to certain parts, but over the years on the international site IMS has become synonemous with the pilot screw that's situated engine side and that operates opposite from the airscrew. Turning clockwise an IMS means leaning out, where turning clockwise an airscrew means enriching. As you read on the international site quite recently it has lead to a lot of confusion again. It's far from me to be school mastery, but I hate to correct numerous posts later on where I could have avoided it by doing it right at the root. No harm intended. Peace in our time. ;)
Post by: hairygit on October 28, 2017, 07:55:05 PM
Sent from my X6pro using Tapatalk
Post by: K2-K6 on October 28, 2017, 08:16:03 PM
There'll always be something along to liven things up a bit. :)
Post by: deltarider on October 28, 2017, 08:36:52 PM
Post by: AndyH on October 29, 2017, 08:34:27 AM
We're preparing for a vacation down to the SE coast of West Aus. for a few weeks, leaving next Thursday, so playing with the bike is interspersed with trip prep. :)
Post by: K2-K6 on October 29, 2017, 08:49:31 AM
Post by: AndyH on October 29, 2017, 09:32:35 AM
Sounds like you're on your way with it, it's great when you can get them sorted and get out for a run.
Your not wrong mate! When we get back from our "Southern Sojourn" the weather should be just right for a few good rides.
There's a club here in Perth (Vintage and Classic M/C Club) which does weekly rides so I'll be hooking up with them! 8)
Post by: Johnwebley on October 29, 2017, 10:21:00 AM
Sounds like you're on your way with it, it's great when you can get them sorted and get out for a run.
Your not wrong mate! When we get back from our "Southern Sojourn" the weather should be just right for a few good rides.
There's a club here in Perth (Vintage and Classic M/C Club) which does weekly rides so I'll be hooking up with them! 8)
its your summer,our biker night rides finished earlier this month,
go and enjoy,(lucky s*d !! )
and post lots of pictures
Post by: AndyH on October 29, 2017, 10:29:29 AM
Post by: sgd37 on October 30, 2017, 12:00:32 AM
QuoteThanks.Don't mention it.
https://www.4shared.com/office/jC4Zzkqhce/Honda_Motorcycle_Carburetor_In.html
Hi,
I'm interested in getting the right airscrew balance for my bike as well, but can't seem to be able to download the document.
Does anyone have another source? or maybe they could send me their version.
Cheers
Post by: deltarider on October 30, 2017, 06:53:30 AM
Post by: sgd37 on October 30, 2017, 05:54:27 PM
Am I missing something?
Cheers
Post by: K2-K6 on October 30, 2017, 06:40:09 PM
When you've done one cylinder, then correct the idle with overall tickover stop screw. Then do subsequent cylinders the same by repeating the routine.
It's trying to produce the same mixture for each cylinder at idle irrespective of hardware variance.
If you reach the inner or 3 turns out position without reasonable response, it would indicate that the idle jet was wrong size (possibly non std air filters) or that circuit is not clean. This should pinpoint a dirty idle circuit with dismantling or guesswork as well.