Spring Frustration - Need Advice

let me get this straight. the only way I can raise or lower the vacuum (mercury level in manometer) on carb 3 is with the main idle adjustment screw, correct? and if the main idle adjustment screw is all the way out then I gotta re-do the bench sync?

btw: here's a preview of my plug colors just for curiousity from 1 to 4. I realize these will only be adjusted after I complete running vac-sync

 

As far as I know. BUT, when I do my syncs, I don't care what the idle is on #3 specifically. I warm the bike up and make sure that I have reasonable idle, whether a little high or low I don't really care as long as it idles as smooth as it can. Then, I turn it off, remove the tank, hook up the gauges, fan, and aux tank. Then I start the bike and wait a minute for it to settle back in. Then I start balancing 3 and 4 only. Adjusting the idle speed if it drops to far for my taste. Blip the throttle every couple adjustments and let it settle back in. Adj., blip, adj., blip, idle check, adj., blip, etc....... until 3 and 4 are as balanced as I can get.

Then I go to balance 1 and 2. Same procedure: adj., blip, adj., blip, idle adj., blip, adj., blip, adj., blip, idle check.... etc........ etc........ til 1 and 2 are as balanced as I can get. double check 3 and 4, double check 1 and 2.

Now, I balance 1 and 2 combination with 3 and 4 combination, , adj., blip, adj., blip, adjusting idle as needed.

when satisfied, I stop the bike. Put on the vacuum port covers, tube, hook up the tank, start it up and go for a short ride to check it out.

FWIW, I use a Morgan Carbtune.

Usually about 15 min time.

As far as your spark plugs..... I like the look of 2 and 4. 1 still looks a bit lean, 3 looks too rich to me.

dave

 

thanks for your help Dave. step one: adjust 4 to 3 I can't get past this step. like I said, 4 has a lower vacuum (mercury level is lower than 3 by quite a bit) so in order to get them level I turn the sync screw between 3&4 counter clockwise which make the butterfly closed or closer to be closed. when I do this the main idle increases... so to counteract I try to turn the main adjustment idle screw out with my hand but I can't do this since its bottomed out.

does this mean my bench sync was done incorrectly? its frustrating to think my "almost" perfect bench sync was "almost" perfect yet I'm bottomed out on the first step. anything I'm missing or could I try something else?

 

I would still try to get 3/4 together regardless of if the idle increases or not. If the idle screw is already all the way out, so be it, and I'd try to get 1/2 together and see what happens with the idle. Hopefully it'll start to come down once you start pairing 1/2 with 3/4.

I'm not out there, so it's tough for me to describe what I'd do from here. Sorry!

Dave

 

2 thoughts: You really only need to bench sync to get it running, so if it is running you don't NEED to bench sync again.

A good bench sync will make it easier to sync, if you have fiddled around and feel like you've lost a good bench sync, you MAY want to try to bench sync again.

OK, 3 thoughts...if 3 is closed (not idle screw out, #3 butterfly closed) and 4 is on it's way to being closed (sync screw) how on earth GIVEN THAT NOTHING ELSE IS WRONG is the idle going to go UP? Clearly one of those conditions is false.

Something's not right. I'd take it apart and double check everything is in it's right place. Air jets, fuel jets, pilot spring>washer>o-ring, etc.

Slow, methodical double check of your work. Things just aren't adding up!

 

until now the bike will be ridden as is. 3 outta 4 carbs are balanced with one another & it idles really nice. i agree day7a1. i don't get it. a couple jets are chewed up so that could be a culprit. float levels have clearly been lowered & can snap pics for you fellas to verify

i appreciate any and all input from you guys. thanks again

 

is this true for you other folks?!? I haven't gotten much response from besides Dave here. I trust Dave its just I'm still trying to solve this problem. more will come later in a video format and better description

 

If you can't get 4 to Sync with 3, ...

The 4 Carbs got a Vacuum Leak!

Since it's severe enough to cause a differential which cannot be overcome by adjusting the No.-4 Sync Screw ... Inspect the Manifold.

Particularly, ... the Manifold -to- Head joint.

Tightening the Fasteners may be impossible
Loosening the Fasteners may cause a MAJOR Problem.

The BEST course of action is to SEAL the Manifold to the Head by GLAZING the Joint. "Smearing" RTV into the space where the Manifold and Head meet.
Run a bead all around that Manifold to Head joint.

See if that works to correct the Vacuum mismatch.

 

i appreciate your assistance Rick. you've helped me numerous times during my upper engine rebuild: remember the conversation about my head gasket a few months ago... compression results increased to much better numbers thanks to your help personally

anyhow: those rubber manifolds were loose about a month ago. re-torqued them after installing new gaskets behind them as well. Also, I inspected the rubber manifolds for any cracks. notta single thing wrong from what I could see. also checked for air leaks afterwords and notta increase in idle whatsoever. keep calling me a liar I don't care. I'm desperately trying to solve this problem. movie on its way shortly

 

okay folks I need some desperate hope. I've started riding the bike to my new job fresh outta college(whoo hoo!) the last week or so with great idle response and nice buzzing to and from work 40 miles one way. gas mileage is not that great however (30~32 mpg). ALL WHILE KNOWING THE BIKE ISN"T PROPERLY SYNCED!! i played around with the manometer a few weeks ago, got the idle to blip nicely no backfire whatsoever. so I called it end of story: even though I knew it wasn't balanced.

I'd like to improve the gas mileage. so back to step one: which you can read in my quote. I NEVER got past this step. and to prove that I am at least trying I took a video this time. youtube video

please, please give me some suggestions. I've checked the manometer tubing by switching them around for verification. I've also got the mercury level to be even across all four cylinders but the bike is just screaming at 5k rpms. and yes the main idle adjustment screw is all the way out. so what's the problem?

what I don't understand is that if I just turn sync #4 screw clockwise the idle will drop. in otherwords, with carb #3 already bottomed out (closed) and I close #4 the idle drops.

 

Replace the No.-4 Sync Screw.
It might be stripped.
Check the No.-4 Sync Screw SPRING ...
It might not be the correct Spring.

If you have a Major disparity between two Holes not able to be brought together during synchronizing ...

Run a Compression Check to see what condition the 3 / 4 Holes are in.

 

Hey Rick,

now I'm wondering....is it remotely possible to have put the butterfly shaft in wrong and have the screws/springs in the wrong positions? I can't see how, but I'm wondering anyway.

Mole - Ear (snicker),

I don't have a problem with idle dropping as you try to sync 3/4. Makes sense that it would keep dropping if the butterflies are closing down.

I DO have some thoughts/questions-

Why is #3 plug so dark?

your mpg's should be closer to 48 +/-

Is is possible that something is not in the correct order in the idle screws or the enricher assembly?

Based that you don't get a racing idle with propane or something, I am still leaving out the vacuum leak/lean surge idea.....plugs look ok except for the really rich one

Is it possible that a butterfly is on backward?

Is it possible that airjets under the diaphragm are in the wrong holes?

Is a pilot jet or main jet rolling around the bottom of the bowl?

Is there an airfilter in the box?

You didn't put sugar in the tank, did you? (ha ha, just checking to see if you're still reading.....)

Just going through my list of things I have seen, now. If we need to, we go aalllllll the way back to square one and start all over yet again.....

While this thread has been going on, I did a complete teardown and cleaning of two sets of carbs. Both bench-synced, and both when put on the bike started up with in a few cranks. After about 10 minutes of running, I synced them both and both took about 10 minutes each. Both bikes now on the road.

SO, WITHOUT GETTING FRUSTRATED, let's keep at it. Eventually we'll find the problem and say, "THAT was it?!?!?!" and we ALL learn something else to look for.

Dave Fox, Host
Central NY Carb Clinic #5 (CNYCC#5)
Early June 2012

 

i just went out and looked at a set of carbs, the sync screw springs are right, it does make a difference but his are right.
maybe try taking off the c-clips on the outer carbs and see what those throttle shaft seals look like, it's about the only thing he hasn't done and they will give you a vacuum leak that comes and goes

 

But he's sprayed enough stuff around there that that should have showed up. I'm not ruling it out, but I'm not leaning to that either.

Thanks for checking the springs setup...........

Dave

 

I'm gonna have to go back to the top and start reading the whole thread again, too.

Heck, I may even offer to take a look at the carbs and see if I see anything if worse comes to worst.

Dave

 

thanks Polock for checking as well. I reassured myself about a possible vacuum leak by spraying starter fluid on the c-clips you are talking about. no change; which is what I expected since the throttle shaft seals are new as well.

i appreciate any insight you guys have to offer. sometimes it can be the easiest thing to miss

 

"he's sprayed enough stuff around there that that should have showed up"
spraying stuff is what could have killed them !
it's kind of hard to get something sprayed down between the carb bodies past the springs but it's even harder to get out

 

Hey, Moellear - I'm serious on the offer to look at the carbs. If you don't get it figured out by the time you put the bike up for winter PM me. If you send the rack out to me, I'm willing to go through it to see if I find anything amiss. I'm just to your east in the middle of NY.

I can't do it now as I am swamped with trying to finish things up for the summer and back to work soon, too, but I'm willing to take some time for them once we're past october.

Dave

 

stumped am i

 

Misplaced AIR Jets is common.
Stuck or Maladjusted Enrichment Plunger is common.
a) Kinked-over Top
b) Dirty, actually sticking open
c) Lifting Forks bent / Not in drilled detent.
d) Cable too tight.
e) Cable strand broken. Sticking cable.
f) Mount on wrong

Wrong Main Fuel Jet
Diaphragm Piston Sticking
Pilot Screw O-ring flattened / missing / flipped-over upon install not below flat washer.

Mistake with Throttle Plate Mounting or Incorrect Assembly would make linkages bind.

If Petcock Vacuum Line is attached to No.-3. Test.
Remove Hose from Manifold.
Suck on the Vacuum Line to TEST Petcock Membrane.
Tasting Gas means Membrane Perforated and allowing Fuel to enter Manifold.

Egg Shaped Emulsion Tube Opening
Wrong Diaphragm Assy
Wrong Diaphragm Piston Needle Valve.

Blow-by
Valve Seal
Bad Guide

 

I never knew whether this was suppose to be on #3 or not. friend of mine told me it shouldn't matter since the function would be carried thru on a different manifold. so I've had the vacuum hose on #1 nipple for as long as I've had the bike.

I've tested the line,, its good and trustworthy. thanks Rick for all your suggestions..

 

I've had the vac. hose on 1,2,3 but never on 4. Hasn't made any difference for me, and the ONLY reason I've never had it on 4 is cuz I've never had a vac. line long enough that I needed to reach to 4. If I had, I don't know if I'd leave it or cut it off for a shorter one.......probably leave it so that if/when an end dried up and started splitting I could trim it off and still have plenty more.

Dave

 

What cylinder the vacuum hose is attached to doesn't matter on your bikes. The only ones I'm aware of it mattering on are the 600s and that's because the #2 carb is jetted differently; the only possible difference being that's where the vacuum hose goes on those bikes.

Traditionally, the petcock vacuum line goes to the #3 intake manifold on the 650/750/900s; while it goes to #2 on the 550s.

WHY, I dunno. That's how they came.