Adjusting newly-cleaned carbs (no Yics-tool)..

Described my cleaning and reinstallation here: http://xjbikes.com/Forums/viewtopic/t=2 ... rt=45.html

- and have now tested..

Turns out I´m running (too) lean (mixture screws turned out 3 turns). Plugs whitish/grey and idle creeping when warm (2-3500 rpms). (Didn´t pre-sync the carbs before installing - stupid; I know).

Í didn´t check for false air (gonna get some start spray tomorrow) but all carb rubbers looked fine, when I reinstalled (also all plugs are equally coloured)..

Also haven´t yet checked if my throttle cable is hanging (don´t think so but will do).

I got a Clortune (3 day delivery from UK to Denmark) and have a borrowed Morgan Carb-tune but no YICS-tool. should I try to sync and mixture-adjust without the tool to see if I can get rid of the lean-ness?

Can´t find the thread, but somebody asked if you couln´t just use a almost-fitting metal rod through the Yics passage - to do some blockage of the connections. Would it be worth a try, or?

Any comments or things I forgot but could be worth checking? (I´m hoping, of course, that I don´t have to disassemble the carbs again - though reinstalling wasn´t so hard as expected).

 

If I recall correctly, they were wanting to use a full length of fuel line or similar, with a rod through the middle, then compressing the line with a washer and nut. Basically instead of using 3 seperate blockers to isolate the passages, blocking them all off with one big piece. I dont think a metal rod would work too well, because even the slightest leak of atmosphere between the passages would make your results screwy.

I was able to get all the parts from Home Depot to build 2 YICS tools for like $10, and built one in about half an hour (never did put the other together)...

As for your running issues, I'd pull the carbs off and bench sync them. It's nothing more than popping them off the holders, and using a feeler gauge ( or WD-40 tube) to make sure the butterfly valves are all about the same amount open). The difference my bench sync had was night and day, even though my carbs were spotless.

 

Ok, I see. Hm.. then might as well try and make the tool, then..

I haven´t been able to track down silicone hose that I trust is more heat resistant than f.i. fuel hose..

Part of the reason why I didn´t bench sync them was that I was confused with recommendations; Wd-40 tube and a piece of paper is quite differrent in thickness, I think. But maybe the importance is that they are evenly open?

Thanks gremlin - may be easiest to pop them off and bench sync..

 

Gremlin nailed it on the YICS tool and needing something to expand and close off the passages. I would not remove the carbs and bench sync. I would try the Carbtune first. You could tune with it and be DONE! It will sync without the YICS tool but will be a little harder. Still closer than bench syncing.
PM injuneer to find out about where to get some high temp silicone tubing.

 

Agreed - don't pull the carbs to bench sync now. Only reason to bench sync if you are going to vacuum sync is to make sure it runs so you can vacuum sync it.

For clarification on bench synching: Synching is to make sure all the butterflies are open the same amount. Idle stop screw controls the amount they are open.

 

I used fuel line on mine. I figured it wasn't in there for more than 10 minutes, so I really didn't think much of sourcing the really high temp stuff... It ended up working just fine.

 

Thanks guys for the advice and clarification; I´ll hook up a fan and the carbtune and see how it looks.

 

I used fuel line on my unit and haven't had a lick of trouble yet. Best of luck to you Finn.

 

Thanks Robert

An update: Synced the carbs today: 1+2 even, 3 low and 4 way too high. Got them down to an equal level though the idle kept being very finicky; it would race when the engine got warmer and even when the sync was ok, when I blipped the throttle, the revs were only slowly coming down.

Put in the Colortune and no matter how much I turned out the mixture screw, the flame stayed blue..

I ended up checking the fuel levels (on the 2 outer carbs) (which I had previously outruled, while they were dead-on in the bench with the carbs levelled) - and they were 2-3mm´s low! :?

So - the carbs are now on the table again...Gonna check them levels; maybe the diffence in that the carbs are tilted slightly forward when on the bike, means something? gonna start by checking them levelled (like before I reinstalled them) and then try to imitate how they sit on the bike (measured the forward tilting to 7mm difference from rear to front floatchamber gasket-edge).

I´ll be back 8)

 

The combustion FLAME is SUPPOSED to be BLUE.

You run the Pilot Screws IN until it starts to show traces of Orange or Yellow ... then, back out until it's a pretty BLUE and it's Done!
. . . . . . . . . . . . . . . .

The #-3 Carb is the BASE Carb. Everything should be Bench Synced to match-up with the 3-Carb. There's NO adjustment on 3. Open it with the Manual Idle Adjustment Rod.

Then, match 1 -to- 2 ... 4 -to- 3 ... finally, 2 -to- 3. Since 1's connected to 2 when you adjust 2 -to- 3 ... the 1 Carb goes along for the ride.

 

I know it´s supposed to be blue - but being quite sure the bike is running lean judging from the look of the plugs and the hunting idle, I was quite eager to get away from that - to see the orange colour..

I think you´re wrong about turning the mixture screws in will richen the mixture - I´ve read the opposite..

My scenario was, i couln´t get any sign of yellow/orange no matter how far out I turned the the mixture screw.

I may have found three possible causes:

1: The mentioned difference in float bowl fuel level - from levelled in a bench and slightly tilted on the bike - a difference I verified by checking the 2 positions in the bench afterwards. the difference in fuel level is 4 +/-1mm..

2: My temporary fuel tank (from a lawnmover) was probably too small (approx. 3/4 liter). I used it at first in the bench test afterwards but got no (!) fuel through the floatbowl drain plug (checked on 2 floatbowls) - though it was elevated fine and no restriction in the supply hose...(I did notice the inline filter while syncing and using this tank was only half full..)

3: False air: Prior to syncing I made a start spray-test and I had a sligt increase in revs from a couple of places: Around the cylinder intake rubbers and/or the vacuum nipple plugs - and around to of the diaphragm covers (gonna follow your advice on synthetic grease for seating and sealing the diaphragms when reassembling - I didn´t read it before I assembled the first time, and it was a bit scary not being able to see, if the diaphragm stayed in the groove, while mounting the cover...).

So - what confuses me the most is issue no. 1. gonna try and set the float height according to the service manual (a couple of mm´s higher than they are now - and check the fuel level again).

thanks for the info on bench syncing - I´ll use it as reference to check todays vacuum sunc.

 

Those heights are fine. Technically, fuel-level1.jpg is a smidge too-high ... but, missing high isn't a problem.

That first pic ... with the level at the top of the screw is Purr-fect-toe.

I Closed-off ... all the way IN ... my screws and ran-it-out until the cylinder started firing ... and kept tweaking it out until the flame was steady yellow-orange ... it seemed to stay like that for almost a full turn ... then started being blue with flashes of yellow and then it got blue to stay.

 

Finn; Let me know if you can't find tubing for your YICS tool. I can send you some (good for 500 degrees +) Or, I could build you a YICS tool like the one I made. Either way, I'll get you set up if you need it. PM me.

 

Yeah Rick - I also came to the conclusion that the fuel level probably isn´t my (main) problem. Checked with the service manual and it states to jack up the bike so the carbs are levelled when measuring with a tube.

Also searched the XJ-owners maillist and found recommendations to tube check holding the tube in the center along the side of the bowl - where the Hitachi-mark is on these carbs.

So probably gonna leave them (for a final bench check) and use the opportunity to check other things:

-free passage in enrichment circuit,

-redo the Clunk test and maybe just in case polish the slides - also on reinstallation use grease (I have silicone grease) to seat and seal the diaphragms

-look for replacement screws for the diaphragm covers (as some of the current ones don´t seem quite "trustworthy")

-last but not least: the tiny o-rings below the mixture screws were a bit worn; I don´t think they have problems sealing but the inner side on a couple of them had a small "edge" (see pic). Finding replacement o-rings could add yet another fun challenge, right :roll:

And, as I probably won´t be finished this week-end - should I consider disassembling the carb-cylinder intake rubbers (Installed them with hardened screws and new gaskets) and smear the gaskets with a bit of high-temp rtv? (I redid the start-spray test with the Carb-tune hoses attached to the vacuum-nipples - and still had a slight increase in revs. around two of the rubbers. As stated earlier I was able to turn all the screws 1/4-½ a turn - but just in case...)

So - with the fuel levels ok and eliminating false air intake - what could possibly go wrong 8)


CaptainKirk - Thanks; I pm´ed you..

 

The photograph of the teenie-tiny O-ring, with nothing else for perspective, makes it look like a worn-out, old front tire, snapped from a distance.

I doubt that it would be the culprit, looking like that, but ... it can't hurt to change them.

Did you find them in Standard Plumbing Supply or are they Special?

 

FinnogAngela must be your lucky time because I just ordered some orings for a set of carbs I am rebuilding. PM me your snailmail addy and I'll send you four.

 

Rick, haven´t found them yet - and then again ..

Blue: Thanks man; PM´ed you.

 

2. installation..

Including:

- new O-rings in the mixture screws (thanks, Bluemaxim..)

- Diaphragms seated in silicone grease

- new vacuum-nipple plugs

- new vacuum-hose

- new intake rubber gaskets with a light smear of high-temp silicone gasket.

Bike started right up, full choke - but wouldn´t idle when cold without choke. took off for a ride and discovered after 1 mile I had forgotten to push down #4 spark plug cap after the last colourtune attempt.

Pushed it down but still running rough..Home after 15 minutes I found out #1 pipe was barely warm, other 3 ok.

Looked at the plugs (still grey, whitish) and changed #1.

this time all 4 pipes ok warm after ½-1 minute - but still won´t idle without choke.

Gonna hook up the Carbtune tomorrow and check sync and mixture screws (all set out 3 turns).

I´m close, I think

- only shortcut I took was fuel level #4 a bit low (I hope my lazyness won´t fall back on me...)

 

Forums › XJBikes Talk › XJ Chat › 1980 Maxim runs but won't go!

Read this thread ...

I think you got the same trouble.

 

Here's a free YICS Tool ... too.

Forums › XJBikes Talk › XJ Chat › FREE YICS Tool's for EVERYBODY ~~> FREE!!! By: Rick Massey