recent purchase '82 RJ SECA idling high rpm when warm

Right.

Thank you fitz.

Will make sure I dont let it idle below 1050......!

Many thanks for all your help...sure Ill be back for more soon!
Got to colortune yet........(?)!! Just sending for another one - I sent for 12mm one, instead of 14mm!

Regs.

 

Well, here I am back again!

Bike idles nicely up to operating temperature @1050-1100, as advised.....
When I take for run and go over 50-60mph, and the rpm's rise above 3500+, etc, I come to a stop at lights whatever, and the idle wont come down past 2250, and sticks at that.....

Turn off machine, .........idle comes straight down to 0 obviously.
Immediately turn back on and nice steady idle at 1050 (does not shoot up to 2500) again...????.............'til I set off again, get up past 50-60mph again, and the throttle probably about half open........come to a stop and sticks at 2250-2500rpm in idle again.....until I turn off.......and restart button again....steady idle...............

What is this please?

It is manageable, by just turning off, and then turning on again, a few seconds later, when you are to pull away again, but.......please!?

I did state earlier in my thread, that I noticed two small 'scuffs' or 'grazes', on one of the diaphragms in the top of one of the carbs, but I held it up to the light. as advised, and could not see any light thro'.........?

I have bought some liquid electrical tape since, to repair it, and I dont have to take the carbs off the bike again to do so, do I(?). If this is causing my symptom, (does damaged diaphragm cause my symptom - is it vacuum leak caused only when throttle half open, and piston is sticking or something)

Anybody have these symptoms, in the past.......any ideas?

Regs.

 

:? What had I done?
On advice given, made sure idle was at 1050-1100, and set off on my journey, but NOT UNTIL operating temperature, had been reached.
So - I had turned up idling knob, just after starting machine, from say 850-900, to 1050-1100, THEN set off......THEREFORE....6 miles down road, and nicely warmed up........stop at lights,...........idling at 2500+
I jumped to 'worst case scenario' mode.....
Today, waited til reached op temp, and a bit high on rpm's again, so just turned down idling knob....nice and steady again, even after short bursts of acceleration on 7 mile run.........
:roll: I've still got a little 'cough' now and again on #3 or 4, but that might come out in the wash when I colortune, next week......
Regs.

 

You're getting there. My 550s need a bit more than 7 miles to get fully warmed up. Try a 20-mile run, then adjust the final idle.

It does take a few additional "tweaks" as you use the bike to get the idle exactly right where you want it.

 

Just pulled plugs, to inspect their state after @100 miles, since cleaning carbs, and dry-bench synch/vacuum synch.
Idle mix screws set @ 2 and one half turns out each....

#1 plug - dry sooty black
#2 plug - EXTREMELY dry sooty black
#3 plug - almost completely clean - very LEAN (?)
#4 plug - a bit 'brown paper-baggy' - not far out (?) but still a little LEAN

RECLEANED THE PLUGS...........

*COLORTUNE JUST ARRIVED AS I'M WRITING THIS REPORT....*

I have snipped back HT leads, on 3 and 4, 10mm, replaced the caps (after cleaning them) and restarted....

If I take cap off #3 now, whilst idling, cuts-out (NOT FULLY WARMED UP THO')- obviously getting good spark now....

When I used to take cap off #4, when running, - there was no change in rhythm of rpm - now I snipped HT coil back a bit, - defininitely drops in rhythm (if only very slightly), til I replace it....

This diagnosis leads me to the understanding, that #s 1 and 2 pilot mixture screws need to be screwed 'IN', or DOWN, a fraction, if not more, because, these two, are running far too rich (I can smell fuel slightly, when first start up)
Conversely, #s 3 and 4, are running far too lean (before I snipped cables back(-could have been bad spark?), so I need to run again for a while, and recheck after a few miles, to see if the state of the plugs are not so lean, before I adjust pilot mixture screws on these two.....(?)

Am able to colortune now anyway......!!

Correct, anyone........?

Regs.

 

Im back again........!

Can only achieve 1400-1500 idle lowest, when all four carbs are same vac-synched.....idle knob all the way out....throttle cable not hangin...adjusted correctly at bars.....?

Colortune now across the board, well, apart from #4 being a bit 'sharp' but at the cost of high idle....!!

If I have #s1 & 2 carbs @xxx same reading, and #s 3 and 4 at YYY reading the same, I can get a desired idle, but when all in 4 sync......1500 idle. (at temperature)

If I turn down #4 carb's pilot mix screw 'down' or 'in' to very lean, the idle will drop, but then it will be running very hot, and cuts out the engine.

Just bought and installed all new pilot mix screw parts, but hasnt solved issue....

Cant find vacuum leak anywhere by spraying all around when engine running...

Have installed brand new throttle shaft seals, and fuel pipe o-rings....

Been conversing by pm with Len at Chacal, over this issue recently, and he was the one who instructed me that altho' I had got a decent idle (my last thread...) when 1 and 2 were the same vac sync, and 3 and 4 were the same vac sync, but both pairs different readings, - the engine was 'out of sync' if ALL FOUR cylinders were not exactly the same reading on each dial....

So, proceeded to get all four cylinders the same reading.....by adjusting sync screws...HIGH IDLE!
When I blip the throttle it responds immediately, but is very slow to come down to that 14/1500 idle...

I pulled the carbs today, and completely went over the #4 carb, because that seems to be the one that 'makes any changes' if I adjust the pilot mix screw, or the sync screw etc. (and it 'pops' when lean, of course....)

The main air jet is the wrong size @ #55, instead of #50, but otherwise everything is ok - checked piston, diaphragm, cleaned every orifice three times, nylon bristle in jets et al, and on, and on....

All the carb parts on #4 are in their correct positions....

Put a new set of innertube on manifolds, in case there was a vac leak there....
Started up.... and still the same....

Len said that even if all four main air jets were at #55, it would not change the idle as significantly as mine is high at the moment...I have got to search for other reasons.........

What the hell is it?....

Almost a year since I bought this bike, and so many pounds later, I have still got the original issue......??!!!

This is doing my head in! - I think Len has run out of options for me also..!!

Please, yet again....anyone??

 

Try unhooking the throttle cable at the carbs and starting again to see if idle still high.
No: cable routed incorrectly
Yes: move on to next area

You may have installed the butterflies backward/upside down when you did the shaft seals.

Did you replace pilot screw o-rings?
Is the enrichment cable allowing the enrichment plungers to fully seat when off?

Sorry if you have already answered these questions previously, I didn't go back and read the entire thread.

 

Thanks tkaz for your options....
Dont think its the throttle cable, but I'll try what you suggest.
I think the butterflys were reinstalled correctly....(when I did bench sync, I set them so that just about a third of one of the little holes was covered with the butterflys when closed) but you never know. However, cant tell unless I pull the carbs again....
And yes, I replaced with new, all pilot mixture screw parts, including the o rings (re positioned #4 today, and is adjusting nicely now)
I had come to the conclusion that, with #4 main air jet being a size(?) too big, @#55, instead of 50, possibly all the other three might be the same, and a PO, had changed them to tune with a change of exhaust (4 into one perhaps) or something.....?....Then, when another PO changed them back to stock exhaust, they didnt resize the jets in the carbs, back to stock, and so a high standard idle was being the result....?....however Len at Chacal says that even if all four were bigger, (havent checked them yet!) then it still wouldnt be idling as significantly high as it is? (1500 at temperature, instead of 1050-1100) 8O Do you agree?
Thanks.

 

I agree, going up 5 on one carb's air jet should not make a bit of difference.

It sounds like your problem is in the linkage itself, not any sort of air leakage. You'd be surprised at some of the things that can get stuck in a butterfly to hold them open.

One other thing, earlier in your post (finally got a chance to go back and read the entire thread) you said you had an increase in idle when spraying undeer the carbs at the bottom of the boots. Is there a chance that your carbs are not set perfectly tight onto the intake rubbers? I had a dandy of a time getting those carbs back in the boots the first few times i put them back on.

 

By chance, did you record the number and position of the air jets when you had the carb hats and diaphragms off? The Haynes has them listed incorrectly. If someone has messed with them previously and followed the Haynes not knowing this, would definitely cause lots of headaches.

 

Some relevant pointers.
#4 carb has been checked for sizes, positions, and apart from the main air jet size, are ok, but 1-3 carbs have not. Will take off and check all again.
As you re-iterate my theories - PO may have not returned to correct position, and/or different size whatever....
Will check the linkage is 'closing' properly when throttle blipped etc.
I did notice that #4 carbs butterfly, seemed to have been 'the most open', you could see almost all the hole, when I took the carbs off and looked at how the bench sync, 'was sitting', and when I cleaned that area, some bits of crusty old 'glue', at the point where the butterfly sits on the shaft and joins shaft seal washed away....??!!
When I refitted carbs yesterday, they seemed 'the most flush', and all 'popped' on. Tightened up clamps, and positioned correctly.
But will check again.....
Like you say, could be something simple, but easily overlooked.....
Regs tskaz.........

 

Just tried in idle at temperature, a few of the suggestions I could, without the carbs off....

Sprayed everywhere there might be vacuum leak - no increase in rpms
Idle at 14/1500.......

Disconnected the throttle cable from housing on top of carbs, so it hung loose.........idle fell to 1200....!....then rose again to 1250....!

Tried upping and downing, the sync screws, (carefully, and minutely!), and it just raised the idle, from what it was set at....not lowered it

Idle back up to 1300-1500, reconnected throttle cable....

Blip throttle and shoots to 2000, very slow to come back down to 1500....

8O BUT - if I push down on #2 (or 3, whatever, the middle one is!) sync screw, with my screwdriver on the head.... THE IDLE WILL DROP TO A NICE 1050-1100!!?? :wink: Is this signifying something to do with the bench sync settings need resetting really tight....or something sticking at the standard setting as it is now.....?
Regs.

 

If you can observe one Throttle Plate opened more than another, ... BENCH SYNC the Throttle Plates.

Using a Very Thin piece of material, set the Throttles to an EQUAL Setting by Measuring the Clearance of the Throttles, ... nearly closed.

Strips of 3X5 Card
Small Strips of 35mm Film Negative
Strips of Resume' Paper

Use the Material as Feeler Gauges.
Set the Throttles in Mechanical Sync as close to closed ad possible.

Use the Pilot Mixture Screws to get the Bike to Idle.
Allow the least amount of Throttles opened to Idle the Bike.

 

Thanks Rick
Just took carbs off to re-bench sync - took hats off first of 1-3 to check air jet sizes and positions............(#4 has already been established that the main air jet is #55 - wrong size, should be #50)................

#1 - Main - #55 Pilot - 195
#2 - Main - #55 Pilot - 195 (pilot hole is bigger at bottom and 'distorted' and off-centre)
#3 - Main - #55 Pilot - 195

This proves my theory, that some PO had upped the sizes of main air jets in ALL FOUR carbs, probably to fit pods to replace stock airbox, and/or four into one exhaust, to increase performance.........?
This would presumably 'tune-up' the carbs, to run in conjunction with the upgraded air/exhaust system.....?

It has since, by another PO, been returned to stock exhausts, which I received the receipt, with papers on purchase of this machine.....

Whosoever, reverted back to the stock exhaust system, obviously did not realise they should revert the air jets (main) back to stock #50s instead of the installed #55s.....?

8O So, it is not just the one carb, which is metering more air out than the exhaust system needs BUT ALL FOUR..!?

Would this be the cause of an idle of 14/1500 at temperature, instead of the required 1050-1100...? (probably works out at @+40%??)

Havent checked fuel jets in #s 1-3 yet, to see if theyve been changed to bigger/smaller whatever, (#4s fuel jets are correct for stock I think, - its hard to read the stamp, 'cos of wear marks, but looks like 110 main?)

:?: Anyone confirm this may be cause of my problem, or is it the same result if ALL FOUR main air jets are larger, and not just only the one in #4??


Thank you

 

............AND ANOTHER THING........
Just checked positons and sizes of main and pilot fuel jets.....
Main fuel jets are the right size #110, and positioned correctly....
PILOT FUEL JETS ARE #45 - WRONG - SHOULD BE #40!!!
On all four carbs.....
These have definitely been upgraded in the past to accomodate pods and intake/exhaust changes.....
So, another 40% + to the fuel metering?!
:roll: Surely this must be the reason for the high idling issues.....now stock exhaust, and stock air filter, and recently corrected valve clearances??
Anybody confirm please???
Regs.

 

#45 pilot jets are huge........should be #40's.

Might want to look at the main jets NEEDLES and make sure they are etched Y-10 on the shaft (just below the plastic head cap).

When you see one cockroach, you can bet that there's usually a few more than you haven't seen yet..........

 

Yeah no kidding. Do NOT look under the refrigerator.

All I can confirm is that with the carbs horribly mis-jetted, anything is possible.

However, I have two other concerns: You already know that something mechanical is hanging up; if you press on the linkage, the idle goes down. That needs to get fixed. If you broke the rack, you now have a whole lot of possibilities as to where that might be happening. Alignment, tab bindage, etc... fun.

Anytime you do anything with the SYNC screws without a vacuum gauge hooked up, you're going to make it less in sync than it was. And a hanging idle is the sure-fire sign of an out-of-sync condition.

 

Check for vacuum leaks too. Cracked intake manifolds and bad intake gaskets can contribute to your high idle issue.

 

The MAIN Reason for:
High Idle
Surging

Air Leaks ... somewhere.

If the Bike runs-up when WARM you night have what I refer too as an:
Occult Air Leak.

Air seeps-in at the Mating Surface of the Manifold and Head.
The Rubber Sealing "O-ring" is no longer viable.
Air sneaks-in past them.

Tightening the Cap Screws does not help because the Fasteners are Seized.
Running a Bead of Caulk ore RTV around the Manifold helps.
DON"T RISK Breaking-off a Bolt.

 

Thanks ALL!

So glad my investigations have proved fruitful, and this COULD BE the main contribution to the high idle.

I will obviously have to order new parts, and in the meantime (no, BEFORE(?), I will check to see if jet needles are stock size Y10.
Will check rack, rebench sync, check butterfly closures, everything to investigate possible hanging idle etc.
:roll: As I have repeated before, there is no evidence of vacuum leaks anywhere, and when spraying, at temperature EVERYWHERE, I can not find any (apparent) rise of rpm's (?).....but will take on board recommendations and follow thro' as best as I can...that 'surging' Rick refers to seems a familiar 'sound' when its at temperature, subtle, yet evident.....could be at carb to head joints, but spraying doesnt show it up.....?
:wink: Put carbs back on, do vac sync again, coloutune, sync, colourtune etc.... do these checks again for leaks, order parts as necessary, and use bike as it is for now til receive parts, cos this is my only bike now Ive sold my Virago 3 weeks ago........

Regs.