Hey yall I have an issue with an 84 fj1100... The bike has a racing idle issue where by she will climb in rpms until i kil switchl it... Throttle up and despite my throttling down it still stays at a high rpm.. Zso my first thought is a vacuum leak.. What I have checked so far.... New boot o-rings made sure intake surface was clean and clear.. boots are in great condition still no cracks.. Boots were torqued down properly good solid seal.. New vacuum hoses to the tank and the ignitor box. . I have no other idea where the vacuum leak could possibly be other then the ic ignitor and I have yet to see any post on how to diagnose it... is it suppose to hold vacuum?
Oh and yea I am new to the boards and Fjs but not bikes or cars in general. I am a mechanic and have been for a little over ten years now and I currently live in Denver Colorado and I like beer... and girls... and yeah thats about it.. I figure I would introduce myself cuz I will be here a lot asking queztions and searching for some parts and ideas..
Welcome Dracko, how fast is the idle rising? How high does it get before you kill the engine? Does it stabilize at any RPM?
I can not say for sure as in give an exact number to the rpms.. It will max though if I let it.. So no it doesnt seem to stabilize at a particular rpm value..
Also it kinda depends on how fast... if the bike is already warm when i start it agian from just killing it rpm spike is immediate. . As it warms up from a cold start the it is more gradual..
Do you need the choke when it is cold?
Yes absolutely and it will have to stay choked for 2 - 5 minutes..
What is the idle like when cold and under choke?
Elevated but not screaming, sounds normal compared to my other bikes when choke applied..
Quote from: dracko on April 01, 2014, 09:46:33 PM
Elevated but not screaming sounds normal compated to my other bikes whe throttle applied..
At the "screaming" level, what is the RPM indicated at?
I dont have the gauge cluster hooked up yet so I honestly couldn't say.. screaming would be wide open throttle though..
Quote from: dracko on April 01, 2014, 10:01:39 PM
I dont have the gauge cluster hooked up yet so I honestly couldn't say.. screaming would be wide open throttle though..
Oh... Well, perhaps lower the idle adjust screw for starters....
Once off the choke and idling fine if I rev it up it will stick.. I checked the cables, no binding, smooth action.. Same for the choke cable...
I did do that aleady its barely applied..
Quote from: dracko on April 01, 2014, 10:07:29 PM
Once off the choke and idling fine if I rev it up it will stick.. I checked the cables, no binding, smooth action.. Same for the choke cable...
Maybe you have another FJowner near you that can provide some support???
Haha maybe... I work odd hours so I am trying to figure this out on time I have available. . .
I am curious about this IC ignitor though... I applied a vac to it to measure and it doesn't hold vacuum at all.. Is this normal..?
Common for the old diaphragms to leak in the ignitors. The vacuum advance function of the ignitor happens at closed throttle, part of the emissions system, and the loss of this advance will have no impact on the performance of the bike.
Cap off the vacuum port on the intake manifold which serves the ignitor, it can only help with your issues.
I'm not saying that it will solve them, I think you have more going on...
With the fuel tank off, have you looked at your throttle cables and linkages? Are the cables routed correctly?
Turn your handle bars back and forth, look for hang ups on your linkage.
It might be something mechanical causing your woes.
I always try and inspect the simple things first and a cable issue is was first on that list. I made sure it was moving back and forth smoothly with the tank off as you suggested..
Thanks for the info on the ignitor unit I definitely will cap that line off to see if anything changes. . I was hoping that it was the problem as I have eliminated all possibilities that I could think of..
Next on my list is gonna be pulling the carbs I guess and thats a whole other diagnosis tree! Thanks so much for the advice and please if anyone has anymore suggestions I am all ears.. Bike is thirty years old who knows what has been done to it or worn out..
I do know that a valve adjustment was done on it by the previous owner. I wonder if an improper adjustment would cause this issue or improper torque applied to the valve cover bolts. Any thoughts on that???
No, the torque on your valve cover bolts won't affect the symptoms.
If you're going to dive into the carbs, check the o rings (or lack of) on the air idle screws.
If it's not mechanical, then I agree with your instinct, air is getting in somewhere.
Quote from: dracko on April 01, 2014, 11:56:52 PM
I do know that a valve adjustment was done on it by the previous owner. I wonder if an improper adjustment would cause this issue or improper torque applied to the valve cover bolts. Any thoughts on that???
Dracko, these are strange comments for a mechanic of 10 years and an odd problem to seek help with. There are only a small number of things that would cause this. Describing symptoms over the net is always difficult and you should be able to trouble shoot this yourself. Think through in you head what makes engine revs increase.
As far as a vacuum leak goes, where is it going to get the fuel and air to rev that hard if the butterflies are closed?
However, if you are looking for advice, start with the simple and obvious. Is there a little bit of play in the throttle cables (at the carbies), that is, are the carbies fully closing when the throttle is returned and are they frayed? Are the throttles in fact closing?
You say there is no binding with the cables. If it was not returning fully this would not be felt at the throttle and could only be determined at the carbies. It doesn't take much with no load on the motor.
Is the bike new to you and did it come with this problem? Did it start to happen only after some work was done?
Eliminate the simple and obvious stuff first.
If you are experienced with cars and other bikes the FJ won't trouble you, they are the lawnmower of the motorbike world when it comes to simplicity and accessability.
Good luck.
Noel
Quote from: dracko on April 01, 2014, 10:07:29 PM
Once off the choke and idling fine if I rev it up it will stick..
I just saw this, it should give you a clue. If it will idle fine until you rev it and then not return that narrows the field of possibilities.
Noel
I will throw in my 2 cents here. Early FJs have no fuel pump? Sounds a bit like fuel starvation to me. But the carbs sticking to is a good starting point.
Cheers.
Quote from: ribbert on April 02, 2014, 05:09:49 AM
Quote from: dracko on April 01, 2014, 11:56:52 PM
they are the lawnmower of the motorbike world when it comes to simplicity and accessability.
Good luck.
Noel
A 130hp lawnmower, :shok: Yeah..... Bring it on :good2:
Oh bro its not strange at all lol.. you have to understand that in my industry expertise in areas mechanical is just as vast as expertise in alll things medical. . My experience with older bikes like this is somewhat limited. I am a diesel technician by the way.. Expert on cng and lng alternative fuel systems.. Your philosophy is correct though start with the simple stuff and work your way through the tree.. which I have done for the most part.. But before I dive into things further I thought it wise to put my "mechanics ego" aside and ask for some thoughts opinions ideas no matter how far fetched so that I do not over look anything.
A leak at the valve cover would surely be oil rather then vacuum but somwbody I spoke with at work felt that it could be an issue :unknown: i asked just to be sure. So what I have check thus far is throttle cables, good. Carb choke is operating as it should the rail moves propper with out any issue or binding. Vacuum lines are all correctly installed and new. Unused vacuum ports are capped off with new boots.. carb intake boots were carefull inspected for cracks holes damage.. O-rings were replaced and the manifold surface was cleaned to ensure a good tight seal.
The ignitor does not hold vacuum when tested.. as suggested earlier I am going to cap the line and eliminate that off the list.. also the carb plungers I am going to check agian aswell and they should sink down slowly when pushed up as opposed to falling straight down agian immediately. . This was checked when I first purchased the bike but it has sat for 8 months or so probably needs to be rechecked..
Quote from: dracko on April 02, 2014, 09:23:23 AM
Oh bro its not strange at all lol..
No problem, that explains it. Plenty of petrol engine experience here and a very helpful mob.
Noel
even though cables look ok I would try disconnecting the throttle cables at the carbs and see if problem persists
Since you can get it to idle normally after warming up and backing off the choke. I would spray WD-40 or similar product around common vacuum leak areas. If you can get the idle to change by spraying a certain spot then you found a leak.
*Sighs* :morning1: So this weekend I retraced my steps and added a few in there for good measure. I checked and rechecked evrything and I did what was suggested by everyone. I capped off all but one vacuum line that leads to the fuel tank petcock. I rechecked my boots the vac ports clamps and throttle cable. I pulled the top hats off of the carbs and checked every single diaphram. I found a pin hole in the diaphram on carb 1. I called around to checked the price of a new one and I still haven't been able to pick my jaw back up from the floor after hearing what they quoted me.
In any which case I was told that the issue with the pin hole would not cause the idle to race like that. After briefly explaining my situation and what I checked I was told that an improper valve adjustment could cause a high idle issue. Obviously as the engine warms up its tolerances change, if valves are to tight it could cause the issue I am having thus says the cranky old motorcycle technician at Steeles Cycle.
I have done valve adjustments on Cummins and John Deere engines quite a few times before, never seen tight valves give you a racing idle before but thats a diesel engine not a 30 year old Yamaha.
Sooo... What do you guys think? Ever hear of tight valves causing an issue like this...?
I can post video and pics also if that helps btw.
I do want to thank everybody for your help and input aswell.
What about the pilot air screws?
They should be about 2 and a half turns out. Any less and this could cause the high idle issue. JAT.
OooOooH.. Yea.. That was mentioned prior too I believe, but no I have not checked them yet... I read elsewhere in the forums here that you should should tightened them counter clock wise till they lightly seat and back out counter clockwise like you said two and a half turns. At this point you should hook up a carb syncronizer (which I have) and make fine tune adjustments yea??
I'd get them checked sharp-ish then. Lift the tank to get at them. They are located on top of the carbs just before the inlet rubbers.
You can use a synchronizer at this point but to get the best results from it you should check and adjust the valve shims if they need doing and preferably use a clean or new air filter.