My 87 fj had a slight problem for a while which has got a little worse. Bike starts fine and will idle steady and pulls fine all through the range.
The issue was getting the revs to return to idle, as i changed down coming to a junction the bike would come to a halt and hold around 2k revs. Let the clutch out and put the bike under load and it would return to idle 1100rpm. Have driven it like this for months but putting the bike under load tonight didn't bring the revs back down.
So,is there something sticking in the carb or could it be a clutch problem?
Sean.
this interests me, i'm getting a similar symptom.
the bike idles great (once it's warm) at 1000rpm. pulls through all the gears just fine.
but I have noticed if I get on the throttle, or do some freeway riding, if I idle at a light after that it will idle around 2000rpm for a few minutes.
I had figured this is to how a heartrate rises after heavy exercise, but bikes aren't human bodies so perhaps it's actually something mechanically unhealthy?
I had the same problem with my 92 you need to rebuild your carbs you can get the rebuild kit from Randy at http://www.rpmracingca.com/ (http://www.rpmracingca.com/).
I'm sure you are right about having to rebuild the carbs. I also need to do the valve seals.
However i would like to know what is causing the issue prior to pulling the carbs apart.
It's possible to buy all sorts of bits for the carbs,replace them,put them back together,and still have the problem.
Anyone have a reasonable explanation to what might be causing this within the carbs?
Worn needles,diaphrams,o-rings.........................
Sean.
Binding throttle cable ? Grip binding or rubbing against the throttle cable housing ?
A vacuum leak ?
Choke cable / circuit problem ?
I know that's not much but things to look at. Wish I had more.
George
All those things seem to be fine George. Started from cold choke operates as it should,shut off choke and bike will idle fine.
When the engine heats up the revs will then climb to 2k, like the mixture has changed.
My guess is that extra fuel is slipping in somewhere and causing the change.
What's the story with the valve seals, does the engine have to be dropped out of the frame to get the cylinder head off?
Thanks, Sean.
Well I guess if it is nothing external then it has to be in the carbs.. Just hoping it might be something simpler to fix. In the carbs I would check the choke plungers, float height etc.
The valve stem seals are something I would rather approach differently but I want to attend a rally the end of the month so I am going to do (or try) to change the seals without removing the head. The smoking now has gotten to the point it looks like a rich two stroke when cold in the morning. I pulled the exhaust pipes off and can see some of the exhaust valves stems. They are leaking down from the lower part of the shafts. There was some discussion last winter about do this and I started making a tool to do it. Yesterday I ordered new seals and started pulling the cams out. Today I will get back into finishing a tool to do the job.
Here is a guide that I am following on the tool. Open the PDF file in the first post.
http://www.fjowners.com/index.php?topic=10862.msg106443#msg106443 (http://www.fjowners.com/index.php?topic=10862.msg106443#msg106443).
Here is some other information in a thread, you will have to scroll down to the bottom.
http://www.fjowners.com/index.php?topic=10426.105 (http://www.fjowners.com/index.php?topic=10426.105)
Here is another thread page worth reading with good information also.
http://www.fjowners.com/index.php?topic=10426.105 (http://www.fjowners.com/index.php?topic=10426.105)
George
Quote from: Woodsman on May 05, 2014, 04:40:06 AM
I'm sure you are right about having to rebuild the carbs. I also need to do the valve seals.
However i would like to know what is causing the issue prior to pulling the carbs apart.
It's possible to buy all sorts of bits for the carbs,replace them,put them back together,and still have the problem.
Anyone have a reasonable explanation to what might be causing this within the carbs?
Worn needles,diaphrams,o-rings.........................
Sean.
I believe for my it was the o rings but Randy @ RPM can tell you more specific.
Thanks for all the info on the valve job George. Can i assume the head wont come off without dropping the engine?
In relation to my rev issue. I messed around with it today and found the difficulty was holding anything from 1200rpm to 2000rpm on the throttle almost impossible ( no matter how sensitive i was with it ). As the throttle is applied very softly it will surge between this range.
So the problem is in the very initial throttle application and fuel feed.
What controls the fuel in this range and is most likely to wear? The bike has 64k miles.
I just pulled and replaced the head without pulling the motor on an 84 1100. On the 84 you have to remove the fairing. We also removed the subframe etc.
Jeff
I think you have a couple of issues...
First, if the bike starts and idles fine, only to have the idle increase as the bike warms up, indicates to me that the idle mixture screws are set a tad too rich...try leaning the idle mixture out by turning *in* (clockwise) the idle mixture screws in 1/4 turn increments to see if that helps with the hot idle issue.
Second: Poor transisition response indicates dirty pilots, idle circuit, and/or needle jets (aka emulsion tubes)
Time for a cleaning.
Thank you very much gentlemen. I shall endeavour to get the old girl running as it should.
Sean.
I had a problem with mine when I first got it running. I completely rebuilt the cabs with Randy's kits. Put them back on. And once it got warmed up. So went the R's. No matter what I did couldn't get them down. Sprayed starting fluid to check for intake leaks. Nothing. Even tried spraying down with water. ( thought it might drop if it had a leak) still nothing. Took the cabs apart 3 or 4 more times. Still as soon as it warmed up up went the R's. Well Randy had included the intake orings in the carb kits. So even though spraying it didn't do anything. I replaced the intake orings and it went away. Wish I would have replaced them right away... Would have saved me 2 days of frustration.
Tried leaning out the mixture but revs are still kicking up. From the responses here looks as if replacing the intake o rings should cure my problem.
Can anyone tell me which o rings i need?
Sean.
Quote from: Woodsman on May 13, 2014, 03:53:35 PM
Tried leaning out the mixture but revs are still kicking up. From the responses here looks as if replacing the intake o rings should cure my problem.
Can anyone tell me which o rings i need?
Sean.
They are the larger o rings in this kit. The kit is about the same price as just buying the o rings from Yamaha and you get all the other o rings you might need at a later date. http://www.rpmracingca.com/proddetail.asp?prod=carbkit&cat=24 (http://www.rpmracingca.com/proddetail.asp?prod=carbkit&cat=24).
George
Have ordered the o-ring kit along with the uni-pods. :good2: Prob wont get here for a week or so.
Quote from: Woodsman on May 16, 2014, 04:04:57 AM
Have ordered the o-ring kit along with the uni-pods. :good2: Prob wont get here for a week or so.
You are going to like those unipods. Opens a lot of space and makes working on the carbs a lot easier.
George
All my bits arrived in quick time from RPM.Thanks Randy. Old air box has been removed and the Unipods are in place along with the crankcase filter. Might be Saturday before i can get my hands on some foam filter oil. Shame i can't use chainsaw oil as i have gallons of it around,i'd say it's very similar with it's anti-fling properties. Where have people located the crankcase filter after extending the pipe?
I also got the kit with all the o-rings. Where do the larger o-rings ( intake o-rings ) go.Maybe someone has a picture or a schematic that would show me the location.
Sean.
Take the carbs off...take the heat shield off...unbolt the intake manifolds from the head. The large O rings go between the manifold and the head...
Take is opportunity to check the rubber carb boots for any cracks....
Will do. Thanks Pat.
Made a start on this today and have found the bike very simple to work on. I suppose having the unipods helps giving easier access to the carbs. After fitting the unipods i took the bike out for a spin and all was well but still had the rev issue.
Have replaced the inlet manifold o rings, someone had put some kind of sealant on the mating surfaces which had broken down.Maybe this will turn out to be part of the problem.Had to hacksaw some grooves in some of the carb top screws as they had been chewed but all are free and can now be replaced with new ones from Randys kit.
I am going to give the carbs a good clean (lot of crap came out of the bowls) but not change anything else at the moment. Will give it a test run after and see how it goes.Going to get this carb issue sorted before i start on the valve seals.
Is it easy to spot if the needles have worn and need replacing? Just thinking ahead if i still have the rev issue after replacing the inlet o rings.
Sean.
Rising revs are gone. Not exactly sure what the problem was but during my carb clean i found a hole in one of the diaphrams and return on the throttle wasn't a snappy as it should have been.
Ended up 3 turns out on the mixture with the unipods and it runs well. Cleaning has given me a much better transition at lower revs with no bad surge between 1k and 2k.
Smoking at start up isn't bad so i'll put the valve seals on hold and settle for checking the valve clearances soon.
Sean.