Another old trick is just leaving the battery disconnected for a few hours to reset the ECU.. if your at work u could leave it off till u go home, or maybe overnight tonight. no harm in trying i guess!

 

So the fpr arrived from the states on 31st after 'only' 2 weeks of placing the order. Blazing fast right?
Anyways, I thought here comes the solution to all my problems and for a while it seemed to be working as well. It took barely 30 mins to swap it. Btw it gets really messy with petrol spurting out of the fuel rail. It's not really a gushing stream but a steady flow and doesn't get too scary but you need to be absolutely careful. The part arrived with the rubber o ring fitted so the one I ordered separately was not needed.
Ok so after installation, turned the bike on and it raced to 3000rpm like it used to. A few fist pumps later I took it out for a ride and it felt a lot better. There was no snatching-the jerks and surges in low revs are gone and there is no hesitancy in pickup from standstill as well.
But it was too good to last. Starting it up for a small errand a few hours later, the idle is again week and only goes to around 2000 settling immediately down to 1500. It takes less time to reach stability at idle and I don't smell much fuel.
So what now guys? Injectors or wax unit or starter valves? Or my luck?

 

Hi ,the cold start rpm and the warm engine rpm appear to be in the right ballpark, 1200 to 1500 when warm.Is there a problem when running

 

1500 idle is perfectly acceptable

 

Guys sorry, maybe I couldn't say it properly. The warm idle was never the problem. Problem is how it reaches the warm idle of 1400-1500rpm. When the bike was ok it used to shoot up to 3000rpm on cold starts(the autochoke) and then gradually settle down to 1500. The issue I have is that on cold starts the bike only shoots up to 2000rpm and then immediately falls down to 1000 something and then picks up gradually to 1500. The final idle is fine. But it should always fall down gradually to the final idle rpm and never pick up to it right? Besides this I had smell of fuel, low mileage(low fuel warning after 80miles), surges/jerks at low rpms, can spraying soot which all pointed to a faulty fpr. I was hoping to fix these and as mentioned it seemed to work initially as in after replacement the rpms shot up to 3000 on startup and then gradually settled to 1500.I went for a longish ride to Lyndhurst today and as yesterday it was better, a lot better, but unlike yesterday I did notice a bit of surge/jerk today at low rpms which means it has not been completely eliminated by the new fpr. It is a lot less than before though.There is almost no soot and gas coming out of the can as well. I did a tankful thing day so will see how much I get out of it. So I have now replaced spark plugs and fpr with little luck. Next up fast idle wax unit or injector check? Could the fuel filter be a problem? I'd think fuel filter problem will show up as a lean mixture symptom(because of some blockage say) and not a rich mixture?

 

Shame it didn't solve your issue. Well the idle unit should operate as in as it heats up your idle goes down, that alone points to that possibly being an intermittent fault. You mentioned about playing with the idle adjustment a lot. Have you attempted the start up sequence with adjuster full on and off? I say because maybe the piston on that is sticking or something. It is odd though because it seems to perform like it should at times and not at other times. I ask mainly because 1500 is acceptable but a bit on the higher side. Check this by running it and seeing if the **** adjusts it accordingly, perhaps that will narrow it down more.

Now the fuel issue. Fuel lines, fuel vents, vaccum hoses all should be rechecked. Are they old? Cracked at all? Shame because you could probably sort this with a vaccum test. Now an out of sync throttle body could be giving you said idle issues as well, and if they are off the bike they really should be synced when going back on, but you would need gauges for that.

Either way man this seems intermittent but as mentioned above could be different things contributing to this issue. Also you said you replaced air filter, was it OEM? and where did you put silicone at? Seems like its mainly and air/fuel issue here. Kinda stumped on this one...Will ask around my circle and see what I can dig up....will check back. I dont want to be that guy to say just throw parts at it and hope it works. Would much rather find the cause.

 

Wanted to put this here for you in case you didnt see it or have the manual. Run through this checklist.

 

Thanks PossibleOne. I think 3 and 6 are not a problem? I have new fpr and spark plugs on the bike.I know weak spark can be for some other reason as well, but it runs fantastic at high rpms.
For the others, I am basically handicapped at the moment.I think I'd go for 4) first as this seems to be easier, just raise the tank, take off the airbox and the fuel rail.Waiting for the multimeter(yes don't have one!) to arrive which I'd use as per the haynes to check the resistance across the injector.
Next should be 2) but would need carb sync tool for that. Looking at the morgan carb sync, but it's 60 pounds ouch! Thinking of using a making a DIY manometer, but unsure how accurate it'd be also I am lazy lol.
How do we check the ignition timing btw?
Btw the bike again died as it was -5 C in the morning. Same old thing. Started up on first crank but soon died and then wouldn't start as engine is flooded

 

Only thing you can do there is get a timing light. Pull the cover off (right case pulse generator) and hit the light and make sure the timing marks line up. (running of course) If it doesnt then they refer to the other ignition components. Haynes should have a procedure for this if you do have the timing light. For some reason I doubt this is the problem but they have it listed there as first thing to check. Maybe some electrical fault though. But yea get you DMM and start checking stuff and make things are doing what they should. Hell Id start checking things and then check them again randomly. Its still seeming very odd it ran fine before. Check your grounds and stuff. Make sure you arent getting a vaccum leak somewhere again. This is a challenging one. I will say this though, at the shop I work at, nothing likes to do what it should in 20 degrees or lower. Hell some of our diesels do not even lilke turning over untill we heat them up. Either way, not the best diagnostic atmostphere thats for sure. Seems like everything has to work harder at those temps.

Check intake boots again. Hows your coolant? In regards to the wax unit and such all that was clean and clear? Hate to beat a dead horse but eliminating the FPR I keep wanting to lead back to the bodies/ idle unit. The cold start issue could be related to that possibly giving us a sign about it giving you trouble at cold starts. Did you ever verify the starter valve was doing its job. Get the idle adjustment sorted (since this relates to the idle unit and in affect idling and the starter valve. Pull out your hanyes and see what they say regarding those valves and being synced. Maybe something got knocked loose when you were installing? Really would be nice to get a vaccum test the money sucks but sometimes it is what it is..Maybe you could sell it to a mate if you needed to? Not sure on the DIY one...let us know if you go that route.

 

hey guys, maybe you can help me out with this matter, it is driving crazy. Where are my mixture screws located on my 1989 cbr 600F. my bike is a pain to warm up. Im trying to adjust them but i dont wanna drill a hole in my carb without knowing for sure....thank you