Problems after tipped over.
 

Hey guys,

This will be a long post so will start off by introducing myself - My name is Jānis, I'm new to bikes and have had mine for 3 weeks. The bike is 91' CBR 600 F2. (although I'm new and don't have any mechanical experience, please note that I have read THE INTERNET, feels like all of it, so I do have some understanding about my bike)

First thing's first - got the bike and got used to it, it had some other problems to take care of but engine was running absolutely perfect. It would start each time within 1-2 turns, 30 sec on a bit of choke and after that idles calmly on 800-1000 revs. The engine was supersmooth, barely feel anything between your legs, smooth power even on very low revs, no bubbling, no backfiring. It was as good as it would get for a 91' bike.

Set up: Can't tell you much but I do know that fuel petcock has been changed from vacuum to gravity (first 2 weeks I did not close it when not riding, no problems at all) Other then that all pretty standard, feel free to ask if in need of any extra info.

What happened: Somebody tipped the bike over while I was sleeping,s o it lay there on a side for 4-5 hours in just a tad of rain (I usually cover it when it rains but as you know, the only time you don't - it rains)

The problems: So I pick it up, start it and it wouldn't turn the engine, not even 1 time. (no, battery is perfect and alive till this very day) After about 5 min, didn't do anything to the bike - tried again - it did turn it and it did start, put it on choke to warm up , but felt that it was running a bit rough and struggling a bit. So I left it there for about 5 h, didn't close the fuel petcock, nothing, covered and went to work. Cam back, it was leaking fuel not a bit, but pretty much everything I had in the tank, like 5 liters. I did some turning on the fuel petcock (did not have any info by then I just knew which way it's on) and later on at the evening, it was working abit better, started it and went to gas station, 5 min ride. It died before it. Thought I ran out of gas, filled it with like 6l, and still problems, it would start but would only not die if I keep the revs above 2k. Met a guy he tried to help, revved it pretty hard a couple of times and told me to take it to mechanic.

So the next day it's still only working if i keep the revs high, it's under powered, grainy power delivery, firing on all 4 but the sound is not smooth and very rough. So I drove it for like 20 mins till it died and managed to end up some how at mech's. Explained them what happened and left it there.

2 days ago went to pick it up. They said they checked and changed fuel filter below the tank, and cleaned the carbs. (they told me that they also faced a fuel leak so tank was pretty much empty again. The bike started, idled on around 1,4-1,6 k, abit rough but much better. But you know you feel when something's not exactly wight. I felt more vibration from engine, more rattle from CCT, it gained revs slower and was under powered. So as I thought maybe it's just me and was eager to get the bike back I took it and they told me to go to fuel station as it's empty. Sure enough it died but this time it actually gave the symptoms of running out of fuel (some backfiring, power appearing and disapearing completely etc) So the fuel petcock is either on reserve or on (they don't know till now and didn't tell me either which way is which, all I know up is closed for sure. ) So push it like 50 m to gas station and fill it up with about 12 l of fuel, in like 5 sec the bike leaks fuel under it like from an open tap. Ok, I closed the fuel petcock. Tried to start it and it went back to very rough, barely starting, weak etc. So I get it as far as I could with the fuel in carbs and push it back to mechanic, last 200 m up steap hill. (:D)

This time I stayed there to see what they are doing. So they start it and rev it a bit, then they took off my fuel tank and put their own fuel tank (that's like an external thingy gadjet as I understood) Well that the bike didn't work correctly either so that kind of eliminates the fuel petcock being a problem. So the thinker around the bike for some time and then do some adjusting to the screw that change the fuel mixture. As it seemed the bike might be getting to much fuel. They didn't do much else, the guy took it for a 15 min ride and told me it's ready. It was running way better, but again nothing close to what it was, not smooth enough, more noisy, more vibration, rougher sound, no power on low revs, ok power on middle revs and low power on high revs. They told me the the screws are now in about 1 full turn in more then they should be according to the manual. So the fuel must be less rich but it still feels like its drowning in fuel. Took it home again and surely felt all the above problems. Left it for 10 min's off and came back and it's dead again. At first it wouldn't turn the engine but a bit later just won't start.

Next day it did start but with the same problems in a very sad state, so I managed it to drive it back to mechanic.

Now he seems very confused as it hardly adds up, perfect engine, after tipping over not working properly and giving this much trouble.

Any Ideas on this one?

P.S. thanks for whoever too the time to read it and any ideas will be much appreciated.

Sounds like the floats are leaking gas past into the cylinders. This could hydro-lock the engine. But, gas is made up of really small molecules, so it leaks past the rings and then the engine can turn over. Check your engine oil level and smell it. It probably smells of gas.
The floats also can be responsible for the gas overflow out of the carb breathers.

When the bike was tipped over, oil and gas may have gotten into the airbox breather section and could still be in the tubes/filter box. 800 to 1000 rpms is too low for the F2. Factory spec is 1200 rpm in the US and 1400 rpm in California. I would think a Euro model would be in the 1200 range.

With the side panels off, turn on the gas and look with a flashlight where the gas is coming from. Should be from between one or more of the carbs. The floats inside the carbs are plastic and non adjustable. I think you have something holding one or more floats open which floods the motor.

Hey,

Thanx for the answer. The oil was changed by the mechanic 1st time brought it ther because it was mixed with fuel, you're right on that. And the hydraulic lock did happen like 3 times, but it went away after a few minutes and engine turned again.

Idle- ok I might have been abit off on that, it was deffinitely on low 1k side.

Searching for a leak - the thing is - it wouldn't leak always. It only leaked like 4 times, but when did - it was a serious leak.

But wouldn't carb leaning fix the float problem?

cbr floats operate at a very low pressure setting. It doesn't take much to stick one open. Either that, or the needle tips are grooved. Since your bike was running fine before the tip over, I think that some junk got into the fuel system. If you can empty the tank and pull the petcock, you can check to see if there is stuff on the filter screen that surrounds the fuel intake. It can take a couple of cleanings to clear this up. There are drain screws on the carb bottoms. Drain the carb into a glass container so you can see if there is anything floating in the fuel. Water drops, varnish buildup, fine silt, etc.

gpfan1 - you might be right. After one and a half month at mechanic the bike was "fixed" this week but on the test drive started doing it again, and stalled. But for 5 minutes it was running exactly as it should. Mechanic has taken carbs out for like 4 times and each time there was some dirt in them, most probably my fuel tank is full with sh*t. Need to get that cleaned and see if any hoses are blocked?

I've read some stuff about some breathing hoses? Any info on them, where are they, what happens if they get blocked?

There is a screen inside the tank that is attached to the petcock. Pull the tank and drain the gas, remove the petcock and examine for damage. With a flashlight, check the inside of the tank for rust patches.

There are two breather hoses from the tank. One small and one large. If they get blocked, it would cause the fuel to not flow due to vacuum build up. As long as the tank is empty, you can use a compressor to blow air back through them to make sure they aren't plugged. Carb breathers usually vent to the atmosphere and gas comes out of them if the floats are messed up.

Jānis, GPFan1 has you sorted I think, though I will add that with regards to the two hoses connected to the bottom of the tank, only one of those is a breather/vent line (the smaller one), and the other is just an overflow line... you need both of them clear, but if the larger overflow hose is blocked, that will only affect you if you overfill the gas tank, as fuel will not have a place to flow out of the filler area.


We need to talk about this mechanic - personally, I would not recommend going back to this one, :icon_no: here's why...

ONE time off, is all that is necessary for a proper carb cleaning - any mechanic worth their weight in dirt, would not need to pull and clean the carbs 4 times.
If a good mechanic has thoroughly cleaned the carbs, then checked the float bowls and found dirt/junk there again, then they should immediately proceed to pulling/cleaning the tank, and checking the condition of the petcock screen... this is easy stuff, so like I said, I'd be weary of ever returning to this mechanic!

Good luck on getting this resolved!

gpfan1 JNSRacing guys, any chance you can show me the breather hoses on users manual, so I see how they look? That's just for my own knowladge.

Picking up the bike, after 2 months not fixed from the guy, moving it to another guy to see if he can sort it out. Ehh, this has been tiring.

User manual, or service manual? If all you have is the user manual, then I doubt those will be shown there, but if you have a service manual, then they can be seen on 2-11... items 6 and 7 in the image from the manual below:

https://farm6.staticflickr.com/5037/...5d68110d_b.jpg

If you don't have a manual, then definitely get one - I recommend having both the Honda service manual for the F2, as well as a Haynes manual.

Hey,

Thanx JNSRacing

Well I took it from the previous guy, tried to drive to the other mechanic, ended up in the middle of the road. Will tow it tomorrow and see what the other guy says.

This guy after a long fight with him just gave me some pointers on what could be wrong:

-Floats sticking, main jets need to be changed, as too much fuel goes in to engine.
-Fuel petcock needs to be changed to the original Vacuum one (i have gravity)
-Some other stuff in carbs, needles I think, might need changing.

Well when I saw the carbs open it did seem that one or 2 of the floats (the plastic white thingies) don't move as naturally as the other ones, so that might be the problem.

Have you any info on actual small fuel pumps placed mounted on the bike?

Also I'm thinking about the white float thingies if they are the things that can go bad or something else there that operates them?