Hey guys, my f3 has developed a problem purely as a result of my own stupidity. I've topped up the oil when she was on her sidestand and as a result massively overfilled her.

The story goes that on xmas eve I made a (very) last minute dash to a shopping centre and noticed that when overtaking I had a flat spot around 4-5k or so. I just figured it was because she was cold and I was accelerating quite briskly. Just before I got to my destination she started to judder and lose power and as I came to a halt she cut out. When I came back 15 minutes later she wouldn't start at all of the button, I push-started her but was she smoking a bucket load. I had a look at her on boxing day and it became obvious judging by the smoke that it was oil being burnt, checking the oil level confirmed that. I reckon I drained at least half a litre, maybe more. As I did that I noticed there were a few oil drips that seemed to have come from a breather/overflow exit on the front of the engine, below the pipes iirc.

After draining I rode her around for about 30-45 mins, mostly between 30-60mph and after about 15 mins the exhaust smoke finally cleared away but she was still juddering and down on power in the low rev range, above 6k she fine. I changed the plugs today and boy were they black/oily, unfortunately she's still juddery and low on power in the low rev range. I'm thinking of maybe draining all the oil and just putting in the minimum, but I'm also thinking that maybe I've done something that requires more than just a "drain or change", so if anyone has any suggestions Im all ears, it'll be very much appreciated.


Miscellaneous info...
Prior to figuring it was oil I was thinking that it was air or spark/coil/battery related. The airbox seemed relatively clean, the filter is a bit sh**ty but neither seemed oily, as I understand it, and I'm no mechanic, but oil can pass up there in this kind of circumstance. I couldn't check the coils because my multimeter was in my workvan, which of course was back at the depot for xmas. I got it back today but couldn't check for lack of daylight, I did however check my battery which, as I knew already, is not doing too well 11.5 volts or so, after charging for a bit 12.5 or so.

 

Hi Stan, first of all , I would take off the battery and put it on charge while you look at the air filter, under pressure if over filled the oil could be forced up from the crankcase into the filter box, if your air filter is of a type that can be cleaned do that, while thats out of the way ,check all breather pipes from the air box to make sure their clear , blow them through if possible, (take them off first)

 

Even though you said the air box was relatively clean I would thing that a hot oil mist coming from the crankcase breather might have clogged the carbs a little. Dont stunters run their oil overfilled so the pickup still oils the upper part of the engine?

 

When it first broke down I thought it was carbs but I've misdiagnosed problems as carb related in the past so was a bit weary of doing so again, I'm hoping it isn't as that's a job I've never actually done before. I'll def clean the airbox and pipes, how can I tell if I have a cleanable filter? I might just buy a new one anyway.

Thanks for your responses, it's very much appreciated.

 

its fairly easy cleaning the carbs just take them off split them remove throttle sensor .remove pilot .main.jets also pilot screws .flats .float valves .and diaghfram plus needles .remove chock plungers .then boil carb bodies plus pilot and main jets in boiling water and lemon juice

 

Yeh I'll have to tackle it over the weekend, it's not so much the dismantling but rather reassembly and making sure the various screws are set correctly. Thanks for your input Dan.

 

No probs mate .before u split the carbs take some photo's of area's u think u will get stuck on...Read the pics iv uploaded .I know the cvk40 carbs are not for the cbr I think it's Harley .. buell but it gives details on how constant vacuum carbs work

 

Just a quick update to say that my bike is (by magic) running properly again. Due to work commitments and bad weather I wasn't able to work on her until today, alltho' I didn't actually do any work. Before commencing carb cleaning I thought I may as well take her for a ride to see if I could blast the clog clear, I've tried this a few times already and it hadn't work so far. Just as I was coming back the clog finally cleared up, then about 30 seconds later I ran out of petrol and so I'm wondering... coincidence or did the lack of fuel in the clogged jet help force the clog out? I might give it a clean anyway since I've got some carb cleaner and a ton of info from guides that I'm only going to forget otherwise.

Anyway, thanks to Cabaret, Frank and Daniel for chipping in (especially with the pics)... it's much appreciated

 

Glad everything is ok Stan