Hi guys, I bought an unmolested F3 with 56k kilometres and am in the process of recommissioning it.

Plug are Iridium and dark but I have seen worse.
Air filter was a bit grubby but a wash with mild detergent and a dry in the sun got it cleaned up
New battery, put a tester arcoss it and reads 13.2 v with motor running, reving it to 5k reads not much more, but healthy 13.5- 14.0 v will do I think.
Fuel tank was filthy , cleaned that out , drained carb bowls.
Coolant was new
Oil and filter new
Got it running and ...............................................

So here we go with questions :-

It has a gaping hole in the power at 5-7 K rpm , plus it seems honda saw a lot of room around the air box and carbs so decided to fill the space with hoses.
I read to disconnect the solenoid thingy which I did but to no avail, the tank was filthy so I am in the process of cleaning the carbs,and have them on the bench awaiting a rebuild kit to arrive. I wont bother cleaning jets I'll replace them .

1- Will the bike run Ok just using the airbox alone with all the extraneous hoses disconnected or blocked off ? I think yes.
2- I intend to go one jet size up primary and main if I do this to richen up a set up that is set lean in the first place, yes ?
3- Whilst I have it apart, can I remove the thermostat valve, it's a part waiting to fail and we dont need cold start **** here in OZ
4- Can i block off the carb warming **** from the cooling system/water pump, why ? see above question. 3
5- Any traps for young players with cleaning the carbs ? I'm not new to this , the bike has been in regular use but never used to it's full potential. It starts and idles perfectly and runs like a dream untill the dreaded 5-7 K mark, my thoughts are its not gummed up it's dirty and the needles and needles jets are worn, thoughts ? I do have access to an ultrasonic cleaner, but have not been impressed with its results and frankly consider them over rated.
6- If I do all of the above and I still have a gaping hole in the power at 5-7 K rpm , where do I look for ignition/timing issues ? Would the TPI give these symptoms ?
7- Yes I know a new air filter would be a good idea but lets get rid of this gaping hole in the power at 5-7 K rpm ,
8- I looked at one of the main jets and saw an obstruction so maybe thats it and I am on the right track.

Thanks for reading so far, if any of you has advise, or, more importantly, specific experience with the symptoms my bike is showing, please let me know and lets get this puppy going as it should !!!!

Lloyd.

 

Hi LloydJ,
If it was me, I would get the carbs cleaned, replacing all of the seals and any worn jets. Do the proper maintenance and leave the rest alone.
The 'proper' carb clean setup and sync should sort your hole in the power.
Unless you are opting for a high flow air filter and free'er flowing exhaust system you should not need bigger jets.

IDoDirt will no doubt be along shortly, he is extremely knowledgeable on the F3's are will advise on setting up the carbs etc and where to get the seal kits.

Cheers Al

 

Al,

Good advise, thanks . I have a carb rebuild kit on the way and have been at this rodeo before and agree with you to merely get the bike running as it should, I have no inclination to tune it , but would like to avert future problems whilst the thing is in bits.

Cheers, Lloyd.

 

Some hints and tips on the carb cleaning in this thread
https://cbrforum.com/forum/cbr-600f4...rottle-161524/

 

You found an unmolested F3 and your first thoughts are to molest it. In answer to your first question above about disconnecting hoses and blocking them off. That's a big fat NO. It won't run right and you'll spend all kinds of time chasing your tail trying to compensate for all the performance issues that pop up.

Clean the carburetors and focus on cleaning them thoroughly. Make sure those hoses are properly attached and not leaking or plugged up by years of dirt and bugs. Replace the thermostat but don't leave it out. It's lasted this long, so I don't think you'll have to replace it again while you own the bike.

 

Thanks for your reply, I will concentrate on the carb cleaning and re instate all hoses .

 

Top pic is the fuel I drained out of the tank............
I cleaned out the carbs with carb cleaner and lots of air, massaged some grease into the diaphrams and put it all back together ( with all hoses in place !) and all is well, goes as it should. Happy Chappy .

I ordered some carb kits but they were nowhere near the right sizes so sent them back, leason learned there, A mate used the same company to get carb kits for his bike with no issues so it took his advise and got the kits.
Main jets in the kit 103 shame, I needed 143...
So suck it up guys and pay top dollar for these things and you will get what you need.

The front wheel bearings were shot, this I think was due to someone using a pressure cleaner which blasted water past the seals and the result is as shown..

 

Holy smokes, that fuel was bad, not surprised then that the carbs needed a jolly good clean.
Fantastic that it is now running properly
She's looking good now, you need to cherish the old girl being one of the last of the old style steel framed CBR's

 

Curious, did you replace the O rings on the brown T connector in the above image? They're prone to leaking. Especially after sitting for a while.