I have NEVER had these symptoms all at once with any kind of vehicle I've owned....and I've owned some junk. This 88 cbr1000f is a beautiful bike that I've dumped some money into getting it on the road and my wife is ready to choke me if I don't get this cured.


Bought bike, it wasn't running. After checking cables, grounds, buying a good battery, carbs cleaned by someone who knows their stuff it became a starting, running unit. Only....


NOW, when I refer to "won't start" I really mean it wont start under it's own power, or even running cables to a car battery, UNLESS that said car is running. Please keep in mind, once running, I can flip the throttle grip constantly, which would on a unit that was not running well, cause it to stumble and probably stall. It runs like a top. Problem is it does not like to start under certain conditions.


These conditions are: morning starts, attempts to start after motor running for long enough to take the temp into the midrange of the gauge. If I get the bike to run and shut it off right after it creeps off the C on the temp gauge, it usually fires back up. If I push it out into the driveway in the morning and let it sit in the sun at 25 degrees C for 3 hours or so, it usually fires up. At any time, if I run the cables to a running vehicle, it will fire up. It doesn't sound like it's turning over slow, but the only things I can think of that are left, is a starter that's draining just enough juice to cause problems with the ignition or maybe the valve clearances? Anyone believe the valve clearances would cause these kind of issues? I have had plugs out, they are fairly new, colored nicely, and nice blue spark...out of the cylinders anyway

 

Sounds like low voltage. You say you checked grounds. Did you also check all other electrical connections? If not you might get a can of contact cleaner, disconnect, spray out and reconnect every one you can find, particularly those in the starting circuit.

If that doesn't work: Plug wires? Coils weak? You might get good hot spark in mid air but not in compression. If none of that solves the problem and you still suspect the starter, check current draw to it before removing. That might mean a trip to a mechanic that has equipment that can handle the task, add well as finding out what normal cranking current is for the CBR, but that's easier than taking the starter out and finding it's okay.

After all is said, given the bike's age my bet lies with corroded terminals.

 

I do know the starter has had about 10 years of use in the last year trying and troubleshooting this bike. It has been gnawing at me as something to check (starter) but the mechanic I had it to suggested the valve clearance check which is why I'm asking. I guess it's the randomness of everything that drives me. The only thing that stays constant is the need for the running vehicle boost.... it always works. There seems to be no difference how it turns over just from the cables to another battery and no big difference turning over with the running vehicle, just enough. He believed the valves might be tight, not letting enough air/fuel mix into the cylinder

 

got home from work at 4 am and decided to go at the starter wiring. replaced the main starter wire, the main wire from the batt to the relay(as well as the grounding wire) have all been replaced. no difference. pulled the starter itself, nothing seemed too bad, cleaned up the contacts, put it all back together and still the same thing. guess I'll check out the valve clearances today. god I hope that's it, I don't know what else it could be

 

Is it possible that the choke (enriching) circuit isn't doing it's job properly?

Lift the tank and watch to make sure that there are no loose connections when you pull on the choke lever. Is the cable holder loose underneath the tank?

If it is, when you pull on the choke, it just moves the end of the cable but doesn't actually engage the choke.

 

+1

Lift the tank and MAKE SURE the enrichner slide is moving. It is the long thin flat part that is sitting just in front of the carb bodies. When the 'choke' lever is moved, you should see the slide move.

Also, when it is running, set the idle to 1,000-1,200 rpm. That RPM setting usually works best for starting. USE NO THROTTLE while starting. You can only use throttle after a minute or two after it starts. Blipping the throttle before it runs for a minute or two will make it stall.

These bikes have enrichners, not chokes.

What do you have for air filter? Stock should be fine but one that breathes better may require bigger jets if its not starting good.

 

Just a dumb idea but my neighnor just took his kawi to a shop cause he couldn't figure out why it's running rough and hard to start no matter what, we even cleaned and synced the carbs.

Turned out the plug leads were in the wrong order...

 

If it starts OK and runs fine when hooked up to another vehicle, that suggests to me that the problem is electrical.

 

it HAS to be the starter. I had it apart, looked good, but the commutator was dirty. cleaned it up, put it back together and absolutely no change. going to attempt the valves tonight with Malbojah's writeup. Wish me luck. Hopefully they aare out and my problem. Otherwise it is going to be spending money time. I was already all through that bike, checking connectors and EVERYTHING is either clean or replaced

 

enrichment slides work well, cable good, air filter is new and stock. funny thing is, even when it will start on it's own, no more than half on the choke lever or it will not go. once running, it likes full choke for a 30 second or so duration and then I usually back it off to half for another 15-20 seconds and then it will run fine with choke off