I have finally got round to trying to start my "project" CBR J it has been thrown down the road a couple of years ago(not by me) and I have been doing a heap of panel repairs for the last few months.d it was dThought it was about time to check out if the bl00dy thing was going to run so bought a new battery n filled the tank with new petrol,stripped n cleaned carbs new plugs etc, thought I'd try gravity feed to carbs (kiwi TK has my pump) Was eventually able to get it to fire up but ran like a bucket of s**t. Checked the pipes and found it was only running on 1 and 2 this struck me as a bit strange as they are both on different coils and checking for spark with the plugs out against the cam cover there is good strong spark on all the plugs.Plugs at 3 n 4 both seemed to be dry so that would tend to point towards no fuel to the right hand pair of carbs.Question....Is there a secret method of getting fuel down to the carbs when relying on gravity and is there any chance of running too lean when relying on gravity feed on the earlier versions?

 

I'm told that the earlier models needed a fuel pump but only when running flat out - removing it will result in fuel starvation at the upper end of performance. This could mean running too lean and possible valve problems. For those of us who run at normal town speeds, probably never something to worry about. You may want to run a gas analyser on it at "full chat" and look at the fuel/air mix before you remove it.
Them slant eyed engineers at Honda (bless 'em) wouldn't have fitted it if it wasn't necessary.
Just a note for info - when I run at high speed for an extended period (over 200+ KPH or 125 MPH) for more than 10 mins or so, I get a white puff from the exhausts as I back off the throttle...............Looks like it's a bit lean up at the top..............? I know my bike runs rich under normal running conditions, but up in the upper levels who knows. I don't have a fuel pump to help it along which may help.

 

When I do that I find I lose my licence.

There would be very few roads in NZ where you could run like that.

 

Same in my part of this country too. Crap roads, loads of cops and too much wildlife. A short squirt into warp is all you can get away with.

I can't see why a fuel pump would be needed on a carby engine unless the tank was lower than the engine. Maybe the hoses / fuel outlet / carb stubs are larger diameter on the later models without the pumps??

I'd say that Honda were thinking along the lines of what Tim suggested, back in the depths, and they realised it was just another part that could fail. Even Honda can get it slightly wrong sometimes, hence the mark 3 (sorry guys, I'm only stirring...again).

 

Now I feel really old and stupid!!!!!
Spent yesterday morning making up an adaptor so the compression tester I borrowed from work would fit the 12mm plug holes (tester is only set up for 14mm and 18mm)did comp test 150 150 155 150 so that looks all ok .....
Thought "lets check plug lead resistance" remove #4 lead and check resistance (ok) Go to refit lead and see "3" on the lead so think "bu99er" Refit leads LH coil 1 and 4 RH coil 2 and 3. Guess what..........Push starter and it runs like a dream no cam chain noise lots of exhaust noise (has K&N and open mufflers)

How stupid can a guy be?

 

Don't worry about it JK. The main thing is that it's all good now! It's easy to stuff up simple things when you're in a hurry to got the bike going.

 

No comment, other than it it did sound particularly tasty over the phone. Good work bro' you're in danger of becoming a bit of an expert on these things.