Honda CBR XX Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
I'm having trouble getting my bird to start. I've been through the enrichment circuit and cleaned all the orifices and jets. Replaced the fuel filter too. Still it takes forever to finally get going. It used to fire right up with the RPM responding nicely to the choke adjuster, now nothing. I've even got the idle stop adjusted all the way up. Once it warms up it runs great, it's getting it there that is the problem.

Any techies on here that know where the blockage is or what the problem might be?
 

·
Registered
Joined
·
4,007 Posts
I know for sure that the first start of the day requires choke (enrichment) action. To attempt to start without this is to a) over tax the starter motor, b) flirt with a dead battery conditon, brought on by "a". As a start,..and you may have done this already,...ensure that the choke cable system is actually connected, adjusted correctly to bring in the enrichment circuit function.

If this is a sudden on set of this condition I wonder if the throttle position sensor might have failed and so sending a bad signal to the ECU? But then again you state that once the motors running everything works fine,.so I'd correct myself and say the TPS is fine.

Tony
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
It sat for a winter (a cold winter) and then wouldn't start in the spring. I have the tech manual and went through the starting circuit as it suggested. The choke cable pulls the enrichment rack and jets like it should. There is no gum on the needle valves or bodies. Went through the carbs and cleaned out the bowls, slow jets, and every other orifice I could find. There has to be something I missed because it does not respond to the choke.
Once it warms up it runs and idles fine, except the idle stop is dialed all the way up to get it to idle in band. The bike has low miles (<10000) and worked great prior to sitting with ethanol laced fuel for a winter.
I'm out of ideas and don't want to spend a fortune at the Honda shop for a tech to brush up on old bikes with carbs and do the same thing I already did.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #4
One more note. I routinely take the bike out and putter down the road (25-35 MPH) with the choke full on hoping to clean out whatever goo might be in there. No go.
 

·
Registered
Joined
·
4,007 Posts
So the idle adjustment knob on the left side of the chassis below the frame rail is dialed all the way in (clockwise) to effect normal idle setting? Are you sure that the carbs are in fact getting enough fuel from the tank? Perhaps its more a of fuel supply issue rather then a carb issue your dealing with. A test of sort might be to get the bike started and then take if for a top end run to see if in fact you can run the carbs out of fuel..this might prove a fuel supply issue. You don't have to go mach nine..but simply run the rpm's up in a lower gear and hold it there to see if it falls off on power as the float bowls empty. Of course..following the fuel supply issue ...you can also double check the petcock operation (ensure the selector handle is in the flow/run position and not turned off. Secondly ensure the vaccum line to the auto fuel shut off on the petcock is connected to the engine for vaccum source and that the line is not cracked or holed so that it does in fact open the petcock vaccum valve.

As far as storage goes and Ethanol fuels,..well I also store my bikes in a unheated garage where temps can reach -25C or colder. I store the bikes with full fuel loads and there dosed with SeaFoam Fuel treatment as a fuel stabilizer solution. I've not seen any issue related to fuel having done this for the last 15 years or more.

The above has reminded me...perhaps a little Sea Foam through the carbs will help to do a bit of "clean as you ride" kind of thing,...at least it won't hurt.

One other item in a warning sense: Ensure that the carb bank is fully seated in the connective boots between the carbs and head. It is rather easy to not get them seated, more so when the rubber connective parts are old and hard. Like wise..ensure that the boots are not cracked, as often happens to the older hard rubbers when they are disturbed after a long period of use.

One last question...is the stock airbox and airfilter in service?

Tony
 

·
Registered
Joined
·
4 Posts
Discussion Starter #6
Mach nine works great. I have a lot of empty straight road where the bird struts her stuff. I'll take a look at the rubber parts, but I'm pretty sure I gave them a good look when I worked on it in the spring. The fuel petcock is open and I checked the vacuum diaphragm operation when I changed the fuel filter. I'm afraid I'm going to have to pull the carbs again and take them down to their individual screws to find the issue. The bike is still original, air box filter and all.
I'll try the sea foam and see what that does.
 

·
Registered
Joined
·
4,007 Posts
With the ability to approach top end speeds, at wil, l I'd guess is not about fuel supply problems. As you state..it may be time to revisit the carbs and ensure the function of the enrichment circuit. I can not provide any info in that area, sorry to say. There is something that appears to be connected to the starting issue though..and that's that the idle adjustment must be turned full in to effect and hold idle...this should not be the case of course. There should be some adjustment available. Have you made any moves on the Pilot Adjustment screws? The base settings for these, one on each carb, should be 2 3/4 turns out (from lightly seated) for 49 state/Canada models and/or 2 1/2 turns out for California models DO NOT FORCE ANY OF THE ADJUSTEMENT SCREWS...THIS BRASS STUFF IS VERY EASY TO DAMAGE! You will also need to sync the carbs when you get this sorted.

Tony
 
1 - 7 of 7 Posts
Top