So what did I break this time?! - Honda Motorcycles - FireBlades.org
Honda FireBlade Discussion of the Honda CBR 900RR, Honda CBR 929RR, Honda CBR 954RR, and Honda CBR 1000RR Motorcycles.

User Tag List

 46Likes
Reply
 
LinkBack Thread Tools
post #1 of 79 Old 11-06-2019, 9:56 AM Thread Starter
 
Join Date: 11-17-2014
Location: Derbyshire
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Reputation Power: 7
   
So what did I break this time?!

I previously found that having a random piece of carboard taped over the air box made things run but removing it caused the engine to bog down and die. I finally got around to doing the air/fuel adjustment yesterday and appear to have cocked something up

It's a CBR900RR in a kit car and, after a bunch of reading, it looked like I could wind each mixture adjustment screw gently to it's stop then out 2.5 turns. I did this and went for a drive, all was well.

After about 10 minutes, on the way home, the engine died. The fuel filter was empty so I think it did genuinely run out of fuel. 2x5L cans later and it fired up but wouldn't allow anything more than about 1500 RPM. I limped home and tested the fuel pump, all fine and pumping well. I re-set each adjuster to 2.5 turns, no change. I tried 3 turns, no change.

I removed each adjuster completely, all looked fairly clean, popped it all back together and now it's popping and banging and over revving but still won't take any load from the throttle.

Although I thought I was gentle seating each screw, my only guess is that I damaged something doing that but was after any thoughts/suggestions

James
jseaman is offline  
Sponsored Links
Advertisement
 
post #2 of 79 Old 11-06-2019, 10:47 AM
Supporting Member
 
Join Date: 05-27-2014
Location: UK
Posts: 451
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 53 Post(s)
Reputation Power: 13
             
Re: So what did I break this time?!

Symptoms point to fuel starvation. Are you using the low pressure pump from e.g. an early CBR900RR or similar bike, or are you using a car fuel pump with a pressure regulator?
BenelliBlade is offline  
post #3 of 79 Old 11-06-2019, 11:20 AM Thread Starter
 
Join Date: 11-17-2014
Location: Derbyshire
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Reputation Power: 7
   
Re: So what did I break this time?!

Thanks - It's a low pressure 2-3 psi pump, if I pop off the feed to the carb it gushes out and if I block it then it kicks off at low pressure
jseaman is offline  
Sponsored Links
Advertisement
 
post #4 of 79 Old 11-07-2019, 6:28 PM
 
Join Date: 03-21-2005
Location: Wiltshire, uk
Age: 53
Posts: 1,189
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Reputation Power: 20
         
Garage
Re: So what did I break this time?!

all the airlines ok, no leaks? no pinched pipes either? inmey rubbers all ok and carbs seated in them properly?

I had issue years back with my 98 rr.w and found it was a pinched breather to the carbs. I know you have more room in a kit car but worth starting with the basics
thistintivin likes this.
machinehead is offline  
post #5 of 79 Old 11-07-2019, 6:44 PM Thread Starter
 
Join Date: 11-17-2014
Location: Derbyshire
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Reputation Power: 7
   
Re: So what did I break this time?!

Sadly I don't think so, I had a good look around and no signs

I've got a tachometer coming so I'll adjust all the set screws to the full procedure and see if that helps but it feels like something's gone wrong with the fuel screw adjustment, I just don't know what
thistintivin likes this.
jseaman is offline  
post #6 of 79 Old 11-08-2019, 9:02 PM
President: Team Full Chat
 
IanDoohan's Avatar
 
Join Date: 06-28-2013
Location: Connecticut,USA
Age: 47
Posts: 7,177
Mentioned: 70 Post(s)
Tagged: 4 Thread(s)
Quoted: 734 Post(s)
Reputation Power: 102
                     
Garage
Re: So what did I break this time?!

Doubtful it has anything to do with your fuel screw adjustment as that will typically only affect idle to 1/8 throttle.

Check everything else ie. spark, solid contact on all your spark plug wires, loose connections and possibly dirty carbs.

There is also the chance it skipped time. Much to check James.

My 99 900RR Track Build Link:Track Build 900RRX

My Red Rocker 93 Build Link: Café 900RRP
IanDoohan is online now  
post #7 of 79 Old 11-09-2019, 3:34 AM Thread Starter
 
Join Date: 11-17-2014
Location: Derbyshire
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Reputation Power: 7
   
Re: So what did I break this time?!

Thanks Ian, all good suggestions as usual!

I checked all plug wires and will do a spark test next

Never thought about the timing skipping again but will pop the cam cover off and check that too and report back!
jseaman is offline  
post #8 of 79 Old 11-09-2019, 1:23 PM
 
Join Date: 05-09-2019
Location: UK
Posts: 230
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 85 Post(s)
Reputation Power: 2
   
Re: So what did I break this time?!

Quote:
Originally Posted by jseaman View Post
I previously found that having a random piece of carboard taped over the air box made things run but removing it caused the engine to bog down and die.

After about 10 minutes, on the way home, the engine died. The fuel filter was empty so I think it did genuinely run out of fuel.

James
Hello James,

If this was a bike, we'd know the sub-systems and be giving you the right answer immediately <honest > .
- Do you have any photos that show your intake system with/without the cardboard?
- What elements are in your fuel supply line - from fuel tank to carbs?

Since everything was going well until you ran out of fuel, does this indicate that some rubbish has got into the carbs?
Whip one or more float bowls off and check? While you are in there make sure that the float needles are OK?

Can you check and make sure that the accelerator pedal is moving all 4 carb throttles?
Can you remove the air filter and make sure that the main jet sliders are moving freely?
And are they moving as expected with the throttles when the engine is running?
Might be worth taking the caps off and making sure that diaphragms (and jets) are OK?

I agree with Ian's comments.
Duncan893 is offline  
post #9 of 79 Old 11-09-2019, 1:33 PM Thread Starter
 
Join Date: 11-17-2014
Location: Derbyshire
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Reputation Power: 7
   
Re: So what did I break this time?!

It's exactly the same set up as the bike, they've just hacked the top of the airbox off because the bonnet wouldn't close and taped some card over it. Pic attached

Tank through flexi lines and a filter then to a 2-3 psi pump to the carbs. I have used the exact same set up before and it worked well (and has been so far)

I thought the same about pulling some muck in, I'll have a check in the carbs as soon as I can

All throttles are moving and I'm checking the jet sliders tomorrow all being well

Thanks for the comments
Attached Thumbnails
19.JPG‎  
jseaman is offline  
post #10 of 79 Old 11-10-2019, 4:39 AM
 
Join Date: 05-09-2019
Location: UK
Posts: 230
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 85 Post(s)
Reputation Power: 2
   
Re: So what did I break this time?!

Quote:
Originally Posted by jseaman View Post
It's exactly the same set up as the bike, they've just hacked the top of the airbox off because the bonnet wouldn't close and taped some card over it. Pic attached
Crumbs! I was not expecting that!

You've lost a lot of the intake volume and it looks like more than half of the volume above the air filter?

Which I am assuming is a Std CBR900 filter? Does this kind of set-up run rich? And, if so has it been re-jetted?

When you removed the cardboard, what else did you do ......?
Attached Thumbnails
Screenshot 2019-11-10 at 08.37.17.png‎  
Duncan893 is offline  
post #11 of 79 Old 11-10-2019, 4:43 AM
 
Join Date: 05-09-2019
Location: UK
Posts: 230
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 85 Post(s)
Reputation Power: 2
   
Re: So what did I break this time?!

Quote:
Originally Posted by jseaman View Post
It's exactly the same set up as the bike,
Does the propshaft connect with a UJ directly to the gearbox output shaft (front sprocket)?

And, are the UJ's rubber doughnuts or all metal?
Duncan893 is offline  
post #12 of 79 Old 11-10-2019, 9:20 AM Thread Starter
 
Join Date: 11-17-2014
Location: Derbyshire
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Reputation Power: 7
   
Re: So what did I break this time?!

All plugs are the same, looking lean

Checked the timing this morning and it's bang on still (thankfully!)

Yes it's the stock air filter and not rejetted that I'm aware of

Just removed the cardboard, nothing else

Propshaft bolts straight onto the engine with a greased joint

Just fired it up again and still running like crap but after idling for a few minutes it cleared a bit and was revving a bit before bogging down and stalling. I left it a bit longer and could rev more and now I can get all the way through the rev range and it sounds fine.

So it's fixed itself. I guess something in the carbs?

I'll pop out for a drive and see what it does but I think I'll get a full carb rebuild kit next
IanDoohan and Duncan893 like this.
jseaman is offline  
post #13 of 79 Old 11-10-2019, 11:00 AM
 
Join Date: 05-09-2019
Location: UK
Posts: 230
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 85 Post(s)
Reputation Power: 2
   
Re: So what did I break this time?!

Quote:
Originally Posted by jseaman View Post

I think I'll get a full carb rebuild kit next
I re-built my carbs with this kit, it contained what I wanted and, at the time it was good VFM:

https://www.ebay.co.uk/itm/4x-Honda-...kAAOSww4BcuKed

However, just looked to get the above details - Search "CBR 900 Carb Kit" and there is a more comprehensive kit - additional parts include the fuel enrichment slider, trumpet seals and main jet holder&needle - at £39.99!?! But, I cannot vouch for the quality.

And, there is another company but the picture is quite small and I just cannot seem to make out what is in the kit.
Attached Thumbnails
Screenshot 2019-11-10 at 14.57.25.png‎   Screenshot 2019-11-10 at 14.57.37.png‎   Screenshot 2019-11-10 at 14.57.58.png‎  
Duncan893 is offline  
post #14 of 79 Old 11-10-2019, 1:18 PM Thread Starter
 
Join Date: 11-17-2014
Location: Derbyshire
Posts: 152
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Reputation Power: 7
   
Re: So what did I break this time?!

Exactly the kit I am thinking of getting, thanks!
Duncan893 likes this.
jseaman is offline  
post #15 of 79 Old 11-10-2019, 7:22 PM
President: Team Full Chat
 
IanDoohan's Avatar
 
Join Date: 06-28-2013
Location: Connecticut,USA
Age: 47
Posts: 7,177
Mentioned: 70 Post(s)
Tagged: 4 Thread(s)
Quoted: 734 Post(s)
Reputation Power: 102
                     
Garage
Re: So what did I break this time?!

Quote:
Originally Posted by jseaman View Post
It's exactly the same set up as the bike, they've just hacked the top of the airbox off because the bonnet wouldn't close and taped some card over it. Pic attached

Tank through flexi lines and a filter then to a 2-3 psi pump to the carbs. I have used the exact same set up before and it worked well (and has been so far)

I thought the same about pulling some muck in, I'll have a check in the carbs as soon as I can

All throttles are moving and I'm checking the jet sliders tomorrow all being well

Thanks for the comments
Quote:
Originally Posted by Duncan893 View Post
Crumbs! I was not expecting that!

You've lost a lot of the intake volume and it looks like more than half of the volume above the air filter?

Which I am assuming is a Std CBR900 filter? Does this kind of set-up run rich? And, if so has it been re-jetted?

When you removed the cardboard, what else did you do ......?

James, I think it would be cool for you to put the standard top back on with an OEM filter, then cut out the bonnet to allow for the proper top of the airbox to fit, protruding through the bonnet like the old "shaker" intakes on the 70's Trans AM
Duncan893 likes this.

My 99 900RR Track Build Link:Track Build 900RRX

My Red Rocker 93 Build Link: Café 900RRP
IanDoohan is online now  
Reply

  Lower Navigation
Go Back   Honda Motorcycles - FireBlades.org > Honda Motorcycle Models > Honda FireBlade

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Honda Motorcycles - FireBlades.org forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
A valid e-mail address is REQUIRED. You will not have access to any site features until you activate your account using the activation e-mail that is sent to this address.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome