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-   -   Running on three cylinders?? (https://www.fireblades.org/forums/honda-fireblade/69325-running-three-cylinders.html)

temperedtim929 10-03-2008 12:03 AM

Running on three cylinders??
 
I have a 2000 CBR 929 RR. The bike is new to me and Im fairly new to street bikes in general.

My issue is that when I start my bike it sounds like a damn ducati. glug glug glug glug.... when it warms up it seems to come together more (if that makes any sense.) When i crack the throttle while its warming up it def stumble but never when its warm.

Is it possible that its running on three cylinders? if it were wouldnt it throw a fault code. Right now I have a fault code for a MAP sensor(2 short blinks) but Ive had that fault since I bought the bike. Ive started the bike dozens of times but im usually on the bike....when I noticed the new sound I had started it while off the bike. How obvious is it when a bike runs on three cylinders? Would it still rev fine? Id take the bike out to see if it pulls strong but its not registered or insured so the road isnt really an option right now.

The exhaust is a two brothers racing exhaust and the bike still redlines and sounds consistant throughout the RPM range but awful throaty when cold.

3 cylinders firing? Or just the exhaust and a cold motor?

lanbrown 10-03-2008 12:26 AM

Re: Running on three cylinders??
 
The engines are warm blooded at times and like to be up close to operating temp before they really want to work properly. IMO, the early FI engines from Honda were like that; stumbled a bit and when cold.

temperedtim929 10-03-2008 12:31 AM

Re: Running on three cylinders??
 
If it were running on three what are the indications? Also what is the best operating temp?... i never really get into the throttle till its at least 140ish..??

lanbrown 10-03-2008 12:40 AM

Re: Running on three cylinders??
 
I ride wasy until at least 168 and then a few more miles. The thermostat should be 168 degrees.

If it were three cylinders it would be rough and would probably shake.

I_FLY_LOW 10-03-2008 2:01 AM

Re: Running on three cylinders??
 
I had the same problem...
Restored the bike, completely.
I took it for an initial test ride, 3 cylinders from the get go...
Turned out to be a combo problem.
Bad fuel pressure regulator, and 1 bad plug.
I had performed a complete service in the bike during the resto, including brand new plugs.
One plug went bad, possibly due to fuel fouling, with the bad regulator in the mix, on the initial first startup.
replaced those two items, and she runs like a scalded ape, now!
Turned out on mine to be the #4 plug.

On 3 cylinders, there's no doubt it's not quite right...
It's not as smooth as when all 4 are running.
Kinda like the duc explanation...
With it in neutral, when you rev it, it's sluggish...
Inital launch from first gear is sluggish, It'll stutter, and chug on launch.
When riding, there just is no a$$ end to it, when you get on the throttle...
When you have all 4 running, she'll take off like a shot, when you open her up, no doubt...

Try carefully feeling the headers, one will be stone cold..
You could use an infrared thermometer, which can be had fairly inexpensively, if you're not comfortable with the idea of fooling with the headers...
Once you determine which one is cold, try swapping spark plugs around with one from an adjacent working cylinder, and see if the problem follows.
If it does, it's the plug. If not, it's possibly a coil, or wire. try swapping one of those around, and see if it follows.. then it would be a coil, etc...

bladeracer 10-03-2008 3:09 AM

Re: Running on three cylinders??
 
Quote:

Originally Posted by temperedtim929 (Post 725109)
If it were running on three what are the indications? Also what is the best operating temp?... i never really get into the throttle till its at least 140ish..??

Spit on each header and if one is cold it's not firing.
You can also use a non-contact thermometer if you have one :-)
Operating temp varies across engine designs dependent on where the temp senders are located in the cooling system so you can only go off what other bikes are running normally.
I think around 80-85C is considered "normal" for the 929/954 on the OEM gauge while moving.

I_FLY_LOW 10-03-2008 10:54 AM

Re: Running on three cylinders??
 
mine indicates 177-185f when in motion, depending on outside temperature.
Sitting idle, can creep up to 200f and up, depending on how long I sit, and relative to the outside temps, also.
I believe the fan kicks on @ 216f.

temperedtim929 10-03-2008 1:58 PM

Re: Running on three cylinders??
 
Alright. I just started the bike and let it run for a few minutes. I touched each header. all three are hot but three of them you cant even touch for a second without burning your finger tip while one of them(second in from the right while on bike) you can touch and leave your finger there for about 8 seconds before it starts to get uncomfortable. If it were not firing would it be absolutely stone cold?

bladeracer 10-03-2008 2:01 PM

Re: Running on three cylinders??
 
No. It's going to be warm due to heat radiated from the rest of the engine and headers.
Sounds like you have a problem there so check it for spark to confirm.

I_FLY_LOW 10-03-2008 2:20 PM

Re: Running on three cylinders??
 
that's true.. Instead of stone cold, I should have stated noticeably cooler, then the others... But you did find the dead cylinder...
Which cylinder is it?
Sitting on the seat, #1 on the left, #4 all the way to the right...

temperedtim929 10-03-2008 2:49 PM

Re: Running on three cylinders??
 
Well after letting it run a bit longer all 4 four are piping hot.... and it really smooths out and sounds more consistant with the firing. I took it down the road (illegally) and it pulls strong... wouldnt it be falling over itself if it were on three?

I plan to pull the plugs with winter and replace, along with filter, oil and coolant.

Can a misfiring cylinder mean bigger problems?

temperedtim929 10-03-2008 2:50 PM

Re: Running on three cylinders??
 
oh and the cylinder that was a bit cool was cylinder 3.

Atomicpunk 10-03-2008 3:07 PM

Re: Running on three cylinders??
 
You probably have a bad fuel pressure regulator. It's a rubber diaphram that is known to crack and cause the bike to run too rich. This condition could cause fowled plugs. when you get the bike up to operating temp it might be cleaning the plug up enough to run smooth. If you remove the vacuum hose from the regulator, no fuel should come out. If you see fuel, you need to replace the fuel pressure regulator. Good luck.

I_FLY_LOW 10-03-2008 4:00 PM

Re: Running on three cylinders??
 
Quote:

Originally Posted by Atomicpunk (Post 725279)
You probably have a bad fuel pressure regulator. It's a rubber diaphram that is known to crack and cause the bike to run too rich. This condition could cause fowled plugs. when you get the bike up to operating temp it might be cleaning the plug up enough to run smooth. If you remove the vacuum hose from the regulator, no fuel should come out. If you see fuel, you need to replace the fuel pressure regulator. Good luck.

+1... hit it on the head...

Mine actually ran on 2 cylinders, right after I replaced the regulator.
It had 2 plugs fouled. At this point, I hadn't touched the bike in 2 months, prior to this, and It was empty, so I nursed it around the corner, for a tank of fresh fuel and some seafoam, just for good measure.
Still on that short ride, it was still hitting on 2, so I limped it back home.
almost made it home, when cyl 3 popped back to life, so I decided to take it for a ride, to see if 4 would kick in. It never did... It turns out it was bad from the very first run right after reassembly. Fuel had fouled it and the #3 plug, but 3 was able to clear out, while 4 was ruined.
Since the regulator and plug replacement, it's never missed a lick. Starts up on the first couple of rotations, every time, and pulls strong...

temperedtim929 10-03-2008 5:51 PM

Re: Running on three cylinders??
 
I'm going crazy knowing I wont have it on the road till Spring. But its nice to know I have plenty of garage time to get to know the bike inside and out, mechanically anyways, Ill take next summer to get to know it on the road.

But looking at the big picture... the bike needs maintenance but I shouldn't be worried about anything catostrophic right?


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