Starting Problems on CBR400 RR

ajt2 · 03-02-2008, 2:21 AM

Hi can anybody help me on this one.

I have a babyblade (on a J plate) which has been laid up in my garage for around 3 months without being started (silly me). Prior to that it was working fine as the last time it was started was when it was up for sale and someone came for a test ride.

I have now gone to start it and, yes you've guessed, it wont start! Now bearing in mind it hasn't been rode since that time here is a check list of things i have done:

1. Charged battery.
2. Drained old fuel from tank and replaced with new fuel.
3. Drained old fuel out from carb float.
4. Checked that plugs are sparking on turn over.
5. Checked that fuel pump is working by disconnecting from fuel rail.

The bike was on paddock stands front and back for the duration so i have no reason to suspect anything major, however i have just run out of ideas as the bike turns over but does not catch at all! i tried with the choke out and in and also with the accelerotor fully open but to no joy. On a couple of occasions it has back fired when trying to turn over which lead me to believe that fuel was being burnt in the exhaust.

PLEASE,PLEASE,PLEASE can anybody help me or shed some light on this

cheers

Fisch · 03-03-2008, 10:27 PM

How are the plugs -wet? I assume they are gapped properly and sparking sufficiently. Intake/Compression/Power/Exhaust

Air supply stopped?
Jets clogged?
Valves OK?

What is the battery votage? Does the regulator work ok?

Just trying to help you think. I don't have the smoking gun.

ajt2 · 03-04-2008, 1:15 PM

Hey Fisch,

Thanks for the reply. I dont know if you know the layout of this particular blade (J-Reg) NC23 but the plugs are

hard to get to in the cylinder head (or is there a simple way to get to them that i dont know?), so i had to get another plug to check the sparking.

I have been trying to start the engine with the air filter off so no airwaves blocked. i have also used a car battery to try and start but to no avail.

I am assuming if the plugs are wet it means their's fuel getting into the chambers for combustion and if their is no spark (or weak spark) that this fuel that is not being burnt off is being deposited in the exhaust can hence why i was getting backfiring earlier on in the process?

I just thought that it might be something simple that happens when you lay a bike up for a long time as it was working fine prior to this

.

I wish you did have that smoking gun, as i would use it on the bike!

Renegade929 · 03-05-2008, 2:32 AM

shoot some ether into the plug holes, i can almost guarantee you it will start..

ajt2 · 03-06-2008, 9:49 AM

Nice one!

Do you have any other ideas before i take you up on that one?

Fisch · 03-06-2008, 11:05 PM

That is the key part here. You need to get the plugs out. Verify their wetness (health). Spray some ether... see if it will grab. If it does... then you know you have a/ lack of fuel/ lack of flow/ timing is off/ valve is bent.

A compression check woud also be a good check. I believe they made an extension for a 10mm wrench that dropped down into the cavern they put the plugs in.

Renegade929 · 03-07-2008, 9:28 PM

Quote:

Originally Posted by ajt2

Nice one!

Do you have any other ideas before i take you up on that one?

yeah ,you could try shooting the ether into the carb intakes...but the plugs would be alot better, and you could clean them first ......if the bikes was running fine before you stored it, it's not something mechanical

ajt2 · 03-08-2008, 2:11 AM

Thank you both Fisch & Renegade929,

I will try this once i get to the plugs. I did try last night to get to them (AGAIN!), but i am finding it difficult due to it's positioning and the obstacles that are in the way (you know how compact these bikes were made) even by moving the Rad forward and taking the HT coils off there appears to be a "rubber gator" that is covering the cylinder head which will not budge for love nor money so making it impossible to get to the plug caps

Enough moaning i am sure you guy's have better things to do. If you know how to overcome this problem (or anyone who has done this) then let me know otherwise i will soldier on and keep you updated on my progress.

davey.g · 03-09-2008, 3:36 PM

Hi there mate i had the same problem when i had a cbr 400 if id left it for a month or so it took forever to start if it got feul and a spark it should go and i had left mine for about 4 month and it realy took a hell of alot of turning over to get it going about 1 and a half hours

Surffrog · 03-10-2008, 2:17 AM

Sorry for the delay on this. I've only just seen the post. I've got and ride a cbr 400rr all the time (See my avatar). Biggest problem I ever get with starting is after washing, usually when lightly spraying water through the radiator to clean the crud out of it. Water gets back on to the top of the head and WILL find its way through the plug covers enough to make it nigh on impossible to start if I don't take it for a run straight after. It's a pain in the arse because, as you've already pointed out, there not a lot of room in there to get to the plugs.
After taking the tank off, you'll have to take off the coils. Just undo to the two mounting bolts and the whole unit will come away. Don't forget to mark which coil goes to which plug. Then pull back the rubber shield and this will give you access to the plugs. The best way to get the plugs out is by using a standard plug socket with a cut-down length of allen key to act as a drive (From memory a 10mm key drive does the trick here. Then just use a 10mm spanner to undo the plug via the allen key. This will give you the room you need to get the plug out.

Also, change the fuel filter (located just under the fuel tank on the bike's left side, under the fuel cut-off switch), it will only take about 1-2 minutes. They get clogged up after time standing around so it's good practice to replace it.

Oh, and just one more thing. I've done this so please don't think I'm insulting your intelligence, but you have checked the fuel cut off/reserve switch haven't you?
Good luck and I hope this helps

Surffrog

Surffrog · 03-10-2008, 2:31 AM

Quote:

Originally Posted by ajt2

Hey Fisch,

Thanks for the reply. I dont know if you know the layout of this particular blade (J-Reg) NC23 but the plugs are

hard to get to in the cylinder head (or is there a simple way to get to them that i dont know?), so i had to get another plug to check the sparking.

I have been trying to start the engine with the air filter off so no airwaves blocked. i have also used a car battery to try and start but to no avail.

I am assuming if the plugs are wet it means their's fuel getting into the chambers for combustion and if their is no spark (or weak spark) that this fuel that is not being burnt off is being deposited in the exhaust can hence why i was getting backfiring earlier on in the process?

I just thought that it might be something simple that happens when you lay a bike up for a long time as it was working fine prior to this

.

I wish you did have that smoking gun, as i would use it on the bike!

One more thing. The 400's regulators love to sh*t themselves if left for a while. The only time in a year and a half that mine backfired was about 30 seconds before the regulator went bang and took out the wiring in my headlights and melting the high-beam fuse! If its died, for gods sake don't replace it with another honda unit. Get a after-market type with cooling fins!

ajt2 · 03-15-2008, 4:07 AM

Hi Surffrog

thanks for the tips will try and let you know how i get on

Surffrog · 04-16-2008, 5:22 AM

Btw, to all of you guys with CBR 400's, we now have our very own section, so lets start posting there. Hope to see you soon.

Red Rider · 04-16-2008, 10:57 AM

Moved thread to the new CBR400RR section.

yellafella · 04-29-2008, 2:41 AM

Hi there, I have a G Plate and I have suffered the same problem in the past

To solve it easily, I remove the tank and then use a tube leading into a bottle with fresh fuel hanging above the bike to allow a gravity feed. It seems to solve the problem.

I dont know why but it seems to be caused by an airlock from the tank to the carb.

Good Luck

LoopyLee · 04-29-2008, 8:14 AM

I wonder how he got on with his bike.....

I had the same problem.. turned out I had an intermittant fault on my fuel pump... so I took it out!!!! I've been running on a gravity fed system for the last 2 weeks.. the tank is connected straight to the carbs with just the inline fuel filter on..
I have ordered a new one and it should be here this week..

Gothy · 05-01-2008, 3:43 AM

im having the same problem on a ninja 636 at college.
I've done everything meanioned here, even cleaned the carbs and jets.
spark plugs ok.
fuel pump fine.
and has a fat healthy spark.
but it just wont run.

dunno what to do, since it sounds like the same problem everything you guys suggest for the cbr400 i will try on the ninja.

LoopyLee · 05-01-2008, 5:30 AM

I'd suggest testing everything more than once.. When I first test my fuel pump it worked just fine... tested it a few weeks later and it didnt work.. then we tried it a few more times, the same day, and it was working intermittantly!!!!
The new fuel pump for my blade has been paid for and is on its way to me now

so I can get it fitted

Surffrog · 05-05-2008, 2:12 AM

Quote:

Originally Posted by Gothy

im having the same problem on a ninja 636 at college.
I've done everything meanioned here, even cleaned the carbs and jets.
spark plugs ok.
fuel pump fine.
and has a fat healthy spark.
but it just wont run.

dunno what to do, since it sounds like the same problem everything you guys suggest for the cbr400 i will try on the ninja.

Gothy, have you checked the floats and the vacuum slides that hold the needles? Sometimes those rubbers can hide a tear in them really well!

Gothy · 05-05-2008, 9:30 AM

to be honest i havn't touched the top of the carbs,
I didnt think it was a problem, they seem to function fine.
Im back in on wednesday, so ill have the carbs off again, and inspect them too.

LoopyLee · 05-06-2008, 1:36 PM

Fuel pump and new fuel relay now fitted (well.. I did it on Sunday) and now she runs just fine

soupnazi · 05-14-2008, 10:06 PM

Some good advice in here. I recently went through a similar episode with my NC23 project. Having not been started for the best part of 24 months it took some convincing.

I suspect you probably flooded the engine whilst attempting to start it. Keep your battery charged and keep trying it with only a little bit of choke. You'll get more backfires and in a jiffy it'll start turning over. Once it's done this it'll start easier in each subsequent attempt.