Honda Motorcycles - FireBlades.org banner

1 - 14 of 14 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter #1
Hi all,

Thanks for the help last time, when I had a dud battery but now I have a new issue that I need some advice on please! :crying:

I have a 1996 CBR900RR, bit of a bitsa but i love her! I ride for 20-25 miles no problm, then it feels like it is going on to 2 cyclinders, stalls and wont start on the button UNLESS I give her a handfull of choke, she then coughs and splutters as if clearing her throat, then bangs back into life and runs fine for the next 100-120 miles, fast no problem riding.

This has happened three times now when i have been out, and the pattern described happens each time without fail. I have a track day at Brands Hatch (UK) on the 7th September and would be so bloody embarrased if I broke down!! HELP!!!

Steve
 

·
Premium Member
Joined
·
32,034 Posts
Hi all,

Thanks for the help last time, when I had a dud battery but now I have a new issue that I need some advice on please! :crying:

I have a 1996 CBR900RR, bit of a bitsa but i love her! I ride for 20-25 miles no problm, then it feels like it is going on to 2 cyclinders, stalls and wont start on the button UNLESS I give her a handfull of choke, she then coughs and splutters as if clearing her throat, then bangs back into life and runs fine for the next 100-120 miles, fast no problem riding.

This has happened three times now when i have been out, and the pattern described happens each time without fail. I have a track day at Brands Hatch (UK) on the 7th September and would be so bloody embarrased if I broke down!! HELP!!!

Steve

Do you have a vacuum-operated fuel tap?
 

·
Registered
Joined
·
28 Posts
Discussion Starter #3
Hi bladeracer,

Not sure how to check, there are in total 4 tubes running off the tank, 2 large, 2 small. One is a breather, two into the fuel pump and one into the carbs I believe.

What am I looking for if I do? Blocked pipe perhaps?
 

·
Premium Member
Joined
·
32,034 Posts
Hi bladeracer,

Not sure how to check, there are in total 4 tubes running off the tank, 2 large, 2 small. One is a breather, two into the fuel pump and one into the carbs I believe.

What am I looking for if I do? Blocked pipe perhaps?

There would be a vacuum line from one of the intake ports to the fuel tap.
If the diaphram in the vacuum chamber fails, the engine will suck neat fuel directly from the tank into the engine.
If you pull the fuel or vacuum line off the tap and fuel flows out then the diaphram is shot.
If this is the problem you will probably want to change the oil and filter and perhaps the spark plugs after you repair the fuel tap.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #5
Thanks! Will give it a go tonight. Why would I want to do an oil and filter change and plugs at the same time? Are these affected? Thanks again, will keep you posted!! Steve
 

·
Premium Member
Joined
·
32,034 Posts
Thanks! Will give it a go tonight. Why would I want to do an oil and filter change and plugs at the same time? Are these affected? Thanks again, will keep you posted!! Steve


The fuel drains past the rings into the crankcase and pollutes the oil.
Unburned fuel also fouls the spark plugs.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #7
Hi there, took the fuel vacuum line off and nothing came out, so diaphram seems good. Put new Iridium plugs in and did Oil change.

Went to start it this morning and again after 5mins idling in garage, the bike seemed to start to suffer from "strangulation" fuel wise. Almost as if its running on two / three cylinders. (All four pipes when felt are HOT!)

After five minutes or so, and with some chocke, she fires up but rough still, then clears and fires perfectily as if no problem. I have just been out after an hour and again, she fires up perfect. WTF??

Getting close to losing my rag now and canning in the track day but I have been waiting so long! I just dont want to give in, help please appreciated!!

Steve:evilaugh:
 

·
Registered
Joined
·
342 Posts
where are you getting fuel?
overly hydrated gasoline can cause these symptoms.. ive had water in my fuel many times from old run down gas stations and the symptoms are exact.

since water is more dense and has a much higher surface tension, it tends to not flow through things as easily as gasoline would and since oil and water dont mix, it acts as a temporary clog. ifit gets to the carburetor, it usually staysat the bottomof the floatbowl, and litledroplets can comeup and get in the jets.

the fix is simple, drain your float bowls and put a gas dryer in your tank.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #9
I have go tmy fuel from Shell and BP, forecourt stations, seems odd. But I will try anything! Will empty the fuel bowls and see what happens.....perhaps I can see the water if it is present? :crying:
 

·
Registered
Joined
·
28 Posts
Discussion Starter #10
Update....New Plugs (Iridium) / drained carb bowls, found to be sparkling and clean, no odd deposits..... All fuel hoses checked and blown through, no visible blockages......just taken for a test ride and all seems ok, fingers crossed until the next time.

I think she needs a complete carb rebuild. Anybody know of any good suggestions here in the UK for carb rebuild and servicing?

Thanks again for all help, will post pics of track day on another post, a more positive one!!
 

·
Registered
Joined
·
342 Posts
Hi bladeracer,

Not sure how to check, there are in total 4 tubes running off the tank, 2 large, 2 small. One is a breather, two into the fuel pump and one into the carbs I believe.

What am I looking for if I do? Blocked pipe perhaps?
... for a 1996 CBR900rr the fuel is gravity fed into the carbs.. they don't have fuel pumps.. at least not in the US

I wouldhave to think about it for a bit to postulate what effect it would have. running a fuel pump in a normally gravity fed system that is.
 

·
Premium Member
Joined
·
32,034 Posts
... for a 1996 CBR900rr the fuel is gravity fed into the carbs.. they don't have fuel pumps.. at least not in the US

I wouldhave to think about it for a bit to postulate what effect it would have. running a fuel pump in a normally gravity fed system that is.

It doesn't cause any problems - the pump only runs a few psi pressure, similar to gravity feed.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #14
Ok, this is now officially really hacking me off. I did a complete 180 miles (two tanks) and ragging the bollox off the balde with no hesitation whatsoever.

Left her for a week, took her out tonight and shite bullshit thing stalled again. Wait two / three minutes, pull the choke on and presto she starts up again for the next 100 miles!!!

Seems to have a hell of a flat spot that has started now as well, if I pull at say around 120 mark, then back off and reaccelarate, a real hesitant fuel issue....

Perhaps time to take off the carbs in the winter and sort it out once and for all. Drain tank perhaps, but then again, why does it do it so intermittently!!!!! GRRRRRR:crying::crying::thumbd:

Answers on a postcard before I set alight to the bitch!!!! HELP!!!
 
1 - 14 of 14 Posts
Top