Todays update. I remembered that I had an exhaust gas analyzer buried deep at the back of the garage. Hadn't used it in years. Anyway I started her up and was able to fairly quickly make her run without choke. The analyzer showed very very high,rich mixture on both exhausts !

Then I thought . . When I take off the carbs there is always a little bit of gas/petrol sitting just inside the manifold rubbers. So I'm guessing that the float valve's are not sealing correctly and flooding the carb.

What do you think ?.

Now I thought I'd read somewhere that carb cleaner isn't good for rubber parts. Can anyone confirm that ? And I soaked the valves in it and they have rubber tips .

So first thing tommrow I'm off to buy some more. ( if they have them ) ( and their not too expensive) .

Any comments would be welcome

 

As far as carb cleaners go... yes they can damage rubber pretty bad.

However, like I heard another guy say:
"Spray cleaners are like wives/girlfriends. You never know how bad they are until you get really involved."


On the float valve/seat issue, I would think that a good indicator would be to check your oil. If it smells like gas really bad, it may be from fuel leaking from the carbs down the cylinder wall and contaminating your oil.
Running super rich can do this too, I've been told.
Maybe check your air filter while you're at it to see if it's plugged bad and making you run rich. I've been going through this very issue....

 

Went to the dealers yesterday. £34 each and they would have to order from Japan .
So it will have to be pattern parts for me I'm afraid at £7. Got the carbs again and as I did I checked each bowl full of drained fuel. And there is still bits of crud getting through. So off with the rubber feed hoses today to give them a good clean ( but not with carb cleaner ). Its difficult to judge if the valve tips are worn but I can see a ring so far up around the rubber coned tip where it meets the seat. Is that evidence of wear ?

Fantastic weather here . And I cant ride .

Cheers
Mikey

 

Took out one float valve and put some tubing on the thread of the seat. Placed the valve inside and rested it all upright on the bench so that the tube and seat were pressing down with gravity onto the rubber valve. Next filled the tube up with ISOPROPANOL which is a very thin cleaning based agent to simulate petrol. After a while checked the level to see if any had leaked past the seat and rubber tip of the vlave. All ok. no leak. Now I need to test the others but I think the float valves are ok based on this test. I mean the valve was held shut with a minimum of pressure and it didn't leak.

I checked the inlet pipes and found rusty dusty deposits and my latest theory is that this crud is helping the valves to not shut properly. So I am going to wash out those pipes and look at the pump.

 

Little bits of crud can be the reason for all this. You know how small those little pilot jet orifices are.... all it takes is a couple little bits of junk to clog them.
Chunks of crud in the valves will stick them open, too... just like you said.
If I were you, I would make sure you have an inline fuel filter between your tank and carbs so you don't just keep pumping gunk into your carbs.
I'd also check the inside of your tank with a flashlight to look for corrosion.

 

Well, I've recleaned the carb jets and the fuel supply pipes and replaced the fuel filter ( and did that need doing ) . I made sure I primed the float bowls with clean fuel before starting. But on start up not much changed . I ran without the air filter expecting to find a lean mixture after it had warmed up , but it was still rich and ran lumpy and ..just not right. So either my analyzer is wrong ( which I don't think so as seems ok when I check the cars exhaust ) or its not burning all the mixture . Now, when I opened the throttle to about 2000rpm and hold it there, there is poping out of the silencer but just a little.


I think I've ' exhausted ' (!) the fuel side of the investigation apart from carb balancing.
But to recap for 50miles she ran fine and then something happened.

So I'm also thinking valve clearances and a compression test .

And finally at tick over I'm getting a knocking. Using the screwdriver to the ear trick , its loudest on the alternator casing.

Any thoughts , questions would be welcome.
Cheers
Mikey

 

Don't read too much into occasional popping sounds , mine does it a bit if ya run it
up to 2.5 k rpm too ..mine don't do it under load though .......... just take it out a ride
the chit out of it for a few hundred miles... these bikes do run a little rich anyway.
As for the alternator chain lash at idle .....make sure your idle is set around 1250 or
so I would not see that as a big issue either ...... sometimes we over-listen for sounds
and stuff and get hung up on it .

Just my 2 cents man...... take her out and run her good

That motor will sing for ya from 8k rpm on up

 

I didn't read where you flushed the fuel pump. Either you didn't mention it or I misread, but that needs to be done. When I raced my 1000F I can't count how many times I've been inside that motor. These bikes have crappy camchain tensioners (hydraulic for some reason) so that may be the reason for the noise. Does it go away around 2K rpms? The alternator chain has a normal type tensioner on it (alot of people don't know they even have a chain, much less their own tensioner). Doubtful it's going bad, never heard of it happening. If they made more aftermarket go-fast parts for it, I would've kept it (no aftermarket cams available). Loved the bike, just had to replace it with something faster and more parts available.

 

Also I'd go through the carbs again. Sounds like you haven't gotten everything. With pilot jets out, did you spray cleaner in the hole and check for spray coming out tiny hole in front of butterflies? Those passages are very small and easy to clog with debris. And when you remove fuel screws (the ones on side of carb on engine side), spray cleaner and make sure it comes out that same hole (holding your finger over the pilot jet). Alot of people ignore cleaning the passages. This might help...

http://www.rrzone.com/forums/showthr...0462#post70462

 

Thanks for the replies guys. Great advice

I may be listening too deep Sprock if you know what I mean.

Well cbr900racer77 , you're right I didn't flush out the fuel pump. I'll try to do that tonight. I assume that you apply 12v to make it pump and run some clean fuel through ( bit nervous using carb cleaner with its destroying rubber quality ) .

And, you're right again . I didn't squirt carb cleaner up the passages you describe, which is great advice. So thats something else to try later. I know of the tiny hole in front of butterflies but didn't know/see the " fuel screws (the ones on side of carb on engine side) " were.

There's still hope. Thanks for the advice . I'll recheck the noise to see if it goes above 2K and maybe take her for a spin as I would of thought, if there was something major wrong, it would soon show it.
If I get a chance I'll post up a new video.

Cheers
Mikey