Running rich

R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

Hi all,

Having passed my test yesterday I got home and got straight on my 1991 Teapot. I have just got the bike Mot'd as it has been stood for a year and all seemed ok but I was getting a lot of backfires and it seemed to be running really rich. Now after reading a few things on here I have noticed that the fuel tap was on prime and not on. Now would this cause too much fuel? I havent tried it to put it on just on to see how it runs as yet but just wondered if this would cause it to run a bit odd?

Many thanks,
Si

Wafer_Thin_Ham · Super Spammer Joined: 18 Nov 2005 Karma :

Prime is meant to be used to fill the carbs after you've had them off(it doesn't need a vacuum to push the fuel through), so I guess it could make it run rather funny.

Try it with "on" and see what happens.
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R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

Nice one!

Thanks for your reply, I will give it a go tonight!

Cheers
Si

Vincent · Banned Joined: 16 Oct 2006 Karma :

Before vacuum taps, it was normal to turn your petrol On and Off everytime you use the bike. If you didn't, and the float valves were not working properly, it could start to fill the engine and exhausts with petrol with dire results. As far as I know, the vacuum tap was brought out so you didn't have to do this everytime you got on the bike. I suspect your problem may still occur with the tap in the "On" position and may just be a case of cleaning the carb and checking the float height and the condition of the float needle, esp if the bike's been standing.

R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

Vincent · Banned Joined: 16 Oct 2006 Karma :

R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

Before vacuum taps, it was normal to turn your petrol On and Off everytime you use the bike. If you didn't, and the float valves were not working properly, it could start to fill the engine and exhausts with petrol with dire results. As far as I know, the vacuum tap was brought out so you didn't have to do this everytime you got on the bike. I suspect your problem may still occur with the tap in the "On" position and may just be a case of cleaning the carb and checking the float height and the condition of the float needle, esp if the bike's been standing.

Thanks for your reply!

I will check the fuel tap when I get home but is cleaning the carbs something I can do or could I mess it right up?

Cheers

If you are OK with following instructions, can use a screwdriver and are not hamfisted it's fairly easy. Sometimes heavily varnished, (expression given to thye sludge left by evaporated fuel), carbs will need to be done ultrasonicaly as the tiny airways, (galleries), can be blocked. However, 90% of the time, it's just a case of the pilot jet gettting blocked. i used to soak them in carb cleaner and blow them through with compressed air, now I use micro-drills and find them excellent.

Cool, I might give it a go on the weekend then.

Is it in the haynes manual how to take them apart, I haven't looked yet but if it is then should be easy I guess.

Thanks very much!

Si

Vincent · Banned Joined: 16 Oct 2006 Karma :

Should be in the manual yup, You'll probably only need to take the bowls off the bottom of the carbs to get to the pilot jet. Hardest part is getting the carbs off - can be a bit fiddly but again, it should be in the manual.

R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

Thanks!

Do I need to remove them at all from the engine then or leave them attached?

Think I should just read the manual I guess

Cheers for your help!

Vincent · Banned Joined: 16 Oct 2006 Karma :

It differs on different bikes but most fours you'll have to take them off I'm afraid. it's really fiddly getting the bowls off when the carbs are on the bike anyway. Not sure about your bike but on my CB-1 it's a case of tank off, air filter off. Undo cables, (sometimes you can leave these on which makes it easier), undo jubilee clips where the carbs attatch to the motor and Bob's yer uncle - or in my case, yer half brother Wink

R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

Nice one!

Cheers, i will get cracking on that one night in the week then, I have just bought some carb cleaner too made by wuff? Is that any good?

Cheers

StealthDJ · Nova Slayer Joined: 21 Apr 2008 Karma :

Couple of things, before you go pulling your carbs apart (cos it involves less pain...)

1. What sort of condition is the air filter in? If it's clogged, that'll make the bike run rich.

2. You mention it's been stood for a year. Have you been regularly running in during this time? On the choke, perhaps? If that's the case, your plugs are probably pretty well sooted up, which will have a similar end effect - either clean them or replace them. While you're in there, check the condition of the plug caps and leads.

You'll probably still want to clean out the carbs, but those two jobs are a lot easier to do and might well solve your problem...
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R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

Cheers for that!

I only bought the bike in Feb and it was stood by the previous owner so the first thing I done was dump the oil and change the oil and plugs and air filter but since I have been running the bike on pri like a fool i havent checked the plugs again as I think they might be clogged up again.

Will check the above first and see what happens!

Cheers all,
Si

Ichy · World Chat Champion Joined: 15 Jul 2005 Karma :

What makes you think its running rich?

Backfiring can be caused by loads of things, weak mixture, poor spark, dodgy plugs or leads etc.

I wouldn't strip the carbs just yet. I know you have new plugs but give them a good clean and go for a decent ride.

There is some decent carb cleaner that goes in the petrol. BG44K has some decent feedback although it costs £20 - £25 a bottle. Seems a lot of money but when your trying to get the carbs to sit back in the manifold rubbers and the airbox boots you might just wish you'd tried it first. Wink

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R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

Right then peps,

I have been out on the bike tonight again. I tired putting the fuel tap to on and about 5 mins on the road the bike cut out and wouldn't run unless I put it back on to Prime. The bike is sort of a bit better as far as if I pull the throttle the bike wait's a small time and then it goes and goes all the way but it isn't ticking over very well and i can here backfires most of the time.

I want to get it sorted as it is taking a shine of just passing my test and I really wan to get out there but it's doing my head in. I have called a few places today but nonone can fit me in for a few weeks as they are so busy getting others ready for the summer.

I haven't taken the plugs out too see the state of them as yet, I am going to do that tomorrow.

Anyone got any other suggetions for me to look at?

Many thanks,
Simon

Ichy · World Chat Champion Joined: 15 Jul 2005 Karma :

I guess the first thing to check is that the vacuum pipe is attached correctly. with the fairing off on the left hand side you should be able to see the pipes running to the petrol tap. One will lead to the rear of the carbs, thats the fuel line. The other should attach to the manifold in front of the carburettors. This is the pipe that turns the fuel on and off.

You need to clean your plugs. It sounds as if the float valves may be sticking / not working. This has caused excess fuel to get into the cylinders and foul the plugs.
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R6_Rider · Nitrous Nuisance Joined: 03 Mar 2008 Karma :

Thanks,

I am going to strip it tonight to see whats what with the fuel pipes and plugs.

Cheers,
Si