Fuel consumption drama:

[milkman]

Evening all.
Well, as documented, I had a small stack the other day, and when it happened, I did have petrol flood the left carby to the point it poured out on to the ground while she was laying over.

Anyway, everything seemed to be running, except on my way to work I started sputtering. I had only done 200km, and usually get 265ish before needing reserve.

SO i haven't checked anything yet, but any ideas where to start? My speedo is turning over properly, so I don't think it jammed up at all giving me a false reading. I'm going to do the usual things tomorrow, check the plugs, air filter etc, but carbs I'm not good with.

Any ideas would be most appreciated.

[westfalian_alien]

Hi Milkman,
as You say:

I did have petrol flood the left carby to the point it poured out on to the ground while she was laying over

it strongly looks like a hanging needle valve in the fuel swimmer chamber of Your carburettor.
Remove the clip down at its housing and move the swimmer gently upside down for several times.
This will help at first. Until it will happen again (maybe tomorrow, maybe months later).
In this time, get two new needle valves and replace the old. Normally, the are finished at approx. 60 000 km's.
Drive safely
+++
westfalian alien

[westfalian_alien]

Hi Milkman.
Second idea: there may be dirt in the gas tank of Your beemer. A tiny little grain of sand may spoil the function of that certain needle valve. To check this:
1. Close the fuel cock.
2. Remove the swimmer chamber.
3. Put a can under it.
4. Open the fuel cock at "RESERVE" (gives the maximum of pressure). Catch the flooding gas with that can. Than tip the swimmer with Your finger to close.
5. Repeat the whole procedure for some times. Try several times at different angels of positioning the whole bike (a helper will be needed).
If it works, You're lucky. Only dirt. To avoid this in future,
1.) drain the content of the gas tank,
2.) remove its fuel cock,
3.) clean its filter / remove it if there isn't any or if defective,
4.) clean the gas tank from inside and
5.) attach a small gas filter right into the fuel line. Mind its flooding direction, indicated by a little arrow.
BTW: Avoid smoking during this whole procedure.
Drive safely
+++
westfalian alien

[Chris_in_BC]

Hi milkman,
    Anytime the bike falls over , gas will drain out of the carbs. This is normal as the carb floats can't shut off when the bike is horizontal.  
So first thing, always when you tip over, after hitting the 'kill' switch, is to shut off the gas tap.

So your mileage might be out a bit because you lost some gas. As 'alien' said the tip over might have dislodged some crap in the gas tank which has blocked fuel tap.

Personally, I would monitor it for one more gas tank full before getting too worried about it. Tipping over really can't do anything to the engine. On my G/S it is a regular occurrence.  
Chris

[airhead]

Hi Milkman, as a side note, you say you normally get 260ish k's before hitting reserve, that seems a little low. I'm getting 350 k before reserve, so what bike do you have? I have the Mono with the 24ltr tank.

Bill........................;-)

[Chris_in_BC]

Hi,
 Actually, Bill, got me thinking. Our '81 R65 regularly gets around 350km (220 miles) before going on reserve.

Chris

[milkman]

I have an 85 LS. I thought 260 was a bit low myself. I took it on a 400km jaunt the other day, with a small extended period at 110-120kmh (65ish mph) but I still thought that was a little low. I barely got to 300km with reserve. I wouldn'thave had 100kgs on the bike.

I didn't think I spilt that much fuel to reduce my mileage by 60km (that would have to be 2litres or so spilt).
I do have the idol turned up higher for shorter trips around town, but when it warms up on a 30-40min jaunt I then idol around 2200 rpm, but again, that didn't really come into play onthis occasion.

SO I'll follow Alian's advice and might open the carbs and see what I can see, have a look, do some cleaning. Before I do this, am I asking for trouble.Other bikes have caused considerbale greif when I've played with Carbies, but they weren't as accesible.

Thanks for all your advices so far.

[milkman]

Tank size, I think I have about 22-ish litres or so before reserve?

[Chris_in_BC]

I do have the idol turned up higher for shorter trips around town, but when it warms up on a 30-40min jaunt I then idol around 2200 rpm, but again, that didn't really come into play on this occasion.

It idles around around 2200 rpm when warmed up, but you have it higher around town?
Sure high to me, ours runs around 1200-1500 rpm when cold on choke, then 1000-1200rpm when hot.

Before I do this, am I asking for trouble.Other bikes have caused considerbale greif when I've played with Carbies, but they weren't as accesible.

My only suggestion is to only work on one carb at a time. Lot of parts are sided (i.e. left or right) so you don't want to mix. Also if you get one apart and can't remember how it goes back together you always have one to look at.
Before you start though order a rebuild kit. New o-rings, gaskets and diaphragms, these are maintenance wear items. Don't replace the O-ring on the butterfly valve shaft unless you really have a reason to believe this is causing a problem. Everything else is fairly basic.
Chris
 

[Rob Valdez 79 R65]

I think Chris forgot to add floats (swimmers) to his list of maintenance wear items.  If you don't have a record of when your's were last replaced, it is a good idea to put in new ones to have a benchmark.  Especially if they are particularly yellow.  I replaced mine last spring, along with the float needles, which can wear over time, also.

[milkman]

I have the service history of the last two years, so i'll have a look. Didn't eventhink of that because I've never had a bike with a documented history before!
What I meant with the idle was that, since it rarely gets warmed up properly for most of teh city runabouts, I have the idol turned up a little. It idles at 1200 around town onthis setting, but if I ride for half hour or out of town, I notice that when warmed up this idle gets up to 2000-2200. Then I just turn it down a little, so this isn't a cause of the problem.

I'm going to play with the carbs this weekend. Can't pull it apart yet, or I wont to get work, and that would be a shame.

[Chris_in_BC]

The fact that the RPM is changing after the engine warms up (ie going higher) implies that the idle was set the first time before the engine was really hot.
The bike should be ridden hard for at least 20 minutes, get it really hot, then adjust the idle to 1200 or so.

The other potential for idle rising is that one or both of your exhaust valves are too tight. Before you go for your next ride, check the clearances on a cold engine.

Chris

[milkman]

The exhaust valves are good, and you're right hte idle was set for running when the engine was cold, as most of its running prevented it from rarely warming up properly. Still shouldn't be the main root of my feul problems. I'll be carb cheking this morning so we will see what that holds.....

[Semper Gumby]

<snip>
The other potential for idle rising is that one or both of your exhaust valves are too tight. Before you go for your next ride, check the clearances on a cold engine.

Chris

+1 on checking the exhaust clearance.  That was the FIRST thing I thought of since I may now be having this issue.

[milkman]

This morning, I cleaned the carbs without dissecting them. I pulled off the intake pipes and gave things a little run with carb cleaner. Then I looked at my fuel filter.....the plastic was a creamy yellow, not clear, so I'm guessing it was OLD. When I removed the old filter, the rubber around the ends was quite stiff and cracked in some spots. It appears I may have been getting minor seepage here, but when riding the evaporation would be almost instant.

This would only be a minor cause, none the less I've replaced the rubbers. Starting did seem a little easier tonight, though it may be psychological.

While I'm discussing fuel and induction, how asthmatic is the R65 airbox!! Two thin inlets, through the filter, into two crossed intake pipes inside the box!!!! Tempted to pull it all apart, but for experiments sake I will leave it until I find the root of this problem.......then I'm going to extend some small "ramair" pipe off the air box I think.