Wondering why R65LS starts so well on a trip.

[suecanada]

After reading the corroded fuse terminal thread I am wondering why my R65LS (LRB) starts so quickly and easily every morning while I am on a long trip. Is it simply that the battery is at full charge or are their other good things that happen when running everyday? Like cleaned out carb jets and fresh gas all the time?? Probably dumb question but does sitting even for 4 days affect LRB's ignition? I always get to thinking he's in perfect nick when I'm on the road and I can change my mind when he's stored for a week..... Just takes longer to start after a week and idling without help from me takes awhile.

[Barry]

I think one issue with vented carb bowls, is that the more volatile fractions evaporate off in storage leaving the fuel less than ideal for starting.

I ran a kick start only 400cc single for 14 years and it was the same. If used daily it would fire first kick every time but with a week or more stood it was 2, 3 or more. Kick starting certainly sensitizes you to minor variations in ease of starting.

If my airhead is stood for 2 weeks or more, which is rare these days, before starting I'll whip the bowls off and pour the fuel into the tank. They then get refilled with the fresher fuel from the tank.   

[BPT]

Not sure of your ethanol and such in the great white north but what Barry says is true here in the US.
When I bought mine, that was one of the first things the guy showed me. He said it takes no time at all for the fuel to begin to change and that these carbs were sensitive to that.  He told me that if I was having trouble starting and it had been sitting, dump what was in the bowls and try again.  So far, that's worked for me. He blamed it all on our new fangled gas......

[skippyc]

I agree. But i had the same trouble in the 70s with my R75/5 on super fuel, but the idle times were longer.

[clonmore1]

Great tip Barry!

[Bob_Roller]

I've noticed this behavior as well with my carbureted bikes and cars .

I've  had a few low use vehicles for about 37 years now and always wondered if the fuel was the issue .

But fuel injected vehicles, no issue what so ever .

I've had my '01 BMW Z3 sit for 6 months on a battery tender and started up instantly .

Same with the oilhead, the longest it's been unriden, was 8 weeks and fired off like it does in daily use, so a closed fuel system seems to prevent volatile parts of the fuel from escaping .

[Justin B.]

I've noticed that on ALL carbureted engines over the years so it has to have something to do with "stuff" evaporating from the bowls.  My '57 Chevy gets little use and takes a couple "pumps" to get it fired.  If it sits weeks hem a little cranking might be required to get the fuel pump to fill up the ol' Holley.

I think people have gotten so used to FI over the years that they don't remember how it was back in the "stone ages."

[Barry]

The other thing to bear in mind is the difference between summer and winter fuel blends with winter fuel have more volatile components (usually butane) for easier starting. If a bike is put in storage with summer fuel and an attempt to start it is made in winter then you are already up against it to some extent even before any degradation in the fuel is taken into account.

The dates when fuel blends are changed is usually mandated by governments. In the UK the vapour pressure specifications change on the following dates:

Summer (1 June – 31 August)

Intermediate (1 September – 15 October)

Winter (16 October – 15 April)

Intermediate (16 April – 31 May)

[misterpepper]

It seems to me that there ought to be a different explanation. Fuel in the bowls going bad over 4 days through those tiny vent holes, yet I can leave the same fuel in my lawnmower all winter and it starts in one pull? Plus, if it's the fuel and the bike is otherwise fine shouldn't we all be having the same problem?

OP, are you parking the bike on the side stand? Any smoking out of either cylinder on startup after the bike sits for a couple days? I'm wondering if any oil is getting past the rings and fouling the plugs. Do you live in a particularly humid climate that might be playing havoc on your coils or plug wires? Do you ever leak fuel out your carbs if you let the bike sit too long? Maybe your float needles are slowly leaking such that the fuel level rise over 1 day is minimal, but over several days causes the fuel level to rise high enough to affect startup?

[skippyc]

Its different for different fuel containers. the plastic tanks on my wipper nipper and chainsaw go bad in a fortnight, my lawnmower has a steel tank and it lasts a long time. Tipping the fuel out of the bowls of my R75/5 and letting it fill from the tank and it would start straight away, so the fuel in the tank remained good while the fuel in the bowls went off.

[clonmore1]

Some of you have mentioned the fuel 'container', the tank is steel (with a lining) and the carb bowl is alu.

Both the tank and the float bowls are vented? So, the major difference is the storage container material?

Could there be a chemical reaction taking place with the fuel and the storage material?

[misterpepper]

If dumping the bowls works it could still be fuel level related. I just think if the fuel was going bad we'd all have problems starting after a few days. My money is on a slow float valve leak, unless the OP always parks with the petcock off, then it's on old carbon type plug wires picking up moisture.

[Barry]

I don't believe the fuel is going bad in a few days but there is no question that after several weeks some of it has evaporated off and by definition it will be the most volatile fractions which aid cold weather starting.

If you have the bike parked up for a few weeks try removing the bowls before turning the fuel tap on and you'll see that the level is lower.

Regarding fuel level I have another theory which seems to be bourne out in practice.   The fuel level that the floats produce while the bike is in motion bouncing down the road must be a touch higher than the level produced by just turning the tap on with the bike static in the garage.

Part of my starting technique is to take the bike off the stand and give the forks a couple of vigorous bounces which I believe gets the floats moving and raises the fuel level a touch in the manner of tickling carbs of old. I can certainly tell the difference in the way it starts in terms of the amount of additional enrichment required.   

[Billmc]

I'll vouch for the low bowl syndrome.
Saturday while it was in the high 40's here in South Texas (unusual because today its going to be 78), I wanted to run the bike for a while because it had been sitting for a few weeks after a 500 mile RT. Did not open the petcocks or give it choke or throttle. Turned on the key and hit the starter for about 15 seconds to circulate the oil a little.
I then opened the petcocks, gave it full choke and cranked on and off for a good 90 sec. before it sort of caught. Still would not hold an idle and died often. I then turned it off, closed the pets, pulled the bowls and sure enough, they were roughly 1/4 of their running capacity. Dumped that into a coffee can, refilled them with fresh gas and tried the starter again. This time it caught easily, held an idle and eventually I was able to take it off choke.
I still believe it does not like the cold but the combination of weak gas, and low bowls contributed to the no start as much as the temperature.

[clonmore1]

Okay, so another question,

It has been mentioned emptying the float bowls after the bike has stood for a period of time, some say back into the tank, others (I assume) dispose of it.

The float bowls are fed from the tank via gravity, if you think the bike is going to stand for a while, could you run the bike with the petcock off and run the carbs dry? Then, when ready to ride again, go through the start up procedure, open the petcock and the bowls will refill as normal?