issues with starting the bike

[GrimReaper]

 hi all,3 days in a row i have a problem with starting the bike,It fires up,2 seconds and dies.There is plenty of fuel,healthy spark,It looks like it gets easily flooded.if i wait 10-15 min after first attempt it starts easy.
 A week ago the engine start to sound a bit different,A bit louder,and there is a little whining sound(barely noticeable)You can hear it if idling
  Yesterday on idles the bike runs(not rough)but kinda. strange and the same time in high RPM runs great.
 There is no strange strange sounds except this tiny whining sound on idle.
  Any ideas why is so hard to start,
P.S. I even try pushing it downhill and again nothing :-/

[Barry]

Are you using any "choke".  Mine will do that when I start it without choke when I should have used some.  Although if you think it's flooding maybe you are using full choke and not backing it off quickly enough.

Truth is mine starts on the button in cold weather using full choke and also on the button in warm weather using no choke. Temperatures in between can sometimes be more problematic. A technique that works for me in these circumstances is full choke and press the starter briefly to turn the engine over a few revolutions.  Turn the choke fully off and It will then start easily and stay running.

[GrimReaper]

Barry i tried full choke,half choke,no choke no difference,I said there is plenty of fuel but this is at the petcock.After a detailed look it's  look like there is no fuel at the cylinders.Is it possible the idle jet to be the problem,since i have a good high RPM and a bit rough(a bit)low?

[montmil]

Drop the float bowls and check for debris in the float needle valve area. Possible water, too, but that's not likely an issue here. Could be your fuel flow is constant due to the needle being held open by a tiny bit of trash; ie, fuel hose. Check the simple and free stuff first!   Monte

[GrimReaper]

Thanks Monte it looks more like a dirty carb

[GrimReaper]

 Took the 2 carbs out and cleaned them.Put them back and the bike started like before with no problems.
 Since i disconnected the choke and throttle cables,should i synchronize the carbs?

[montmil]

Sinful, If you've removed the throttle and chokes cables, I would suggest a cable synchronization only. Idle air screws at spec for your '87; perhaps half-turn out. You'll need a $4.00 manometer to balance cables at idle and at approx 2500 revs for a smooth ride. Set choke cables to have enrichener fully off with lever closed.

Check the 'bum's site for how-to.

Monte

[GrimReaper]

Monte do you have part number for that manometer or where can i buy it from?

[Bob_Roller]

You can construct one at home, using common materials, a 3-4 foot length of wood, and about 20 feet of small diameter clear tubing from a home improvement store, and some colored oil, like fork oil for contrast .

Secure the tubing to the wood, loop it at the bottom of the wood, secure it at a few places up to the top, put some oil into the tubing, and get it to the vertical tubing mounted to the wood, than place one end of the tubing at one carb, the other end to the other carb, then start the engine , and see what kind of balance/imbalance you have .

Try doing a search for 'oil manometer', I know someone has posted pictures of one that they have made up, once you see a picture, it becomes a lot clearer, on how to construct one .

[GrimReaper]

Found it Bob.Very simple.Soni have to run the bike at 1300-1500 rpm and to look at the manometer right?

[Bob_Roller]

You start out at idle speed, with the engine up to operating temperature .

A fan or two to blow air over cylinders during the synchronization, is a good idea .

Make sure the throttle and 'choke' cables are adjusted so they are slack, and not holding anything open .

Make your required adjustments .

Then adjust the cables back to where you want them .

Open the throttle to about 3500 rpm, and see what kind of balance you have, if it's off, adjust the throttle cables at the carbs to bring them into balance .

[montmil]

Well, some of us have to work occasionally. But like Bob says on the manometer. A yard stick, several feet of vinyl tubing and your choice of fluid; ATF, fork oil... you're in business.

[MightyManfred]

In my next post, I will provide a link for more info on the cheap manometer.

[MightyManfred]

Here's more information on that cheap manometer:

http://brogdensmuse.menofhonorministry.org/Bikes/Carb_Synchronizer.htm

[montmil]

An important point regarding the original author of the cheap-o $1.55 -prices are now up to around five bucks unless you're a well stocked scrounger- manometer and the later "improvements". This helpful tool was originally built to balance carbs on 2-cycle Rotax engines fitted to ultralight aircraft; flying lawn chairs as I refer to them.

The author's notes about idle rpm, "...mine idles very nice around 500-600..." does not apply to airhead Beemers. Depending on the year of your BMW and the OEM installed flywheel (heavy vs later lightweight flywheel) idle rpm for the light flywheel should be just a tick over 1000 rpm. Any lower and the rather primitive timing chain oiler will not do its job adequately. Replacing a timing chain is a PITA way to spend your money and weekend.

http://brogdensmuse.menofhonorministry.org/Bikes/Carb_Synchronizer.htm

Monte