Starting problem..???

[Ctino]

Hi, i started my cafe build in january, im having a few problems with starting the bike. First off i posted a thread with my ultrasonic cleaner back in january, where i foolishly sank the carbs as a whole in them. since then i learned how to strip, clean and rebuild my carbs properly. Having that school boy error off my chest i feel much better..!!!

I think im having a fueling problem with my carbs, the battery takes charge and stands at 12.5 v there is also spark. The diaphram in the carb seems to be working as i blow air in the air hole in the top of the carb it moves up. The reason i think its to do with my fueling is because when i spray carb cleaner in the left hand carb while starting shes fires up then quickly dies. if i continue to spray carb cleaner while accelerating she will run ontill the can runs out. ive checked over the carbs twice now and everything is clear and unblocked even the choke jet in the float bowl. I put new diaphrams, o rings, pins and gaskets when rebuilding the carbs. Petrol flows nicely into the float bowls.
The fuel air mixture is to be adjusted once the motor is running ??
The bike was a hard starter when i got her i had to bump start.
Any help much appreciated.....

[Bob_Roller]

First place I'll go, is the 'choke' assembly is side specific, there is a right and left assembly .

Sounds like both of the idle jets are clogged as well .

[Ctino]

Thanks for your reply... the jets are clear i tanked them in the ultasonic cleaner then sprayed with carb cleaner and replaced the o-ring...

I also rebuilt the carbs one at a time as not to mix parts up. The choke assemblies may have been  mixed up previously how can u tell???

[nhmaf]

I *see* your problem - you are missing spark plug leads! ;-)

So, when you take the bowl off the left hand carb and look into the small well in the inside front corner, there is a decent quantity of fuel in that little column?     When you disassembled the carbs to clean them and re-assembled, you only did (1) at a time or kept them in separate tubs so that you didn't intermix parts from one ot the other?  (the "choke" discs parts are left/right handed and the proper one must go on the corresponding carb, and in the proper orientation, or else the enricher will NOT work properly).   From your description it does sound like the enricher is not working right, either through blockage or other fuel-feed issue.

[Barry]

The choke assemblies may have beenmixed up previously how can u tell???  

The only way to be certain is to look at and understand how the enricher disc aligns with the orifices in the carb body. The pear shaped hole flows air and should be at the top of the disc with the narrow end pointing towards the cylinder head.  The small holes at the bottom flow fuel. Take a look here in our FAQ section

http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1291933920

[donbmw]

I think you need to go back and re clean your carb. Since you are able to keep it running when you spray the carb tels me a jet is stopped up. I have seen this too many times by first hand experience and others cleaning carbs.

Don

[montmil]

[smiley=tekst-toppie.gif]  What Don sez.

Totally strip every component from the carb body. Your choice on the butterfly and those tiny screws and o-rings...

Strip a single copper wire from something like 16-18 gauge wire and probe each and every opening you can find. Don't overlook the small holes in the venturi each side of the needle.

You likely have a clog in the idle system...

have you yet confirmed correct enrichener circuit component installs?

[Luca]

The fuel air mixture is to be adjusted once the motor is running ??

yes, with it good and hot when you sync the carbs... but the engine will not run if your mixture screw is turned all the way in.  There is a base setting for the number of turns to back out the screws.  Cant recall off hand, but you can try backing out 1/2 turn on each carb at a time and trying to start it.

[donbmw]

Back to my post on cleaning carbs again. I have had my 82 R65 do the same thing to me.  Turning the mixture screws and was not seeing any change in running. Went back and cleaned every thing again fixed the problem.

Don

[Ctino]

Thanks for the advice, Ive re-cleaned my carbs, checked my choke discs and everything is correct. With a little adjusting on the butterfly opening and mixture screw, the bike now starts with the choke fully on then after 2 or 3 seconds dies.

What would be the next step to getting the bike running?

[Luca]

Well, while you are at it, you should check your valve lash if you haven't done so.  Tight valves will make a bike hard to start because if they get tight enough you lose compression.  Once you check the lash on a cold (hasn't been run since the day before) engine, do a compression test and make sure you have good compression.

When you dunked your carbs as a whole assembly, what did you dunk them in?  A strong solvent could have damaged the o-rings on your jets.  When you say you "rebuilt" the carbs, does that mean you replaced all the rubber, or just took them apart, cleaned, and reassembled?

For good measure, make sure you have a good, strong, blue spark.

Also, if you don't have an in-line fuel filter, install one.  It's possible that you are letting bits of rust, crud, and old tank liner into your carbs after you clean them.

[Luca]

And, are the vacuum ports on the bottoms of your carburetors plugged, capped, or otherwise sealed to the atmosphere?

[Ctino]

Will have to check the valves also the clearances, haven't done that yet. I presumed since the bike was running before hand they should be ok??

Dunking the carbs as a whole was a mistake i re dunked them stripped. Replaced diaphragms, o-rings, float retaining pins, bowl gasket and choke gasket. I used a tickpour solvent r33 http://www.ultrasoniccleaner.co.uk/tickopur-cleaner-agent/tickopur-r33-2-litre.html .

Vacuum ports are plugged and inline filters are installed.

[Luca]

If the bike came to you hard-starting, don't presume anything.

Airhead valves tend to tighten up quickly, and overly tight valves will make a bike hard to start. They should be checked every 5 or 6k miles.  Supposedly some of the R65's had a bad batch of valves that wear out pretty quickly and thus require frequent adjustment.  You should get in the habit of checking valve lash fairly frequently at first to see how the valves on your bike are behaving.  If they continually tighten up quickly, they should be replaced.  A dropped valve will cause serious damage (There is another thread going on in the technical forum about cylinder and piston replacement caused by a valve/piston collision).

We like to say air/fuel/spark, but what we really need is compressed air, atomized fuel, and properly timed spark (in conjunction with properly timed intake and exhaust flow)

So, go back to all the basics.  Strong spark, good timing, a clean air filter, good compression, etc.

[Ctino]

cheers, I am gonna have a look at the valves on sat see whats going on.