Fellow Inmates, help a newbie get his bike running good, pleasssee.

The rundown. Bought my bike on eBay, pretty clean, running, didn't seam to need any major work. Brought it home where it sat for a few months since I went out of town.

Got home, ran it down the street and did fine. Then broke it down for a modest cafe racer build. We installed boxer metals airbox delete, emgo mufflers, euro electric enduralast charging system, and electronic ignition. Now the right cylinder is just dogging. Sputtering, backfiring, can't give it any real throttle without caughing. Stalls out every now and then. Pretty much unridable. We tried new Bosch coils and new plugs and wires to no avail. We Have not messed with carbs yet.

Really don't know the history on the bike other than the seller said it was running fine and his daily driver. Perhaps the air box delete with filters an the new mufflers are playing a role?

Does anyone have any suggestions what to try next?

Thanks all!

sounds like a timing issue to me but I am the last person you wanna take advice from.

But here is my advice . Check the timing. Set the valves again and check the timing.... again via gun.

After thats all set start looking at the fuel . I would not suspect pod filters as the issue.

What year and model BMW motorcycle do you have?

You have an Enduralast Ignition? Have you checked the timing with a timing light?

Did you do ANYTHING to the carbs?

You have to start at the beginning. It may not seem that this is necessary to you but it is. Adjusting the valves is first. Since you have electronic ignition (?) I think, check the timing at idle and at full advance, 3000 rpm is number two.Since you haven't done anything to the carbs (probably don't know a thing about carbs, or do you?) Check the operation of the floats and see that the float needles seem to be sealing, number three.

This may get you started. You are going to need a manual. The Clymers or the Haynes manual will do but you do need a manual.

You had the carbs off is very likely they are not installed completely or otherwise are leaking vacuum. Leaks in the tubes between the carbs and the engine will cause the symptoms you have.

Actually Tete you are doing pretty good. Who was your trainer? (he he he)

Bike is a 1976 r90/6.

Haven't done anything with the carbs at all and nothing with timing.

I have the clymers manual.

And seriously as new as it comes to bikes. Are these all things I can teach myself or are these things best left to the pros.

The tube between the carbs and engine are very old and dry rotting. Where can I buy?

Oh and lastly, yes. Enduralast ignition installed. As well as the charging system.

lol.. yeah seriously. learned alot from you guys. thats for sure.

I know Im not quoting this properly but...

" if you think you have gas/fuel/carbs problems... its probably the timing." - looking back on it now, if you have any problems,, its probably the timing

lol

EDIT- follow my thread in my signature.. if its not covered there then it doesnt exist. from one noob to another. Short of a rebuild I address just about every gremlin and nooby mistake possible. From dieseling to electronic ignition, and onward. might save you some time... it might not because we are on 23 pages...

According to your recounted history with the bike, it was running fine before the alterations.

Logic says something either isn't right about the electronic ignition install, or something got changed while that was going on.

It is totally possible this is a brand new fault that popped up, but normally IT"S THE LAST THING WORKED ON.

I swear, troubleshooting should be tought in grade school! It's one of those life skills needed for just about everything in life. This is one of the simplest of the troubleshooting maxims - and no one's pointed it out yet!

Of course I can understand getting flustered when things go wrong and having little or no understanding of the equipment worked on. That's a problem right there!

Another one of the troubleshooting maxims that goes hand in hand with the work thus far: - MAKE ONLY ONE CHANGE AT A TIME.

It would have made pinpointing the fault that much easier had the bike been test ridden after each change. Now you don't know which of the changes caused it and will need to check them all out.

A few questions; How long is "a few months"? Same old gas in the tank? How long was the ride "down the street"? 15 minutes or less? I'd drop the carb bowl on the offending side and check for any water, debris or a plugged vent tube (that skinny tube in the float bowl) you should be able to see through it. Also let some gas flow through the carb while lifting and dropping the float, to flush out anything that might be making the float needle stick. Then, like the others have said, adjust the valves, set the timing etc before attempting to adjust the carbs.

Bike sat for I'd say 7 weeks. And the ride was 20-30 minutes no real speed.

Once we did most all the swaps/mods we rode it around and the bike did quite well , pulled good got up to speed good. But if you crank the throttle it would stutter then once the bike warmed up (after riding for 20-30 minutes) it would start getting worse. I would have to ease into throttle ever so slightly to keep from sputtering but eventually it would just sputter than stall out.

Once stalled, i Let it sit for a hour (took it to the mall), then rode it home and it did about the same thing maybe slightly worse since it didn't fully cool down.

COIL(S) may have a problem.....they are known the malfunction WHEN THEY GET HEATED UP......then they function ok, until the next warm up.
Others will chime in.
Good Luck!

Yachtie mentioned the right cylinder in his original post. That narrows it down a bit.

What is the fuel level in the rh float bowl when this breakdown occurs?

Anything affecting only one side and I would guess carb issues. There is an easy 10 minute check. Swap the carbs left to right. Sure it's not a permanent solution but if the poor running follows the carb you know where to look.

It your ignition leads are long enough (or you are willing to extend) you can swap them left to right as well.

As said earlier, do one at a time and I think there is a good chance you will find your problem.

Good luck.

you will learn and you will love it

Thanks all! I have a good idea where to start now. And I bought and installed brand new coils and if anything it kind of made it act a bit worse.

So tonight I plan to Swap the carbs and see if that narrows it down

If that doesn't work, going to look into Ignition Timing

If that doesn't work, i'll look into valve timing.


I do not have a BMW Tool kit, off the top of your heads What tools will i need to do any/all of the above tasks?

On a totally different topic, I'd like to do a oil change as well, do i need a BMW specific oil or can i pick up a oil from a local autoparts store?

Pics to see what are we against

What carbs do you have?

Dont touch the oil yet for your own sakes.

I run standard castol 20-50 from the autoparts store in my airheads, since they have a dry clutch and use gear oil in the tranny. Oil is very subjective and people get very passionate about it. What ever oil you end up using, change it often
Read up on the oil filter, it's special, and weird and very german.

There are a zillion tool threads on here. but a good place to check out is Cruztools, they have/had a list of tools in their kits. That is a very soild list of tools to get, just remember that metric sized wrenches for BMW bikes are not the same sizes as used on Japanese bikes (there's a lot of use of the odd sized wrenches on BMW and the Japanese use even sizes)
6-14mm wrenchs 3-12 hex, 1,2,3 sized +screwdrivers, a selection of standard screwdrivers 8-14mm sockets
A spark plug wrench and feeler gauge are good places to start.
The nice thing about cruztools is if you decide to get one of their sets it's all pretty much there.
More expensive then building the kit yourself, but a big time saver.

As for the bike.
I suspect one of two place
A bad coil or other ignition related electrical gremlin.
Intake valve

Double check your electrical connections Make sure they are clean and well connected.
Make sure both carbs are very clean and free from crud as well as the tank, petcocks and fuel lines
Insulators can be had from BMW (the rubber hoses from the airbox to carb and from carb to cylinder head
Check your valve lash adjustment

How did the plugs look when you swapped them out?

You can do this, with the bike cold, take a hair dryer to the coil, get it nice and warm(not smoking hot but more like hot enough that it's just cool enough for you to keep your hand on it, but it feels really hot) then try and start the bike, is working ok?
Or is the bike running funky? if it's running funky that's where your problem is, if it's running fine. Well then the problem is somewhere else.

Normally, carb issues show up regardless of the bike being warm or hot (There's some carb related things that will change from a cold engine to hot engine)
Electrical issues can be more intermitient (which is why they are loathed by so many people) There are a lot of things electrically speaking that can change from a cold to hot engine.