The New And Improved Unofficial R65 Forum V2

Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: marcmiller001 on April 24, 2017, 08:54:49 AM

Title: Right Cylinder Backfire - Engine Tuning
Post by: marcmiller001 on April 24, 2017, 08:54:49 AM
Hi gang,

Since I am still waiting on a tank and seat - and the valves have been adjusted, I wanted to start up my bike today to warm it up, check my Gen light wiring and gauges (installed Acewells) and check my oil temp sensor I installed.

I also selfishly just wanted to hear it run. It fired up but I noticed that the right cylinder didn't fire. I assume this is from the fuel flow and the right side cylinder not getting the fuel it needed right away so I primed it more and started to get strong exhaust pulse in the right cylinder bank.

I let it run a bit, but I noticed a misfire (exhaust pop) out the right exhaust as it purred at 1500 rpms.... and I also notice the right cylinder and valve cover noticeably cooler than the left. I let it run and the exhaust pop never went away and I am wondering if this could be a timing or fuel flow issue and how would the best course to diagnose it?

Thanks in advance!
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: wilcom on April 24, 2017, 09:25:11 AM
Quote
best course to diagnose it?

You've just had the carbs all apart as I remember....I'd start by fiddling with the mixture adjustment on the faulty side.

Shade tree Joe............
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: marcmiller001 on April 24, 2017, 03:08:40 PM
Quote
Quote
best course to diagnose it?

You've just had the carbs all apart as I remember....I'd start by fiddling with the mixture adjustment on the faulty side.

Shade tree Joe............

So you don't think it could be timing? I pulled the plugs and one looked good, the other was black and wet (right cylinder). I swapped plugs just so I can read them better when I tried tuning again.
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: Bob_Roller on April 24, 2017, 03:26:01 PM
Have you replaced the fuel lines ??

I had a right cylinder issue, that I finally troubleshot, to a kinked fuel line when it came out of the airbox .

I have installed a .25 inch steel line through the airbox and bent at 90 degrees as it comes out of the airbox, then place the fuel lines on the steel tube .

I also had issues with idle jets being clogged the metered orifice at the end is almost impossible to tell if it is clear or not .
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: marcmiller001 on April 24, 2017, 04:41:38 PM
Quote
Have you replaced the fuel lines ??

I had a right cylinder issue, that I finally troubleshot, to a kinked fuel line when it came out of the airbox .

I have installed a .25 inch steel line through the airbox and bent at 90 degrees as it comes out of the airbox, then place the fuel lines on the steel tube .

I also had issues with idle jets being clogged the metered orifice at the end is almost impossible to tell if it is clear or not .

Yes - all new fuel lines... but zero kinks and both carbs completely rebuilt. I assume it is either a carb tuning issue (both carbs are set back to factory spec) or a timing issue (I have not set any timing, only done valve clearance/adjustment). I replaced spark plugs and wires over winter as well, and I checked both plugs have spark, but obviously the right cylinder is running much cooler and misfiring.
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: Justin B. on April 25, 2017, 06:42:55 PM
Have you swapped in a new plug for the fouled one?
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: marcmiller001 on April 25, 2017, 07:07:15 PM
Quote
Have you swapped in a new plug for the fouled one?

I swapped the left side plug with right one but haven't tried firing it up. Think it could be fouled plug?
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: Justin B. on April 25, 2017, 07:13:50 PM
If it's wet and black that's a good recipe for getting it to not fire correctly!
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: marcmiller001 on April 27, 2017, 03:13:26 PM
Quote
If it's wet and black that's a good recipe for getting it to not fire correctly!

OK - swapped plugs - clean plug to the right cylinder, dirty plug to left - fired right up - but same issue of right side cylinder having a misfire and running much much cooler than the left side.

Here are some facts:
[list bull-blackball]
[list bull-blackball]
The right side carb, the mixture has no effect on the idle whatsoever.
[/list]

[list bull-blackball][list bull-blackball][list bull-blackball]Anyone have some thoughts??
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: Justin B. on April 27, 2017, 06:44:53 PM
Well, it's seems that side has very weak spark or is flooding that cylinder.  When you pull the plugs, attach the plug wires, ground the plugs and crank the engine do both plugs have nice fat blue sparks? 

I'm leaning toward carb since adjusting the mixture screw has no affect on idle speed.  Turned all the way in idle should drop drastically and when turned out should increase until idle starts dropping again.
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: Bob_Roller on April 27, 2017, 08:37:02 PM
What ignition coil do you have, a black nd ray, red and black ??
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: marcmiller001 on April 28, 2017, 08:36:01 AM
Quote
Well, it's seems that side has very weak spark or is flooding that cylinder.  When you pull the plugs, attach the plug wires, ground the plugs and crank the engine do both plugs have nice fat blue sparks? 

I'm leaning toward carb since adjusting the mixture screw has no affect on idle speed.  Turned all the way in idle should drop drastically and when turned out should increase until idle starts dropping again.

Last night, I went through a carb tuning procedure. This time, I started with the left cylinder, adjusted air screw until I felt like I got a good tune - and then went to the right carb and adjusted the air screw down and that the idle went down.... opened it up and now I was getting a responsive change in idle. Eureka! The miss-fire went away, idle seems smooth now and throttle response is great. I think I ended up about 1-1/2 turns on the left and 1-1/4 ish on the right and it seems to run fine for now.

Now I have a pesky neutral switch leak and/or pan gasket leak... Already have a neutral switch I ordered when I got the bike, went through Snowburns site and read it twice and curse there are no photos. LOL. I'm more a YouTube University type guy than reading print.

Turns out I believe the smoking is just residual oil from my oil filter change that likely won't burn off until my first decently long ride.... but given the issues with the missfire, it had me more worried than I should have been.
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: marcmiller001 on April 28, 2017, 08:37:34 AM
Quote
What ignition coil do you have, a black nd ray, red and black ??

Ignition coil looks all black to me. You can see it in this photo.
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: Justin B. on April 28, 2017, 02:52:16 PM
The stock BMW coil was problematic, developing cracks which wreaked havoc with ignition.  The only bad one I've had (knock, knock) produced no spark at all and had very visible cracks which was an easy diagnosis.  I have read where others have had small cracks where it would run OK but act up when it was damp.

Probably the most fool-proof thing to do, if you plan on keeping the bike for a long time, would be to put in the Dyna "brown" coil.  Very robust coil and much cheaper than the stocker.

On the neutral switch they are like the coil - not if they fail but when!  The switch is a notorious leaker and fairly easy to get at with the rear engine mount stud driven out and the aluminum spacer removed - you'll see what I mean when you take a good look at it.  I changed one, once, without removing the tube and from then on I learned it was much quicker to remove thew stud and spacer.
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: marcmiller001 on April 28, 2017, 02:58:48 PM
Quote
The stock BMW coil was problematic, developing cracks which wreaked havoc with ignition.  The only bad one I've had (knock, knock) produced no spark at all and had very visible cracks which was an easy diagnosis.  I have read where others have had small cracks where it would run OK but act up when it was damp.

Probably the most fool-proof thing to do, if you plan on keeping the bike for a long time, would be to put in the Dyna "brown" coil.  Very robust coil and much cheaper than the stocker.

On the neutral switch they are like the coil - not if they fail but when!  The switch is a notorious leaker and fairly easy to get at with the rear engine mount stud driven out and the aluminum spacer removed - you'll see what I mean when you take a good look at it.  I changed one, once, without removing the tube and from then on I learned it was much quicker to remove thew stud and spacer.

This one? http://www.euromotoelectrics.com/product-p/dyna-coildc2-1x1.htm

Is this a direct bolt-on replacement?
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: Justin B. on April 28, 2017, 06:44:19 PM
That's it!  If you are good with a hacksaw you can chop up the original mount and make it work but it would be easier to also buy the bracket.
Title: Re: Right Cylinder Backfire - Engine Tuning
Post by: wilcom on April 28, 2017, 06:45:52 PM
Quote
You've just had the carbs all apart as I remember....I'd start by fiddling with the mixture adjustment on the faulty side.

Shade tree Joe............


When trouble shooting always look for the human first, where ever he has been, he leaves a trail of problems.