The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: jonathanrowley on May 29, 2016, 12:31:05 AM
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So after fitting the new Trigger unit I needed to Time the Bike back up.
It ran roughly after a first rough twist of the new beancan - but I had no Timing light. I finally tracked one down yesterday (In Sharjah - look it up!) and eagerly went back to time it and get it running properly.
I tweaked the Can until the "S" lined up with the notch on the Engine Case and the strobe lighting it up nicely.
Believe that is how it should be but maybe someone can confirm?
I've also finally got round to upgrading the carbs to 32mm BING Carbs so had to set them up and balance too. (I was waiting until I had the ignition back up and running.)
To explain - I was previously running 28mm Carbs as it was originally an R45 until I upgraded the pots.
I've read and re-read a 100 times all the articles on Timing and I'm no stranger to getting it running but any tips on timing and setup welcome.
The picture shows the two bits of kit any Airhead owner needs!
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You can set the timing as you did at low idle (less than 1500rpm)
But the most important timing is at High idle (over 3000rpm)
You should set you timing to 32deg BTDC at 3500 rpm that will be a "Z" or a "F" mark on the flywheel and let you base timing fall where it is after that. But it should be close to the "S" mark at low idle.
If you get a dual plug ICU by accident your base timing will not come back to 6 deg but will fall at about 10deg
That is why you need to check both.
As the old mechanical advance bean cans wore the max would get higher causing spark knock and then when you would adjust it back to 32deg your base timing would get lower causing a rough idle
I added a timing pointer to mine to help in setting the timing more accurately
I did this by drilling a hole at an angle down into the flywheel housing towards the timing marks and inserting a roll pin
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I did something similar by making a timing tool with a pointer that inserts into the timing hole. Th pointer is offset to align with the chisel mark.
I also concluded that the pointer should not be aligned perpendicular to the engine case as the casting gets thicker towards the top. I used this picture to make a more accurate alignment. The difference is approx. half a tooth or 1.6 Deg
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OK, so I set it at low idle and got the S mark to line up with the notches. I got that spot on with the strobe.
I didn't try to do the 3,500 rpm timing - as it makes so much lovely noise from my shorty pipes it would wake the whole apartment complex up so I have to be mindful of that.
It's banging and popping away, though feels strong, I'm just wondering whether that is timing or carb related? Any thoughts?
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Getting that timing light "square" to the flywheel can be a chore what with carbs and cables blocking a straight visual shot. Since you're there abouts, some owners will use a Q-tip saturated with carb cleaner to clean off the debossed markings, then smear some white paint on 'em. Then, when the paint is mostly dried, a thin paper shop towel, with a dab of that carb cleaner, will clean off the excess leaving clear markings for your next, and easier, timing drill.
Here's the deal. If you make two major alterations and do not feel one is perfect before making anther major change, say new carbs and ignition system for example, you really don't know where the final problems are. You'll end up chasing your tail and, eventually, find the fault.
You may want to write that down. <sarcastic humor> [smiley=wall.gif]
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OK, so I set it at low idle and got the S mark to line up with the notches. I got that spot on with the strobe.
I didn't try to do the 3,500 rpm timing - as it makes so much lovely noise from my shorty pipes it would wake the whole apartment complex up so I have to be mindful of that.
It's banging and popping away, though feels strong, I'm just wondering whether that is timing or carb related? Any thoughts?
Not sure what you mean by popping and banging
Are you talking about back firing thru the carbs or spark knock or pinging
You really need to check it at full advance.
Can you ride the bike out to a parking lot somewhere and check it there.
It would be good to have it warmed up any way.
Popping back thru the carbs can be from different things.
Most of those are not common to the Air head engine as far as I can tell
Like sticking valves and the distributer be installed 180 deg out ;D
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That is a good Idea Barry
With my pointer i will have to drive it out before I can remove the flywheel.
I have been wanting to check how close my pointer is to being accurate but I figured the most important thing is that you get a solid f reference point to go off of when retarding the timing to correct a pinging issue
I know one thing if a advance the timing any further than 32 deg I get pinging.
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Not sure what you mean by popping and banging Are you talking about back firing thru the carbs or spark knock or pinging
Yes, on the overrun it's backfiring - sounds great, but not sure it's right?
It's not pinging or spark knock - popping and banging.
I want to know if it's likely to be timing related or overfueling?
Any ideas.
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You really need to checkitat full advance.Can you ride the bike out to a parking lot somewhere and check it there.It would be good to have it warmed up any way.
Thanks, and yes, but it's 115 degrees in the shade here right now and a minute in a carpark with a Hot Airhead engine doesn't really appeal!
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Here's the deal. If you make two major alterations and do not feel one is perfect before making anther major change, say new carbs and ignition system for example, you really don't know where the final problems are. You'll end up chasing your tail and, eventually, find the fault. You may want to write that down. <sarcastic humor>
Thanks Montmil, I kinda like the challenge and the tweaking. I static timed the Bike, and it pulled like a Horse - much better power through the new Carbs.
I also balanced at Idle the Carbs with the dials and set the Mixture by ear. Bike pulls great, just backfires once I throttle off.
Chasing our tails, is what home mechanics are famous for!
It's that tradeoff between knowing a little but not enough - so I'm always striving for more understanding!
Thanks for responding and the input - appreciate having other owners experience.
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On my BSA it was lean and a leaky exhaust.
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Some of the more experienced tuners may know better but I think leaning out of the mixture is the most likely problem
I don't think the timing is the problem.
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Some of the more experienced tuners may know better but I think leaning out of the mixture is the most likely problem
I don't think the timing is the problem.
[smiley=tekst-toppie.gif]
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Could the shorty pipes contribute to the problem?
Bob
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If by popping you mean the engine is missing or 8 stroking then usually an air leak or lean mixture. Reduced back pressure from the exhaust might also do it.
I have been wanting to check how close my pointer is to being accurate but I figured the most important thing is that you get a solid f reference point to go off of when retarding the timing to correct a pinging issue
I know one thing if a advance the timing any further than 32 deg I get pinging.
I agree it's about reproducibility rather than out right accuracy. Once you establish a timing that doesn't ping the pointer helps reproduce the exact same timing the next time around. When doing static timing it also enables an accurate check that both cylinders are the same.
Mine pings easy too.
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Bike pulls great, just backfires once I throttle off.
Replace the rubber unions between Carbs and cylinder head if they look even slightly cracked. If they are in good condition, tighten the clamps,
If that doesn't cure the popping, have a look at your exhaust system to see if air is getting in at the heads or the cross over pipe.
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Bike pulls great, just backfires once I throttle off.
Replace the rubber unions between Carbs and cylinder head if they look even slightly cracked. If they are in good condition, tighten the clamps,
If that doesn't cure the popping, have a look at your exhaust system to see if air is getting in at the heads or the cross over pipe.
Why would air from the exhaust cause it?
How does that make for banging...
But I do think that could be it, the shorty pipes don't have a complete seal with the crossover for sure....
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I also balanced at Idle the Carbs with the dials and set the Mixture by ear. Bike pulls great, just backfires once I throttle off.
Have you noticed the large, knurled screw on the bottom of the right-side perch?
It can be used as a sorta poor boy cruise control as the threaded end has a bit of nylon that contacts the throttle tube and holds it in place.
It's true purpose is to balance the carbs at around 3-4K rpm. This drill is done by tweaking the cable adjusters at the carbs, insuring balanced vacuum readings in the engine speed range normally seen. The cables, at rest, should also be free enough so that they may be lifted just a bit from the adj ferrules, insuring a carb butterfly is not being held open a wee bit.
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Bike pulls great, just backfires once I throttle off.
Replace the rubber unions between Carbs and cylinder head if they look even slightly cracked. If they are in good condition, tighten the clamps,
If that doesn't cure the popping, have a look at your exhaust system to see if air is getting in at the heads or the cross over pipe.
Why would air from the exhaust cause it?
How does that make for banging...
But I do think that could be it, the shorty pipes don't have a complete seal with the crossover for sure....
Ok, here goes.
When your exhaust valve opens it releases still burning fuel into the exhaust pipe, it also sends a supersonic shock wave down the pipe, and again when the valve shuts. The effect of this supersonic wave is that it creates a mild vacuum behind it (which helps to scavenge the combustion chamber) if there are significant air leaks around the header pipes or cross over pipes this will draw in fresh air, which if introduced tot eh still burning and somewhat rich mixture that results from closes throttle over-run - will explode - hence anything from a quiet pop and grumble to a full on backfire.
You should hear what happens when you have a burned exhaust valve!
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Does your bike still have the horrid cold air injection system that Cali required and Motorrad supplied on ALL North American imports? Dump it. That is likely the cause of your "popping" on off throttle ops.
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Does your bike still have the horrid cold air injection system that Cali required and Motorrad supplied on ALL North American imports? Dump it. That is likely the cause of your "popping" on off throttle ops.
Howdy, my Bike is a European/UK Bike and running K&N style filters. Airbox removed
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When your exhaust valve opens it releases still burning fuel into the exhaust pipe, it also sends a supersonic shock wave down the pipe, and again when the valve shuts. The effect of this supersonic wave is that it creates a mild vacuum behind it (which helps to scavenge the combustion chamber) if there are significant air leaks around the header pipes or cross over pipes this will draw in fresh air, which if introduced tot eh still burning and somewhat rich mixture that results from closes throttle over-run - will explode - hence anything from a quiet pop and grumble to a full on backfire.
Hey Tony, thanks for taking the time to explain. Been out on the Bike today, in Dubais sunshine - pulled like a train but still banging away - sounds like a shot going off!
I think I'll run it into a place called Café Rider and let them set it all up - I've got limited facilities and it's damn hot here - circa 110F each day so not much I can do beyond the basic timing I've done.
I think I'll ask them to look at sealing the silencers properly where they join the original BMW pipes and cross tube. Sounds logical and great knowledge you have there!
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Now you're talking ! KN filters, no muffler, bad jointing at the crossover make for a complete carb tune and adjusted jets.
The jets and needle of our Bings are set for the OEM air filter and exhaust.. not for the inexistent air filter or muffler... This explains this ...
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Now you're talking ! KN filters, no muffler, bad jointing at the crossover make for a complete carb tune and adjusted jets.
The jets and needle of our Bings are set for the OEM air filter and exhaust.. not for the inexistent air filter or muffler... This explains this ...
Thanks, so needs a complete re-set as you say, I didn't know until posting, but yes very little back pressure. Wonder what Jets need to be?
Makes a great noise though! witness this short Vid I have just posted on YouTube. Witness an R65 Roar... Short Pipes are pretty much straight through, you should hear the first pop, just as it comes up the ramp.
Location is Media City with Dubai Marina in the background.
[media width=800]http://www.youtube.com/watch?v=SKV8V_hDgvI[/media]
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To me it sounds pretty normal for your configuration...
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To me it sounds pretty normal for your configuration...
Hey Justin, Thanks - so are you saying this is how it will probably be?
i.e. Go with the noise, everythings OK.. no harm is being done..
Here's an Air and Pipes close up