Monday, 22 December 2008

800 kms after the engine rebuild.....

Got to go for a wee ride yesterday. Not far. About 270 odd klicks. From home here to Glenorie. Then down to Sackville Ferry. Up to Bilpin. Back to Glenorie and then home. All roads I have done and reported on in this blog.

Sharon, a very dear and old friend, has this year started riding. Her first bike was a GPX250. Now she has a very nice and loud red Suzuki SV650S. She rang and wanted me to go for a ride with her. How could I not.

The LT has not had a good ride since the stud repair. Commuting to and from work is not a ride. It is a chore. So 600 odd kilometers after the repair I headed up to Glenorie to collect Sharon. The LT is purring along nicely. It is good to be back on the open road again. Arrive at Sharon’s and she fires up the SV. She has had a Yoshi muffler put on it. Oh the magnificent sound that comes from the new muffler is pure music to the ears. She has asked me to ride the SV later so she can hear what it sounds like now.

Off we head. I set a pace that I think she can keep up with. The black tar flies under our wheels as we both boom along having a ball.

After a stop I follow her and her bike sounds wonderful. She has debated about putting the baffle in. No way. Its sounds great at speed. She would ruin how a V-Twin should sound. I will have to ride her bike and let her hear it.

We pull over on Pitt Town road at a 25km/h 90 degree corner. My turn to ride her bike. Wish I had not now. It has way more power than my Bavarian Tractor. Brakes that make mine feel like a boat’s anchor thrown over the side. The ride position is a killer for me. Low bars and a big tank. My back is made for upright tours that’s for sure.

I fly past her a few times so she can hear the Yoshi orchestra in full song. This engine loves to rev. So she gets to hear it in all its glory. When I pull back in the smile on her face is so broad the top of her head nearly drops off. She is now convinced not to put the baffle in. When I got back on the LT it flet like a huge tractor. Slow to accelerate and slow to stop. Soon though I was back into the swing of my bike and still love it to pieces.

Time to play with my camera and get some ride by shots. Something I will have to perfect as can be seen by the below photos.

Something New and something Old. This 1100S BM came by and I could not resist the photo.

I am very happy with how the LT has turned out after the stud fix. I needed this ride, all be it a small one, the settle in my mind that the bike is ok and going strong again.

Sharon. Good ride girl. Your skill has gone ahead in leaps and bounds. The SV has made you a better rider than if you were still on the GPX.

Monday, 15 December 2008

Tuning 40mm BING CV carburetors for BMW motorcycles by ear.

Steve Doyle has put together this great and simple guide to tuning your Bing carbs. No need for expensive tuning equipment. So over to Steve...... Any feed back on this How To please email me and I will pass it onto Steve.

There are 3 common methods to syncing the carbs. They will all work
1. Shorting the plugs. and
2. Using a manometer of some sort. Carbtune, Twinmax or home made
3. Using your ears. No comprehensive articles that I could find..

In the spirit of learning to service and tune at home and after lots of reading, I decided that for me the "by ear" technique might be the most useful, as it doesn't require any special tools and can be performed anywhere. There is no risk of electrical damage to the bike or the one doing the adjusting.

It was very difficult to find a comprehensive description of the procedure, so using the combined knowledge and input of many at, other internet articles, the 3 usual BMW tech manuals and the BING manual, I have put this together.

I have tried to do it for the carb novice...someone in an early learning phase of carb maintenance, eg me. I have used the 40mm carb 'cause that's what I have, but the principles are transferable to other cv carbs.

Starting notes.

*Warm up. Minimum 15 minute ride. If not done, you will be left with a high idle once the bike warms up.
*This procedure is done with known good valve and timing settings, and a clean air filter. Ensure no air leaks around the carb connections or at the inlet stub on the cylinder.
*Throttle cables must have free play 2-3 mms. You should be able to slide the throttle cable outer (at carb) up and down in the cable adjuster 2-3mm.
*The jets/carb orifices, manifolds, seals etc are all clean, tight and not leaking.
*All adjustments must be done on the centre stand. Don’t use the side-stand at all.
*Tools. You will need a working pair of ears, a flat end screwdriver, a 10 mm open end spanner and a fan for engine cooling. Do not let the bike overheat. A second person can hold the throttle open at 1500rpm, or use a throttle stop of some sort.
*When assessing equilibrium between the left and right, place your head between the exhaust outlets and listen for synchrony. Don’t stay there too long as exhaust fumes aren't useful to you.
The orange highlights are the basic setting adjustments. Tuning involves ensuring the effect on the engine is equal, and smooth. Everything else is supportive information.

To simplify the procedure, break down the whole procedure into 3 smaller procedures, doing them one at a time.

You must adjust and set-
1. Idle speed.
2. Idle mixture.
3. Cables in synchrony above idle.

1. Idle speed adjustment. Look down onto the top of the carbs. The throttle adjuster is the straight screw head between the carb and head, which sits above the throttle arm. The arm has the throttle cable attached to it. Your aim is to set the butterflies to open simultaneously.
If you are rebuilding or are just about to mount your carbs onto your bike, these settings can be visualized and adjusted easily before mounting. Otherwise, do them once mounted.
On both carbs, if they're mounted, you can use a thin piece of paper between the throttle adjuster screw and where the screw touches the throttle lever. Set equal opening of the butterflies here. Tighten / loosen the screw until it just grabs the paper. 1/2 to 1 turn tighter (clockwise) is about idle speed. That’s where you start to play with a screwdriver and your ears.

2. The idle mixture screw is under the carburetor. Set both carb mixture screws equally, by clockwise rotation in all the way (the leanest), then back out counter-clockwise by 1.25 turns.

***These settings provide the baseline, so if you haven’t already done the 15 minute warm-up ride, now’s the time. It should run, unless there are other problems like blocked jets/orifices, inappropriate float levels, enrichener circuit is bad.
If you plan to further adjust back in the shed, then it’s important to have a decent fan set up ready to switch on once you have parked the bike. The aim of the fan is to prevent overheating. The adjustments should not take more than 6-7 minutes without a cool down ride. Alternatively, go for a ride, take a screwdriver and a 10mm open end spanner, and plan a few stops on level ground to tinker. Leave your earplugs at home.

Making adjustments. For post 1980 bikes aim for 1100 rpm, and 1000 pre 1980. When one carb starts to dominate, that side muffler will start to "pop" more than the other side. Using the throttle adjuster adjust the other side up to match, or back down the "popping" side. ALWAYS USE SMALL INCREMENTS, eg 1/8th-1/4 turns. If you adjust one side up to match the other side, and it runs too fast, then you need to lower the other side to match.
***You may need to do this a few times to get it exact.

3. Setting cables, or the equal movement of the throttle lever, above idle speed is much the same method except you adjust your cables, not the mixture or idle speed screws.

• the idle speed is set, or at least both carbs at the paper "pinch" point
• the twist grip is fully closed
• throttle cables follow a nice path with no tight turns or impingements.
• 2- 3mm free travel of the outer cable over the inner cable.

If you don’t have movement of the cable outer, the adjuster is screwed up out of the carb too much, you have a tight turn in the cable route or you may have a frayed cable inner. To increase the free play, loosen the lock nut and screw the cable adjuster in. Loosely "tighten" the lock nut ready for further adjustments.

***You must have that free movement of the cable outer. If the rpm increases when the handlebars are moved lock to lock, then your free play may be to little or the cables aren't positioned freely.

Set the cables with the engine just above idle at about 1500 rpm, kneeling at the back of the bike and listening just as in setting the idle speed.

You'll read a variety of opinions at which the rpm should be set, and I have chosen 1500 because it represents something like the most common opinions. It worked for me, however the cable sync was the more difficult procedure and did require multiple adjustments. Use the throttle stop screw, or something between the right grip and throttle housing to maintain the 1500rpm. A helper is otherwise useful here.

How do you assess your settings?
Idle. Your ears between the exhausts will hear synchronous, glorious harmony, if you're lucky the first time! Listen for difference and make adjustments accordingly. If you’re deaf, another method is to observe the bikes vibration, feel the muffler exhaust pulses simultaneously or have a clear cup with water fastened to the tank or seat. Watch for the smoothest movement of the water whilst adjusting. They are boxers, so don't expect absolute smoothness of water.
A ride when you think you're done will confirm how you've done.
Cable synchrony. Take note of the transition from idle to higher rpm. If it's smooth then your good, but if there is vibration or shudder, then you need to revisit the cables.
After a long ride, let the bike cool then inspect the plugs, looking for an even light gray color. The colour of the exhausts at their tip should also be light gray and even.

The BING manual, page 13, suggests a different order of approach starting at setting the cables first, at 1200-1300rpm with a free play of 1/32 inch (about 1mm would be close).
The manual describes setting the idle speed next, followed by the idle mixture screw adjustment. The manual describes clock-wise (in) rotation of the mixture screw until the engine all but stops. Then take your screwdriver with you on a ride, stopping occasionally to tweak each screw ccw x the width of the screwdriver blade (they call that a notch). Expect the performance to bog for at least 2-3 minutes (until warm) before starting adjustments. When the bogging down disappears is ”the point the idle mixture is as lean as the machine will tolerate, yet provide smooth transition. Anything further ccw would be a waste of fuel.”
You may need to reset the idle speed. Repeat step 1 as described above, using very small increments when turning the screwdriver.

Steve Doyle 12/2008

Clymer On The Lift 1983 BMW R80RT Motorcycle Road Test

1983 R80RT road test by Clymer Manuals. Shame about the backing music. ;-)


Thursday, 4 December 2008

R75/5 from San Jose BMW shop....

Chris from San Jose BMW shop has allowed me to share this great cafe styled BM with you all. Chris had posted this up in the Old Skool forums over at the ADV site. This is not just a stunning show bike, it is used in anger. It holds a land speed record. Amazing. To see this bike being built CLICK HERE.

Last Winter we were upstairs at the San Jose BMW shop, and found that we had enough spare parts to build a new airhead. Thought that some of you might like to see the results...

Like everything at SJBMW, we just had to race it - So off to Bonneville we went. And we got a new 750cc record - Just over 130 mph! Not bad for a 750 at 4600ft of elevation and a 100 degree day.

The bike was built to be very period correct - vintage parts for a vintage machine. This included items such Makuni round slide carbs, Akron high shoulder wheels, drum brakes, and a VERY custom, period correct fuel tank.

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