Search This Blog

Monday, November 30, 2020

RG500 Carb Synchronization

Performing an RG500 Carb Synch will make the engine run much crisper. The factory manual briefly describes a procedure which gets the carbs sorta close to synchronization. The steps described here get the engine running much more precisely. A major improvement over the factory procedure is using a flow meter to dynamically balance the carbs at idle and at running speeds. You will smile when you enjoy the improvement in rideability from properly synched carbs. 

RG500 Carb Synch Static Adjustments

Make sure that the cables are routed correctly to their respective carbs. The cables are numbered at the junction from 0-4 with 0 being the oil cable. 

The oil cable runs under the right rear exhaust pipe then across the back of the engine on its way to the pump. 

The cylinders are numbered LF=#1, RF=#2, LR=#3, RR=#4.

The longer of the two choke cables goes to the #4 carb.

Here is a video which shows the static adjustments detailed below. 

Run all the carb top cable adjusters completely in then verify all four slides are completely bottomed out in their bores. 

Back out the carb top cable adjusters 2/3 turn. Leave the locknuts loose for now.

Next up is initial adjustment of the Throttle Stop Screws, which affect the idle speed. The factory manual specifies adjusting the screws so the slide is lifted .5mm from totally bottomed out. Half a millimeter is about .020 inches. It has been suggested to use a .5mm drill bit. Stick the bit under the carb slide then adjust the Throttle Stop Screw so the slide is just barely lifted off the drill bit. You can tell the slide is off the bit when the bit can be moved back and forth a little. I don't have a .5mm drill bit so I used some .032 safety wire. It's OK to be off a little with whatever you use to set the static slide height because later on we are going to precisely set the idle by adjusting the Throttle Stop Screws using a flow meter. What matters now is having them all be set the same.

Figure out a method of holding the carbs partially open. One method is to anchor a bungee cord onto a radiator mount, wrap it around the handgrip, and attach the other end to the preload adjuster sticking out of the top of the fork. Another method is to wrap some 1/8” vinyl hose (or clothes line, or 12ga wire, etc.) 1.5 times around the throttle between the handgrip and the switch housing to act as a friction brake to hold the throttle stationary. If you just like using shiny tools you may want to use a vise grip lightly cinched onto the handgrip with the handle resting on the brake lever for this purpose.

Starting with the right side carb bank, open the throttle to raise the slides until the timing dot of #4 carb (right rear) is completely visible and just brarely touching the top of the carb throat. Make sure the handgrip is secure because all the other carbs are going to be synched to this one.

It helps to use a flashlight to properly illuminate the dot and throttle bore to dispel shadows when positioning the slides for adjustment

Now go to #2 Carb (right front) and use the carb-top cable adjuster to line the dot up with the top of the carb bore just like you did on #4. 

Repeat with the left two carbs. Note: The left side adjusters typically ride about a couple of turns higher than the right side. It's just how the cables are cut.

Check the oil pump and adjust the dash marks to line up on the pump and cable cam.

For bored carbs, I recommend a richer than stock oil pump setting since the slides are higher when the dots reach the top of bored out (taller) venturi. Here is a video about adjusting the oil pump. 

Remove whatever is holding the throttle open and let all the slides close.

Leave the carb top cable locknuts loose for now. They will be tightend up after completing the following Dynamic Adjustment step.

Adjust the throttle cable slack at the handgrip to have a 2-3 mm of play.

Dynamic Adjustments

Get a STE Sychrometer Flow Meter because balancing the carbs with a flow meter makes the bike run much sweeter. Here is a link to a source for them which has a good image of one. There are many other internet sources for these tools.

Cut a few mm off the Synchrometer's snout because otherwise it runs into the carb slide and cannot seal the carb's mouth.

Here is a video about the next steps, detailed below, which shows how to balance the carbs while the engine is running.

Start the engine. Warm it up.

Use the Synchrometer to adjust all four Throttle Stop Screws to make all the carbs flow the same with an acceptable idle speed.

Now do final throttle cable adjustment using the Synchrometer. Lining up the dots is as close as we used to be able to get. Now that Sychrometers exist we can sych the carbs much more closely. Using the throttle grip holding system you previously employed, get the engine running at a fast idle. Just get it running at a couple thousand RPM. 

Use the Synchrometer and adjust the carb top throttle cable adjusters so all four carbs flow equally.

Shut the engine off.

Tighten all four carb top throttle cable adjuster locknuts.

Start the engine again and verify all four carbs are still flowing the same while running at a fast idle.

Make sure all the the throttle cable locknuts are tight before pulling the rubber cable boots down into place over the cable adjusters.

Operate the throttle to confirm there is no bind or obstruction and that it operates smoothly.

Set the Idle Mix Screws to their default position: 1 1/2 turns out from seated. They are brass and soft which makes it important to be gentle when screwing them in to the seated position. Turning them hard as if they are a fastener can screw up the tips. Turn them until they are just barely seated, then back them out 1 1/2 turns.

Turn the Idle Mix Screws back and forth to find the setting which yeilds the fastest idle. In the video about dynamically adjusting the carbs I said there would be a seperate video about adjusting the idle mix screws. I have developed a method of setting those screws based upon initial pickup from riding along on flat ground with the engine just idling along. Problem with this method is finding a stretch of flat level pavement which is safe to ride on at a fast walking pace. Kevin Cameron made our lives easier by publishig a detailed article about carb tuning. His method of setting the idle mix screws is simply adjusting them to get the fastest idle. Which can be done in the safety of your garage. So I didn't make the video, I wrote this up instead :-) 

Carburator Idle Mix Screws are designed so three turns out from fully seated is the same as changing the pilot jet one size. Gamma carbs have it upstream of the carb slide which means it changes the amount of air going into the system. Backing it out lets more air in which makes the idle mix leaner. If the bike idles best with the idle adjuster screw all the way out then try going one size leaner with the pilot jet. If it idles best with the screw all the way in then try one size richer pilot jet. Most bikes work fine at the default setting of 1 1/2 turns out from gently seated.

When carb synch is complete it will idle like this.

The very last step is setting the needle clip position. Go for a ride someplace where you can roll along at 5 to 6,000 RPM in 6th Gear and roll the throttle open. If it just sits there without accelerating it means the needle is too rich. To lean out the needles raise the clip. There is a little washer on the needle which is used to make 1/2 clip position adjustments. Moving the washer from above to under the clip makes it just a little richer. Putting the washer on top of the clip makes it just a little leaner. Gammas are sensitive to clip position.

Note: There is a mistake in the video. My stroked-out brain said the washers are twice as thick as a clip positioning slot on the needle. What I meant to say is the slots are twice as far apart as the washer is thick. Putting the washer under the clip is the same as raising the clip one half slot; making the needle a little richer. Putting the washer on top of the clip is the same as dropping the clip one half slot; making the needle a little leaner.


Monday, March 23, 2015

RG500 engine start after rebuild

I made significant notes about what is going on at the YouTube site. Please read them.




Demonstrate best initial start after rebuild procedure for RG500. Also works for RZ500 and RD500. Assemble _dry_ pistons into _dry_ cylinders and start engine with premix gas. Immediately upon starting engine reach down to oil pump and hold it wide open. After 30 seconds or so smoke will start coming from the pipes. Each smoky pipe proves oil is being delivered to that cylinder. The dry start gives the rings nice sharp ninety degree edges which seal really well.

How to tow a motorcycle

Whenever towing a motorcycle it is _very important_ to rig the tow rope so the towed person can drop the tow rope at any time. 

Weird things happen with towed motorcycles.  Sometimes the tow-er is looking forward and cannot see the problem developing with the tow-ed motorcycle so keeps on at full speed.  This can result in a crash and subsequent dragging of the bike along on the ground.


The way to do it is to bring the rope in between the handlebar clamps, loop around the handlebar once or twice then run a bit out to the left handgrip.  The tow-ed rider can hold the rope against the grip with his fingers.  If a problem develops he can just let go.  The towing force will immediately unwrap the rope from the handlebars and the tow-ed bike will be free.

Sunday, March 3, 2013

RG 500 break in oil

Running in an engine is all about doing a certain amount of wear to the rings and cylinder bore surface. Unless some wear happens the rings may never seal properly.

When a Cylinder is bored and honed it finishes with many micro-ridges. They look like swirls going around the cylinder. After a while these ridges get smoothed off by the running action of the rings.  The key is getting the rings properly seated before the cylinder micro-ridges wear off.

Since synthetic oil virtually eliminates wear it is forbidden during break in. Using synthetic oil during break in of an old school cast iron cylinder (which Gammas have) will result in poor ring seating and reduced power until the next set of pistons is installed. Assuming the next set is run in with non- synthetic oil :-)

Go to a car parts store and get 2smoke oil for a lawn mower. Drain the oil tank and replace it all with lawn mower oil.  It's about 1500 cc of oil , so gets two bottles of lawn mower oil.

Gammas continue to run in the rings for about as long as it takes to go through an oil tank's worth of
Milage.

Tuesday, January 22, 2013

Engine Leak Detection


Athlete’s foot spray powder is very useful for leak detection.  It is sticky so it stays on the engine until hosed off.

Clean the engine.
Spray athlete’s foot powder all around the suspected leak source.
Start engine
Let engine warm up while bike remains stationary
Riding the bike will blow the leaky fluid all over the place which makes finding the source very difficult.
Eventually while the bike is running in place the leak will manifest itself.
Follow the leaking liquid trail up through the white athlete’s foot powder to the source.
Hose the powder off (It's easy and all of it flows off with a bit of water)
Fix the leak.

Tinactin powder spray is the best for leak detection.  It is the stickiest.  Make sure to the label specifies Tinactin _Powder_.

Monday, January 21, 2013

Lance Gamma Big Bore Motor - Take 2

Starts easier.  Less abrasive engine sound while putt-putting through town.  Pulls so hard up top I haven't found where the power tapers off yet.  I used to run my 500cc motor to redline all day long.  It's so intense with the Big Bore up there that I always upshift.

This is what I bought my Gamma for.  I wanted a big motor so it could ride through town discretely while also being able to scratch my speed itch out in the country.  Suzuki installed a crazy powerband for publicity purposes.  Lance Gamma has finally evolved the engine to what Suzuki should have released in the first place.

Rick has been telling me to try running a gear or two higher than usual.  When I do that the bike is buzzing less than I am used to at any given point in a corner.  Less buzz makes me more comfortable, which leads to carrying more speed.  Going faster makes my suspension work harder.  Going faster makes me have more speed entering the next straight.  Which means I have more speed when the next braking zone comes up more quickly than expected.

So what starts out being more comfortable winds up also being faster.  Who woulda thunk?

This engine will take a while for me to explore the limits of.  That's a good thing ;-)

Thursday, January 10, 2013

Philosophy of engine building / RG500 Stator Installation


I have recently proved to myself once again that it is possible to work too fast building an engine.  

A mistake which would have taken another minute to carefully avoid during construction can turn into twenty hours of consternation and repair work later on.

OK, here's a recent war story from my RG500: I skipped looking in the manual at the stator mounting page.  Seemed fairly simple, just three screws after all.  Didn’t see the notice to use locktite.  Didn’t use locktite.

Turns out stators are under lots of periodic stress as the magnets in the rotor whirl around and electricity is generated.  Lack of locktite resulted in stator becoming loose.

Loose stator rattled around for a while.  Until a few windings wore through against the rotor and shorted out.  Causing one of the three yellow stator output wires to break and the stator to fry. 

Fifty twisty miles from home on the Coast Highway while zinging along in 6th.  Sudden and complete spark disappearance.

Talk about a buzz kill.
---
Here's the fried stator:

---
Here's the RG500 Shop Manual item about installing the stator.  I don't know what Thread Lock 1342 is.  I used Red Locktite.  It's OK to use Red on small threads, it's only large things that need to be heated for disassembly.

---
Here's the loose screws.  Looks like they were rubbing against the inside of the rotor for a while.
---
It would have been a lot easier and less time consuming to have read the manual and used Locktite than to have to remove the stator again.  Here's a pic near the end of the job with the replacement stator in place:
---
It is important to pay attention to every word in a shop manual.  When they say "Route the stator lead wire properly" they mean it.  Suzuki cast a little post and threaded a mounting hole for a bracket just for this purpose.  After a previous rebuild I found out that if this bracket is left out the wire will rub the rotor, wear through, and cause the bike to stop running.

I made my own bracket.  It's in the top right of this image:
---
Suzuki wants lots of Locktite around the stator and rotor:
---
Factories are vary sparse with the words in shop manuals.  Each word is important.  Read it or weep ;-)
---
Of course, there is another possibility.  Maybe I verified the words of an old AMA Pro friend "Never put a fastener on part way."  It is possible that I put the stator screws in finger tight then never made another round for final tightening.

Which ties in nicely with my opening statement about how important it is to be patient while building engines.