New Rider, Old XS650 - A Begining

[gggGary]

7mm is wear limit Replace the brushes clean the slip rings, the brushes are not happy at 7mm. See if hte weak spark improves with new brushes. I don't think the coil and ballest resister is a good idea you are just wasting electric energy heating up a resister with no useful work performed. Get a good coil with the correct primary resistance. Yeah grease the shaft get that advance working right. then after you know the bike is good, think pamco, points suck IMHO! There is a good reason that old mechanical design was abandoned 30 years ago.

 

[5twins]

If you run less than 4 ohms on a coil with points, it will burn them up fast. On your oil filter protection plate, you want to cover the area just to the right of the magnet in your last pic. That's the spot that's most prone to blowing out.

 

[Shadow24v]

Hmm, I'll add brushes to my next mikes order then. I thought they looked a little short.

On the ignition side, using a resister is not optimum, but in leu of $100 for a pamco system, free parts on hand are...well.. free I'd like to go with a pamco later, but funds are not available now. In order to be able to get the bike back up and running in the mean time, thats what i have available. On the points part, thats why i asked about the amps. I wasn't sure if running that much power through the points was a good idea with only 1 resistor. Ill probably go with both resisters for the lower amp draw.

Ill probably re-work the baffle plate next oil change then. i thought it was that side that took the most force, not by the magnet... =shrug=

 

[Shadow24v]

Well, did get a bit done on the bike this weekend. Got the DIS coil mounted at least, still need to wire both resistors in series (2x1.8ohms + .8ohms primary resistance = 4.4 ohms).

Also got the solid state rectifiers wired up and bolted on. Hopefully next will be the voltage regulator then decent spark so i can get the cabs synched. just takes time...

 

[retiredgentleman]

Shadow24v;

As Gary pointed out, your ignition is not going to work very well. The GM DIS is a CDI system and not designed to work with points. Points are for an inductive system that uses a collapsing field to generate high voltage. The CDI system use a short duration voltage pulse.

With two 1.8 ohms resistors and the coil at 0.8 ohms, means you would only have 2.4 volts across the coil. If you get a spark it will be quite weak.

A coil with 4 ohms or greater primary and no ballast resistor is the way to go.

 

[Shadow24v]

Hmm, this is only meant to be an intermediate step between points and either a pamco or an HEI module'd hall/opto triggered setup, but....

as far as i can figure, I should be OK voltage wise. Pulled out Ohms law again to make sure and this is what i came up with. Please correct me if i'm off somewhere though, I only dabble in EE every now and then...

I=V/R (power)
Volts__resistance___Amps
14.5____.8________18.125
14.5____2.6________~5.6
14.5____4.4________~3.3

V=I*R (voltage)
Amps___Resist____Volts
18.125___.8______14.5
5.6______2.4_____14.5
3.3______4.4_____14.5


As far as i can figure, the ballast resisters are not affecting a voltage drop, but are only performing a current limiting function in order not to totally fry the points with 18A of current.

 

[Shadow24v]

RG -
Ok, figured out my goofup, your right. (called my Father-in-law who went to school for EE-something). I was wielding Ohms law incorrectly, using total system values and not totally understanding my results.

1 ballast resistor was going to give me a voltage drop of 10v, only giving me 4.5v at the coil. Even running 2 resistors in parallel (8v drop, 9amps), i'd still only get about 6.5v at the coil with something like 100 watts dissipation on EACH ballast resistor. well, back to the drawing board i guess.

 

[Shadow24v]

Well, i think i have found a solution to my ignition problem. Was surfing the web and came across the following page. In it, it describes how to build an inverter circuit to run an HEI module off of points. Didn't cost more than a few $ for the 8 or so components to build it. I went with the 4th option but omitted the failover switch as my .8ohm coil would burn out my points in short order.

http://home.comcast.net/~loudgpz/GPZweb/Ignition/GPZheiModForPoints.html

Just a mockup before assembly, Missing the input and output wires.

Found a DIY CDI module diagram during my surfing as well. I may build it if i can figure out if the circuit will work off of points...

Also, I pulled my advance rod and greased it up. weights would not snap fully closed. they would always stop about 1/8" out. Added the new springs from Mikes (kept the old ones just in case), and it still doesn't snap fully closed. Even greased the weights pivot posts too. This normal or is something still off on my advance system?

 

[5twins]

The new springs from Mike's have been reported to be too weak right out of the bag. Clip one coil off of one spring in your old set and re-install them. Shortening just one is usually enough.

 

[Shadow24v]

hmmm, I'll give that a try on the old springs. Thanks twins

 

[5twins]

Actually, I should probably explain this a little better. Clip the hook end off of one end of one spring then bend the next coil out to form a new hook. That effectively shortens the spring by one coil.

 

[Shadow24v]

i figured as much. thought about it for a few minutes and came to the same conclusion Thanks though

 

[Shadow24v]

Well, was able to ride the bike to work today

was able to finish wiring up the HEI module and GM DIS coil yesterday. got good spark on both cylinders. Messed with the carbs just a little bit and it idles between 1200 and 1500 real steady with a LOT less vibrations than before.

Tried to use the manometer with 20w50 oil for indicator fluid but all it wanted to do was suck it up the manometer into the motor...must be doing something wrong. I was connecting to the vacuum port in the carb boot so =shrug=. I had set the balance screw by hand when i was rebuilding the carbs. sighted down both carbs and adjusted the balance screw until they both showed the same amount of light past the butterflies at the same time on throttle opening. probably a good enough ballpark for now.

For the most part the bike runs well. although it seems to have a lean spot about 1/4 to 1/3 throttle under cruise. Open it up a bit more and she runs like a raped ape. Not sure if this is symptomatic of having sit for a month or so (had to fix a stuck float valve also, just dropped the bowl and moved the float a time or two and fixed it) or if its from the PO putting aftermarket mufflers on the bike. I currently have stock air filters in place. I also have a set of one step up mains and pilots in case i need to up either one... have to go re-read about how carbs work, so used to the programmable ECU on my car. I THINK i need to up the pilots if its that low of throttle and rpms (2500-3500ish).

Also did the spring mod on the old springs (snipped one coil off and bent a new hook) and greased the shaft and advance pivots. Advance seems to be working quite well now Replaced the alternator brushes as well. One was worn way down the other only about half as much. bike seems to be charging well, but couldn't check as my VOM was broken. I'll check charging volts today with a better DVOM.

All in all, it seems like its slowly starting to come together. Probably have to replace the chain soon, running out of adjustment room. At least i can do that when i get the funds to switch to a 17/32 sprocket setup...

 

[5twins]

If the manometer wants to suck the fluid up one side into the motor, that indicates that side is running too fast and the carbs are way out of sync. Adjust the sync screw a bit and try again.

 

[Shadow24v]

hmm, i only had one side attached when that happened... would this not be an issue if both sides were attached? (idle also lowered since then to about 1200)

 

[5twins]

Well yes, you must attach both sides or it's gonna suck it all up into the attached side, even if the carbs were in sync. Attach both sides THEN start the motor. Be ready at the kill switch to stop the engine quickly if it looks like it's going to suck up into one side. As I said, that indicates that side is quite far off. This homemade manometer is a bit more difficult to use because it's so sensitive. You need to get the carbs close 1st or it will suck the fluid up into one side.

 

[retiredgentleman]

Shadow24v;

You're using an amplifier circuit, letting the points control the base current of a transistor, therefore very small points current. Those circuits have been around for a long time. You still have the points mechanical wear and need for occasional adjustment.

Did you still use the 0.8 ohm coil? They say you should have 2.4 ohms minimum or risk overloading the module's heat sink capacity.

 

[Shadow24v]

RG - Yes, i did use the .8ohm coil. I read the data sheet on the HEI module and also the circuit designer's notes on the primary resistance. He advocated the use of a 2.4ohm coil to prevent the HEI module's current limiter from ever activating. All using a .8ohm coil will do is create more heat to sink/dissipate (but nowhere near the 200 watts from 2 parallel ballast resistors).

From what i could gather, the HEI module will current limit at ~5.5amps (OEM replacement, MSD/Accell versions upped the amp limit to around 7.5amps for high performance automotive use). With using the .8ohm coil, I will certainly hit the current limiter and start to dump some power in the form of heat. I believe I have located the HEI module in a place where it should have adequate heat dissipation (underneath the tank below where the original coils were bolted) and also the HEI module and heatsink are bolted to the frame adding additional heatsink capacity (or so i theorize )

 

[Shadow24v]

well...bad news....

Bike was running pretty good with the ignition hop-up. Switched the pilot jets to 47.5s last night, rode it fine today, look it on the highway some and everything seemed OK. Plugs looked good, no surge etc (still some popping on deacell but mufflers arn't sealed to the headpipes well). Took the wife to go out for dinner and on the highway started to loose power, as i was moving over to the right shoulder, i got a nice cloud of blue/white smoke from the right side. motor died when i disengaged the clutch.

Motor would only run on the left side when i did get it to catch. Had to have our roomate come get us and the bike in the truck (luckily the cop that stopped was real nice and a fellow rider to boot).

Got home, pulled the right plug and found.... a nicely holed piston with 0 compression. Left side came in at about 140psi compression though. i have NO IDEA what ate the piston that bad that fast....

Now i am in need of advice on how to R&R this motor without costing an arm and a leg. a real bummer this riding season due to all the issues. As much as i enjoy working on the bike.... I actually wanna ride the dang thing!

what is necessary, recommended, good ideas and optional when fixing something like this?

 

[retiredgentleman]

Shadow24v;

That is bad luck. Had you checked the timing recently? Its real important that the timing does not go past the full advanced mark. The little ears or tangs on the fly-weights of the ATU wear, and this expands the timing range past the full advance.