I think Oil Galleries are clogged.

gordonfi

XS400 Enthusiast
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when I got this bike, first time starting, only cylinder fired and ran. Then I found the Valve cover plugs and put ATF fluid in it (High detergent) for two reasons. First, changed the oil and it was clear on the dipstick. So, if I was successful in clearing the galleries with ATF and running, the oil in the crankcase would have some red in it and I could drain it out again along with the guck. So, when I poured about a quarter cup of ATF on the cold cylinder, it started firing. Then the next day, hard to start, so I put ATF in both, and away it went, along with some backfiring that lessened as it ran. BTW, I had the carbs out 5 times and cleaned more each time, they're good now. Finally did what I was told. lol.

After a few attempts and intermittent starts, I've decided that I might have to remove the top covers and manually clean out the galleries. I really don't want to put out the $90 for a torque wrench at this point and since the top cover doesn't expose the piston, I am wondering it I can get away with removing it, cleaning the galleries without a torque wrench? Hopefully I can get at them without removing the cam. That would definitely require one, and I'm looking for the diagram that I saw of the oil galleries to see where I need to poke around. Anyway, thanks in advance for any advice.

(Update)
Well I replaced coils and have new points on the way but I found something interesting. I ordered and installed an auto advance mechanism from Ebay and from that point on could only get backfiring no matter what I did with the timing. Then I took the new one off and compared it with the new one. The flat spot where the points close was different! Anyone wish to explain this to me? I am thinking that this part is not as generic as I had hoped and is probably linked to the timing chain position. Am I right? anyway, as soon as I put the old one back, got it to fire properly but weather is still too cold. Maybe next weekend.

Anyway, weather is warming up. Painting now and have the seat out for reupholstering. Getting close! Pics later.
 
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I'm still learning, and haven't learned enough to comment much on the issues.

You certainly don't have to buy an expensive torque wrench though. I had the same dilemma at first, then I went to Canadian Tire and bought a $23 torque wrench.
http://www.canadiantire.ca/en/pdp/torque-wrench-3-8-in-0588661p.html
Nothing wrong with it, just doesn't click. Also doesn't require calibration.

Actually kind of cool seeing the exact torque reading as the beam moves.
 
Do a dry compression test on the motor. The only oil feed galley goes up the block stud into the cam/rocker area of the motor and has nothing to do with the pistons. I highly doubt it is plugged. My guess it your pistons/rings are bad and not sealing. Yes you need to torque the rocker box and in a specific sequence.
 

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Thanks for the info. I did have it running, but only after pouring oil in the Rocker arm covers. I'm not sure why, but this is the only way it got started on many occasions. otherwise it just backfires. I did static timing and also found an open, or likely intermittent wire going from the right side point connection to the coil. I have to fix that first before I go on. Would explain backfiring I suppose if the short or open was intermittent, and, at the wrong time. I still want to at least take a look under the valve cover for anything stuck or dry. I agree the galleys must be ok because the ATF I put in on the left side went town to the Alternator cover side. Not sure about the right side though. Right side is the one backfiring most and has the broken wire. I'll finish up with points and timing before I move on. I don't suspect the rings because when It was running properly on both cylinders, no smoke out the exhaust. Only when I sprayed a shot of WD40 would I get smoke puffs out that side, and then nothing. What's frustrating is I've heard it running and after warm-up, spark advance now working fine (wasn't before). Just cold starts are a problem so far with dry tappets. Many thanks for the suggestions.
 
I should have taken the "pour oil over everything" suggestion seriously. Today, I was pulling my hair out trying to static time it. Result, backfiring and no starts unless I placed the point assembly way out in left field. Well, I found out why. That "Automatic Spark Advancer" was the culprit. I had a hard time getting (persuading) it off in the first place, then I found that it was seized pretty tight. So I threw it into a pot of boiling water for a few minutes, took it out and gently pried the pieces out and as soon as I did, they started moving freely again. Added some cooking oil (Just cause I was in the kitchen) and they're good to go. I have a hunch the timing will be better now and I still haven't taken the head off yet. Leaving that to a last resort. Anyway, just my update. I'll check in later. Thanks all.
 
I am going to take a break. I cleaned and lubricated the Advance mechanism and put it on this morning, set the points to where I saw in the pictures and all it did was backfire. I moved them all around with a similar result. Next, when I have a bit more time, I'll redo the static timing and see what happens. To me it all looks like the wires have been reversed for the L and R cylinders. Could someone clear this up for me please. Is the Left cylinder the one when you are on the bike, or otherwise could be called the driver's side? That may be what's getting me going down the wrong path. Thanks!
 
Compression test would probably still be a good idea. It can still run even if the compression is not in spec. It might also make sense why it runs better warm since the metal would expand and seal a little better yielding slightly better compression. The test isn't really hard, and we are talking 30+ yr old gaskets. If you aren't willing to fork over the $25 for the testing equip, you may want to stop now. These bikes cost a bit to maintain and troubleshooting can really cost money.

Also, I know Harbor Freight has really cheap torques but I don't know if they go into Canada or if there's an equivalent.
 
The left cylinder would be you sit on the bike. Have you synced the carbs with a manometer? What exhaust and air filters do you have on it?
 
How do I upload pictures? Anyway, I was timing with the light tonight(static timing) and found that it was firing in two places during a cycle. That's why the backfiring. I looked closely at the setscrew by one of the springs (Bent metal strip connecting to the point) and noticed it was very close. And as I turned the engine over, sure enough, it was hitting there. and shorting out the points. Anyway, I bent both of them so they would no longer touch and did a static timing again. It started after much persuasion. Still have to sync the carbs though. Oil is still clean which concerns me. I may have to do some extreme cleaning soon.
 
Thanks for the info, xschris. Isn't the crankcase split? I remember taking off the alternator cover and the oil coming out WAS a little dirty, but the dipstick side was still clean. I'm thinking the galleries on the alternator side have opened up then, right? Also, I did ANOTHER carb cleaning and found some jets clogged. Was about 1/64" dia. and when cleaned about 1/16". Another question. Would carburetor problems cause backfiring? That might explain the backfiring when cold, because I did the static timing and tweaked it after it was running. Maybe?

Another interesting symptom. When starting, cold, It backfires a lot before firing. Then, when I remove the condenser connection. No more backfiring and starts to fire, and eventually start. THEN, after running, plug in the condenser, and all is fine. I'm thinking this may point back to the carb? Why? I can't explain. But, the Condenser is a new Honda type. Which reminds me, does anyone know the actual capacitance value of the condenser? As in 0.1uf @ 50V. I'm curious. Because if the stock one is different from Honda, that could be another explanation for the backfiring. Also if the value is different from what I'm using, I can build one from my stock of capacitors with the proper value. Thanks again! Everyone.
 
If I were you, I would clean the carbs a couple more times then adjust valves and balance carbs. These carbs areVERY sensitive and can be dirty even when they appear clean. Ultrasonic cleaner and compressed air above 100 psi is the best way. I have seen peole who have cleaned their carbs 4 times and still not had it clean enough to run properly. Every time you do anything to the carbs, including cleaning, you have to balance them on the bike. If you skip this step to save time, you are in for a world of hurt. Only after you are absolutely, 100%, without a doubt sure that its not the carbs, I would move onto other avenues.

You can search the forums here and find some of the crazy most insane problems associated with dirty carbs and lack of balancing them. Be diligent. I hope this helps.:bike:

Edit: inline filter from the gas tank will help your jets from clogging again.
 
Thank you rugbywarrior89. Good advice. I assume that you are saying that the backfiring can still be caused by carburetors? I'll see how my work pans out later on tonight. I still would like to know what the actual capacitance vales are on the condensers, if anyone knows. Thanks again everyone.
 
Make sure the points are clean with no pitting on them and gaped to spec. If the condenser is bad you will see sparks as the points open and close as it is running. Sync the carbs with a manometer!!! Condenser value should be .24uf Lots of new ones on ebay for the sohc xs400.
 
Thanks xschris. The points had intermittent weak yellow sparking, but only occasionally. I'll measure the capacitance of that Honda set tonight and see. I bet it's less. I'm assuming the voltage rating is 16 Volts or higher. I can put in 35V caps if necessary. Just as a curiosity, I wonder if the primary of the coil has counter emf which could cause spikes in reverse polarity, which brings to mind protection diodes that they use in Relay circuits to protect Semiconductors. There are no semiconductors in this circuit but I wonder if a diode could help things a bit. It has no effect on the forward voltage of the circuit. It would only short out reverse voltage coming from the coil when the points open. OR, does the capacitor need that to function. Food for thought.

I'm also wondering if there could be a primary wiring problem to the coils. The gauge lights go on and off while it's running indicating to me a possible bad ground somewhere and the low beam of the headlight doesn't come on even though I've measured continuity across that terminal on the light itself. I'm really tempted to remove the coils and redo the wiring by taking off the tape an using spy-wrap that they use in other automotive and electrical applications. That way, when I take the tape off, I can inspect the wires for shorts or wear and replace as necessary before applying spy-wrap to them.

I'm anxious to try the carbs again since I've cleaned for about the 6th time. lol. But, it may have to wait until the weekend. We'll see. Thanks again to all of you.
 
Yea. That's the plan, xchris. Thanks!

I'd like to add one more thing. All the trouble I've been having, I think, is mainly because when the temperature here is usually below zero (and has been), I usually can't even get it to fire. When I use the heat gun to get the engine to a more of a Summertime temperature, it starts, and when up to temperature all seems to be OK. I'm wondering if I'm fussing over nothing since I'll never be riding this in the Winter and if it starts with summer temperatures, why would I worry about it? If it were a Snowmobile, I'd have a different view on things, but it's a summer vehicle AND, I think the storage symptoms are much amplified by the cold weather AND, I think once it has been run in warmer temperatures the gunk should come out easier. Sorry, I guess I should have mentioned all this earlier. But, hey, I'm old. LOL Many might think, too old for a "Biker"...
 
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Yea. I tested the coils again and found that one was intermittent. Up to 200k and back to about 30k. I have some new ones coming. I'll be working on the wiring soon while I wait for the coils. I didn't think a bad coil could cause backfiring, but I guess anything is possible. I have until April to get this baby going, so we're making good progress.

I have the air filters off at the moment until everything is set up and it starts easy. Will put them back on with the gas tank later. Got somebody locally reupholstering the seat too. I'm thinking of just grinding down a poor weld and sanding/painting the fenders. I'm not sure of the expense on re-chroming them but it is an alternative. I think painting may be cheaper. Any suggestions on this?

Thanks everyone for all of your help.
 
Thanks for the advice. Changed coils and it helped but still had to sync the carbs. After all that it runs much better but can't get it to idle for very long. Had the carbs out 6 times, cleaning, and I've added injector/carb cleaner into the gas tank. I am assuming this will help over time. I am disturbed about one thing though. I've changed the oil about 3 times so far and it comes out of the drain plug dirty, also out of the left side when I take the alternator cover off, dirty. BUT, on the side where the dipstick is, it's clean! That's what makes me believe there is something plugged somewhere. I am wondering if I lean the bike over to that side for a while, if things may work through. Also it didn't come with a center stand so when parked, it always leans to the left. So it would never get drained to the right side under these circumstances. And I just realized that when I take it for a test spin down the back alley, since there's no plates on it yet, I always turn around to the left! Maybe I'll try turning right a few times and see what happens. The carb syncing really improved the performance though.

I also had an issue a week ago when it backfired and blew out one of the rubber plugs beside the points. Then it ran only on the right cylinder, no matter what, and I heard a little top engine noise. So I bought the torque wrench from Canadian tire and took off the tappet cover (Or is it head?). Anyway, I found that the rod that the lifter pivoted on, shot out the plug as well! So after a day or two of looking. I found the rod in my toolbox and the rubber plug under the bike. Put it all back, readjusted the lifters and attempted the timing again. I didn't realize that point gap was part of the timing issue. I static timed it according to the manual and it still was hard to start and still backfired on the right cylinder. Then I just twisted the outside timing all the way clockwise as far as it would go. Then it started and seems to be ok, although there is an occasional backfire when I go to start it. But at least now it starts. The static timing marks are way off according to how it is running right now. That has me confused but as long as it's running, I'm happy.

I also took out the battery compartment and cleaned the alternator connections. Now it is charging as well! One final note. The manual said the torque for the head bolts is 22-25 lbs, the tappet covers was 10 lbs. I torqued the bolts to 20 lbs and one of the head bolts broke. So is what I took off, the tappet cover, or the head? I thought the tappet covers would be those screw out plugs over each tappet adjustment. When I replaced the broken bolt, I torqued them all to 12 lbs and seems to be ok now. No leaks because I used that forma-gasket stuff as I put it back together. We're getting close!
 
Running the bike without the mufflers and filters will not give you an accurate picture of you bike. The carb jets' performance relies heavily on the air flow resistance encountered due to obstacles including but not limited to air filters and exhaust system. If you have converted to pods and modified the pipes at all, you are going to need to rejet. If I'm not mistaken, backfiring can be a result of running without the air filters.
 
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