Rebuilt top, won't start, kicker binds up, and backfires

A couple of thoughts from someone who has re-ringed a few 350s.

#1, your compression numbers will not be consistent until you break in the new rings. If you have one side at 90psi and the other at 110psi, I wouldn't worry about that for now. Run the bike, it'll smoke a lot, then less, than only a little, then finally not at all. After it doesn't smoke at all, re-check and I bet you're high and consistent on both sides. If you didn't hone / deglaze your cylinders, the rings may not seat and you may always smoke and have bad compression.

#2, that backfiring that you noticed is absolutely the advancer. I have had that happen once (I had no idea why or how it happened) and then a second time (I was much wiser then). Now that its corrected and you're back to an engine that's coughing, you're okay.

#3, your carbs pouring gas into your cylinders will absolutely prevent you from running. I have had this happen before and it can often trick you into thinking you have other issues. If you're pouring gas onto the floor (could be out of the pods), you really should not proceed until you've corrected that. If you didn't set your floats, set them. If you did, add 1 or 2 mm to the setting and try again. This will close the floats sooner, aka less gas in the bowls. If THAT doesn't work, you will need new needles and seats (very cheap IIRC).

Once your carbs are set up, try starting again. I bet it runs and then you'll be able to check your timing. I had a 350 once that ran like shit, and it didn't give a consistent 'blink' on the timing light, more like an intermittant one. It was a bad point. Replaced it and the motor ran beauty. Just something to keep in mind.

Cheers

DS

Thanks to everyone so far for all your insights. I did have the cylinders honed before reassembly. I put in new plugs today, adjusted the floats to add two more mm, and checked the advancer. The old plugs came out wet after a few kicks, but the new ones came out wet on the threads but appeared to be dry on the ends. For the floats, it still seems as if the right one wants to leak all over the floor from the overflow tube, even after the adjustment. I just put some new needles and seats on order. The Advancer was off too, but not 180 out. This time I found that the last time I put it together I hadn't properly seated the thing on the camshaft. I put it back together properly this time and gave it a few more kicks with no avail. When the carb parts come in I will try it all again and double check the static timing before giving it another go.

One trick I have used with stubbon motors that wont start (after I know that all the basics are right) is a squirt of areostart or Start ya bastard. Dont know what its called where you live but Im sure you know what I mean.

I find the best method is a short squirt into the carb intakes. (easier if you got someone to help). Sometimes this is all it needs to get it running, then you can tell whats needed by the way she runs.

IMPORTANT: If it does'nt start after a couple of tries, STOP using the start spray. You can fill the sump with gas and cause a BIG explosion. Leave it for 30 or so minutes before trying again.

The saga continues as my self-confidence plummets. I received and installed new fuel shutoff pins and seats, readjusted the floats and this all seems to have fixed the fuel overflow problems. So I shifted my attention back to the timing and points advancer. The last time I took the advancer plate off to see if it was properly seated I may have put the cam back on 180 out again. Low compression backfires confirmed this for me when I tried kicking the engine over. So I switched it around and the engine seized and wouldn't kick at all like it did when I originally had the thing out 180 degrees.

Could small backfires be caused by anything else? And I am still uncertain why the kicker would seize simply because the advancer cam was out? Could it be that when seized the cam is actually in the right orientation and that some mechanical engine issue is going on? Would a bent valve do this?

Sorry, I meant to say the advancer.

Any serious valve train issues might cause the kicker to bind up, yeah. Might be time to pull the rocker cover and inspect things.

I may have made some progress. Spark rechecked, synched throttle cables, set air/fuel mix, retested battery. I then tried to start with starting fluid and got some serious backfires out of the carbs. Since I've compression (enough), spark and fuel, and since the thing seems to be running lean and backfiring out the intakes, my conclusion was that it was firing out of time as many of you have suggested.

So I pulled the top cover, turned the rotor by hand so that the index line on the cam sprocket was lined up. I then gave it another full turn and deduced that it was set 360 deg before TDC. Does this make sense? In other words, I didn't set the sprocket index line at the top of the compression stroke.

Now I'm having trouble getting it set right because I am second guessing which turn is the compression stroke. I've fiddled with it three times now and keep getting the same results, even when holding the rotor in the correct spot while adjusting the teeth of the sprocket. Any suggestions?

If the lines on the cam are parallel with the top of the head when the crank is at LT (left top dead center), then that's all you need to do. Don't worry about lobes or valves or compression or exhaust; it's all irrelevant.

Really? Shoot. Then this wasn't my problem, and therefore not the source of my solution. Now I am back to my original conundrum of the kick lever binding. Upon testing things today, I went back and forth a bit between the blue and yellow wires of the coils and points. When all colors are matched, the kick binds. When I switch them so blue coil connects with yellow point/condenser, the kicker moves freely, but I get backfiring.

For the life of me I cannot figure out why a wire issue would effect a mechanical process?

Because what you're getting isn't binding. It's an ignition timing issue. The spark is firing too soon (your timing is advanced) and your foot is trying to kick against the combustion of the bike.

Here's a vid of it happening to me:
http://www.youtube.com/watch?v=IrhvJ3CVmnc

You can see at 14 seconds in, the kicker kicks back because of the advanced timing (my timing is intentionally advanced because of my engine modifications).

Instead of switching your wires, turn your points plate about 1/8th of a turn counter-clockwise and see if it makes a difference.

Ah. That makes so much more sense. Thanks and thanks for the vid. Doesn't it completely jar your leg to kick against it like that? I'll give it another go tomorrow.

aconley003 said:

Ah. That makes so much more sense. Thanks and thanks for the vid. Doesn't it completely jar your leg to kick against it like that? I'll give it another go tomorrow.

Click to expand...

Yes, it does. Doesn't happen all that often though, I was kind of (un)lucky to get it in that vid.

Well in recent news, ye ol' 350 still doesn't want to run. But I have located an issue that may remedy my problems, yet will require me to tear it apart again. Upon timing it to a "T" today, double checking everything and even getting some fresh gas, I noticed oil seeping out from the bottom two gaskets (head gasket and the one on the bottom of the barrels where it meets the bottom case). Lack of seal would definitely give me bad compression, and I suspect my compression has gotten worse since I had a tester a few weeks ago (90-120). And this is leaking just from trying to kick it over repeatedly.

Even if this isn't the ultimate problem, I still have to rip it down and try again. The joys of learning!

I found what looks to be fresh metal shavings (small) on my camshaft. Looks like I will be opening the bottom case to clean and inspect. Any suggestions on how best to go about cracking the crankcase? What bonding agent do I use to reseal it and where can I buy it? Thanks.

I prefer Threebond, but Honda sells their own equivalent at the dealership. I think it's about $10 or so?

Upon inspections, this bit of scoring on the clutch basket is the only place I can find thus far that might contribute to metal shavings mixed into the oil. Is this wear normal? I've measured the clutch and friction plates and they are still all within specs. The clutch springs are within spec too.

And here is a (poor) shot of one of the ribs in the cam case. The shavings that I found were aluminum. I measured the thrust washers upon realizing that they might be different widths and, sure enough, one is .1mm and the other is .2mm. Could being out by this small amount really effect clearances enough to begin shaving down rib surfaces?

I've another question for those who've rebuilt motors. When I took the top end apart for the second time the top rings on my pistons were well set into the groove and wouldn't move around. I had cleaned these groves well before installing the new rings. Is this stickiness normal to a ring properly seating or should it float more freely?

Here's the latest update in case anyone else stumbles upon this open thread.

I tore it down again because I found oil leaking from the seals on either side of the barrels. I found some aluminum shavings too, so I decided to split the crankcase and clean it out completely and check for wear. Once it was all apart I did another leak down test on the head, relapped the valves, but couldn't get it right. So I took the head to a local vintage repair shop to recut the seats. It is sealed and perfect now. With everything clean, I reassembled everything, triple checked the timing on the cam sprocket (replaced the chain too), and it's all sealed up nicely. The metal shavings, I deduced, came from the cam rubbing down one of the ribs on the bottom of its case during assembly the first time around (see picture). I added new clutch plates.

I also tore out the wiring harness and rebuilt it properly. It had been spliced together for far too long, and I must say that it is nice to have cleaned it up and know for certain that things are routed in the right directions.

Unfortunately, I still can get it to turn over. I've got spark and my power coming from my coils is solid. I kick it and kick it and will occasionally get a small backfire out of the exhaust pipes. But it just doesn't want to even pretend or cough like it wants to start. It feels/sounds like it did when I had a dead battery, but I bypassed the battery today with no alterations in performance. I did notice that the pink/common stator wire was not connected to the tang on the stator, so I put a connector on it and reattached it.

In the end, I am at a loss as the saga continues.