Just finished replacing coil/timing advance unit a few months ago which completed a whole electrical overhaul. I got to ride a few times to be sure everything was good and then the cold weather hit and I couldn't stand a 20 degree drop in the mornings, overnight, so I stopped riding for a while. The last ride I made was about a 3 hour tour in the north GA mountains with the wife on the back. It did great. 2 months later, I decide to gether out again. One, because I wanted to blow the dust out of her, and two, the weather turned incredable - mid 70's.

??? NOW SHE WON'T START ???

Checked for spark and fouled plugs, good. Checked for gas in cylinders, good. Pulled of AC cover to be sure filter is not clogged, good. I have drained a full battery 3 times with no luck. She dosn't even give me a sign of ignition. WTF!!!For the one month that I had everything straightened out, she was a dream with no problem starting up at all.

By the way, she's a '77

Any suggestions?
Rich

 

Got some more info.

Back before I did a 4 hour run in Sept. my dad came by and helped me get the timing and mixture set up.She was running great.A few days later I got a set of points/condenser in the mail, (the old ones were worn with a hole in the center of the contact point). Put the new ones on and couldn't get it right. Put the old back on, in the same position it was in before it came off, and without doing a test ride, loaded it on the truck and went to TN to meet up with a buddyto do the Cheerahalla Skyway loop, (about a 4 hour ride). It felt a bit rough when we started out but I didn't think much of it till 1/2 way around when she started to miss every now and then. By the time we got back, she was only firing on one cylinder and missing on that one every now and then.

Told you all that to tell youthat I think I did some damage to my valves and/or valve guides on that trip because now she will smoke heavily from the rear cylinder, but only till she warms up. I think it's a guide because I read a post somewhere that suggested oil in the rocker cover will seep into the cylinder when not running and need to burn off during warm-up. Makes sense to me.

Back to the original topic. Compression in both cylinders was 125 before that trip. Now they are both at 100, (just checked tonight for the first time since that trip). And, the fins under the rocker cover gasket are oily, not dripping, just smeary. (This is something I knew about for quite some time and was planning to investigate this winter).

Knowing all of this, is it possible that it won't start because of bad valve guides? Here is my logic for that... Although I have had a leaky rocker box gasket, the oil has kept it swelled and helped to keep the pressure in the cylinder, even with a worn valve guide. However, after sitting for two months, the gaskets have shrank a bit and because of the bad valve guides, the oil has drained down into the case, thus, not giving me enough compression to cause ignition.

Does that sound plausible, a bit of a stretch, or am I smokin' crack? If it is possible than how long would it take of me turning the engine over before I get enough oil back into the rocker cover to get the gasket to swell again and to get compression back up to what it use to be? I don't want to burn up the starter.

Rich

 

That thing should fire with as little as 60lbs of compression. I would drain the gas tank & fuel bowl on the carb, put in fresh fuel and a new pair of plugs. Then with the air filter off, make sure that the accelerator pump is doing it's job by checking to see if you're getting a good stream of fuel in there.
Check pushrod adjustment to be sure things are right there. That could have caused the problem of only running on one cylinder.

 

Pyro......
With regards to your present problem:
<Back to the original topic. Compression in both cylinders was 125 before that trip. Now they are both at 100, (just checked tonight for the first time since that trip). And, the fins under the rocker cover gasket are oily, not dripping, just smeary. (This is something I knew about for quite some time and was planning to investigate this winter).

Knowing all of this, is it possible that it won't start because of bad valve guides? Here is my logic for that... Although I have had a leaky rocker box gasket, the oil has kept it swelled and helped to keep the pressure in the cylinder, even with a worn valve guide. However, after sitting for two months, the gaskets have shrank a bit and because of the bad valve guides, the oil has drained down into the case, thus, not giving me enough compression to cause ignition.

Does that sound plausible, a bit of a stretch, or am I smokin' crack? If it is possible than how long would it take of me turning the engine over before I get enough oil back into the rocker cover to get the gasket to swell again and to get compression back up to what it use to be? I don't want to burn up the starter.>
I cannot agree with that at all. Here are my reasons....
The 100 psi in each cylinder is both good and bad.
Good because it tells me both cylinders are the same, meaning one of them has not suffered some kind of serious damage due to a bent valve, broken rings etc.
Bad news is that 100 psi is a bit on the low side for compression.
Before you do anything check the valve push rod clearences. If they are too tight this will keep the valves off their seats and result in lowered compression.
Also, if the engine has been run anytime at all with the tight valves, then the valves have been burned and the seats as well. This will cause low compression. This is the reason proper valve adjustment is so critical on an ironhead.

Oil leaks may be from the rocker box gasket(s)......but they could very easily be from the push rod cork washers as well. Look at those corks! There are 3 in each tube. The top cork gives the most trouble, followed by the bottom cork and the mid cork is the last to leak in my experience.

Now ,while you may well have some worn guides, that in itself would not cause it to not start. Worn guides can[color="#0033ff"][size="4"][font="arial"] cause the engine to foul the plugs and that will cause hard starting, but the worn guides in and of themselves will not.

Low compression has nothing to do with worn guides. What is going to cause the compression to drop lower than it was before is the valves are no longer seating as they should due to worn valve faces and worn valve seats. The two surfaces touch each other and wear away together. This causes compression to leak past the valve seat(s) and can also cause hard starting.

Rocker box gaskets......
These gaskets do not swell and shrink. They leak because they need replacing and tightening down to the proper torque. Of course the face of the heads and of the rocker boxes must be flat and clean before you put a new gasket on.
The heads, being cast iron, are going to need just a good cleaning off of the old gasket. The aluminum rocker boxes should be cleaned and then put on a piece of 400 wet/dry paper, laying on a piece of glass or other flat surface. Add a little mineral spirit to the paper to wet it and sand the rocker box in a figure 8 pattern. Just nice and slow and steady. After a minute look at the surface. Is it smooth, dull and even all over? I bet not. Continue to sand until the rocker gasket surface is completely dull and even. Now you have it flat and it will not leak.

The rocker boxes have no pressure in them to speak of when the engine is running.

 

I had a similair problem with the rear cylinder smoking and hard starting I drain the tank, changed plugs, adjusted valves, cleaned card and I just recently put something called mystery oil in the oil and now it starts easily. Previously it was last started 3 years ago and road 300 miles before that it wasnt startedfor about nine years. after i adjusted my valves and changed my exhaust clamps I have very little almost none when starting and none when warm. adjusting the valves were the best thing I did I do beleive. I still do have a seloniod going bad and a breather problem I am tring to straited out but the bike runs almost 100% now. When I picked it up 3 weeks ago it wasnt in the greatest shape but not bad for a 25 year old bike this site helped me out great also i bought bought the cylmers and HD service manuals andthat has saved me many times. good luck with it I havent read everyone resonse above ut I would say from my experience is do the valves it can take 15 minutes and does wonders.

 

toPG - I love your long replys so don't sweat it.It deffinatly made some things clear.

toall - A neighbor of mine came over for a fresh look on Monday, went through the motions again and then he sniffed the gas. Not good. It was real hard for me to believe that could be the problem after only two months because I've had other bikes (Honda's) that sat all winter and the only issue would be the battery. I let the riding lawnmower sit forsix months and as long as the battery is charged, it cranks right up, and I put **** gas in that. Other vehicles that had to be repaired and sat for four months or more, no problem. Drained the tank and re-filled.Instantly started up and was ready to go. It blew my mind that the sporty was either that sensitive or the gas was that bad. Anyway, thanks for all your input.

I still have some things to clear up this winter but for now, she runs again

Rich

 

Glad you found your problem. A few years back I could not get my old BSA started. I had run the thing about three weeks before, and it ran great!Now It would not start. good compression, good fuel, spark, ect. turned out that a mud wasp had built a nest in the exhaust and plugged it up hard. I like to think I'm pretty sharp at figuring things out, but this one about whipped me.