Day 1: it's aliiiiiiiiiiiiiive..... well, just about.

When I bought her, she wouldn't start at all. Just a firing of the odd cylinder to tease me.

I attacked it this morning and since 3/4 float bowl drain screws were stripped, I just took off the whole carb rail.

I took it inside, dismantled everything, cleaned, unjammed a couple of jets, de-crudded a pile of sediment & deposits, slapped it all together and voila.

It's running on 1, 2 & 4!!!!

Since 2 is running and 3 isn't, I'm assuming the coil aint bad. I cut off 3/4" of the plug wire and reattached the cap. No difference. I see spark when I ground the plug on the block but it's not very strong-looking. Odd, considering #2 is running fine.

NB: when I had the carbs all torn-open, I noticed one of the diaphragms had a tiny little hole in it. Very tiny - I had to hold it against a bright light to see a pinprick of light through it. I know it has to be changed but I thought I could at least bring her to life.

But would a tiny little vacuum leak cause one cylinder to not start when all the others came back to life without too much fuss? I'm not even sure which cylinder it was, to boot

Or are you thinking plug cap?

Any insight appreciated.

in any case, I can't believe it's alive at all on day 1!!!!!! I was expecting a bigger fight than this.

 

is this the bike in your signature? It could be the fuel mixture screw is clogged...the little brass fitting in front of the carb, in back of the intake boot. If you are going to pull the carbs (could be the pilot jet clogged too) I'd check the idle mixture screw holes. I had an xj700 give me fits like this and I did this as a last resort and she ran like a top after that. Check those pilot jets too...

 

is the fuel mixture screw the one that's covered by a little rubber puck? I didn't even notice that until after I had reinstalled the whole rail, when one of those little rubber pucks came loose.

If that can cause a whole carb to be ineffective, maybe I should just put the whole project on hold until I order a replacement for the diaphragm, since I'll have to tear her-down again anyway.

I think I read that you can 'repair' a minor defect in a diaphragm. Think I'll search that subkect further. Is repairing a diaphragm a duct-tape solution? Should i just pay the $60 and get a new one?

 

no duct tape lol.. a repair is a temp thing. if you are serious about riding the bike get a new one. you can temp put a super thin layer of silicone over the hole but it ain't going to last long.

Oh the mix screws are the ones on the top of card where they slide into the boots closest to the engine. mine weren't covered but yes they were all sealed at one time. make sure you count ow many turns out tey were to get you back in the ballpark. You will most likely have to retune anyway after everything is clean.

 

Mystery is solved
before, I'd remove & check plugs for wetness/fouling and when I put the caps back on, the firing cylinders would "move-around" (sometimes # 3, #4 etc...). Very hit & miss. So I bought new plugs and caps.

Now it's consistent. It's only #4 that isn't getting spark. Seeing as how #1 and #4 share the same coil and #1 runs fine, it's logically in need of a new plug wire.

I'm a little intimidated by the job, since the original wires need to be 'dug' out of the coil so I'll get this done by someone more talented than me.

Know what's cool though? Running only on #1, 2 and 3, even when it's close to freezing outside and the engine is 100% cold, I put the choke on and just TOUCH the starter and she's purring smoothly. Within a few seconds, I have to back the choke down and it settles into a smooth, quiet idle...... AND THIS IS ONLY ON THREE CYLINDERS!!!!! I can't wait to have all 4!

Very exciting. That's why I've resolved myself to letting someone do the plug wire properly. This is too much of a find to have me hack my way through it.

After that, a proper color tuning and carb synching with YICS tool and this bike will run & sound like new.

 

Oh, I forgot: 85maximXX, I didn't mean I would fix it with duct tape, I meant is repairing the diaphragm not a proper or long term solution. (IE a quick fix or "duct tape solution")

I just don't want any detail on this perfect specimen to be anything short of perfection.