Newbie with a passion for buying crap which doesn't work....

[Cureforsanity]

Now then, howdo and ey up from Lancashire.

Some have mid life crises where they go out and buy an Harley and get a tattoo, others a teenage nymphomaniac and a convertible 911....

I on the other hand am still in my first childhood but have recently found myself attracted to (or maybe attracting) crap that doesn't work.

Usually I can fix it, but after a long long time without a bike I fancied getting another stroker and gradually trading up to the LC350 which I sold for peanuts in the early 90's.

I've started with a YB100 (Please don't laugh!) which has a good spark but won't fire.

I've cleaned the carb out so fuel gets to the cylinder but still no joy. I assume because I'm getting a spark at the plug with the ignition switched on but no battery connected it should still start?

Head's coming off tomorrow to check the piston is intact with it obviously being such a highly tuned race item.....

Any ideas to stop my foolishness turning into stupidity like last week when I had to do a silly dance outside the pub after eating a full bag of ghost chilli flavoured pork scratchings?

[ZebraDriver]

Is it fitted with the right length of spark plug?. A mate of mine once bought a bike for a tenth of its value because the previous owner had fitted the wrong plug...

[almostthere]

I tend to buy piles of junk that I can see potential in, once I've bought it I usually can't be arsed to do much with it and leave it in the back garden, doesn't annoy the wife one bit
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Beer, It's the reason I get up every afternoon
www.mfairco.uk

[stickybackbob]

Where are you in our fair county?

Is the plug getting wet with petrol when you're trying to start it?
How long has the bike not been run for?

[Ariel Badger]

I buy piles of junk and race them. How are the crank seals?
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Bikers make great organ donors, get 115 on your licence today.

[wodge]

If you trickle a little fuel into the spark plug hole, refit the plug and give it a start it should fire up for a second. That will prove your ignition is ok. If ignition is good then the piston isn't sucking fuel in so it could be crank seals, cylinder gasket or leaky connection to the carb.
Do yb's have reed or rotary valves? If it is rotary valve is it fitted correctly? Is the exhaust blocked? Or, as you think are the piston or rings knackered.

My RXS was bought as a non starter. It turned out to be the cylinder base gasket, or more precisely the one and a half gaskets as the previous owner had refited the cylinder without removing parts of the old gasket.
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nolidge iz pouwur.
Yamaha RXS100 RS100

[Robby]

If the bike is meant to have a battery, then fit one. A self-exciting ignition system can start a bike without a battery, but if the bike hasn't been started for a long time then you want to give it all of the help that you can.

Give the age of the bike and the sort of owner it will have had over the years, all sorts of things could be the problem. All of the replies so far are a valid thing that may have failed.

Anyway, easier bits first. We can assume you have fuel now. Even if the carb is misbehaving a bit or there is a small air leak, it will at least cough and probably run (badly).
You have a spark. Is the spark happening at the right time? If it has points, are they in the right position. If it uses a hall effect sensor off the flywheel, has the flywheel slipped on the crank?
Compression needs testing.

The easiest way to tell if it going to run or not is to try bump starting it down a long hill.

[Iain.]

[A100man]

[Cureforsanity]

Cheers chaps, I'll stick a new plug on it and sort a battery in the morning.

I now have a new problem though, my partner in grime decided to strip & clean the carb on Saturday after I did it on Thursday and now it's leaking petrol from the float bowl overflow.

He doesn't reckon he's left anything out but it sounds to me like he's tipped it upside down and lost the spring from under the float valve so now it's stuck open....

Ah well, at least I can get a repair kit but now it seems the starting of the thing may have been put back a few days.....

[Cureforsanity]

Well.

What can I say?

Bought a new spark plug, BP7HS (the one in the hole was a BP6S) and it started first kick!

Admittedly it blew a smokescreen out of the back to begin with but after that it was quite clean!

Now it didn't run for too long and it doesn't respond to the throttle or choke really and occasionally it has a tendancy to scream up the rev range so I knocked it off but I think a carb overhaul will do it a power of good.

At least I know it runs now and the 'pipe is gas tight and quiet.....

Hmmmm, I don't like quiet pipes

Sooooooooooo Flog it as is or go with my original idea and make it into a bit of a 'racer'? Admittedly I've found a pair of period Tomaselli clip ons so I'll assume the latter