Poor low speed running and cutting out - sometimes runs ok, few days later bad

[simon gilling]

I have had my '72 Z1 for 7 years and it has run pretty fine til now. When I woke it after this winter, it was reluctant to start then cleared out ok. I have ridden itquite few time since, starting is hard, seems like #1/#4 are not picking up (pipes cooler), then it clears and it runs fine from tickover to redline. This week though, it would start then cut out below 2000 rpm. I have drained the float bowls, small amount of crap in bottom and tried a different set of plugs. still poor. I do not want to go all around the houses so would welcome suggestions as to most likely root cause. The thing that I do not understand is that it ran really well last week and now it is sick. so I do not think it is major. Next thing I might try is a spare set of carbs. Any other ideas. Could it be that a Z1 should not share garaging with and H1? The H1 starts and runs fine after the same storage, but the fuel bills are horrendous.
Thanks in advance Simon

[zed1015]

Probably just crap that's settled in the tank over winter floating about in the fuel and getting in to the pilot circuit intermitently.(Are you running an in-line filter) no point trying other carbs, just blow out your jets with the air line that should do the trick. As for cyl's 1 and 4, if you stored the bike on the main stand these are the last to get any fuel when starting from dry and may take a few seconds longer to fire properly, otherwise the only other factor these cyl's have in common is the ign system which may have developed a dodgy connection due to damp storage. Personally i'd go for the crap in the fuel, OK.

[chrisu]

wot he said.

clean carbs, drain and clean out tank, clean filter.
check coils - swap to see if fault moves.

[Ed Z1-R]

simon could be either a fuel / carb or indeed coil problem

[simon gilling]

It's Fixed! Found no spark on plugs #1,#4, so tank off and found a loose connector to the ignition box. This had caused poor running to completely cut the motor, then connected 1/4 coil to the 2/3 connector. 1/4 coils gave good spark. then traced through the the 1/4 wire from ingnition box and found a break, repaired it and the Zed is running fine. Thanks for everyones suggestions.

[chrisu]

you're welcome

[Ed Z1-R]

yeah no worries mate.