Missing

[donnybach]

Here’s where I’m hoping Andy (motorang) and scottieh are still around here somewhere. Recently noticed she (1vj) was missing/stumbling a little on the open road. I’ve posted my carb settings here elsewhere after the second carb sigma6 adjustments. Just took her out to suss it out again. Seems like she’s misfiring above 4-5000rpm on neutral throttle/cruise. I was about to start resetting the jets, as she bogged like hell when I opened the choke (so not lean) when I checked the book. It appears the advance (to 36 deg btdc)starts at 4000rpm, almost bang on where my issue is.
So likelihood my second pick up is failing? And anything known that can be done to test/rectify?
Long post I know. Cheers guys.

[jibber]

Scotties still about, posted earlier today, maybe a pm?
Motorangs not been on since Jan.

[Peen]

I know may not seem very intuitive, but if you havent already, remove the sidestand switch and short the wires together.

I chased a similar issue that I was convinced was the carbs for weeks after a full rebuild, it would run fine a low rpm upto about 3-4000rpm and fine at high rpm mostly, but would stumble and missfire in the mid range. It turned out that the wires on the back of the sidestand switch had worn through from rubbing on the frame and were only connected by a few strands and somehow that was affecting the bike at certain rpms, maybe certain vibrations. Removed the switch and it has run perfectly ever since.

[donnybach]

Sidestand switch is removed and bypassed but I’ll check the connectors and wires.

[donnybach]

Speaking to one of the guys in work, a biker and mechanic, he seemed to think (hopefully) that it may actually still be carb related, as it’s when coasting , not under load, when a pick up fault would show more. Dug the book out yesterday so I’ll test the pick up resistance maybe when heated too, and have another look at the carb settings. Thanks for the replies.

[scottieh]

Beetlejuice beetlejuice BEETLEJUICE! Call and i come on command. I am always lurking. :)

My guess would be carb. My 600 engines always seemed to bog or stumble around 4500 rpm, usually under heavy load like a hill, and especially when in 5th gear. Fuel float height, larger main, larger secondary. Never had an adjustable cdi to advance or delay the spark to play with.

[donnybach]

thanks Scottie
Got a 150 main in at the mo, and I drilled the secondary jet as per sigma six kit. So you reckon I should up my main as it’s when coasting? Or you mean lean it out a little?
I’m guessing the secondary is ok as it’s fine on the throttle.
P. S. Now I’m worried in case I’ve mentioned candyman too many times.

[scottieh]

thanks Scottie
Got a 150 main in at the mo, and I drilled the secondary jet as per sigma six kit. So you reckon I should up my main as it’s when coasting? Or you mean lean it out a little?
I’m guessing the secondary is ok as it’s fine on the throttle.
P. S. Now I’m worried in case I’ve mentioned candyman too many times.

Have you done a sparkplug check at the troubled throttle positions? Drive the bike out to a long, flat straightaway. Put in a new plug and get up to your problematic throttle position/speed and hold the throttle there for as long as you can then immediately cut the engine and coast to a stop. Check the plug for color and diagnose rich or lean conditions.

Try it a few times with new plugs each time.

[donnybach]

Good idea. Cheers.

[motorang]

I'm back. Had some health issues to cope with. Did you sort the bike out?

Andy