Yam but not FJ

[chiz]

Maybe one of you learned gents may have a tip sorry not FJ
Hoping for a bit of help here. Over the summer I cleaned and set float height on carbs re-located the new Amazon battery and solved some indicator issues and only just recently started riding my bike which can be considered a striped 80 Yam special 850. The bike worked fine in 21 with no engine issues misfires etc.
After setting float heights I noticed the bike started sooo much easier as it was a pain for years I suspect the height was set between 24 and 26 so kick starting is not an issue anymore there is no electric start. I suspect I am running a higher fuel level hence  easier starting.  The bike is now a pain to ride though the backfireing, missing and surging is entirely new and after paying attention gets increasingly worse as the engine warms up.  At first I thought it was a fueling problem but after going over the xs750 carbs mainly cleaning again I am now looking at electrical but haven't a clue how to proceed The plugs are a mid chocolate brown and that is all I have got just don't know where to go from here any good guesses?  Chiz

[Pat Conlon]

The bike worked fine in 21 with no engine issues misfires etc.

Unless you had mice, if your bike worked fine last year, it's doubtful you have an electrical issue.

.....After setting float heights I noticed the bike started sooo much easier as it was a pain for years I suspect the height was set between 24 and 26 so kick starting is not an issue anymore there is no electric start. I suspect I am running a higher fuel level hence  easier starting.  The bike is now a pain to ride though the backfireing, missing and surging is entirely new and after paying attention gets increasingly worse as the engine warms up.  At first I thought it was a fueling problem but after going over the xs750 carbs mainly cleaning again I am now looking at electrical but haven't a clue how to proceed The plugs are a mid chocolate brown and that is all I have got just don't know where to go from here any good guesses?  Chiz

Your carbs are too rich. With a rich setting, the start up is fine, actually, quite good as you described.....however as the engine warms up, the rich fueling symptoms show up.....again, exactly as you described.
Lower your floats, you're flooding your engine. If you have problems starting the engine, clean your choke circuits and idle circuits......that's my guess...

[chiz]

That's awesome thanks.

[twood1972]

Set floats last year and ran fine last year. Are you reading last years plugs? Surging and backfire can indicate a lean condition. Might be worth checking your carb bowl vents, fuel line for linking. Emulsifying tubes. Been around that mulberry Bush. Can be frustrating.

[Pat Conlon]

Tim brings up a good point about plug reading  
I'll add another twist. If your 850 has a vacuum advance feature like our FJ's (for emission control) you need to cap off the vacuum to the advance module to get an accurate read on your plugs.
Ever wonder why your FJ plugs look white? It's the advance that happens when the throttle plates close. This advance flashes off any unburned hydrocarbons, thus turning your plugs white.

The first time I looked at my FJ's white plugs I freaked out....alarming as hell. Holy crap,  I knew the US EPA required a lean setting on the carbs, but so lean that my plugs are white?
Only by disconnecting the FJ advance can I get a true plug read.

Perhaps your 850 has the same? Your dark (fuel rich) plugs are reading lighter due to the advance?

[Waiex191]

Clean the carbs.  Then take them apart and clean the parts you missed and skipped.  Then do it one more time for the rest of the stuff you missed and skipped. That's how it went for me anyway.

[Firehawk068]

Tim brings up a good point about plug reading  
I'll add another twist. If your 850 has a vacuum advance feature like our FJ's (for emission control) you need to cap off the vacuum to the advance module to get an accurate read on your plugs.
Ever wonder why your FJ plugs look white? It's the advance that happens when the throttle plates close. This advance flashes off any unburned hydrocarbons, thus turning your plugs white.

The first time I looked at my FJ's white plugs I freaked out....alarming as hell. Holy crap,  I knew the US EPA required a lean setting on the carbs, but so lean that my plugs are white?
Only by disconnecting the FJ advance can I get a true plug read.

Perhaps your 850 has the same? Your dark (fuel rich) plugs are reading lighter due to the advance?

I always understood that it was the "wasted spark" design that fires the plugs on both the compression, and exhaust strokes that caused this.............

[chiz]

Ok changed tack and trying to get mother loving chainsaw to run,,. gave up for now. So float heights were 2+ mm high I was shocked what happened here???anyway back down to 26mm will slap them on later. No vacuum to spark unit no need to worry here... sick of smell of gas taking a breather.

[Pat Conlon]

I always understood that it was the "wasted spark" design that fires the plugs on both the compression, and exhaust strokes that caused this.............

Hey Alan, I think the wasted spark helps keep the plugs clean, for sure, but turning them white?
My Miata also has wasted spark and I can read those plugs. (not really needed with an O2 sensor and laptop)

The white on our FJ plugs comes from the 40*to 50* advance that happens under high vacuum (closed throttle)

[chiz]

OK was just about to go for a rip  Ha kicker jammed solid I give up.

[Pat Conlon]

Hydro locked?

[chiz]

Naa  She done this before first time it fell over and ended up being a small loose bolt in the primary that never made sense... and she rolls in gear with the plugs out.Perhaps I'm reading this wrong though?
Chiz

[chiz]

The bike worked fine in 21 with no engine issues misfires etc.

Unless you had mice, if your bike worked fine last year, it's doubtful you have an electrical issue.

.....After setting float heights I noticed the bike started sooo much easier as it was a pain for years I suspect the height was set between 24 and 26 so kick starting is not an issue anymore there is no electric start. I suspect I am running a higher fuel level hence  easier starting.  The bike is now a pain to ride though the backfireing, missing and surging is entirely new and after paying attention gets increasingly worse as the engine warms up.  At first I thought it was a fueling problem but after going over the xs750 carbs mainly cleaning again I am now looking at electrical but haven't a clue how to proceed The plugs are a mid chocolate brown and that is all I have got just don't know where to go from here any good guesses?  Chiz

Your carbs are too rich. With a rich setting, the start up is fine, actually, quite good as you described.....however as the engine warms up, the rich fueling symptoms show up.....again, exactly as you described.
Lower your floats, you're flooding your engine. If you have problems starting the engine, clean your choke circuits and idle circuits......that's my guess...

Thank you,,, You were bang on. forums are great.