Topic: white film / residue inside #2 carb

[kbfromvt_400F]

I have searched on all 3 links provided in the "Before you post" thread at the top of the his forum.   If I somehow missed an old thread that answers my question, I apologize in advance.  I'm a newbie to this forum and a newbie to motorcycles.  I like a lot of other fine folks have decided to toss my hat into the CB cafe conversion arena.  I hope I don't frustrate anybody to much with my lack of what some may consider "basic" knowledge.

This past weekend I traded an old woodstove I had sitting in my backyard for a 1975 Honda CB400/4 SS.  I did not need the old rusted woodstove and I've been looking for a project bike, I figured, hey, what the heck.  I used to drive 125cc and 250cc dirt bikes when I was younger, but never anything 400cc or bigger.  I thought a 400 would be a better start for me than a 750.  Maybe I'll migrate to the 750 later.  I'm 247lbs, 6'3" tall, so maybe the 400cc will end up being to small for me.

This bike will not currently run.  I know the former owner and I know he's honest.  He said he hadn't ridden the bike in about 2 years.  Last time he rode it, he said that it was running well.  He let it sit for quite some time, then when he went to start it and it wouldn't turn over, so he gave up.  I decided to do a "tune up" I guess you could say.  I pulled the spark plugs which didn't look so great, but nothing to write home about, except for one, the #2 cylinder plug was covered in a cloudy gas mixture, basically looked like dirty gas.  When I pulled the carberators all looked decent, except for the #2 cylinder carb, which had this thick white residue/film inside the inlet pipe that goes into the cylinder.  Also, on the female side on the engine there was the same thick residue/film on the inside.  I have tried shining my mag light in there and also down into the spark plug hole, but I can't see much if anything, I can't see how far in the residue goes.  This is the only cylinder this is on, the rest look good based on what I can see, and on the carbs.  Also, the stock airbox that all the carbs connect into had a dirty gas mixture sitting on the bottom, about 6-7mm deep, I presume just from having choke on to long and flooding it.

I was going to just try to get it running, ride it around a bit while the weather is still nice.  Then come Aug-September start a full tear-down and rebuild into a cafe.  Pull the engine, the whole nine yards.  Do you guys have any thoughts?  SHould I pull the engine now and forget riding this year?  Any idea what the white residue is?  My searches where for "white residue" "white film" etc. 

Thanks guys for any input, it's appreciated.  My name is Kyle, nice to meet you all. 

[750goes]

Hi Kyle & welcome,

I would do the following things first then make a decision on what to do next...

take all the plugs out - pour in some light oil  (even the number 2 cylinder) kill switch set to "off" and ignition "off", and either try and kick the motor over or use the starter button - with a fully charged battery of course...only short pulses on the starter button - or lots of kicking you decide.....
if the motor sounds like it does not want to turn - don't force things too much - pour some more oil down the plug holes - leave it a few days and repeat the above

when and if it comes good and loose - then on to number 2....

[SteveD CB500F]

Kyle, you need to define "wouldn't turn over"

Do you mean:

• it would crank (starter or kicker) but wouldn't fire
• the engine is frozen and will not crank at all

If frozen, do what 750goes says

If cranking but won't start, investigate fuel flow and ignition.

Post back

Steve

[kbfromvt_400F]

Kyle, you need to define "wouldn't turn over"

Do you mean:

• it would crank (starter or kicker) but wouldn't fire
• the engine is frozen and will not crank at all

If frozen, do what 750goes says

If cranking but won't start, investigate fuel flow and ignition.

Post back

Steve

I apologize.  The engine is cranking just fine, appears to be no problems there, it just won't fire.  I've always said "turn over" as in "won't start", I guess that's a habit I should lose.   So I will go the fuel flow and ignition route as you suggested, which is the direction I'm already headed in.  I'm attaching an image of the #2 carb and hopefully you can see the white residue I'm referring to, almost looks like corrosion.  My digicam doesn't do so hot with close range pics. 

[nickjtc]

That looks like alloy corrosion. If it is it means that moisture has got in there some how.

[SteveD CB500F]

OK. So two things to fix.

1.  Carbs need a thorough clean out (!)
2.  Engine won't fire:

Once you have cleaned the crud out of the carbs (be very particular with the tiny low-speed jets and passages, you need to check the spark (sorry if I'm being too basic here)

If plug is wet and no spark - ignition
If engine spits and farts but doesn't run - timing
If plug is dry but does spark against cylinder head - still got a fuel problem

Post back.

[kbfromvt_400F]

OK. So two things to fix.

1.  Carbs need a thorough clean out (!)
2.  Engine won't fire:

Ok, I'm with ya.  The other carbs are clean enough to eat off of, it's just this one.  I'm going to finish cleaning, reassemble and do as you've suggested.  Thanks very much for the help.  You should hear from me within the next week.