Author Topic: rich... no matter what I do... (Read 2275 times)

fmctm1sw · « **on:** July 12, 2009, 10:50:58 AM »

Both my 350Fs are rich. I set both float levels to the standard 21mm. I have both bikes' needles dropped as far as they go. Both bikes have new air filters and standard air boxes. Air screws between 3/4 and at 1 turn out. The bikes run pretty well (and I just did a 1000 mile report on my '72) but the '73 will stumble a bit at 3/4 throttle. As a drastic measure, I lowered the float level down to like 25 mm on my '73 and it is STILL rich. Carboned plugs after less than 10 miles ride. Timing was checked the day before that and it was right on and the advance was right on to. The plugs for both bikes are both D7EA (one range hotter). I just had my '72 out after I cleaned the plugs. I ran it with the air box lid off. Still starting to carbon up!

I'm starting to think along unconventional means. The weather there is in the 90's every day? I'm at sea level? One of the things I started to thinking about it the ignition system. They're both the standard set up with no new parts (except the batteries) anywhere. Might I have weak spark? The only thing I ever thought about with spark was, "is it there or not, ok move on." The charging systems checked out last time I looked.

Industrial Cafe · « **Reply #1 on:** July 12, 2009, 10:56:00 AM »

i wonder if your jets are .... worn?

Industrial Cafe · « **Reply #2 on:** July 12, 2009, 10:57:56 AM »

http://pjmotorsports.com/keihin_jets_&_parts.htm#%C2%A0Pilot/Slow%20Jets%20&%20Other%20Jets%C2%A0

they're press in, i think, maybe the emulsifyers

are clogged

(the little holes in the jet that add air)

fmctm1sw · « **Reply #3 on:** July 12, 2009, 11:05:54 AM »

On my '72 I just lined the tank. The fuel path is spotless (emulsifiers too). The point about them being worn though is well taken. Clean? definately. Worn ... possibly. Was reading some other posts, I think I'm going to measure voltage at the coils, then maybe film my spark and put it into a picture....

Patrick · « **Reply #4 on:** July 12, 2009, 11:31:28 AM »

FWIW, I preface this saying I know nothing about 350s, but perhaps what I learned from 750s might be applicable. A carb is a carb.

I has trouble with my K5 running rich, no matter what I did. Finally, I replaced the needle jet. This is the jet in the middle of the carb that the needle slides through above the emulsifier. Just like needles wear, so do their needle jets. After that my carbs ran like new. I hardly had to adjust the air screw at all.

If your 350 carbs have needle jets I would look there.

Patrick

mlinder · « **Reply #5 on:** July 12, 2009, 11:47:11 AM »

What size jets you have in there? Are you sure your choke is opening all the way? Are you getting above 1/4 throttle very often?

gane · « **Reply #6 on:** July 12, 2009, 12:18:20 PM »

Random thoughts, old plug caps often become porous (sp) and leak to ground. look for fireworks and listen for arcing .2nd, lean miss-fire will also cause carboned plugs, spray intake mainfolds w/wd40 or flamible other and listen for rpm changes. luck g

fmctm1sw · « **Reply #7 on:** July 12, 2009, 12:51:54 PM »

Quote from: mlinder on July 12, 2009, 11:47:11 AM

What size jets you have in there? Are you sure your choke is opening all the way? Are you getting above 1/4 throttle very often?

I have the stock 75 main and 35 idle jets. I'm usually at 55/60 with it. Half throttle maybe. The exhaust is an aftermarket Jardine (open) so if anything I''d expect to be lean. The results of my voltage test is this:

72 350: battery: 12.4VDC / Coils (both): 11.93VDC
73 350: battery: 11.91VDC / Coils (both): 11.57VDC

I'll add photos of my spark when I get them sized up...

*edit* hard to see but here threy are. Normal?

*edit* the bikes were running when those were taken...

mlinder · « **Reply #8 on:** July 12, 2009, 01:12:28 PM »

Choke opening all the way?

fmctm1sw · « **Reply #9 on:** July 12, 2009, 01:13:57 PM »

Quote from: mlinder on July 12, 2009, 01:12:28 PM

Choke opening all the way?

Yeah, both sets of carbs operate well are real clean internally. I've had them both off a number of times..

mlinder · « **Reply #10 on:** July 12, 2009, 01:21:42 PM »

OK, do us a favor, then.
Put in a new plug, go run it at 3/4 throttle to WOT for a little bit, shut her off (while at those throttle settings) and take a picture of the plug for us.
Then do the same at less than 1/4 throttle, please.

I can't really make out the deposits in those pictures you posted.

TwoTired · « **Reply #11 on:** July 12, 2009, 01:28:52 PM »

Are the carb internal parts using Honda component of parts from and after-market kit. Any numbers stamped on the needles?
I don't know what the correct numbers are, but the number format is different between Keihin and aftermarket components. Might be a clue there.
Have you verified the air jet feeding the main jet emulsifiers are clear as well as the passageway between the two components?

Jerry Rxman Griffin aka MuthaF'er · « **Reply #12 on:** July 12, 2009, 01:39:17 PM »

What's the resistance across each of your plug caps? If everything before the caps is fine then the caps could be your problem. Next in line going backwards would be the connection between the plug wire and the cap. Trim the wire back and reconnect.

These things are easy to do and cost nothing.

I'm assuming those were 2 different plug pictures. Looked to me like the darker one had a weaker spark. Switch the other wire from the same coil to that one and see if it improves. If so it would be the wires, the connection between the wire and the cap, or the cap.

fmctm1sw · « **Reply #13 on:** July 12, 2009, 06:34:39 PM »

Quote from: TwoTired on July 12, 2009, 01:28:52 PM

Are the carb internal parts using Honda component of parts from and after-market kit. Any numbers stamped on the needles?
I don't know what the correct numbers are, but the number format is different between Keihin and aftermarket components. Might be a clue there.
Have you verified the air jet feeding the main jet emulsifiers are clear as well as the passageway between the two components?

I don't recall the specifics of the jets when I had it out. I concentrated on cleaning them. I'll try to get them out next weekend and look. Air jet feeding the main jet emulsifiers

I know my idle circuit is clear but I wasn't aware of this one. That's something to check.

My plugs were cleaned up somewhat for the photo. You don't get a real good idea of what they looked like. I'll check out my caps as well and try to get a chop in....

Industrial Cafe · « **Reply #14 on:** July 12, 2009, 07:09:04 PM »

I know it sounds stupid, but half a bottle of lucas fuel treatment works wonders on the carbs.

fmctm1sw · « **Reply #15 on:** July 12, 2009, 07:44:33 PM »

Quote from: Industrial Cafe on July 12, 2009, 07:09:04 PM

I know it sounds stupid, but half a bottle of lucas fuel treatment works wonders on the carbs.

Got it, I've used Seafoam before. It just baffles me that it both bikes, every plug....

Industrial Cafe · « **Reply #16 on:** July 12, 2009, 08:27:14 PM »

you'll never fix em.
350s are junk.
just ship em to me.

Trevor from Warragul · « **Reply #17 on:** July 13, 2009, 12:18:27 AM »

Try side gapping the plugs.

http://performanceunlimited.com/documents/plugsidegapping.html

I'm doing this on all my bikes (except the Kawasaki H1A which burns perfectly on crap fuel).

Trevor

fmctm1sw · « **Reply #18 on:** July 13, 2009, 06:13:53 PM »

Quote from: morini on July 13, 2009, 12:18:27 AM

Try side gapping the plugs.

http://performanceunlimited.com/documents/plugsidegapping.html

I'm doing this on all my bikes (except the Kawasaki H1A which burns perfectly on crap fuel).

Trevor

Interesting read...

DavePhipps · « **Reply #19 on:** July 13, 2009, 07:00:24 PM »

My 2 cents.
If everything checks out Ignition, carb setting, etc, then I would try and replace the emulsion tubes. I know that on my FZR600 a worn emulsion tube will lead to rich behavior even if everything is correct. Unfortunately Yamaha/Mikuni made some way soft tubes for the FZR.
When you take the carbs apart again check the tubes. If the orifice is even a bit out of round then replace them.

jhasewhite · « **Reply #20 on:** July 13, 2009, 07:14:01 PM »

retarded ignition timing will act rich and foul plugs, especially at idle. check your advance lobes and check with a timing light.

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Author Topic: rich... no matter what I do... (Read 2275 times)