Topic: 1980 Honda cb900c custom, has Kerker, running lean?

[Hondawggie]

So I did somewhat of a 'plug chop' today, my 2nd day of riding the 900c, and all 4 spark plugs look like this:



I suspect 2 things:
1) I've read on the board here that bikes got set on the lean side from the factory.  This is a bone-stock bike except the pipe: stock airbox etc.

2) the prior owner put on a 4-into-1 Kerker and it does make some noise, its not a hush-hush 'looks only' pipe

3) so I bet the prior owner did not rejet for the better-flowing Kerker pipe

Doesn't this plug look a bit on the lean side, all dry and the whitish top?
Does it look *dangerously* lean, ie. leading to overheating?

I'm wondering if the yellowing at the top of the header pipes right at the cylinder indicates overheating?

Does it need a rejet or just leave it be?

Check out the yellowed header pipes in this photo I took -- from the front view the yellowing is across all 4 pipes and is *very* noticeable, maybe she's too lean and overheating

[Alan F.]

too lean or too rich could be related to two other factors best not forgotten, a K&N or other high flow air filter will flow more air leaning out your carbs, same for pods or no air filter in the airbox. The other thing you can do is check your exhaust baffle, if it's not wrapped, wrap it. You may run a little richer for it, and you might enjoy the difference in sound too.

I'm not sure without checking bikebandit or servicehonda what the stock jetting for that bike was, but only a visual inspection of your jets will tell you what's really in there. (unless some PO drilled your jets...)

Checking with the dohc4 sited like www.cb1100f.net and www.cb750c.com may reveal real answers from those who've been where you are now.
Cheers.
Alan

[MoMo]

HW,  was that a full throttle run, shut off and then visual inpection?  If  so, it does look a bit lean from the photo.  Yes, back in the  80's the government was putting pressure on most vehicle manufacters to lean out the vehicles so they did not "pollute". Worst running bike I ever had was a 1982  Yamaha 650 Seca.   Larry

[Hondawggie]

HW,  was that a full throttle run, shut off and then visual inpection?  If  so, it does look a bit lean from the photo.  Yes, back in the  80's the government was putting pressure on most vehicle manufacters to lean out the vehicles so they did not "pollute". Worst running bike I ever had was a 1982  Yamaha 650 Seca.   Larry

It wasn't a perfect scientific plug chop but close.  It is running lean, you're right.  One thing about the pictures above is the white dryness of the plug is not coming through that well on my cheap digital camera.  It's like 'the camera will add 10 lbs to you in a picture,'  its 'the cheap camera will make your super white lean plugs look only a bit lean.'

The bike has a stock air filter and it it very clean.    I don't think the baffle is wrapped, excellent idea, I have some fiberglass from my 2-stroke, may try that next.   Last think I want to do is rejet.  Can do but will try all else first.  Thank you for your suggestions.