71' CB500 monoshock with no name...O2 sensor success!

Re: 71' CB500 monoshock with no name...electrical hiccup?

MotorbikeBruno said:

From the myriad of posts that was something that was very notable. Do NOT use a linkage type shock in a straight design. I suppose I'll keep it as-is for now and try to change the mounting point a bit as mentioned. I do not see it being a problem, but there's a difference between good and bad design I suppose :-\ Onward! ;D

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ive seen all kinds of conversions that use a shock from a linkaged lashup and running without linkage,and it works fine, there is no reason not to do it
many have done it on the TL's to loose the terrible stock setup

Re: 71' CB500 monoshock with no name...electrical hiccup?

Live and learn I suppose. Must have been some grumpy old guys talking about math and doing poor calculations. Thanks for the heads up and help so far gents.

I looked and yes the force is on the downside and shouldn't be there. I'll change that over the winter here to make it work correctly and then get the frame cleaned up/powdercoated/painted etc. Much appreciated. In the mean time.....I was having issues getting it to idle properly. I have the stock pilot jet in there, and 105's for the mains. Turns out that the stock pilots are too RICH? So now I'll have to go back and verify that they are in fact stock and not drilled out previously etc. That's what winter is for right? Either way, I wasn't even on the scale for my Air-to-Fuel ratio (under 10) I was able to get it up to 11.9 or so by turning the mixture screws lean at 4 turns and that wasn't even enough to really get it where I want it (which means I need a lower pilot jet most likely #38 )

The good news is that it idles nicely now and doesn't die at street lights anymore...which is amazing since it's kickstart only for now

Here's more pics, as if I didn't post enough right? :-X

And the gauge. 21 shows when the sensor has warmed itself up enough to be used. One step closer!

This just got alot more interesting.

Wow, cool Bruno, that will make it a lot easier to get the jetting right I bet, no more pulling plugs and guessing for sure.

I'm not sure if it was discussed or if it was posted, but what gauge is that and what o2 sensors are you using (gm wide band?)?

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Thanks guys. I clean carburetors for people on the side (www.motorbikebrunos.com) up here in MN. I've had a few people ask if I could "tune" their carbs. I said I would rather not as it takes quite a bit of time, and I have less of that as the days go by (first little one on the way T-minus 1 week!)

So here was the answer "wideband O2 sensor" which have finally come down in price! Not "cheap" but I see so many carburetors that I'd like to get them all the best I can. I've got the Bung version for MY personal bikes and weld the bungs in, I also have the tail-pipe clamp version too for customers that want it, but do not want to weld in a bung. I'm just getting into the tuning aspect of the carbs so it's going to be a fun ride for sure!

I went with the ZT-2 and snagged a gauge on Ebay for $40 lower than Zeitronix wanted it. So I can see it in real time as I drive. It will help me find and eradicate those flat spots ;D ;D ;D

http://www.zeitronix.com/Products/zt2/zt2.shtml

It was a toss up between Innovate's product and this one. In the end I'm very happy so far with my purchase of the Zeitronix, the other guys were short and annoyed with any emails I sent. (It wasn't any sort of dumb question you can answer if you read the website ) BUT this is where I got the muffler clamp from since it's nice and easy for customer bikes.... http://www.innovatemotorsports.com/xcart/home.php?cat=250

Thanks a bunch, yeah I don't like short snippy answers from vendors, I find it unprofessional. Now you said the clamp on gets it really tuned in. I was planning on putting sensors on my 400f to get the CRs dialed in. I figured the sensor on each cylinder would be more accurate than a sensor at the tailpipe getting info on all cylinders at once.. Am I wrong in that assumption?

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ronnie said:

Thanks a bunch, yeah I don't like short snippy answers from vendors, I find it unprofessional. Now you said the clamp on gets it really tuned in. I was planning on putting sensors on my 400f to get the CRs dialed in. I figured the sensor on each cylinder would be more accurate than a sensor at the tailpipe getting info on all cylinders at once.. Am I wrong in that assumption?

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No problem. (I fixed the post above, sorry for the confusion) The WELD in is what is best, but I can't weld a bung in every customer's bike that wants it So it's more of a general tuning at that point, which is better than not knowing anything. But yes, if you notice where I put mine, I welded it into the joint pipe of cylinders 3/4 so I'm reading 2 of the 4 cylinders. You don't want to have the sensor too close to down pipes as they get too hot and can shorten the life of the O2 sensor greatly. I'll do another bung on the 1/2 carbs if I feel I need it. If you are REALLY looking to tune each carburetor perfectly, you would weld a bung in each pipe and go through and take readings from each one. Driving on the street tells you far more than when it's just "sitting" there idling or you are twisting the throttle.

I got my weld-in bungs on ebay, The curved ones are slick! But don't forget you will need a bung cap to go with it for another 4-5 bucks when you aren't using the system.

http://www.ebay.com/itm/O2-Oxygen-sensor-bung-02-fitting-wideband-nut-PRE-CURVED-LESS-WORK-Better-Fit-/231035380140?pt=Race_Car_Parts&hash=item35cac821ac&vxp=mtr

Ah, great thanks for the tips. Yeah, I saved that auction so IL have it later on. Hopefully I'll be at this point by spring time. Much obliged man

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Not a problem, I'm hoping I can save a few bucks here and there and finally get the frame taken care of etc. so it's all done in the spring. I'll Garage-test in the winter with the O2 setup until I "think" it's right and then in the spring I'll verify. And by that time I should have my other 71 cb500 and my OTHER 76' CB550 ready to roll too I keep finding free/killer deals on these things....ha! Let me know if you have any questions or need any more info about the system. If you were near me I would have been glad to help you out personally! haha

Haha yeah, I have to let things go because I know if I don't I'll more than I can handle with bikes haha! But Yea man, I appreciate the help and when I get there I'll probably have questions. Keep it up though!

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ronnie said:

Haha yeah, I have to let things go because I know if I don't I'll more than I can handle with bikes haha! But Yea man, I appreciate the help and when I get there I'll probably have questions. Keep it up though!

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Sounds good!

I drove it to my work for it's final resting place as-is...(aka heated work space for the winter!) Time to swap out or fix that rear shock angle, finish the frame, finish the swinger and start tuning the thing. She rides nice at 70mph all the way to the shop. Couple of stumbles on the low end, but I assume that's from having the mixture screws 4 turns out...which is really a band-aid until I get some smaller pilots.

I'm not meaning to be the bearer of bad news, but you really want that sensor located on the exhaust headers. Too far down stream and you're going to be getting lean readings even when the bike is running fine. Fresh air actually gets sucked back up into the exhaust between pulses and the closer your get the sensor to the exhaust port (within reason), the better your readings will be.

Matt, it's true that too close to the open end of the pipe creates false readings, but where it's at should be fine. In the headers it will probably overheat. The right place for it is in the collector/s.

For peak power you don't want 14.7:1, you want about 12:1 or even richer, but for peak economy you are looking for about 15/16:1. At idle 14 is OK but 12 or 13 is usually better. The reason is probably that as you crack the throttle open, the motor needs more gas to accelerate but it goes momentarily lean as the slides rise and air rushes in faster than fuel.

Sonreir said:

I'm not meaning to be the bearer of bad news, but you really want that sensor located on the exhaust headers. Too far down stream and you're going to be getting lean readings even when the bike is running fine. Fresh air actually gets sucked back up into the exhaust between pulses and the closer your get the sensor to the exhaust port (within reason), the better your readings will be.

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That may be true for a car sensor, but the instructions on the kit specifically say NOT to put them near where the headers come out. I'm not disagreeing with you, as the O2 sensor we put on my father's airplane engine (experimental Bede-5 using a geo metro engine) is only a few inches from the exhaust port. For some reason the kit said it shouldn't be within 16 inches of it? Or maybe I read that wrong? I'll have to go back and have a look. I remember I did it for a good reason, even though I know otherwise from the other engine stuff. As for lean readings...well that means I'm insanely rich, being that it read a very rich 11.9 with my air screws maxed out. I'll keep you updated.

This is probably my favorite looking monoshock conversion. nice work.

MotorbikeBruno said:

That may be true for a car sensor, but the instructions on the kit specifically say NOT to put them near where the headers come out. I'm not disagreeing with you, as the O2 sensor we put on my father's airplane engine (experimental Bede-5 using a geo metro engine) is only a few inches from the exhaust port. For some reason the kit said it shouldn't be within 16 inches of it? Or maybe I read that wrong? I'll have to go back and have a look. I remember I did it for a good reason, even though I know otherwise from the other engine stuff. As for lean readings...well that means I'm insanely rich, being that it read a very rich 11.9 with my air screws maxed out. I'll keep you updated.

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Do what the kit says, but I've never heard of having one down so low.

I run mine a hair behind the collectors (to average all cylinders) and have tuned just fine, with an open pipe it may be different, but with a proper muffler, it seems to be accurate. As far as power, on these old bikes I've found 12.5 or so to be dead nuts fastest, any richer and they seem to stumble. As far as tuning in the garage, well... it's not going to do squat for you, if the bike isn't under load, then all you're tuning is your 0-1/16 throttle. You need to ride it to tune, even with an o2 sensor. the o2 sensor is just going to keep your tuning efforts headed closer to the right direction than purely "feel".