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View Full Version : Audio Diagnostics... Help Needed Gents! : )


RobG
03-12-2009, 01:43 PM
I am going to post a full thread on my restoration, start to finish, soon, but for now I am in the final stages (mechanically) and could use a second and third opinion. I took the carb off and dipped it and it's components today. I wasn't able to take the floats off but I am fairly confident that it is able to flow fuel freely and is pretty much clean as a whistle at this point.

There are basically two running configurations. It starts and idles with no choke, but requires mid choke to rev well.

It actually seemed to run better before I rebuilt it so I have a strong feeling it is the timing (since I messed with this quite a bit... Why will be explained in my full thread). I will try adjusting that this weekend. Here are three videos you can use to listen along.

Granted, in this videos it is 28 degrees outside and the bike hasn't really been warmed up...
http://www.youtube.com/watch?v=0tBfUSvh9zU
Essentially, when you hear it rev, thats me twisting the throttle to rev it, but after about half a twist, further throttle stops the rev and it starts to loose power.

With more choke-
http://www.youtube.com/watch?v=FzP7-A7hJOo&feature=channel

And just for fun-
http://www.youtube.com/watch?v=LqQFc0RXubU

As I accelerate, I am cranking in some throttle. When the engine slows and gargles a bit, I am still adding throttle. It just seems to have a sweet spot where it runs, and not well above or below.

So like I said, I will play with the timing this weekend because I am *fairly* certain the carb is clean now, but any other advice or ideas are welcome.

Throttlejockey
03-13-2009, 01:18 PM
Did you check the float height?

RobG
03-14-2009, 06:52 AM
I haven't checked the float height. I will do that this afternoon. It doesn't seem to be the timing so my wishful thinking didn't work. I will look into this and report back.

So close, yet so far away : )

RobG
03-16-2009, 01:04 PM
The float height seems to be correct. I actually worked on it every day this weekend and decided that I was pursuing a bit of a moving target. The bike now runs without choke but still has a 'gargle'. It revs freely quite well and sounds great, but under load it often has a bit of a stumble and a miss.

Today it is running substantially better than yesterday. It still seems a bit lean with the throttle easily out-running the power. The ambient temperature is warmer today than it was yesterday. I hadn't thought about this, but it is very possible some of the uncertainty and difficulty troubleshooting is due to the bike just not wanting to run in cold weather. Today was in the 60s and the bike has run better than ever.

Now if I can just fix the slight lean-ness and the gargle it will be a champ. Here is an updated video that sort of gives the sound.

http://www.youtube.com/watch?v=It1ZnW_8A9w

So far as I can tell, the 'air-screw' and the idle-adjust are the only two working adjustments to control the mixture in the carb?

Smithers
03-16-2009, 11:04 PM
I just saw this thread for the first time today... I don't know how I missed it but o well. Yeah the carbs are really really simple. It looks like your carb system just needs to be run more. I think there was obviously some sediment (or a gummy layer of old fuel) in the carbs that just hadn't worked it's way though the jets. Just the old varnish from sitting around builds up and the more you run the engine the more it will clean out. You can't ever get a carb to just run amazingly better just by soaking them. They clean out as they are used after it's been sitting for a while.

Read the Honda Service Manual carb section. You really need to understand what is all going on in there. People always overlook the powerjet and assume everything is all clean and good. There are a lot of little places for buildup to hamper a carbs ability to function like new. I bet that the more you ride it the better it will run.

Another hot tip: Don't ever run 2 stroke oil in it... only in an extreme emergency or to get home or something but drain it out or dilute it a lot.

Smithers
03-16-2009, 11:07 PM
Also did you see my video of my cruisin the Honda 160 out one afternoon? I just was on my way home from visiting a friend and thinking how awesome it was to be able to cruise around on an old bike. Then I was thinking that a lot of people are missing out... then, "heck I have my little camera that can take videos too, why not?". So I pulled over and let the camera do it's thing while trying to rev-match the shifting as best as I could. :D

9VbTKfXLGgg

OH also for you other cool youtube posting people here. I programmed in an additional tag so that you can post the videos and have them pop open once you click on the "I agree" disclaimer. Just copy the video link which is the last digits at the end of the http line that appears after the = sign.

So for example my video html link for my youtube video is: http://www.youtube.com/watch?v=9VbTKfXLGgg

The video tag for that is after the = sign which is: 9VbTKfXLGgg

Now use the tags {youtube}9VbTKfXLGgg{/youtube} BUT REPLACE THE { } with [ ] so that the code will work.

Carry on.

Smithers
03-16-2009, 11:23 PM
I also have been playing around with the Honda CL70 and last week it was running kinda funny but I knew it ran totally perfect before that day so I knew I wasn't going to touch the carb. It started up and would die under throttle unless I put on at least half choke. Then when it would warm up it would run totally normal. So it did this for 2 days. Then later this past weekend it started up and ran totally like it always had, perfectly with no choke monkey business. Just riding it more has been making it run better.

Now the blue CA95 just needs it's carb back in and I can then hit the open road with that thing. Now that my sister is the sole owner of it (now divorced) I'll have to fix it and then convince her it's running reliably again for her to go ahead and get the registration paid. But that sucker REALLY needs to be ridden because the new pistons and rings and fresh cylinder doesn't even have over 15 miles on it yet. Poor little neglected Honda.

Ok back to the carburetor tuning... sounds like RG has some more cleaning to do maybe? Some Honda manual studying?

RobG
03-17-2009, 05:29 AM
Excellent video. I will embed them from now on. That was the same routine I did in my video. I had a little point and shoot camera with short video capability, so I turned it on, held it by the wrist strap in my teeth, got into first and got rolling, then held the camera in my left hand and did my best to match revs and shift sin-clutch with my right. I would say I didn't do badly. Technology, Bah!

You don't happen to have a link to a good service manual. I never did find one. I know there was mention of a PDF at one point but I don't know how that was resolved.

I think you hit it on the head. Definitely some cleaning and studying to do.

I am also going to try to hit some stable temperature days for the tuning. I don't know how sensitive these little carbs are to changes in air density, but here in Indiana in the spring time things can be crazy. Over the last week of me working on it we have had days that ranged from 21 degrees and snowing to 70 degrees and sunny with all forms of mid-temp and rain in between. I go out one day and get it running well in the cold and the next day it is hot. It *seems* to be warm and stable for the next week so maybe I will have a stable mark to hit.

Study Time!

Smithers
03-17-2009, 07:17 AM
I was shocked how well the video came out. I didn't think it would be that stable at all. Plus my shifts weren't as smooth as I would have liked but it didn't translate into bad shifting on the video at all. The tranny is so tight on that bike that it's not so easy to shift without the clutch. You would think it would be easier to shift clutchless. I have shifted many-a bigger engine clutchless perfectly all day long. Kinda makes me laugh.

PDF's are $50 : )

RobG
03-17-2009, 08:46 AM
Your mention of the power jet earlier opened up a window for me. I didn't realize this little carb had such a thing. My hypothesis is that the main jet is either still dirty or needs to be slightly adjusted to provide more fuel.

I was really confused because the bike would idle fine, so the slow jet seemed fine. It would also rev like a crazed banshee. It just wouldn't run smoothly under load at middle rpm.

I understand now that the power jet is probably clean (I did dip and scrub it) which is where the beautiful high RPM is coming form. But the main is the problem. Without the power jet I couldn't understand how it would run well at high and low rpm but not well in the middle. Now it makes sense.

I will test this theory tonight and report. So close!

RobG
03-18-2009, 08:50 AM
The service manual pretty closely describes the trouble I seem to be having. It looks like the adjustment I need to do is to raise the needle in the throttle valve. Unfortunately the clip that holds this in place looks a bit rusty and I can't really tell how best to do this. Any advice on doing this?

I also don't yet have an air-filter and need to put one of those on since the bike is in a bit of a dusty area. It is very possible that the combination of added a filter and the temperature continuing to increase will make the bike richer anyway so adjustment may not be necessary.

Any advice on an airfilter? I see some OEM ones on Ebay but wasn't sure if there wasn't an easier way. I don't necessarily need it to be back to stock at this point.

Smithers
03-20-2009, 09:23 PM
Hey chief, busy day here with the weather being so nice. I had to take my Aprilia out for the first time in a couple weeks for a ride. Woohoo, that thing is fast. The bike also gets awesome fuel mileage so it saves me a couple bucks to put miles on it.

Get a sharp scribe or something and put it down under to try and pull up that clip a little. I'm sure any e-clip would fit on there if you deform the Honda part. It'll come out. Also they spin when not rusted in place so lightly grab the needle with some flat pliers and spin it to break it free.

I would put a foam Uni universal filter on it. You can get them at most any motorcycle shop. Uni has been putting their displays and universal filters in every motorcycle shop in the world. Look for em. You can put their universal filters on anything. I got one on my big BCS rototiller and it looks awesome, custom style haha. You don't see the filters anyhow and the foam ones are MUCH better than anything else.

Check out their massive application guide: http://www.unifilter.com/online%20catalog/universal.html

http://www.fourwheelperformance.com/honda/uni_filters.jpg

I should get one for mine too but my stock filters seem to have always been fine. I'll make it a point to go pick one up for my 160 next time I see one. I definitely recommend changing the spark plugs and filter first before you start tuning. You might not have to do any tuning with just those new pieces installed.

RobG
06-12-2009, 05:25 AM
Well, it has been a few months, but I will throw an update in here since I did get this working now.

The retainer clip that holds the e-clip in place is pretty easy to remove if you take the slide clean off the bike and take the throttle cable out of the slot it lives in. This way you can rotate the clip around and get behind it through this same slot. Realizing this made the process a 30 second deal.

Raising the needle 2 notches (as far up as it will go) fixed my tuning issues. I was quite concerned about why it would be this far out in one direction, but I also realized that this slide and needle came from a different carburetor from what is on the bike, so it is possible that they were jetted slightly differently.

Still, adding the air filter was the final step in making it run just about as perfectly as I could have hoped for. Without the air-filter I still get the occasional miss.

Smithers
06-21-2009, 06:25 AM
That's good news. I'm going to change the position of the needle clip in my 160 sometime and try it out. I know it's running a bit lean as well.