Author Topic: Carb installation and fuel flow (Read 3315 times)

iDorsey · « **on:** August 01, 2013, 12:06:26 PM »

Hi,

I have a 1981 cb650 that I'm trying to get running. I've been doing everything on my own with little mechanical experience so this forum has been a huge help. I used a guide to clean/rebuild the carbs and I think I did a pretty good job with them. The thing is, the carbs were out when I got the bike and the only thing I can reference for installation is a set of grainy images from my clymer manual, which details carb removal and not installation. This process is further complicated by the fact that the previous owner removed the non essential connections, so I have more places for the hoses to go than I have hoses. I hope that makes sense.

I've posted on here before while trying to figure out how to install the throttle cables, and now I'm trying to figure out where the various hoses go after attempting to install the carbs and getting no fuel flow. I checked the petcock and fuel line, so I think the problem is that there is no vacuum allowing the fuel to flow. Of course I could be wrong.

Here are pictures of the carbs. http://imgur.com/a/Ok7IO I am not sure if the smaller hose on the petcock is in the right place(s). If you look very closely between the 1 and 2 carbs you can see an opaque male-end for what looks like a hose fitting. I'm not sure what this does or if it needs to be stopped up.

Also as a side question, I was wondering what you all think the best method of obtaining a battery is? I'm trying to save as much as possible as I know that saving 5$ here or there will add up in time. Would it be cheaper to order online?

Thanks in advance for any and all responses!

LesterPiglet · « **Reply #1 on:** August 01, 2013, 12:10:23 PM »

Does this help at all?

http://www.cmsnl.com/honda-cb650-1981-usa_model7224/partslist/E++20.html#results

http://www.cmsnl.com/honda-cb650-1981-usa_model7224/partslist/E++19.html#results

http://www.cmsnl.com/honda-cb650-1981-usa_model7224/partslist/E++1901.html#results

iDorsey · « **Reply #2 on:** August 01, 2013, 12:23:02 PM »

Yes, that helps immensly, for both my understanding and it helps me communicate the issues.

So, referencing the image at this link: http://www.cmsnl.com/honda-cb650-1981-usa_model7224/partslist/E++20.html#results
here are my issues. I don't believe I have part #3, labeled as a fuel tube. I also do not have part #5. I don't think I have #7 either.

I see what looks like the opaque male end between carb 1 and 2 in the diagram, which connects by part #4. Is part #4 the smaller hose in my picture? It looks like it to me.
I can't really see where it goes connects the other end of the diagram. If that hose doesn't go where I have it now, what is the brass colored male connection for?

Sorry if this is confusing but it seems like the best way to communicate it. Please let me know if anyone needs clarification. Based on this description, should I be ordering parts? I don't really like the whole "It's not necessary so throw it away" attitude of the P.O., given that honda's are designed by amazing engineers.

LesterPiglet · « **Reply #3 on:** August 01, 2013, 12:31:19 PM »

Any suitably sized fuel line will suit the purpose of the missing pieces, just cut to length.
You really need to get a decent manual. Try the FAQ section for links to download one.

curemode2002 · « **Reply #4 on:** August 01, 2013, 01:15:58 PM »

The smaller hose is not number 4 it is correct it should feed vacum to your petcock. Basically you have a vacum petcock the opaque connection you notice between 1&2 is the fule connection. You have the line from the tank connected correctly but there should be another fuel connection (usually on the bottom of the petcock). This will connect to the opaque connection between the carbs. (see the attached pic the green is good red is bad)

As for batteries I ordered one online from Bikemaster and got a Gel Battery that has worked out way better, for me anyway, than anything else I have tried.

iDorsey · « **Reply #5 on:** August 01, 2013, 01:22:07 PM »

Quote from: curemode2002 on August 01, 2013, 01:15:58 PM

The smaller hose is not number 4 it is correct it should feed vacum to your petcock. Basically you have a vacum petcock the opaque connection you notice between 1&2 is the fule connection. You have the line from the tank connected correctly but there should be another fuel connection (usually on the bottom of the petcock). This will connect to the opaque connection between the carbs. (see the attached pic the green is good red is bad)

As for batteries I ordered one online from Bikemaster and got a Gel Battery that has worked out way better, for me anyway, than anything else I have tried.

Thank you, this has helped a lot. So, the part that I'm missing appears to be 3? Is this obtainable at any autoparts store given I have the measurements (Tube,fuel,7.3x90 )?

curemode2002 · « **Reply #6 on:** August 01, 2013, 01:57:24 PM »

yeah should be it is basically just fuel line I think 5/8 inch if I remember right. I would take the hose you connect to the tank just to be sure.

iDorsey · « **Reply #7 on:** August 01, 2013, 02:50:34 PM »

I just realized I messed up and I actually do have part #3 and it is connected to a point between carb 2 and 3. Here is a picture. http://imgur.com/kAlJX5R Sorry about that. This leaves open the question of what the qpaque connection between 1 and 2 is.

Also I haven't removed part 3 at all. If that were blocked for whatever reason, might that be my fuel flow issue? I'm going to take it off an check this evening.

curemode2002 · « **Reply #8 on:** August 01, 2013, 03:04:40 PM »

What does it go into below?

iDorsey · « **Reply #9 on:** August 01, 2013, 05:24:48 PM »

This metal fitting: http://imgur.com/6sjl6ly

the hose was clear of debris, it has a very large diameter, I think a bit larger than my other fuel line the goes from the tank.

curemode2002 · « **Reply #10 on:** August 02, 2013, 09:32:15 AM »

Okay looking at the schematic below you should have two fuel lines running up from between 1&2 and 3&4 the fuel line connections are listed as number 19 for the assembly in the picture, they each connect to number 20 which is a T connection that should hook back in to an outlet on the Vacuum Petcock (from the previous diagram it looks like 7 connects to the T fitting labeled 20 in this diagram). With number three connected is there another port on the Petcock?

http://www.bikebandit.com/houseofmotorcycles/1981-honda-cb650/o/m1975#sch44146

iDorsey · « **Reply #11 on:** August 05, 2013, 12:01:48 PM »

Sorry about the delay in response.

There is only one connection on the tank petcock, for the main fuel line. I should add that the tank is from another bike, not sure which.
There is an unused port in the mechanism where the fuel line connects on the carb. (What's that called?)

you're right that I'm missing part 20. Do you know what it is for? This is the part that P.O said wasn't needed. I have a hunch that my fuel flow problem is not related to this part...at this point my carbs just kind of sit there when I crnak the engine, nothing moves and no fuel flow.

I took the carbs out to have a better look and I realized I have two opaque connections, as I should, one between carb 1&2 and one between 3&4.

This morning I decided to try plugging up the two opaque connections with vacuum caps, and also the unused port in the mechanism when the fuel line connects on the carb. Just in case that was why i wasn't getting a vacuum.

Still no fuel flow when I crank the engine. Not sure what the next step is besides ordering that t-connection

curemode2002 · « **Reply #12 on:** August 05, 2013, 03:51:39 PM »

So with the CV carbs you have 20 is the T fitting that provides fuel to the two opaque fittings you describe between 1&2 and 3&4. One thing you can do once you have 20 and both lines you can hook straight up to the petcock on the tank and bypass the vacuum petcock this will tell you if the fuel will flow to the carbs correctly or not. With the vacuum petcock on the carb rack the issue may just be a bad vacuum line or diaphragm causing it to never open to allow fuel through.

iDorsey · « **Reply #13 on:** August 06, 2013, 03:03:38 PM »

Well, when I bought my bike I also bought an extra set of carbs and some spare parts. I found this http://imgur.com/P4uyT5K after rummaging through there.

As you'll see the ends are pretty badly worn. The rest is in good shape. Any ideas on how to make this functional again?

Also I'm a bit confused on how the connections work.

curemode2002 · « **Reply #14 on:** August 06, 2013, 03:30:53 PM »

so with the pic you just sent the two far ends would hook in to the opaque connections between 1&2 and 3&4. The T junction in the middle you could hook directly to the tank petcock this will tell us if fuel can flow into the carbs.

iDorsey · « **Reply #15 on:** August 06, 2013, 05:12:58 PM »

Okay I see what you were describing before. Thanks again for all of the help. Would you happen to know how to fix the ends? The rubber is all torn up. Are there websites where I can order them that you are aware of? I can't seem to find them after doing a quick search through the webs.

I can't think of any way I can fashion a DIY fix to it.

wowbagger · « **Reply #16 on:** August 06, 2013, 05:50:44 PM »

Best battery I've found so far are the Scorpion batteries. They are sealed batteries that are a direct swap for the OEM one. Looks like you can get one shipping to you for $59 from batterystuff.com:
http://www.scorpionbattery.com/powersports-batteries/yt12c.html

iDorsey · « **Reply #17 on:** August 06, 2013, 08:19:43 PM »

I can't find anything but good reviews from them, thanks, I'll be ordering a scorpion battery.

iDorsey · « **Reply #18 on:** August 08, 2013, 12:40:07 PM »

I've done a bit of research on bypassing the vacuum petcock, and it seems that I may be able to hook my tank line directly into where part 3 goes into the middle of the carbs here: http://imgur.com/kAlJX5R

Is this what I need to do? thanks

(for part reference http://www.cmsnl.com/honda-cb650-1981-usa_model7224/partslist/E++20.html#results )

curemode2002 · « **Reply #19 on:** August 12, 2013, 12:04:02 PM »

I would give it a try as this will bypass the vacuum petcock that may be bad and tell us if the fuel can flow correctly through the carbs. Just remember when you put it on a side stand to shut the fuel off at the tank.

iDorsey · « **Reply #20 on:** August 13, 2013, 10:06:46 AM »

I was going through my spare parts bin, and I realized I had an extra vacuum petcock. After staring at it for a while I figured out it was a different vacuum petcock than the one I had on there.

I think this is the source of my confusion. According to pictures from my owners manual, the roundish spare seems to be correct for the 1981. Does anyone know where the part on the carbs may have come from?

Here is a picture:

http://imgur.com/0gtURRt

iDorsey · « **Reply #21 on:** August 13, 2013, 02:51:46 PM »

I put the new vacuum petcock mechanism on the carbs and tried starting her up again. I'm still not getting any vacuum, but I did try some starter fluid and the engine tried to start, but didn't run. Something combusted, some smoke came out of the pipes. I guess the next step is to try to bypass it and see how that goes. I'm still wondering what the issue with the vacuum is though, if I can I'd like to run the bike as close to stock as possible.

Edit: I just realized I forgot to connect the engine breather hose when I tried to start it. You can't achieve vacuum without that, can you? I guess I have to try starting it again tomorrow.

lucky · « **Reply #22 on:** August 13, 2013, 02:58:32 PM »

Get rid of the vacuum controlled petcock AS SOON AS POSSIBLE!

Many of your problems will go away.

iDorsey · « **Reply #23 on:** August 13, 2013, 03:23:50 PM »

Quote from: lucky on August 13, 2013, 02:58:32 PM

Get rid of the vacuum controlled petcock AS SOON AS POSSIBLE!

Many of your problems will go away.

(apologies for my lack of mechanical knowledge and problem solving ability. I don't have anyone to bounce ideas off of but you guys.)

Does that consist of modifying what I already have, or getting a new part?

News:

Author Topic: Carb installation and fuel flow (Read 3315 times)