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Discussion Starter · #1 ·
After gapping the plugs and adding seafoam to the tank, I rode around the block. The bike wasn't running right so I got out the can of ether and found a vacuum leak at the little hose (see red arrows for my replacement) at the top of the carb. I looked around for a week but didn't find any premade hoses that I wanted to buy, so I made my own. In the photo, the front carb in on top. See below:
Automotive tire Motor vehicle Gas Tread Auto part


I put everything back together but when I try to start the bike, it cranks but won't run. I pushed in the choke to the off position but still no joy. My first thought was no spark. However, every once in a while, it'll catch but at approx 200 rpm. If I give it some throttle, it dies. So I sprayed some ether into the air cleaner and it'll run that way. That told me I had spark. So I thought it's a fuel problem!
Fast forward to tonight and I pulled the tank so I can get serious about burning my eyebrow off. When I pour fuel down the throat, it'll run until dry. Ha! it's the fuel pump! When I go through turning the key and pressing the red button, the pump didn't run. I'm on to something!! I pulled the fuel hose to the carbs off and sprayed fuel all over when I turned the key on. So the pump works. If I drain the fuel bowls, the pump will run until they fill up again but the bike won't run unless I pour fuel down it's gullet.

Is it telling me the jets are fouled? If this were an edlebrock on a 350, I'd just get a hammer and fix it....

And then there's something else I don't understand. When I do get it running and twist the throttle, only the front carb looks like it's working. See below (again, the front carb is on top)
Automotive tire Gas Automotive wheel system Machine Engineering


Is that normal or do I have larger issues?

I took these screen shots from a short video I made to explain what I'm seeing/hearing.


I appreciate any insight and suggestions you may have. I feel like I have all 3 components of noise and fun but I can't get them on the same page!
 

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Ethanol fuel left untreated for a few months can absorb moisture, gel up and foul carb passageways. Likely time to clean and rebuild carbs. Never had to do it but lots of good videos out there. Sync the carbs when finished.
Videos in link below...
 

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Discussion Starter · #4 ·
So, the bike had been tuned up....that should say "tuned" up prior to me getting it and I made the mistake of thinking things were gapped correctly, idle screws were close to factory...you know, basic stuff. I found out the plugs were gapped over 0.09 and the idle screws were out 6 turns on the front and 7 on the back. After looking up the numbers and resetting parts, I pulled the float bowls and sprayed cleaner all over and into things like my eyes and jets. But still no joy. It still wouldn't run unless I add fuel down the throat. After a few minutes of creative cussing, I decided I wasn't in the right frame of mind to noodle this out. After a few light scotches and a nap, I went to youtube and found a guy who had the same problem and showed the fix. Apparently there's a tube with a hole in the side that the needle uses. If you (meaning me in this case) don't align the hole with the main jet they you get an engine that runs on the idle circuit but falls flat/dies when you crack the throttle. I believe when I took things apart I got those holes in the wrong spots. The Edlebrocks on 350's don't have those silly little holes and neither did the Carters....so I had no idea about that little detail. Moreover, since I didn't look up any instructions or exploded diagrams and was working off of the notion that "carbs are carbs, how hard can it be???" I overlooked that little detail in the rebuild.


le sigh.....
 

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the way to clean a carb is remove the jets and spray carb cleaner in the passages front wards and backwards. remove the mixture screws and spray cleaner thru. the pilot jets are the most problematic.they have small holes in the sides hold up to a light and look thru them. and do not mix the jets up maybe take photos plural.when you spray cleaner thru the passages watch where it comes out and spray back thru. the three important jets are main pilot and mixture screw.
 

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Discussion Starter · #7 ·
Last night I took everything apart again and used brushes and little carb pokers along with cleaning spray to clean. I made sure all the holes were open, and I even polished the needle on the rear carb. Then I put everything back together, no air cleaner, sprayed a little ether into the carbs and finally got it started. Eventually I got it to idle consistently but twisting the throttle was a killer. Just for grins, while it was idling I placed my hand over the intakes; covering most of the openings and it idled better. Like, a lot better! It even responded as expected when I cracked the throttle. So I put everything back on to the air cleaner and it's running. Next on the list was balancing. I finally got the hoses hooked up and got them balanced. What a pain! A whole 350 cu in motor can run off of 1 carb with no air cleaner! I thought the SU's on the MGB were finicky! Holy moly, at least it's over for a while.

So much learning these last two weeks....

Hopefully, I'll get some time this weekend to go roam around and give it a good shake to see if "I done guuud" as some people say 'round here. When I took the needle out of the rear carb, I saw the diaphragm wasn't seated correctly. I'm surprised it was even running before. But before I go for a romp, I've got to put on the raging boar fender pig! Pix will follow.
 

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Discussion Starter · #8 ·
Yesterday I threw the bike on the lift and adjusted the valves. The marks for the front cylinder line up pretty good but rear cylinder is way off. How important is it to have them line up as in the picture?

Font Circle Parallel Auto part Line art


Say, for grins, the marks like up something like this:

Font Circle Parallel Auto part Line art


Would that be considered something a person would want to try to fix? Or would you just adjust the valves as is? Just curious, asking for a friend.....
 
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