Author Topic: Carb leaking gas... :-/ (Read 4502 times)

novi87 · « **on:** August 31, 2016, 11:01:22 AM »

Hey, This is unfortunately my first post. Wish it was something better than a dumb carb quesiton! So I'm riding a cb750k7 and carb #4 gushes out fuel... Here's the back story;

Bought the bike, ran pretty good! Rode over 100 miles home and a few the next day, the day after however she foiled plug #1 so I swapped plugs and it foiled again about 5-6 miles later... plug #4 looked great so i figured it probably wasn't a spark issue ( I tried cutting a little off the plug wire ect) so I jumped on the carbs and pulled them out for a good cleaning. Cleaned every nook and cranny of them put them back together and fuel just poors out of carb #4... I tried to adjust the float, same issue, I cleaned the float needle/seat same issue, I hooked up the fuel with the bowl off and held the float up to check that the needle was seating and it does... so I have no idea at this point. The float works/ the needle works/nothing is stuck in the seat so I'm not sure. Any Ideas would be great! Thanks!

flybox1 · « **Reply #1 on:** August 31, 2016, 12:49:06 PM »

where's the fuel coming from?
bowl gasket?
overflow tube?
fuel line between carbs?

novi87 · « **Reply #2 on:** August 31, 2016, 12:59:05 PM »

Sorry, I should have mentioned that! The fuel was coming right out of the main circuit, where it should when the bike is running! But I blew out the float bowl overflow tube and it stopped leaking... Must have over looked that part? But she is still not running 100% She will ride fine for a few minutes and then have a sudden loss of power with a few "pops" from the left exhaust (1 & 2 Cylinders, i'm pretty sure) and on acceleration she occasionally falls flat or just jumps from power to less power back to more power quickly.. Sorry Its pretty hard to explain.

flybox1 · « **Reply #3 on:** August 31, 2016, 01:48:21 PM »

what of the 3000mi maintenance list items have you completed?

novi87 · « **Reply #4 on:** August 31, 2016, 02:29:12 PM »

No idea, I've only had the bike for a few days so far. It's just weird that she would run great for over 100 miles and then start to act up.... those hundred miles where amazing...

Gene · « **Reply #5 on:** August 31, 2016, 02:36:15 PM »

You're jumping from all 4 cylinders to less - now, why would it do that? Is it possible that some gunk found it's way into the carbs after that 100 mile ride? How long had it been before the bike had been ridden that far? You have some research and some work to do, but don't worry - the bike will be back in fine shape once you've completed your 3K mile maintenance procedures (find your manual - of utmost importance) and completed any trouble-shooting items. It's rare that you would buy an old bike and it would run amazing - so don't get discouraged.

novi87 · « **Reply #6 on:** August 31, 2016, 02:59:59 PM »

Ok thank-you, he said he rode it almost every day to work about 20 minutes from his home. I should do the tune up, hopefully everything goes well!

flybox1 · « **Reply #7 on:** August 31, 2016, 03:00:48 PM »

haha...typical of a 35+ year old bike with questionable history/maintenance.
Your best chance at making this bike roadworthy and giving it a new life is to download the Honda shop manual, and completing all of the 3000mi maintenance items.
Once that is done, the forum can better assist with troubleshooting specifics.

http://www.honda4fun.com/materiale-documentazione-tecnica/shop-manual

rotortiller · « **Reply #8 on:** August 31, 2016, 03:07:20 PM »

Maybe the float is fuel logged (leaking).

novi87 · « **Reply #9 on:** August 31, 2016, 07:53:40 PM »

@Flyboy1 the 3000 mile tune is just timing/valves/cam tension/oil right? Thank you! @rotortiller I thought that also, but everything was in spec i just over looked something haha my bad..

flybox1 · « **Reply #10 on:** September 01, 2016, 07:00:29 AM »

Quote from: novi87 on August 31, 2016, 07:53:40 PM

@Flyboy1 the 3000 mile tune is just timing/valves/cam tension/oil right? Thank you! @rotortiller I thought that also, but everything was in spec i just over looked something haha my bad..

Those are the main items, yes...

Duanob · « **Reply #11 on:** September 01, 2016, 10:24:38 AM »

Quote from: novi87 on August 31, 2016, 07:53:40 PM

@Flyboy1 the 3000 mile tune is just timing/valves/cam tension/oil right? Thank you! @rotortiller I thought that also, but everything was in spec i just over looked something haha my bad..

Don't forget a clean air filter. Clogged or dirty can create problems.

new condensors and clean and adjusted points too.

Spark Plugs? Check end caps?

You should sit down and read everything that is on the 3000 mile tune up.

novi87 · « **Reply #12 on:** September 03, 2016, 12:38:31 PM »

OK! I'm back for more! Did the 3000 mile tune up, po had the timing off, not but much but it was deff off! She starts right up and sounds like a sewing machine! :-D only problem now is a huge lack of power?! Cyl 1&4 are not getting nearly as hot as 2&3, I checked the coil its reading 5 ish ohms from the one side and nothing from the other (maybe I'm checking it wrong) but she does sound a lot better now! Any imput would be great thanks for your help so far! I feel like I'm so close just not there yet.... pretty painful haha.

flybox1 · « **Reply #13 on:** September 03, 2016, 04:58:05 PM »

plugs caps....check resistance on all.
Anything above 8k ohms is too much with your D8EA's

Fuel level in bowls. 3mm below the bowl gasket seam. easy to check with the clear tube test and your PD carbs.

Report back..

novi87 · « **Reply #14 on:** September 03, 2016, 06:04:55 PM »

Hey, I checked resistance between the caps (secondary) before work on multimeter at 2000k and read 40, not sure what that means (the electrical on this bike is new to me) I'll check everything else tomorrow. What do you mean pd the carbs? I set the floats in the carbs already but will double check with a tube. Also I checked for spark on cylinder #1 by grounding it at the case and saw nothing (I would have checked #4 but had to run to work) thanks for the help so far!

novi87 · « **Reply #15 on:** September 03, 2016, 06:10:27 PM »

Also I tried to swap coils from 2&3 to 1&4 but the plug wires where to short ha-ha.

Gene · « **Reply #16 on:** September 03, 2016, 07:09:21 PM »

Points - gap 'em and check 'em again. You will curse points, but then you will grow to love them.

novi87 · « **Reply #17 on:** September 03, 2016, 07:11:51 PM »

I'll check them again tomorrow. I re-set them today hoping that would cure the issue but no luck.

Gene · « **Reply #18 on:** September 03, 2016, 07:15:30 PM »

Check and/or replace your condensers too. Couldn't hurt and it's cheap. I'm betting it's a points problem, but hell, I'm an idiot.

Good luck.

novi87 · « **Reply #19 on:** September 03, 2016, 07:19:01 PM »

Thank-you! Yea I'm a moron to but with do little time left in the season I'll try anything

flybox1 · « **Reply #20 on:** September 03, 2016, 08:34:13 PM »

Turn your ohmmeter to the next higher setting, to get a more accurate reading.
The 77/78 750s had PD carbs.

novi87 · « **Reply #21 on:** September 03, 2016, 08:46:11 PM »

Ooh ok yea, my multimeter only goes to 20k :-/

BomberMann650 · « **Reply #22 on:** September 03, 2016, 10:59:16 PM »

At first read with the overflowing and the poppin whatnot, I thought maybe a sunk float.
But that only applies to hollow brass and plastic floats so eh.
I lost a pair of cylinders after mucking up a point breaker.
+1 Git gud at points timing

Welcome to the madhouse novi

novi87 · « **Reply #23 on:** September 04, 2016, 12:50:23 AM »

Thanks Bombermann, its fun. Luckily its not my first rodeo I still rock my 73' cb350 but its a twin so a lot simpler. I'm going to test continuity between the points and the actual coil (along with my plug caps ect) in the morning, anything specific I should look for? Does the blue wire from the points run directly to the coil or does it plug in somewhere else? The PO put everything in a battery box he made and it looks to be just kind "stuffed" in there haha. Thanks everyone for the help so far!

novi87 · « **Reply #24 on:** September 04, 2016, 09:16:58 AM »

Hooked up my continuity tester to the blue wire and it shows a connection with the points open, put on a new plug cap and I'm still having the same issue? Any ideas?

News:

Author Topic: Carb leaking gas... :-/ (Read 4502 times)