Now this is definitely NOT right..................

nhsteve · Aug 14, 2019

Working on a '78 E model, standard unit, with 4" UNI pod filters (lightly oiled) and brake booster valves on both breather tubes (thank you 5twins). Carbs have been vapor-blasted clean, then got an ultra-sonic bath, so I was thinking they should be pretty clean. Timing (conventional points/condenser setup) is statically on the F mark, with gap between .014" & .015". Checking timing dynamically shows timing on the mark, seems to advance properly.

Carbs have new aftermarket jets, but correct for the year/model. (I'm prepared to try to adjust for the aftermarket filters and mufflers). Initial short rides have resulted in very bad carbon-fouled left plug. Right side seems ok, possibly a tad lean.

After double-checking the timing, etc., I swapped the carbs for a set of my good running '77, and problem seems to have all but gone. So, into the carbs again, and this is what I have come up with so far. Note the split in the enriching circuit tube at the bottom. Would this be the cause of the richness? I'm NOT running the bike with the choke on, but could the split allow more gas than should be to get sucked up somehow?
Also note how beat-up the main nozzle is. The top 2 sets of holes are pretty rough. I've ordered replacements with O-rings, & will let the group know what shakes out.
(apologies for the main nozzle photo. That black at the top is a blob of dried paint on the bench!)

XSLeo · Aug 14, 2019

The only time that fuel gets drawn up the enrichener tube is when you use the choke.
Even with all you did to clean the carbs, which is good, Did you squirt carb cleaner in through the pilot jet to see if the cleaner came out through all the tiny holes by the throttle plates?
How about float levels? Did you check level on both floats? They can get bent so one side sets higher than the other.
Leo

5twins · Aug 14, 2019

Your needle jet (what you're calling the "main nozzle") looks pretty bad. It's probably worn larger on the inside too, and that's what flows the fuel. So, there's a good chance that is responsible for your rich running. Yes, replace it and see if that cures the issue.

nhsteve · Aug 15, 2019

I did replace both float needle valve assemblies, and wound up setting them both to 24mm above the carb body. The Haynes manual I have does not give a height for the '78, but rather a fuel level using a tube arrangement held next to the carb body, ALA Kawasaki Z1/KZ. I honestly did not have that exact tube setup, and didn't think it could be that different from the '77, so I set them to that spec. This was all done after I had the vapor-blasting & ultrasonic cleaning done, along with the new jets.
New pilot jet (sized for '78), and yes, I have seen carb cleaner come out those 3 small holes. One question in my mind- when I do this it is very difficult to see 3 jets of fluid come out, as it kinda comes out all at once, if you know what I mean.

I was also thinking back to my dirt bike days about the needle jet/main nozzle, as those items would rapidly wear on the 2-stroke bikes from the '70s (DT, YZ, RM, TS, etc.). So I was not fazed to consider replacement. So far the only real break-through on the left side carboning up I have found is the enrichening tube, which apparently may not really be in play.

Thanks for the replies, I do have small parts ordered and will follow up. I know those responding like to see closure for problems they have chimed in on.

5twins · Aug 15, 2019

Yes, that small crack in the choke take-off tube shouldn't hurt anything but you might try patching over it with some JB Weld to see if it helps. 24mm is the '78-'79 carb set's float level spec. The '76-'77 set is actually a little different, 25mm. 24mm would be in it's spec range but at the rich end of it. Here's a chart I made up giving the specs for the various year carb sets .....

By studying it, you can learn a few things about these carbs. Your '78-'79 set came with the largest mains paired with the smallest needle jets. Your '76-'77 set came with the smallest mains paired with the largest needle jets. You will also notice the large size difference in the two types of pilots used. This is because of what they flow. The VM22/210 pilots sized in the 20's flow straight fuel. The BS30/96 pilots with much larger sizing in the 40's flow the already made weaker fuel/air mix. That's why they're so much bigger.

nhsteve · Aug 16, 2019

Thanks for the chart 5twins. I already see my mix screw setting was/is wrong!

gggGary · Aug 16, 2019

Great first post in this thread nhsteve! Couple more notes. Terms matter, 5twins is referring to the needle jet, what you show in this picture;

NOT the float needle valve. That needle jet is junk, and if that is what most of your brass looks like you prolly need to replace it all....

I cannot recommend vapor blasting a carb. Vapor blasting is wet sand blasting, SAND and eroding soft precisely machined metal, not a good thing.
It's been shown many times that aftermarket carb brass is a real crap shoot. Few things worse than adding unknowns when chasing carb problems. I'll add; do a float hot water test, if you aren't using new GENUINE floats. Many have had endless problems with poor fitting not to spec aftermarket floats.

gggGary · Aug 16, 2019

I'll give a quicky reply til 5t ponies up. Not a copyright, just a "watermark" .Cuz almost no one gives credit to the OP when stealing web content.
Almost no one... :sneaky:

5twins · Aug 16, 2019

Yes, just a watermark, and exactly for the reason Gary said. I don't mind people using and re-posting my images. I can't expect it not to happen here on the world wide web. At least this way folks know where the info came from. Some of the stuff, this carb chart in particular, took lots of work to put together. I researched all the old manuals and spec sheets I could find, then combined it all and drew up the chart on my computer. Back when I did this, obviously all the info was out there but not all together in one easy to reference chart.

650Skull · Aug 16, 2019

I have found wiring charts and other pics made, from "the 81Simplified wiring diagram" first done on 650 rider, and from this site, and these are on a site you have to pay to get into to get at the diagram..........i do more than just water mark all pics that i modify extensively or any i have taken with my camera............State, Not for commercial use, add a copyright with a date and a few other marks throughout the pic.........

But then this site has a policy that the owner owns the copyright, with the proviso that the forum host, (XenForo) can use the pics for promotional purposes without paying any copyright fees...........the biggest under cutter of the copyright is, XenForo cannot guarantee or have any jurisdiction over third party policies that may be different to XenForos policy, or what they can do with your pics............Third parties can to use these for promotion's or on sell the pics for commercial gain......depending on their policies

nhsteve · Aug 22, 2019

Update from moi: parts have been ordered, not all are in due to shipping delays. Needle and needle jet both will be OEM. (I think I used the 'main nozzle' term, as that was what I saw on the parts website I was on??) I do recall replacing these on 2 stroke dirt bikes often enough in the '70s. Should've remembered

doh

Point taken on vapor blasting the carbs/brass. Will avoid in the future.

By a 'hot water test' on the float (it does not seem damaged physically), I should get some hot water and see if the float sinks in it, proving there is a pin hole?

gggGary · Aug 22, 2019

Get a cup of water steaming hot, grab the float with a pair of needle nose, submerse it in the water for like 2 seconds. If a trail of bubbles appears, FAIL!

5twins · Aug 22, 2019

The needle jets, or actually any of the jets, actually wearing out isn't really an issue with these carbs, they get eaten away by gas varnish if the carbs were allowed to sit a long time all gummed up. The "textured" look of your needle jets indicates that's what happened to them.

If you did manage to find OEM replacements then good for you because they are NLA. Usually all you can get are repops.

Brassneck · Aug 22, 2019

Just a note on vapor blasting (Not to stir the pot), but traditional vapor blasting is done with water/glass creating a slurry. It's actually safer for aluminum and brass parts, vs. sand. The downside (especially for carbs) is that slurry gets everywhere...and you have clean and re-clean and re-clean all holes/air passages, etc. with air and carb/brake cleaner...as that stuff get's caked in. I've done a few bikes and even after what I thought was a solid clean job, I still found a white powdery residue on parts and definitely left in passages.

You can vapor blast carbs, but be vigilant on the post clean-up process.

MaxPete · Aug 22, 2019

5twins said:
Yes, just a watermark, and exactly for the reason Gary said. I don't mind people using and re-posting my images. I can't expect it not to happen here on the world wide web. At least this way folks know where the info came from. Some of the stuff, this carb chart in particular, took lots of work to put together. I researched all the old manuals and spec sheets I could find, then combined it all and drew up the chart on my computer. Back when I did this, obviously all the info was out there but not all together in one easy to reference chart.

Besides, on this forum that watermark almost invariably means that whatever information is being offered - is correct.

Pete

nhsteve · Sep 6, 2019

Update to this thread: I had my local guy 'hot tub' (aka: ultrasonic clean) the left carb for me again. Obtained new OEM needle jets, O-rings, and needles, installed them, double check the float height is to spec (24mm in my manual for a '78 standard E model).

Before fitting them, I did a 30 mile round trip on it using the good running carbs from my '77D model, returning with 2 nicely tanned plugs. Left side carbon fouling issue seems to have abated. Installed and synched (mercury sticks) the now very clean '78 E carbs and did the same ride (back-to-back).

Bike now seems to run very well, however the plugs seem kinda lean to me. Pic shows them pretty well I think.

Running 4" UNI filters with power brake booster valves on the breather tubes as suggested elsewhere, and some kind of aftermarket Sportster-type muffler.

Suggestions on jetting? Raise the needle? Bigger main jets? Reinstall the airboxes with stock or K&N filters? Sell it and buy a pogo-stick(kinda hate to, as riding it really makes me feel like the little kid in myavatar! :bike:

)?

gggGary · Sep 6, 2019

Those look fine to me???

nhsteve · Sep 6, 2019

I was actually pleased to finally see them running about the same after chasing my tail with the left side carbon-fouling. It's just that the '77 is not as light as these, and certainly I don't want to cause internal problems from a lean condition. Pulls great, and even idled about 1300rpm when I got back.

Brassneck · Sep 6, 2019

Those don't look lean to me... However, are those brand new plugs? Also, all they may really tell you is your how your bike is idling. If you're tuning for WOT, or mid-range, etc...you need to do an effective plug-chop at that rev range over a period of distance...and then not let the bike continue to run in any other range, like idling when coming to a stop. Additionally, you're looking at the base of the porcelain where it meets the metal which is tricky to see (and definitely can't be seen in the pic)...if you cut your plugs in half, it would be easier for us to check, but probably more trouble than it's worth (You can look down it with a flashlight and see how the color looks). And finally, modern fuels will have an impact on the color as well...so unless you're having serious overheating, pinging noises, backfiring, or acceleration issues...I wouldn't sweat it based on how those look.

But that's just me...and I'm definitely not an expert in plug reading. This is just what I've learned from this site and racing little Honda twins over the past 3 yrs...which is pretty fascinating when you get into the weeds of what it means to do fine tuning with plugs that look totally extreme (especially running with a mixture of 100 low lead fuel).

Good luck!

nhsteve · Sep 6, 2019

Thank you. You are right, those are not 'new'. I have a plug sandblaster (GASP!!!

) that I cleaned the plugs with before both rides, then rode the same road at about the same clip, then pulled them to look as an overall read. Mainly I have been chasing the left side carbon fouling, which seems now gone (I hope). But with discussions here about jetting after installing the UNI filters and aftermarket mufflers and such, was looking for feedback (which you have provided, and I am thankful! :cheers:

)

P.S.- nice avatar!

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