Another 34 Pic 3 Build!

[dkl]

Great Job, Check it all over for leaks, and Dial Her In.....

 

[fivestring]

I will pull the intake back off and add one more application of Seal-All around every joint. Then paint it purdy.

I am excited to get it out on the road for a test drive. I have only ridden this bike for a 3 mile test after much work putting a box of parts back together into a set of stock carbs. Number four cylinder was running lean to the point of generating much heat on my left shin by the time I got back to the shop. It did run pretty well beside my buddy's 82 GL1100. We were evenly matched on acceleration but I was done with the stock carbs after that test ride. Ever pressing onward, never look back!

One other assembly note, I had to drill out the barrel cable stop to accommodate the throttle cable. I think I used a 1/8" bit.

IMG 20160807 105056572 HDR

• fivestring
• Aug 7, 2016

Thanks for the kind comments and help! More to come!

 

[dan filipi]

Glad it's going well. Looking forward to the ride report.

 

[joedrum]

well it seems dialing in ...simply has nothing to dowith plug and play ...the record of people who havnt been successful here with the several variations of this carb ...makes this part the entire job ...success or failure ...im rather confident 5string will get it done ...ive been waiting for thread to move along like this one has ...

to me it seems most idle circuits on car carbs are quite big for oldwing use ...it was for me with the dft carb and more than jetting had to be done ....i think the vw carb is much closer to work with ....the carb seems to be plenty big to run an oldwing motor ...with me jetting and passage feed to idle had to go way lower to idle in a dial in state ...but from there jetting went the other way as rpm increases ....

the one thing i see with vw carb set up that i dont like is air cleaner ..air cleaner is like a air jet or bleed ...to many vw carb bikes seem to run out push at high rpm ...just make sure its not one of those small air cleaners made for a motor that dose just 1/2 the rpm and oldwing can ...like its getting choked out ...this is just opinion as i havnt worked with vw carb much.....it could be like hooch and demand huge jetting to get rpm .....oh and i did change to a bigger air cleaner and proved to myself it was needed ...dialing a carb great is much bigger than just adjusting screws and changing jets ..especially when parts dont go together like vw carb and oldwing motor ...there both different animals to mate together to super success ... :ahem: opcorn:

 

[fivestring]

Joe drum, I think too the real challenge lies ahead. I'm not dissuaded though. I look forward to seeing what I can do with it
I am believing I may have to live with a wet idle as I don't see an easy fix. The upper end is a different story. I read the main jets can be interchanged with Mikunis of which I have a few different sizes.

But a road test is first.

 

[joedrum]

well i thought the same thing as you just posted though i constantly tried stuff to lean out idle ....started out wrong by trying to increase air to fix it ...turn out this was bad move as the actual problem was to much gas not a air problem ....i could get things better ...but at idle it was always rich ...rich is costly ...on my bike 35mpg was about the best it would do ....riding super conservative actually produce even less mpg....

it wasnt until i went after gas feed to idle circuit without messing with the just off idle circuit did things change ....on the dft carb i can tell you 80% of all riding is done here ...on dft carb if this circuit gets plug up ..motor simply just wont run ....on stock carbs the idle jets are .035 ...if your idle jet is bigger than that ...id solder it up then drill it to .035 .....and start from there .....

 

[dkl]

I use the largest diameter air filter that will fit inside frame, it has helped top end some, jumps to 90mph with authority....as for the rich idle,,,after it warms up that is when I adjust, it can be idled down at that time. Trick is to find ur happy place so it will crank when it is cold, and not be so rich.....I can find it, so can you.

 

[fivestring]

I have it all pulled back off right now for painting. While off I checked a few things.

The idle jet in the stock carb is a 55. I have found there is a 50 and a 45 available online if I need to go that route. I will look at the main jet size before I put it back on the bike, just so I know what my baseline is.

I had the small screw set at 3.5 turns out and the big one only .25 turn out. When it goes back together I will start over with 2.5 and 2 turns respectively and go from there.

I get almost zero time during the week to be in the shop. This dang work thing sure gets in the way of my motorcycle time! Come on Friday!!

 

[joedrum]

carb drill bits are fantastic thing to have ....after dan and me sort of ..as i was a 1000miles away worked with his jeep carb ...it was acting a lot like yours is though completely different carb ....im just about positive a 55 idle jet and the passage system to handle such a jet ..is way big for oldwing ...as stated my first move would be to go to 35 jet and try to dial it in from there .....dan got awful good at soldering up the idle jet and drilling it out with carb bits ....if its to small you drill out more ...i think you have already proved 55 is to big ....in my opinion...

in dans case it seems nothing but the jet change had to be done ...and his bike instantly ran better to a point it could be adjusted in with the screws.....there is no jets out there in the smaller sizes to buy ......in the dft carb case on hooches modded motor ...with draw it has the whole idle system had to modded to not to be to rich ....

but im hoping this carb is just some jet changing ....heck hooch has gotten impressive mpg close to 60mpg once ...seems to me that maybe this carb if dial in great could beat that ...

anyway pulling for you all i can opcorn:

 

[fivestring]

I guess I need to get some tiny bits. What I've found so far on these 34 pict 3 carbs is that the jet sizes are a true metric measurements so that will help. I am not afraid of soldering the jet and drilling, actually sounds fun and these carbs are SO easy to change out jets right on the motor, nothing like Mikunis and Keihins.

I just ran out to the shop before getting out the door to work and pulled the main jet to see what size was in there. It's a big mystery. I looked all over that jet under a lighted magnifier and there isn't a single stamp on it.

So I compared to my jet collection and found a Keihin 126 is very close to the same size. And I am sure my Keihins will fit right in there for swapping out. Same OD and same thread. And I have them in sizes from 110 to 144. The numbering scheme may not correspond with Solex/Empi/etc but it doesn't really matter. It will be a seat-of-the-pants dyno when it comes to choosing a main jet.

But I'm not ruling out what DKL said last. He got his identical setup tuned in without the jet changes apparently. I'm shooting for that scenario first. It's just interesting to look into the possibilities of what tweaking can be done. And like his intake experiments, you don't know if you have the best arrangements and settings until you try several different ones, especially when marrying a VW carb to a Wing. There's nothing in the Haynes manual on this one.

 

[dan filipi]

What I found fun about jetting size changes in the Solex is just a .05 mm change up or down can make a huge difference in how it runs once you're approaching the ideal jet size.
I found too on the Solex that idle and primary jetting seem to be completely separated in the rpms, whereas a change in idle jet in the dft would have a profound affect on primary also. I like this old Solex.

 

[fivestring]

So Dan, are you running the 34 pic 3? If so, do you know what jets you ended up with?

 

[joedrum]

dans is a chineese copy of a solex carb ..made for jeeps in the late 40s ...itrs a lot different than your carb ...but also very similar in size

 

[dan filipi]

Sorry I don't know more about the pict 3 but the jet sizes I ended up at may help for a base sizing, I really don't know first hand but I have those sizes at home I can post later.

 

[dan filipi]

Forgot that I put my final jetting in "my bike logs"
viewtopic.php?p=161661#p161661

 

[fivestring]

I've been looking up soldering jets. Joe and Dan have been down this road quite a bit. I found a lot of good info and several good threads on here concerning running rich with the single car carbs so I am going to order a set of bits now. I'm convinced I will want to lean out that idle jet first thing before trying to dial in the rest. I found a set of bits on ebay starting at 0.30mm going up in 0.05mm increments so they are on the way.

One thread suggested mounting the jet on a bit that fits before soldering so you don't fill the entire jet with solder. So I would set my 0.55 jet on a 0.55 bit then solder the hole closed with just a tiny bit of solder. Do I understand that correctly?

 

[dan filipi]

I used a very thin electrical Solder. It drilled easy.

 

[dan filipi]

And a dab of flux in the hole cleans the brass for a good solder bond.

 

[fivestring]

I got the micro bits today.

IMG 20160813 125202595

• fivestring
• Aug 13, 2016

I soldered and drilled to .35mm. It ran lean even at 4.25 turns out. I could get the idle as low as i wanted but there was a big hesitation on acceleration from idle.

IMG 20160813 151434

• fivestring
• Aug 13, 2016

So I drilled to .40. Pretty much the same scenario even at 4+ turns out on the idle mix (small) screw again. Then I noticed if I held the rpms between 2k-3k the engine would slowly decrease rpms and die. If I let go of the throttle before it quit, it would recover and go back to idle. Above 3k rpms it was fine and would run as long as I wanted. After playing with the idle speed (big) screw I noticed if I turned up my idle speed just a little the bike would not die at 2-3k. That whole flat/dying thing just vanished. So it seems there is a correlation between the big idle speed screw and the off-idle performance. I believe the main is keeping things alive above 3k and the small idle mix screw is doing the same below 2k but that idle speed screw must be supplying fuel in between.

Back to the bench, I drilled to .45. This seems pretty good. I get a decent idle at 2.5 turns (best vacuum as well), and I get real good, quick response when applying throttle. And I can get my idle to around 1300 without developing that dead spot at 2-3k. Below that idle speed and the dying thing redevelopes.

Haven't road tested yet. Still installing new controls and lighting.

Guru's ideas and thoughts welcome.☺

 

[fivestring]

A funny side note. Apparently,California causes cancer! Who knew!?