engine and drivetrain Carb decisions....keep the 38/38 or dive into the DCOE 40s?

[zinz]

I check my mileage at every fill up. It lets me know if something is amiss. I get 20-21 on my stop-go commute and got as much as 27.5 on the hwy last year. ...I've never been accused of being a light foot. The only thing that I ever struggled with was the distributer...not the carbs.

No... They are not a "slap on" mod, but sheesh... If I can get an obsolete pair of Solexes to run this well, modern Webers can't be such a mystery.

I'll be happy to show my setup to anyone interested at Eureka Springs this weekend.

Ed Z

[KFunk]

The stock dual Mikunis on my cheapo Yamaha 400 seem much more complex and finicky compared to my 40 DCOEs, and they're extremely common (4 of them on all the bigger Japanese bikes).   The Mikunis use a couple different methods of regulating fuel at different parts of the power band (a fragile diaphragm, round slide, and calibrated needle), and I've had to take them apart several times to clean little passageways to make them run right.  The 40 DCOEs just have different jets for each part of the power band, and there's enough of them to overpower most issues.  

Edited April 23, 2015 by KFunk

[M3M3]

No... They are not a "slap on" mod, but sheesh... If I can get an obsolete pair of Solexes to run this well, modern Webers can't be such a mystery.

unfortunately they are such a mystery to many of today's "plug and play" generation.  folks are used to "bolt on 50hp" mods or the "chip it" mentality with the 5minute utube video of all you need to know.   I loved the multiple sets of DCOES i had on my 2002's....but i am a terminal tinkerer who likes to do the reading and research to understand exactly how things work... and the cars were not my daily drivers.  for a daily driver and or someone who just wants the car to go quick without having to know how to jet and balance multiple carbs (regularly), the 38/38 is just so much better.

Edited April 22, 2015 by mlytle

[kbmb02]

With the proper engine compression/camshaft/distributor combination, either set-up can me made to work well. Sure, there’s a certain bling to side-drafts, in both how the look and sound. In my opinion and experience, a proper linkage set-up is crucial (did a nice one recently on Brandon’s car) and tuning is more involved in you want it really right.

 

 

Blah-blah-blah … I won’t pontificate. However, as a reminder, a down-draft engine can sound pretty sweet, too. -KB

 

[KFunk]

I can't really compare to a 38/38 at all, so please disregard my opinion on that matter.  I've never used one at all.  I just happened to find 40DCOEs locally, so I did that.  

 

But to keep my streak alive in annoying people:

I've only synched my carbs 2 or 3 times in 8 years.  I borrowed a synchrometer once when I first got my carbs, and just recently finally bought one of my own.   

Synching can help throttle response to be a tiny bit smoother, and maybe idle just a bit smoother.  I wouldn't say it has to be absolutely perfect though for general driving or power.  I'm not sure if other people do it quite often while trying to hunt other problems, or they're more sensitive to these things than I am.    

['76mintgrün'02]

My guess is that people would be content with theirs, if they did not have a wide band to tell them otherwise.  

 

Do you know what your 'numbers' are?

[KFunk]

My guess is that people would be content with theirs, if they did not have a wide band to tell them otherwise.  

 

Do you know what your 'numbers' are?

 

Yeah, I'm well aware of this, and the endless spiral of tuning that might go on if I had a wide-band sensor.

 

I've chosen to stay ignorant all these years, and it suits me fine.  2002tis didn't have wide-band sensors, and they did fine.

Sure, I could be making a lot more power I'm sure with some tuning.  I may get around to that some day.  I've been OK with tuning by ear and checking plugs though, old style.   

Edited April 22, 2015 by KFunk

[zinz]

zinz, on 21 Apr 2015 - 8:17 PM, said: No... They are not a "slap on" mod, but sheesh... If I can get an obsolete pair of Solexes to run this well, modern Webers can't be such a mystery. unfortunately they are such a mystery to many of today's "plug and play" generation. folks are used to "bolt on 50hp" mods or the "chip it" mentality with the 5minute utube video of all you need to know. I loved the multiple sets of DCOES i had on my 2002's....but i am a terminal tinkerer who likes to do the reading and research to understand exactly how things work... and the cars were not my daily drivers. for a daily driver and or someone who just wants the car to go quick without having to know how to jet and balance multiple carbs (regularly), the 38/38 is just so much better.

 

+1, Marshal.

 

I must have read my Solex Tuning book 4 or 5 times over the course of several months... from carb purchase throughout installation and final jetting.  The extra effort to find pilot jets from a German-only-speaking dealer in Berlin, sending the cold starter units off to have special diaphragms made, hand-making some widget that couldn't be found anywhere... well, that was part of the adventure, for me.  Plug and play?...hell, I don't even own a laptop (makes programming my 123Ignition dizzy a challenge

 

In any case, I said it before.  A 38/38 might likely perform just as well, but my setup is about bullet-proof as any carbureted engine can be.  It runs SIGNIFICANTLY better than the practically brand new Weber 32/36 that came on the car...pew. Terrible mileage and would vapor lock at the first hint of summer... same scenario I can remember from the 32/36 in my '69, long ago.

 

Kbmw02's race motor???  Well...that thing is just plain sick.  I'm not sure how he harnessed the devil into that M10, but it sounds awesome.  Love. It.

 

Ed Z

[jrhone]

Ken. Expect an email soon. I know we have discussed before. Thanks guys for your input. While I am a tinkerer at heart I do like simplicity. The urge to do them is compelling especially since I have a pretty clean matched pair in the garage that just need a rebuild. Also since my 38 is leaking fuel and lately has been finicky this may be the time. I already have the bypass hoses and water neck in the car.

[Doug Riparetti]

38mm Keihin flat-slide motorcycle carbs that have been hogged out to 40mm, mated to the "Lynx" manifold. I ran these carbs on my "Pro-4" when I was racing circle track. I'm going to do the install after Brisbane and Bimmerfest

[Rocan]

As a CB350 owner... I have a soft spot for Keihin Flat slides. I would love to hear that run!!

[Doug Riparetti]

I'll be doing the work at the end of May, as soon as I get back from "Bimmerfest" in Fontana Ca. I'll post the results when it's complete

Edited April 23, 2015 by Doug Riparetti

[BeMyWay]

With the proper engine compression/camshaft/distributor combination, either set-up can me made to work well. Sure, there’s a certain bling to side-drafts, in both how the look and sound. In my opinion and experience, a proper linkage set-up is crucial (did a nice one recently on Brandon’s car) and tuning is more involved in you want it really right.

 

 

Blah-blah-blah … I won’t pontificate. However, as a reminder, a down-draft engine can sound pretty sweet, too. -KB

 

WICKED!  Wasn't expecting this type of explosive response...I had headphones on and it made me jump...LOL

Edited April 23, 2015 by BeMyWay

[Marsattacks]

Another! http://youtu.be/_j65Pv2D-Zc

[TobyB]

I can't believe Marshall wasn't the search Nazi on this one, as we did this not so long ago.

 

i'd chime in with "get a good linkage or don't do sidedrafts"

 

and everything else has already pretty much been said.

 

t