Twin Weber 40s on a GL1200?

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RazMan

RazMan

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The shocks are aftermarket (by Craftride) and measure 12" (302mm) eye To eye. Made for Sportster 883 1200 Street rod etc. They originally came with 13mm bushings which I changed to suit the Wing. Spring rate seems ok considering my bike has been on a radical diet. They lower the bike a fair bit - you can see how far the rear wheel is off the ground when on the centre stand (I am going to shorten it to suit)
 

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RazMan

RazMan

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Another milestone has passed - the motor is alive!! It fired up on the first push of the button and sounds awesome and actually ticks over quite well. Cant wait to take it out for a test ride but I am still waiting for the seat to come back from the upholsterer and some better handlebar levers. I've also got to look into an overcharging issue (possibly a new regulator needed) but when all of this is done its time to hit the road!
 

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RazMan

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In my case it was just the fact that I had forgotten to connect the regulator sensing wire :rolleyes: 🙃
 

Motörhead

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Looks awesome! I had trouble balancing a set of four Webers on a 289 Cobra once. Turned out a backfire twisted one of the throttle shafts, I always checked the butterflies to be sure after that.
 
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RazMan

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I have some more progress - the engine ticks over quite well and low road speeds are ok, however when the throttle is over half open things get a bit unstable - feels almost like fuel starvation so maybe the main jet needs changing (147 at the moment)
It occurred to me that the ECU has a vacuum connection which I have not connected yet - is it looking for a vacuum to adjust the timing? Should I block it off?
 

Motörhead

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1985 Kawasaki Concours
1975 Honda GL1000
I have some more progress - the engine ticks over quite well and low road speeds are ok, however when the throttle is over half open things get a bit unstable - feels almost like fuel starvation so maybe the main jet needs changing (147 at the moment)
It occurred to me that the ECU has a vacuum connection which I have not connected yet - is it looking for a vacuum to adjust the timing? Should I block it off?
Connect it, the engine needs more ignition advance as RPM rises.
 
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RazMan

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Triumph Rocket 3
I can't believe I didn't figure that one out for myself :rolleyes: I guess I am getting too used to having fuel injected, super tech bikes these days - I forgot that the Wing is old school :LOL: A couple of feet of vacuum hose now fitted.
 
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RazMan

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Well she runs - sort of .....

I still have to sort out the carbs sync properly but at low revs she behaves quite well. Mid range is where the problem is - there seems to be a big black hole where all the power is supposed to be ...... if you open her up, ride it out and wait, full power kicks in and you wonder how it can run so well at low and high revs (or throttle ) Part of it is inevitably the terrible Randakk manifolds, also the mis-match in port sizes - 32mm / 28mm with a 'ledge' which must really screw up the gas flow.

As the rest of the bike is performing really well - surprisingly well for an old girl - I am tempted to persevere with these Weber clones and maybe do some cave man porting on the 1200's heads and manifolds - I have come this far.
 

derrick woods

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Well she runs - sort of .....

I still have to sort out the carbs sync properly but at low revs she behaves quite well. Mid range is where the problem is - there seems to be a big black hole where all the power is supposed to be ...... if you open her up, ride it out and wait, full power kicks in and you wonder how it can run so well at low and high revs (or throttle ) Part of it is inevitably the terrible Randakk manifolds, also the mis-match in port sizes - 32mm / 28mm with a 'ledge' which must really screw up the gas flow.

As the rest of the bike is performing really well - surprisingly well for an old girl - I am tempted to persevere with these Weber clones and maybe do some cave man porting on the 1200's heads and manifolds - I have come this far.
I've really not found anything randakk sells worth buying not to mention overpriced. Back when he was based out of North Carolina he was pretty good to deal with now the only way you can even contact them is email only. That pretty much done it for me I'm old-school I like being able to talk to someone or at least text message
 

joedrum

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Razman if it's running good low rpm and higher rpm but not AR mid rpm ...it flowing ok ..it's my opinion that it's either ignition timing advance issue or carb issue ...the reality is thetes way to much carb in this set up in my guess I'd say it's just getting flooded with gas charge and not enough timing advance to fire it then when the rpm gets faster the motor seemingly gets bigger through rpm and kicks back in takes off ...
 

joedrum

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Porting may help but it might actually hurt it ...this is the big problem with this set up ..I never seen one actually perform well ..this is all opinion as I've never work on this set up at all ...but ran with one once it was no challenge at all .. Not what I would high performance set up
 
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RazMan

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After struggling to find an easy solution, I had a re-think about this project and came to the conclusion that this will just be a money pit and it is better to cut my losses and put the original carbs back on. I could try porting the heads but that will take a lot of time and of course more cash. After all that it might still run like poo and I will have trashed a pair of perfectly good heads.

It pains me to say that I have now put the whole setup on ebay, serviced the old carbs and put them back on. She runs like a dream now! I had forgotten how smooth these engines are and after a radical diet, the performance is quite surprising and the handling is more like a nippy sports bike now.
 

joedrum

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Good move this randakks push of this set up was a complete failure and extremely overpriced ...plus he discounted people like me and others who used single carb set up ...claiming stocks were better ...but his side mounted exposed to weather was better than stock ...it was all pure BS ...I HAVE NEVER COME ACCROSS ANY OLDWING 4 that comes close to running like the hooch bike ...it's basically modded 1200 motor mostly with other yr parts ..it has a highly modded Weber progressive linkage 2 barrel carb and custom programmed ignition it's so fast it's dangerous ..many unstablizing problems with a high powered boxer motor and shaft drive set up to say the least ...I don't ride much any more but it's been 30 thousand miles since built hurt me once pretty and almost twice the last time I got it down to about 20mph before I totally lost it ..lol I was very lucky ...I don't think I would ever sale it ..it a great build but it's dangerous ...I pretty much into my vettes now with 4 wheels but they are convertibles lol ...
 

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