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ih8boats

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Dec 4, 2011
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Saint James City Florida
Ok so i cant leave well enough alone. basic stats. of project '86 gl1200 with gl1100 heads and cams,compression 155-160 cold, wot. new dynatek green coils 7mm copper wire w/no resister caps, iridium ngk, stovebolt tom's weber atop a vw plenum welded to1" sch. 40 runners bushed for gl1100 turndowns. cold start ok, idle steady 1200 rpm when warm,consistent 34.5 mpg mixed, 32 towing tool trailer. sounds pretty good right ,well i have been tempted and have tasted the forbidden fruit and lemme tell ya iv felt the potential and its awesome! i bought my self a birthday project this year of randakk's gen 2 manifolds and a new set of empi 40 hpmx carbs from an online retailer somewhere in California. I really like the well built manifolds, and the carbs can be made to idle great, not to mention that wot. in all gears is amazing" imho". But ! and i know you been waiting for it,there is a problem just off idle and at average cruising rpm 3000-3400 one carb has a lean sneeze i cant seem to clean or tune away. I feel i may have chosen unwisely in the empi over European webers. i have collected all kinds of ride data if any one has opinions,input, suggestions or comments on the matter or any and wants to discuss at all
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more pictures too if ya want ta see.
 
yes Denver cruising down the road with aircleaners off i can spy and hear#1 slight backfire an issue that followed the carb after i swapped it from left side where it was #4
 
also i have disassembled,cleaned out all manufacturing dross from both carbs in an ultrasonic cleaner twice blown out all circuits and verified transition ports 4 times,checked throttle plate alignment,and float levels. fuel pressure is a steady 2 lbs carbs linkage mechanically synced as well as synced to each other via techmate(vacumate) electronic synchronize r and no venture leads another appreciably from idle through 5000 rpm under load. im stumped.
 
Jetting ?, might try to swap them, see if that could be it. :headscratch: Not knowing anything from experience with this set up, :nea: only a shot in the dark at best. :whistling:
 
yes im running one size larger idle fuel jet then recommended on all 4 and realy backing out on the mixture volume screw for that cylinder seems to almost mask it at speed but my idle becomes more than fat and sassy its sooty and eye burning in the shop.
 
Do you have the size recommended size to try? :roll: Too much air in your mixture at one point from leaning it out too much? :headscratch:
 
Cool setup,hope you get it fixed

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theres a problem with this type carb set up and it is air......a wellset up dft will trounce the webers .....i have yet to see one run as goodas hooch dose.......on the bigger dft im using ...32_34 im getting upper forties in gas milage.....the wo stage air flow of dft carb is hard to beat
 
Thanks joedrum i agree with you on the dft, im running one on my wife's '83 1100/1200 as well as the perfectly good rig i removed from this bike. both make me smile with their performance and reliability but i was just exploring another avenue. i guess the reason for my post was to seek out like minded oldwingers who might have experience/opinions on the empi vs real weber dual rigs as there are a few things where fit/Finnish is questionable and would like to compare them to webers.or if anyone can clue me in to something i may be overlooking in tuning or adjustment. ultimately im committed to see this configuration through even if that means stepping up to the plate to order new European made webers.
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EMPI carbs I've read were fine or junk. Might be just the skill of the authors of these reports that varies. Regardless of that you are essentially back to stock configuration with one carb per cylinder. So vacuum gauge and accurate tach will be your best tools. Exhaust gas analyzer would be nice too especially if you had 4-4 exhaust. Good luck in setting these up.
 
Yes slab i feel i may have balanced the luck of the draw by receiving one ok and one junk carb from empi. as for vacuum gauges this synchronizer tool i have from tech-mate is pretty cool if you ever get a chance to check one out.i can actually drive and watch the balance of all the carbs as they pull vacuum through the rpm range under load and single out the one giving me fits. i intend to weld in a pair of wide band o2 sensors after i get past this little hiccup .
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In starting this thread I was hoping to reach out to the folks here who have experience with this type of downdraft carb never having put my hands on an idf weber before, maybe start a discussion of there specific characteristics and how they might relate to oldwings of different displacements,heads or cams. Of-course i have no intention or desire to reveal any of randakks hard earned proprietary tuning specks,with that in mind i hope to hear from anybody willing to help me discover if i have a repairable carb or a shinny paperweight . By the way I have not bothered Mr Washington yet with this partially because i feel a bit embarrassed for not following suggestions of choice of carb,my "creative"linkage,my results and the possibility of an i told you so
 
While I have no experience with those particular carbs.I'll help what I can. I believe Ian is also planning to run them on his bike but it is yet incomplete. Maybe he too will chime in.
 
If you can post an exploded view of the carbs that will help in understanding how it's supposed to function. I expect the airflow through the carbs to be at least equal to stock so that shouldn't be a big issue. I expect a rich condition will likely be the major issue.
 
What proprietary tuning specs? That sounds rather silly to hold onto information to get a mod like this running right gees.
I can only help in so far as what I know about carbs, and not those carbs in particular but they all basically work the same.
By your description of the symptoms it sounds like it's getting way too much gas making it necessary to run at higher rpm to even run. Does that sound right?
 
iv learned that the idf has three separate fuel circuits idle,midrange transition and main each has an effect on the other in different throttle plate positions and vacuum levels. im confident in how the idle jets and mixture screws act and respond im unsure how the transition circuit is being effected by what i can see happening down the bore of the secondary venturies #1 bore has what i believe to be lean sneeze just off idle and at 2500-3500 but at higher rpms the mains flow and dribble in that bore and do not in #3 and #4 seems almost dry in comparison
 
Going lean mid range to me suggests a rich idle. Are the idle plates at the bottom of the carbs drilled? Maybe in one carb and not the other? Do these carbs use the same jets throughout the range or are there high speed jets to transition to?
 
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