Sudden Posted January 9, 2013 Report Share Posted January 9, 2013 ^^^^^^^^^^ Couple great posts^^^^^^^^^^^^ Thanks guys!! Sudden: Great idea on shimming the springs. Never thought about the rate at which they rise! V8 guys, running holleys for instance, buy a spring kit to adjust the rate in which their vacuum secondarys kick on. Why didn't I think of this....... Lol thanks. Are you having random lean burn issues? I shimmed the springs because I wasn't 100% sure what drilling the slide holes did. and that is a permanent mod. I can't seem to source any more bike carbs at all on this dang island. and the ones on eHay etc are all about the price I pay'd for my car so... no xD On another note. engine bucking as i approach 4500-5000rpms? :s why does this feel ridiculously random? When I mod my plenum (carbs closer to head) and build brackets to stabalise them ill report back on this....or I may get lazy and retard base timing and test again. random bad fuel? i stopped using octane booster when I read that its bad for the carb diaphragms. and I can not risk damaging my only set of bike carbs :unsure: Quote Link to comment
spudly13 Posted January 10, 2013 Report Share Posted January 10, 2013 Might be picking up my set on saturday.Then I guess I'll have to build an intake, buy a header, jets, and electronic ignition. Still cheaper than a new Weber. What motor are you gunna be puttin em on?? sorry if you already said :blush: Quote Link to comment
VintageRice Posted January 10, 2013 Report Share Posted January 10, 2013 Lol thanks. Are you having random lean burn issues? I shimmed the springs because I wasn't 100% sure what drilling the slide holes did. and that is a permanent mod. I can't seem to source any more bike carbs at all on this dang island. and the ones on eHay etc are all about the price I pay'd for my car so... no xD On another note. engine bucking as i approach 4500-5000rpms? :s why does this feel ridiculously random? When I mod my plenum (carbs closer to head) and build brackets to stabalise them ill report back on this....or I may get lazy and retard base timing and test again. random bad fuel? i stopped using octane booster when I read that its bad for the carb diaphragms. and I can not risk damaging my only set of bike carbs :unsure: Not having issues related to that but Just thought its a cool new aspect of being able to tune these carbs. Put that in the old "tuning ideas" file. :D Quote Link to comment
slingshot532 Posted January 12, 2013 Report Share Posted January 12, 2013 I did some long distance driving today. When I am cruzing, not accelerating and not deselerating, foot lightly on the throtle, butterflys just cracked it goes way lean. I thought the "no hubs" where getting lose so I reset everyting and tightened them back down and it still dose it. the only thing I changed was putting the filters on. I did cut the hood so the tips of the filters are exposed to the wind. I thought filters would make it run richer. It runs slightly rich at idle and slightly rich after throtle starts to open but it has that lean spot at throtle open. I was reading back through one of the carb tuning sites and it says that is controled by the pilot system, so I will start there. It's anoying because that is the spot you use the most on the freeway. I have to keep speeding up and slowing down to keep the mix from going lean. Quote Link to comment
72240z Posted January 12, 2013 Report Share Posted January 12, 2013 Are you using a wide band? Quote Link to comment
VintageRice Posted January 12, 2013 Report Share Posted January 12, 2013 If you are using narrowband, you might just be barely lean, which if I remember right I think I've read that being slightly lean while cruising is ok, especially if you want good fuel economy. You Just dont want lean on WOT and if your running forced induction. Then it can get dangerous. But this is just going off memory of what I THINK i have read..........not sure on this. Quote Link to comment
72240z Posted January 12, 2013 Report Share Posted January 12, 2013 Depends how lean is lean and how rich is rich. Thats why I ask about a wide band. A narrow band is next to worthless for what we are talking about, its only going to read right in its designed range, which is very narrow go figure lol. Lean cruising within a certain range is ok but weather its better or not for economy is debatable. Running lean will make less power creating the need for more throttle and.... more gas to maintain the same speed. Rich on deceleration isnt desirable either because it washes the cylinder walls. To me for cruising stoich afr is ideal. Leaner for deceleration and richer for acceleration as the most power the motor will make is in a slightly rich area. Tuning those parameters into a make shift bike carb set up is ridiculously hard though which why Im opting for efi. Even running easier more well known and documented triple webers as I am now after months still haven't gotten them 100% as I would like them. With this set up I wouldn't expect to ever be perfect tune wise. I personally would tune them to have a fat curve and always favor rich, as slight as possible. You wont have the best fuel economy but you'll always have the most power and best drive-ability. Thats the goal right? I mean for better mpg there better options lol Quote Link to comment
xtrememotorworks Posted January 13, 2013 Report Share Posted January 13, 2013 Pilot is no more than just off idle. My guess is your more into needle/clip position tunning area. Been awhile but don't think the stock needles are adjustable. Could shim them or get a needle with a richer taper.What afr are you running? Quote Link to comment
slingshot532 Posted January 13, 2013 Report Share Posted January 13, 2013 Damb it why do you guys always call me out? It is a nerrow band sensor, in keeping with the cheap build. So I don't know the exact AFR. I am usualy in the middle of the rich GREEN section of the sensor display. When it goes lean it goes off the red end so no lights are showing. Is this too lean? if not than I won't worry. My concern is crusing for a long time, 10-20 minuets and overheating the combustion chamber. As far as needle adjustment I found o-rings the same size as the needles and they work great. I think I posted pics on here. Quote Link to comment
xtrememotorworks Posted January 13, 2013 Report Share Posted January 13, 2013 If you really want to be spot on a nice wide band or a trip to the dyno could save you days of tunning. Also with hood cut pulling in fresh cool air over hot under hood air will lean it out. Quote Link to comment
slingshot532 Posted January 13, 2013 Report Share Posted January 13, 2013 This is how I am setting my needles. I am curently running no o-rings, tomorrow I will put one back in and see how it runs. On my gay, cheap, nerrow band sensor. Quote Link to comment
xtrememotorworks Posted January 13, 2013 Report Share Posted January 13, 2013 I tuned for years with nothing a butt dyno and reading spark plugs lol changing needle position just might not be enough either. Have to figure the carbs where tuned to pass emisions and run at 11k. Few different tapered needle might be needed to find the perfect one. Quote Link to comment
slingshot532 Posted January 13, 2013 Report Share Posted January 13, 2013 This car is just for fun nuthing crazy. I don't do anything for a few mounths then get back to it. I don't spend much money on it. I actualy don't know much about carbs. I knew the basics before I did this swap and I have learned a lot. I don't race it , and I don't care if it's not perfect. The car needs so much other stuff anyway. So as long as it runs good and is not burning it's self up I'm happy. Quote Link to comment
Sudden Posted January 13, 2013 Report Share Posted January 13, 2013 what size are those o-rings? :) Quote Link to comment
xtrememotorworks Posted January 13, 2013 Report Share Posted January 13, 2013 Orings work, but if you can spend another couple bucks getting the correct washers will help dial it in better, one oring is a pretty big jump in fuel metering. Here are some on ebay, hell might even be able to hit up home depot and find some small washers that will work also... http://www.ebay.com/itm/TRIPLE-Carb-Needle-Shim-Kit-Mikuni-Carburetors-/110604954027?_trksid=p3284.m263&_trkparms=algo%3DSI%26its%3DI%26itu%3DUCI%252BUA%252BFICS%26otn%3D21%26pmod%3D110604954045%26ps%3D54 Quote Link to comment
Sudden Posted January 14, 2013 Report Share Posted January 14, 2013 I just need to know the size to fit the mikuni needle. currently i've overshimmed to compensate for my too small main jet.( trying to think of a way to block the air jet temporarily to see if that would help) Quote Link to comment
xtrememotorworks Posted January 14, 2013 Report Share Posted January 14, 2013 All the circuts overlap a bit, but the main jet, when wot is not really effected by the needle. Unless you have some deep gears and really reving the motor my guess is your not into the main much at all for tunning wise. This is why the shims and taper of needle is so importian. Most driving is done in the mid range and this is where the needle does it work. Tune the pilot for off idle/throttle respose, tune the main for WOT and then spend all day messing with the needle, slide hole and spring until your really piss off lol Quote Link to comment
Sudden Posted January 14, 2013 Report Share Posted January 14, 2013 i have my idle and needle where i need them. approaching high rpms i start to starve for fuel (narrow band gauges are not useless) i have 2 problems noted currently. on smooth road after 5000-5500rpms my fueling starts to head from the richer side of stoich through to lean and then id i don't ease up it will backfire through the carbs (lean condition). Ill measure my needle diameter to get some washers tomorrow. I'll also test resticting the main air jet to see if i can get it to pull closer to the engines actual redline. Quote Link to comment
72240z Posted January 14, 2013 Report Share Posted January 14, 2013 I didnt realize so many people would get butt hurt lol. Narrow bands arent useless, they make a good switch, which is what they were designed for. To switch between lean to stoich to rich back and forth etc... operating between .1 and .9v. They are unable to accurately tell how lean or rich because of that narrow band. Because of this they ARE useless for tuning. A wide band (1-5v range) is needed to take a real, accurate measure of the exhaust gases. That function range pic is cool, should help people out a bunch. Quote Link to comment
slingshot532 Posted January 14, 2013 Report Share Posted January 14, 2013 what size are those o-rings? :) They are the same size as the needle. I can't remember, but if you take your needels in to O'rileys they can match them up. I put one o-ring on each needle and drove it. It runs smoother and the AFR stays in the same section of the meter, from the begening of the rich section to the middle. Feels like it has alittle more power. Quote Link to comment
slingshot532 Posted January 14, 2013 Report Share Posted January 14, 2013 Orings work, but if you can spend another couple bucks getting the correct washers will help dial it in better, one oring is a pretty big jump in fuel metering. Here are some on ebay, hell might even be able to hit up home depot and find some small washers that will work also... http://www.ebay.com/itm/TRIPLE-Carb-Needle-Shim-Kit-Mikuni-Carburetors-/110604954027?_trksid=p3284.m263&_trkparms=algo%3DSI%26its%3DI%26itu%3DUCI%252BUA%252BFICS%26otn%3D21%26pmod%3D110604954045%26ps%3D54 I thought shims wher only for needles with slots cut in them. I didn't think of using them to stack to fine tune. That is a good idea. Quote Link to comment
Sudden Posted January 22, 2013 Report Share Posted January 22, 2013 Well I'll be damned. knowing main jet is too small is one thing. having an alternative to replacing it is just plain awesome. I test blocked the main air jets to see the results, then closed them with silicone So much win. I can now enjoy moar rpms. :D I can now drop my needles a clip since I'm no longer compensating for my main jet woes and dial everything back down. I have conquered :D. My high compression build can now Commence! Quote Link to comment
HudsonMC Posted February 18, 2013 Report Share Posted February 18, 2013 Those with the bogg brothers manifold... I had it bolted up with some nasty tri-mil headers I had laying around, but switched to the factory manifold and am running into interference issues. Before I go grinding away at the stock manifold, anyone else experienced this? Quote Link to comment
sick620 Posted February 20, 2013 Report Share Posted February 20, 2013 Im going to post this again just because it looks that good lolLet it take us away formt his nonsense....... not really a fan of the looks of that, looks like it should be playing me a song, not carrying me down the road... tho im sure its pretty beastly :) Quote Link to comment
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