madkaw Posted September 10, 2012 Author Share Posted September 10, 2012 Needle and seats on order from Todd. Not sure if that is the issue, but used Mikuni's - I'm probably lucky I havent issues yet. Gonna check plugs tomorrow. Quote Link to comment Share on other sites More sharing options...
madkaw Posted May 3, 2013 Author Share Posted May 3, 2013 Well it's been a few days since I have posted on this thread. I am still pursuing the perfect tune on these Mikuni's, and still having fun while I'm at it! Currently running 70's in the pilots 150 main fuel 180 main air 40 acc pumps Not a lot of difference, but I think I have reached the max pilot jet for my motor. Still- I have a lean spot during moderate acceleration. Now that my wideband works well, I can watch the lean spot come on as my rpms get into that magic zone of 2500-3200. At this point I think maybe I have been barking up the wrong tree here. I have neglected to consider the possibility that I might need to drop down my main air some more. It seems obvious that my cam demands a lot of fuel down low just by pilot size alone, so why wouldn't I consider bringing in the main sooner to help with the dry spot? I haven't tried this because I don't have anything smaller than 180 main-airs, and I just ASSUMED that 180's should be low enough for my engine. Honestly, this little l24 has been really suprising with it's low end torque. What else that has been a pleasant suprise is how well the Schneider cam and Mikuni's have made a very civil and well tempered driving machine. Putzing around in my neighborhood in 4th gear at 25mph at 1200+ rpm and it it hardly chugs. Wide open and it's pure delight. I want a BIGGER cam though;0 The only other aspect of the Mikuni's that could use some help is the fuel smell(mostly in the garage). I'm pretty much positive it is all about the fuel bowls venting out the CAI. I have been reading about the possibility of doing a charcoal canister, but I need to do some more research. For now, I have my electric pump on a hidden kill switch and I shut the pump off a few blocks from the house. I literally run out of gas pulling into my garage---no fuel smell. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 4, 2013 Share Posted May 4, 2013 10 or 12mm booster venturis? If you have 12's go to 10's and your main comes on earlier and wil clean up that lean spot. That should be where the mains start to tip-in. Alternately you could raise your float bowl level incrementally to see if that changes the point where the lean-spot happens... Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 4, 2013 Share Posted May 4, 2013 And there are EVAP carbs that Mikuini made for Toyotas. You would need a properly sealed air box, canister, and bowl vents accordingly. Look for photos of later-model JDM Celica GT, Camry GT (1980) Sprinter/Trueno with either the 18RG or 2TG engines. The 2000GT would likely be the most applicable, there is a rudimentary 67-70 EVAP setup on it equivalent to period comparable 240Z, and is triple Mikuini OEM offering. It was available in the US Market, so you might be able to see some routing and accumulation information from Toyota USA sources. Technical details for the EVAP system are in the manuals for the other respective JDM vehicles. Joel Luz at Toysport may be able to sell some diagrams...if you can't get it all online with some searching. Quote Link to comment Share on other sites More sharing options...
madkaw Posted May 6, 2013 Author Share Posted May 6, 2013 Booster venturies? I been looking on line and at Wolfcreek racing at their diagrams and parts and couldn't find them. I imagine this is what i saw depicted as 'smaller venturi"? So main -airs are not a logical solution? As as evap, I might be screwed with my CAI. It seems the only way to make an EVAP system work is to first have a closed element and I believe mine is considered open. So the fuel vapors will just vent right out the front through the filter unless I had some kind of flapper to close off the box. So I'm not sure what technically makes the difference between and open or closed element system. I look at old V-8 metal enclosed air cleaner vs. open element filter and I think there's not much difference. The old style metal enclosed filter still has a big opening for air to come in, or let fumes out! I can hook up my valve cover vent back up to my box easy enough. My tank vent system is still present and accounted for except the small hose going to the previous airbox is hooked to nothing. Quote Link to comment Share on other sites More sharing options...
madkaw Posted May 6, 2013 Author Share Posted May 6, 2013 Been snooping around for those elusive 2000GT engine pics--drool Pics aren't helping much as far as deciphering what they did on that car for EVAP. I imagine the filter is in that airbox inclosure-sealed! Quote Link to comment Share on other sites More sharing options...
madkaw Posted May 26, 2013 Author Share Posted May 26, 2013 Tuning nightmares!!!!!!!!!!!!! So I am chasing a dead spot that happens during moderate tip-in around 3000+ range. The Mikuni manual suggests small float adjustments to fix transition issues.To my advantage I have the newer Mikuni's that have adjustable float option on the outside of the carb. I have had new needle valves in my possession, but haven't installed them yet. So I thought I would change them out and at the same time verify that the adjusters for the floats actually work. I am impressed how accurate the adjusters are. Each half a turn on the adjuster moves the fulcrum on the float to make a total adjustment of 1mm. I reassembled everything and drove around for a while pushing the transition areas and no luck, so I slam the throttle wide open, where I know it still runs there, and it sounds like sh%t and no power. What the hell happened now? So I start checking everything out from ignition to vacuum leaks. The only thing I really changed was the float needle assemblies. So I pull the covers off again and compare old assemblies with new. The needle assemblies I have are 1.8's and I had 1.5's , so more fuel right? Make a call to Todd at Wolfcreek and he says "yep", no longer carry the 1.5's-should work fine. I recheck the float adjustments and put it back together at 13mm height. Still dead at high rpm WOT Well maybe I need to back off my mains to compensate, but I doubt it. I pull the jet assemblies and lay them out on the bench and start swapping out main jets--WAIT-I'm one short. The main jet fell off or I didn't install it??? Man I don't want to pull all the covers off again to look. So I install the next size down and drive around and things are seeming good again. So this missing jet was throwing me way off, but now I can start fine tuning again. Third time out with a pilot change and WHAMMO, it's doing the same thing. So I immediately go for the main jets and found that my carb ATE another jet. WTF!!! So now I have two main jets laying in my float bowls(I assume that's where they are). So maybe the first time I screwed up and forgot to tighten down the jet properly. I usually pull all of the assemblies out of the carbs at once and do an assembly line change. Maybe I got in a hurry the first time. The second time, I'm not sure. Maybe I am not tightening these jets down hard enough. I know brass relies on the newer threads to cut and hold, so maybe the many changes I have made have worn the threads down enough that they don't hold as well. Not sure if there a solution other than new jets? I gave up for the day at least knowing there nothing major wrong with the car. These kind of days make you pull your hair out. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 27, 2013 Share Posted May 27, 2013 Rich=Shift Ctrl Arrow Up Lean=Shift Ctrl Arrow Down Use mouse to select an area of the map, hold Shift-Ctrl while you Left-Click and drag over the cells you want to change... The above keyboard shortcuts will then affect ALL load points in the table equally... "CARBS ARE EASY!" Quote Link to comment Share on other sites More sharing options...
madkaw Posted May 27, 2013 Author Share Posted May 27, 2013 That's why I have the other thread started- Carbs are a PITA! Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 28, 2013 Share Posted May 28, 2013 You have transcended into the Yoda-Like Beast who wants to say to those spouting "carbs are easy!" "Up you should shut, for your ass from a hole in the ground you do not know the difference!" Quote Link to comment Share on other sites More sharing options...
madkaw Posted June 7, 2013 Author Share Posted June 7, 2013 I went on a fishing expedition yesterday to find my jets. Carbs might not be easy, but as much as I have fiddled with my set-up I am getting pretty fast and efficient at R&R! Number 2 carb had both main jets laying in the accelerator pump cavity. One jet was still half way in the bore of the main jet. It had to be impeding flow to that main side -which in turn was effecting WOT. I went ahead and adjusted the acc pumps to the hole on the top for faster tip-in response. I have had the slightest studder as mild tip-in and want to see if this effects that situation. The acc pump rods are the biggest pain to adjust on these carbs because I have a heat shield and you can't get to or SEE what your doing when trying to change the setting on the rod. I actually put jesus clips on the first and second hole of the rod. This way if the first setting is too high, I can go back in and just pull those clips and let the rod fall to the next setting. It's much easier to pull one of those clips then trying to install one in a new setting. As far as pilot jet settings, I am now fudging a bit on the '1' turn rule, which according to the Mikuni manual is actually 1.5 turns. I'm back to running 65's on the pilot because anymore size increase did nothing to help transition issues. With the 65's I stay in the 14-15 AFR range at light throttle and cruise with a high 15 at idle. I might lean towards the 67's in the end, but more tuning will dictate that. Obviously I have had other issues which could change things once fixed. Now that I have kind of started over again I will need to resync my carbs which hasn't been done in a while. I have rigged up a bar that will clamp off my vacuum lines to my vacuum log so I can individually sync the carbs. Quote Link to comment Share on other sites More sharing options...
madkaw Posted June 17, 2013 Author Share Posted June 17, 2013 The tuning adventure continues. I did wind up resetting the acc pumps to the second hole- just too much fuel at tip- in. 67's on the pilots worked pretty well but still have the slightest bobble at the same zone. I am going too richen my floats in last effort to clear this. The only reason I am trying this route is that the bobble seems to be like the bobble at hard right handers I called Todd at wolfcreek racing and didn't have much to offer. When I reported to him my AFR readings at idle and cruise and WOT, he said I was in a place that most guys don't achieve and I am at the limits of a street performance triples. I did pull my plugs after a weekend of combined cruise and hard driving and they looked good Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 17, 2013 Share Posted June 17, 2013 I agree with Todd. By the sounds of it they're pretty dialed. One thing I wanted to try was different emulsion tubes. The Mikunis don't have all the different options like the Webers do, and pretty much every runs the OA, but there are the OBs and the 8s to try. IIRC the 8s were supposed to be a "street" setup so I was thinking of trying them on the hunch that they might do better on the transition. Never got to it though. Quote Link to comment Share on other sites More sharing options...
Leon Posted June 17, 2013 Share Posted June 17, 2013 (edited) Have you tried smaller air jets? It could either be a progression hole problem or a main circuit tip-in problem (solved by the right combo of e-tube and air jet). Edited June 17, 2013 by Leon Quote Link to comment Share on other sites More sharing options...
madkaw Posted June 17, 2013 Author Share Posted June 17, 2013 Jon, I believe I have the 8's in there now Leon, I have tried smaller air mains and it does not solve that small zone of leanness . When I say small zone, I mean its a very narrow band that I notice this, but I can watch the AFR real time go lean right into the bobble. This happens during a less then moderate tip in at 3000- roughly. If I get into it any harder the acc pump helps it through this zone without bobble. I will try and make a video this coming week. Quote Link to comment Share on other sites More sharing options...
madkaw Posted October 21, 2013 Author Share Posted October 21, 2013 So I have verified that the emulsion tubes have a 8 stamped on them, but couldn't match that with anything in the catalog. The bleed pipes had a 'T' stamped on it, again, it matches nothing in the mikuni catalog. If I were to temporarily alter the emulsion tube/bleed pipe to start transition from the main sooner, how would or could I do that? Quote Link to comment Share on other sites More sharing options...
Leon Posted October 21, 2013 Share Posted October 21, 2013 First thing I'd do is check whether there are any air bleed holes above the fuel level. If so, plug them. Use a toothpick, Loctite, etc. Then, you may need to up-size some lower bleed holes to get more air in, which will help accelerate the fuel faster during tip-in conditions. I'd also try to contact Keith Franck, he knows a lot more than I do when it comes to this. I'm just relaying Keith's findings. Quote Link to comment Share on other sites More sharing options...
madkaw Posted October 21, 2013 Author Share Posted October 21, 2013 Holes in the E-tube or the bleed pipe? How would I go about contacting him? Or is that only through the Yahoo Group? The other interesting thing is that some mikuni's don't even use the bleed pipe. Quote Link to comment Share on other sites More sharing options...
Leon Posted October 21, 2013 Share Posted October 21, 2013 Holes in the E-tube or the bleed pipe? How would I go about contacting him? Or is that only through the Yahoo Group? The other interesting thing is that some mikuni's don't even use the bleed pipe. I'm not very familiar with Mikunis but Keith has modeled them up. You can contact him through the group. Quote Link to comment Share on other sites More sharing options...
Leon Posted October 21, 2013 Share Posted October 21, 2013 Holes in the E-tube or the bleed pipe? How would I go about contacting him? Or is that only through the Yahoo Group? The other interesting thing is that some mikuni's don't even use the bleed pipe. Steve, tried to PM you but it said you can't accept any new messages. Send me a PM with your email or phone #. Quote Link to comment Share on other sites More sharing options...
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