Keg86

I would LOVE a set of these. KA24DE powered 521 running on R1 Carburators!!!

Hendrik, Yes that is correct. If your WOT is anything higher than 14.7 try plugging the Main Air Jet (shown in my post on page 63) which should richen up the the existing jet. After that you can check again and see if it comes back to a reasonable number. If it is lower, depending on how low, it might be fine. i have mine at 13.5 right now (i think. my O2 sensor died) because outside air temps can make that fluctuate a little. As far as adjustable needles i would look at getting the kit from Dynojet (model numbers shown in post on page 63). the kit comes with everything you need plus extra main jets (#14) and a new pilot jet that will help you bring the #8 screw in more. have you done a bench sync on those carbs since you got them. you mentioned the a/f ratios going up and down quite a bit. you might have one carb that is out of adjustment. so if you pull off the carbs to change anything you might as well do that too.

Hendrik, Just want to make sure that i am reading your post right. you are getting an A/F of 19 at idle and 12.8 at part throttle while cruising, correct? What is your A/F at wide open throttle (WOT)? The idle of 19 is concerning because you are running super lean although not under load so it isn't quite as bad as if that was a cruising. Luckily that is an easy fix. If i were you i would screw all of your pilot screws (#8 from the parts diagram) IN all the way then back each of them off 3-3.5 turns and check your A/F while the engine is warm. That should put you in the correct range. You can adjust incrementally from there to get around 13-13.5 A/F which is where I have mine currently. Next, with your part throttle being 12.8. That shouldn't really be an issue since you are a little rich which is safe for the motor. If you want to bring it up to 13.5-14 you can to get the last bit of power. Do you know if you have adjustable needles? these carbs didn't come with them from the factory but if you have them then it is a relatively easy thing to move the setting. However, make sure that your main jet is correct first before adjusting these because if you change the main, to get your WOT air fuel to a correct ratio, it might change the needle setting you need to use. Finally, Since you pulled the air box and replaced it with pod filters I'm wondering what your A/F at WOT is because that might be running lean too. If it is lean you should look into plugging your main air jet then checking and seeing if you need new main jets. This is all dependent on the readings you are getting from your wideband. Hope it helps. Let me know if you have any questions.

Yeah with the standard mechanical fuel pump pushing 3.5psi you might see some fuel weeping but that wasn't the issue that i saw. I have a wide band A/F and even when it was dumping fuel out of the overflows my ratios were still rock solid also since i am using the fuel pump from the bike the carbs came from i think the pressures are good. Since i fixed all my carb boot connections it hasn't happened again (fingers crossed it wont). For the life of me i cant figure out why a loose boot connection would cause it to dump fuel out the overflows tho. Hix1985 - I haven't heard of anyone commercially making them in the states yet. However, i got mine from the Bogg Brothers in the UK and the price was pretty reasonable and i had it in my hands a week after i ordered it. I would totally recommend them. They put these carbs on everything and are super knowledgeable if you have any questions. That is my $0.02

My R1 Fuel pump from 98-02 doesn't use a pressure regulator since it is specifically for those carbs and internally regulated to a outlet line pressure of 3psi. It is a really nice electric fuel pump option since it uses simple two wire 12v power, controls itself and are like $25-30 on ebay.

Nice man! I'm glad to hear that it is working for you. Plugging those ports makes all of the difference. I finally got mine dialed in to 13.5-14 at WOT, 13.5-14 at part throttle and idle at 13 flat. Sadly, i only got one reading cruise then my O2 sensor died so I'm hoping it is still good cuz i have SMALL 138 jets in there for my L20. The pissing gas thing has happened to me too. I found that it was related to a vacuum leak between the carb and the valves. Somehow, if there is a leak there it starts going crazy, not sure why. When it has happened to me Ive tightened my connector boot clamps and that seemed to stop it. I'm running the R1 fuel pump if that makes any difference. Sucked cuz it just starts pumping like crazy until you turn the engine off with key out and find the leak. Also, just realized that my profile picture was taken when i was pulled over after the first time it puked gas all over my headers while out on a cruse. haha Datsun memories.

I just did a bench sync and it seems fine. I put a vacuum port on each runner to sync that way but it didn't quite workout in the way I had hoped.

Yeah, I hope it helps and let me know how it goes. Also, i cant stress enough to buy 5 or 6 of those plugs. They are TINY and i dropped one followed by 20min looking for it. As for timing, I am at ~16 BTDC if i remember correctly running mid grade gas. The only reason i am in so far on my idle air mix is because i haven't changed it since i set it up with the dynojet kit. I HATE doing those screws because you have to wait till everything is hot to get an accurate reading and always burn the shit out of your knuckles on the headers. I'll probably bring that up to 13:1 eventually but since it is really only the idle that is effected i am procrastinating.

After reading through this thread and seeing some conflicting/confusing and sometimes vague information on how to tune these carbs I thought I would throw together a post on exactly how I did mine for my 1972 510. First my engine specs: L20b with a U67 head Mild Cam Regrind (came with motor, unsure of specs) Old Nismo Header 2.25” custom stainless exhaust W/ Innovative Engineering Wideband O2 Sensor (for tuning these carbs specifically) Ok, now that that is out of the way, I got my set of 2000 R1 Caruburators (98-01 will work) on ebay for $150 and set to work. I sourced my intake manifold from Bogg Brothers in the UK ( http://www.boggbros.co.uk/ ) for ~$300 and verified their L20 intake manifold flange using my cad model to make sure they have a good layout. (Note: their manifold comes with a bar between the two halves that you have to cut out picture below) I also asked for them to give me an individual vacuum bung on each intake runner so I could manifold them to provide vacuum to my B210 brake booster. I liked the idea of manifolding them over just running one bung off of cylinder 4 (their typical seen on other manifolds from this thread). I also sourced my throttle cable, choke cable, and main jets (170s and 180s just in case) from Bogg as well. I got everything in the mail within a week and installed it. Note: I am not using vacuum advance but haven’t had an issue with it. Initial tuning: Idle air screw 3.5 turns out Nonadjustable stock needles 180 main jets A/F results from wide band: Idle – 13:1 Mid – 14:1 WOT – 15-16:1 Here is where an issue with these carbs on the l16-20 engines comes up. Because of the proximity of the float bowl to the headers as the engine/headers get warmer the AF Ratio climbs and climbs. I saw as high as 19:1 on a long freeway cruise (had to pull over, let it cool even though the temp gauge never changed) and had to limp home. Need to build a heat shield. This is the point that I knew I needed to get a little deeper into the carbs. Since I had the stock nondjustible needles so I called dynajet to get their tuning kit. After completely confusing the sales guy by explaining what I was doing with the carbs I was transferred to their Lead Carb Tuning Engineer. Sadly, I forgot his name but this guy knows his shit. He knew exactly what I was doing and steered me towards their 4165 Jet kit ~$125 (http://www.dynojet.com/pdf/4165.pdf includes adjustable needles, an assortment of main jets, larger idle jet, etc) Now, this part is important, this carb magician told me to buy 4 (buy 5 they are tiny) of their DCO500 Corrector plugs ~$2.00. These plugs go in the main air jet (see picture below). This jet, according to him, works by allowing air into the main jet and aids in fuel emulsification. This system works great with the stock R1 Airbox but if you remove the airbox and increase the size of the main jet you get a compounding problem that exponentially lowers the fuel (increasing the air) going through the main jet. So a 180 jet will flow only marginally less fuel than a 200 and worse as you go up. (Read Main Air Jet section here http://www.dynojet.com/jetkits/jetkit-info.aspx ) Once I got the jet kit and plugs I installed everything and Tune 2: Idle air screw 2.5 turns out Adjustable needle at the midpoint (as directed by dynajet) 180 main jets A/F results from wide band: Idle – 12:1 Mid – 13:1 WOT – 11:1 Installed the 170 jets I had from before and Tune 3: Idle air screw 2.5 turns out Adjustable needle at the midpoint (as directed by dynajet) 170 main jets A/F results from wide band: Idle – 12:1 Mid – 13.25:1 WOT – 11.5:1 So now, using the same main jets I’m quite rich but everything else seems good. So I needed to order more main jets. Since you can use the main jets from a Weber 32/36 DGV I ordered a couple sets of jets 150s (Part number – 73801.150) and 160s (Part number – 73801.160) from Carbs Unlimited (http://www.carburetion.com/Weber/WeberDGEVParts.asp). I received the parts in 2 days and installed the 150s. Tune 4: Idle air screw 2.5 turns out Adjustable needle at the midpoint (as directed by dynajet) 150 main jets A/F results from wide band: Idle – 12:1 Mid – 13.8:1 WOT – 12.5:1 That is as far as I have gotten but I might go down to the 138 jets that came in the dynojet kit just to see if I can get my WOT up to ~13 consistently and I’m probably going to have to have to richen up the mid a little once I do that. All in all it runs like a completely different car. It’s much smoother with a super quick throttle response. It doesnt even compare to the 32/36 I had in there before. Hope this all helps someone.