Carbed 4age first start, leaning out with throttle....

[demby123]

Managed to get my 4age started up and running today but with a bit of a problem, it runs lean as hell and pops through the carbs with any sort of throttle. I'm thinking the main jets would be the cause since idle is mostly fine. Idle jets may come in handy too though since the idle mixture screws are out a good 6-10 turns.

The mains that came in the carbs were keihin 155s IIRC (I still have them in a bag with the car at the moment so i'll have to verify that tomorrow) And I switched them out for 160s. Since keihin jet #160 should be 1.6mm I and the recommended drill size for most bike carbs on a 4age is 1.6 or so mm I figure it would work, but most engines running bike carbs use R1 carbs which are bigger in bore size and are used with a bigger 1L engine, so mabye 160s are a bit too small for mine, which come off a yamaha 600r.




If I do need jets, are there any motorcycle shops in the dfw area that sell keihin slot type jets?

[dr.occa]

I know I messaged you on C4AG but if you have the time, share your jet sizes. Also, would you care to share a screen shot of your ignition map since you're using MJLJ @demby123? There maybe some timing issues as well.

[demby123]

I know I messaged you on C4AG but if you have the time, share your jet sizes. Also, would you care to share a screen shot of your ignition map since you're using MJLJ @demby123? There maybe some timing issues as well.

Heres a screenshot, I'm trying to get close to the stock ignition map. Do you think its a bit too conservative?

[dr.occa]

Try the default map based off of Brent Picasso's GZE setup:

default-ig-map.jpg (69.38 KiB) Viewed 3091 times

Don't worry about anything above 100 since that's for boost.

Here's what I run:

dr.occa-ig-map.jpg (69.76 KiB) Viewed 3091 times

[86boy]

Hey @dr.occa.... is that a base GZE map?! LOL I've actually been trying to find a "starting place" for my GZE.....

I don't think i will never understand why the load numbers are never linear... I think OCD kicks in because that bothers me... that's like counting 1, 2, 5, 8, 15, 16, 18, 20, 25 lol!

[dr.occa]

Chris ( @86boy ), the top is what Brent Picasso (founder of Autosportlabs) ran on his GZE. The bottom map is mine. LOL at your counting analogy! Haha!

[86boy]

Chris ( @86boy ), the top is what Brent Picasso (founder of Autosportlabs) ran on his GZE. The bottom map is mine. LOL at your counting analogy! Haha!

Yeah Im going to try that map...only in Haltech and pull a few degrees out above 3000 rpms. Just to be a super safe starting point for tuning ignition timing. I've been looking for something like that, and then all of a sudden you post it up. haha!

In the mist of my searching I have been looking into way to detect knock. If you get a chance look into KnockSenseMS http://www.viatrack.ca/ I'm tempted to pick one up. $100 dollars shipped for the version that has the output for datalogging/ pull timing and add fuel in your stand alone when knock is sensed. Just have to calibrate it from what I can tell. Definitely be worth while even after tuning in case you pick up some bad gas from your favorite fueling station. Also allowing you to get a better tune

[demby123]

Haven't replied in a while because of silly crap that keeps popping up preventing me from working on the car. So far everything's working much better than it was, there was some lean out at high rpm/ high throttle but after researching for a bit I found out where the air correctors were for these carbs, which control AFR at high rpm( Didn't think there were any on these). I blocked them off and the leanout went away but it ran pig rich at higher rpms so I put together a little setup similar to this to control it better. Unfortunately my MTX-L decided to die right as I began testing, so that will have to wait.

In the mean time I'm still trying to figure out why revs cut out at around 5500rpm. Timing light shows it cutting spark completely at that rpm rather than retarding ignition at the correct rpm set in the megajolt. I don't have a hard rev limiter and according to autosportlabs, the EDIS shouldn't have a built in rev limiter at all...

[demby123]

problem solved. still cuts out but it cuts out where it needs to be...


I also have the AFR's right where they need to be under all conditions except cruise

[dr.occa]

problem solved. still cuts out but it cuts out where it needs to be...


I also have the AFR's right where they need to be under all conditions except cruise

Way to go there @demby123.

Can you elaborate some more on the whole "cutting out" and would you care to share your carb specs (i.e. jets, choke sizes and carb sizes), engine specs, etc...

[demby123]

problem solved. still cuts out but it cuts out where it needs to be...


I also have the AFR's right where they need to be under all conditions except cruise

Way to go there @demby123.

Can you elaborate some more on the whole "cutting out" and would you care to share your carb specs (i.e. jets, choke sizes and carb sizes), engine specs, etc...

the cut out was the VR sensor losing sync because of vibration. I'll have to take some pics of my crappy home made cam sensor later, but It went away after I reinforced it with some extra nuts, a washer, and some rubber gromets juuuust to be safe.


Engine: Stock Bigport 7 rib from an 87 mr2 rebuilt with mostly toyota stock parts

Carbs: keihin cvk 36mm from a yamaha 600r

Main jet: Drilled out to .178

Idle jets: stock

Air correctors: I can't practically measure this, but I used a home made version of this setup with a ball valve and some vacuum tubes going into each Main air corrector.The gap in the ball valve is about .5mm though. Idle air correctors were left alone.

Ignition: Megajolt lite jr running the map you suggested with cranking advance turned down to 5. The Trigger wheel is a 72-2 wheel I made with some gear cuts, nuts and bolts and old mr2 4age distributor parts, here's a pic of it.


With those two additional nuts at the bottom, it now revs all the way out to 7200 rpm smoothly, I didn't test any further because its still got 1500 more miles untill its fully broken in, and I don't plan on revving it any higher than that anyways.

On another note, do you know if the VR sensors for these cars can still be bought new? You posted a part number for just the sensor but i'm not sure if its the exact same sensor. It'd be a good future reference just in case I need a sensor since any sensor I get is oil soaked with brittle wiring from leaky oil seals. Also note, the fc3s uses pickup coils like these IIRC.

[dr.occa]

Great job on that man

I never even tried going with a 72-2 gear setup in the dizzy primarily because of the teeth gapping: I was concerned with poor definition. Seems like they're good for at least factory rev limit. If they're good even to 10K, it would make the MJ system that much more attractive.

As for the VR sensor, you can also try using one from an RX7 dizzy or CAS as you postulated in your post . You may need to custom fit but hell, look at what you did with yours already .

Again, great going man! Is that the same gear that Dean924s from Autosportlabs' forums used by chance? If not, do you mind sharing the part number and where one could obtain such an object? You've reignited (pun intended) my interest in doing this mod for a current 4AG project I'm working on for someone.

[demby123]

Great job on that man

I never even tried going with a 72-2 gear setup in the dizzy primarily because of the teeth gapping: I was concerned with poor definition. Seems like they're good for at least factory rev limit. If they're good even to 10K, it would make the MJ system that much more attractive.

As for the VR sensor, you can also try using one from an RX7 dizzy or CAS as you postulated in your post . You may need to custom fit but hell, look at what you did with yours already .

Again, great going man! Is that the same gear that Dean924s from Autosportlabs' forums used by chance? If not, do you mind sharing the part number and where one could obtain such an object? You've reignited (pun intended) my interest in doing this mod for a current 4AG project I'm working on for someone.

I wouldn't doubt the stability, im pretty sure mine could reach 8-9k if i added more nuts,but a better option would be to simply mount the VR sensor in its stock location and get the distributor shaft shaved down to a bare shaft, buy some gearstock from https://sdp-si.com/eStore/Catalog and get it press fit onto the shaft. Or you could make a custom spacer for the VR sensor so you'll have a flat platform to mount it too and get some gearstock machined for a press fit.

My setup was actually taken from Alexander's lotus europa, which is like Dean's but its much more compact and able to fit inside of a distributor cap, which is convenient.

The main reason I went this route was because of the silly T3 Trigger wheel that just wasn't practical at all and I also plan on getting A/C setup in this car, so even If I could run a crank sensor, the bracket placement would make mounting an A/C compressor there tricky if not impossible.

The part number used for Alexander's setup was: A 1C29MY05072

I couldn't afford to cut that at the time so I bought 2:A 1C2MY05072 (you may have to search for this one, IIRC search doesnt take the part number for some reason)

And here are some of his build threads
http://www.autosportlabs.org/viewtopic. ... ight=#7241" onclick="window.open(this.href);return false;
http://www.autosportlabs.org/viewtopic.php?t=1648" onclick="window.open(this.href);return false;

It's even better than this now...

[decepcionez]

very interesting, don't mind if i steal the map .....GREAT WORK !!