R1 Carbs (lots of pics)

[MantisX620]

I capped off my vacuum line on runner one and it hasn't done it since. I think these carbs are just really sensitive to vacuum leaks. Ill also retighten my boots for good measure. Right now im running without the vacuum advance hooked up. I hope performance doesnt suffer much.

[Hix1985]

Bogg Brothers seems good I was thinking that the shipping would kill it, I guess I will just have to email them and fine out.  This does seem like a lot cheaper then doing dual side draft Webers.

 

Question anyone running the R1 carbs without a power booster?  did it no if it made it hard to tune with out the it.

[hendrik6073]

hi,

 

I do not own a Datsun, i do have a motor carb setup on my Matra Murena 1.6. Hope you don't mind a ask a question about this setup.

did read a whole lot of information in this topic, because i'm not very familiar with carburator setup adjustment i want to ask some questions before i going to adjust the wrong way and damage something.

 

Like i said i own a Matra Murena 1.6, it is a 1982 4 cilinder car with a Mikuni (Yamaha) 5LV1 37mm carbs. Ignition is by MegaJolt with MAP.

I bought this car a couple of years ago, the motor carbs where allready there, also was a custom made airfilter box mounted.

 

Last years i did some modification, i replaced the airfilter box with open filters. Mounted MegaJolt etc etc.

 

This car is just a nice drive, it has a nice sound and good looks. It is not a race car, and that is how i like it.

I just drive it for fun and i want it to be healthy.

 

Because i did have backfire's i wanted to check the fuel mixture and mounted a ASPX Wideband AFR gauge. 

Now that i know that values are not as it should be, i want to fix it.

 

When the car runs idle or when i open the throttle just a little my AFR reads 19. When i drive on the highway about 120 km/h (3500 rpm)

the values are steady around 12.8, when i push the pedal it goes down a bit, when i let loose the pedal it goes up a bit.

 

Reading this topic i think i might get the 12.8 value a bit more to 14 if i lower the needle a bit (should i or is 12.8 not a problem?)

What should i do about the 19 value ? Is this something i have to adjust with jet's inside the carbs or should i be corrected with pilot air jet screw ?

 

thanks for youre help !

 

 

 

 

 

 

 

[Keg86]

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.

[hendrik6073]

thanks for the reply !

 

yes, you are correct about the 19 and 12.8 situations. sorry for my rusty English.

after adjusting #8, first al way in and then 5 turns out, mij idle is now about 12.5 so this is much better. I can turn it a little back in.

 

At WOT i have to check, i am not at home right now, gonna test it this weekend.

 

I have to check if the needles are ajustable, if not do you know what needles i should buy (on ebay) that fits these carbs ?

If i understand you correct;

                                             - if WOT is about 14.7 than adjust needles,

                                             - if WOT is far high or low than first change #14 main jet 

 

Idle is now quite okay with little open throttle is still get readings 19, after giving more throttle a steady 12.8 on highway or when i drive city traffics values are jumping up and down.

To get better values on little open throttle do i have to place a bigger #16 pilot jet ?

 

thanks again ! 

[Keg86]

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.

[Dolomite]

Hendrik, your light throttle or cruise afr can be in the 16s as long as it richens up when you step into it, its good for fuel economy. My light throttle afr goes to 17 sometimes but goes to 12.8 or so as it opens up, been running like that for about 12 years. As long as it isn't in the red on your wideband at light throttle, you're ok. You also want your idle afr to be as close to stoichiometric(14.7) as possible, it'll idle better and is better for your engine. They say 13.5 or so is best for power at full throttle, closer to 14.7 is best for mileage. Hope this helps.

[ap72license]

That's somewhat incorrect, but close. Idle afr's will almost always be around 12.5:1 when optimal. They need to be uned for maximum vacuum signal, which is somewhat hard to do with IR carbs. Cruise should be a little leaner, around 15-15.5:1 for optimal mileage. Max power will usually be produced around 12.2-12.9:1 afr's. Make sure your timing is correct first. It will affect your afr readings.

[ap72license]

Dolomite, are you running vacuum advance? If not that is likely why your afr's appear really high at light throttle. The mixture isn't fully burned yet.

 

Timing will affect the readings of the oxygen sensors and of course the combustion efficiency.

[Lockleaf]

Why would you want idle afrs so rich?

[hendrik6073]

Thanks for all response !

 

Have some work to do.  

 

Thanks pointing me to page 63, i missed that post completely.

Gonna try one of those DynoJet kit's, i check if it is availeble in Europe or find a way to not double the price while shipping.

 

With last modifications to my inlet manifold i made vacuum tubes that i use for vacuum to my MegaJolt, also use it to calibrate my carbs using a CarbTune Pro.

Now that i can use my CarTune and have a AFR gauge i can really get into it.

 

Never looked at timing really, car runs fine. I gonna get into this now that i can measure the effect on combustion.

Right now i am glad to have mostly safe values on cruise and idle. Gonna try WOT and post my readings.

 

thanks !

[Dolomite]

Why would you want idle afrs so rich?

Simply put, you wouldn't.

[Dolomite]

Thanks for all response !

 

Have some work to do.  

 

Thanks pointing me to page 63, i missed that post completely.

Gonna try one of those DynoJet kit's, i check if it is availeble in Europe or find a way to not double the price while shipping.

 

With last modifications to my inlet manifold i made vacuum tubes that i use for vacuum to my MegaJolt, also use it to calibrate my carbs using a CarbTune Pro.

Now that i can use my CarTune and have a AFR gauge i can really get into it.

 

Never looked at timing really, car runs fine. I gonna get into this now that i can measure the effect on combustion.

Right now i am glad to have mostly safe values on cruise and idle. Gonna try WOT and post my readings.

 

thanks !

Also take into account my advice is for stock engine. Hotter cams, higher compression, forced induction usually like afrs on the richer side. Hell, some engines idle best in mid 13s. Best bet is to start with idle around 14 and slightly richen till you get the most stable idle. Light cruise in the 15.5 to 16.5 range, and full throttle around 13 and see how your engine reacts. Engines can be a bit like people, they like different things depending on how they're built.

[ap72license]

At 12.5:1 or so the idle afr's are NOT "rich". Thats where you normally find the optimal idle. As noted bigger cams and such will want a richer setting.

 

14.7:1 is where you have complete combustion under laboratory conditions. An operating engine does not replicate those conditions, particularly when air speed and distribution is suffering (idle).

 

The only time you should be at or slightly over 14.7 is at cruise, and even then you won't want to be more than about 15.5 or fuel consumption will start to go up.

[Dolomite]

Whatever you say boss...

[Lockleaf]

https://www.diyautotune.com/support/tech/other/idle-tuning-megasquirt/

 

Me? I'm thinking these guys know what the hell they are talking about, so I'm going with them.

 

Sequential injection - 14.7:1 idle

 

Batch fire injection - slightly richer, maybe in to mid 13s, due to intake reversion.

 

Sooooo, Dolomite FTW!

[hendrik6073]

would this be the kind of DynoJet we are talking about ?

 

http://www.ebay.com/itm/Dynojet-Research-4165-Jet-Kit-Stage-1-/141698008085?hash=item20fddc0415:m:mZ9YJSNM4I4EgeuL0fJUNhA&vxp=mtr

 

 

just tested WOT, readings change depending RPM.

At low RPM AFR 11+  going up to between 3000 and 4000 RPM between 12 to 13 AFR

[ap72license]

The guide by DIY is to get you started. You are also not running sequential injection and it is not for final tuning. Idle tuning should never be done with an oxygen sensor but rather by the vacuum signal. When the idle is properly tune it will more than likely we fall in between 12 - 13 to 1. The optimal idle mixture will always be richer than 14.7.

 

You want the leanest mixture that will provide the highest vacuum signal seen at your target idle rpm.

[scooter]

My car idles the best and has best vaccuum around 12.5-12.8:1.... It also makes the best power around there. It has a giant cam though.

My car also shows zero signs of richness on the plugs, but my exhaust pipe is a nice tan colour from the lead ;)

 

Everyones car will tune differently. I will side with ap72 and say find the best vacuum...-turn idle mix till peak rpm, then lower your idle speed. As long as its not off the scale in either direction, you gotta see what your engine likes.

 

Ive tried to lean mine out more, but it starts running like shit, richer does the same thing. Pretty sure i have its happy spot dialed.

[hendrik6073]

Got my DynoJet kit, hope to have some time these weeks to expiriment with it.

 

Do i understand it right that i could use the DCO500 plugs if i expirience a sudden jump to value 19 if i drive a continous speed ?

When i drive the highway for example 120 kmh for a longer time suddenly the afr goes to 19. i have to slow down or play the throttle to get i back to normal.

than values stay right for a time an suddenly jumps to 19 again.

 

thanks 

[G-Duax]

Not enough fuel delivery, you are sucking the carbs dry.

[hendrik6073]

okay, should't i notice that in  behavior ? engine seems to run fine at those moments, can push the throttle, car speeds up. runs smooth....... 

[hendrik6073]

today i got the DCO500 plugs, they are little !

 

maybe i should have checked before, it seems that my carbs are a bit different from the carbs on page 63, seems i only have a pilot air jet ??

 

any sugestions ? No time left today to look into the DynoJet kit, hope that will fit  :confused:

 

 

 

 

 

[DADZSUN]

Wow, good to see this thread is still alive. It's been a whole year since I've last been here. 

 

...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 )

 

 

That's some great info, I'm going to try those plugs because my Innovate A/F just starts to creep to 14+ if I wind out a large gear and higher RPM. Any WOT from mid-gear shows a nice ~13'ish A/F. Typical driving is around or just below 14 but can be 14-15 while at steady-state depending what circuit I'm on and throttle applied.

 

Here's a few other issues which really haven't held me back but do prevent this setup from being an EFI-clone:

 

- A consistent miss on idle which is about 14 but climbs to 16-17 when hot (a pilot might be clogged). I also noticed that the manifold doesn't sit flush with the head so a puddle builds during idle and could also be a source.

 

 

 

 

 

- About 25% of the time hot starts need a couple of throttle blips immediately after fire-up or else it sputters out after a second or two. I get maybe one more attempt to start, then she's a bit of a bitach w/o getting a backfire, which did happen last year... 

 

 

- When driving around in freezing temps and conditions are damp, the engine can miss under load and lean spikes. I suspect freezing is temporarily blocking the main jet. Apparently Silkolene ProFST is a good fuel antifreeze which I might try. I might also tap into the cabin heater's coolant line and run it through the carb.

 

 

 

I'm getting about 24MPG when I behave and no bike, and 20MPG (US) on average when I run the KA a bit and drag my MTB around (essentially a big sail). 

 

 

Besides that the only other change is to swap out to Bills B Racing filters. No difference in performance from the Pipercross setup I have now sitting on the shelf, but it does add a bit of nostalgia. 

 

 

Next up is a Facet fuel pump installation (#40105 2.5-3.5psi) recommended by Bogg. My stock R1 pump is going strong but apparently some are starting to show their age & crapping out. This install is purely for reliability.

[Lozer]

Awesome thread guys. Just picked up some RX1 carbs (same as R1 just different angle for floats)  and Im wondering if anyone has a spare Lseries intake for r1s they would want to sell or trade for something????