S3 E31 We tune the Keihin CVK carburetor to work on the 670 cc predator engine in the Renault R10 

finally my weekend is complete

Can't wait for the diesel powered insight. Retrofitting hillbilly engineering into modern classics is fantastic. Have a good week filled with successful steps in these projects that you so graciously bring us along for our viewing pleasure.

I knew you were gonna stuff that Kubota in the Insight, it just makes perfect sense. Might end up with an actually good and practical car like that.

I follow a lot of automotive channels but recently have "gotten tired" of the usual stuff. This channel is so refreshing to see. Love the weird

Growing up my dad was always in the garage working on and tuning different Harley's. As a result I've got a soft spot in my heart for the V-twin and hearing this thing purr is music to my eras.

Never forget, a simple way to get a smaller jet if you can't buy one is to solder up your current jet and re-drill with a smaller drill. Works great and the brass/bronze of these jets takes solder beautifully.

Check Float height, its the most important thing you can do before tuning anything on the carb (Besides the screws). Also be sure to note that you can adjust the needle position on the throttle for rich or lean for mid to low range rpms

Yes! The insight is getting the Kubota! That 500 lbs weight difference should net some amazing milage and acceleration

I was struggling with a real bummer of a mood that I couldn't shake, then this episode came up. Thanks Jimbo!

Man, this channel is just all the things i want to do with cars. Putting bigger engines in things is pretty par for the course these days, seeing how little you can get away with is a way more fun engineering challenge.

Jimbo you never disappoint, no matter what my mood is i always smile and feel cheerful at the end of your videos thanks man!

Alright, I didn't get to watch 8n the morning, but this is probably my favorite video so far. Love the donuts, and the new insight, I can't wait to see more!

You could probably make a little 3D printed hood that clips onto the fuel/air ratio sensor, to block out reflections and somewhat improve visibility. I think you could even get it to spin under reasonable force so you can adjust it on the fly if you're say holding the box. Could also do black craft paper and tape, but I think it'd be trickier to make that stay on well and also not fall off under normal driving vibrations.

Oh Magoo, you've done it again! Jim Backus was my favorite in It's a Mad, Mad, Mad, Mad World, a great movie for old Mopars.

Your videos inspired me to get my home built go-kart made from a 1960s Wheel Horse tractor and resume building it. It should be running in a week.

As a french guy i more than enjoy what you doing whit that little Renault. It's a rare car even in France...

Man, you dropped this video at the perfect time again this week!!! May God bless your soul you mechanically advanced RU-vid rockstar!!! Love the work you do on so many levels. 🙏 Thx again..

Sunday morning is complete! I got a fresh coffee and am enjoying the weather.

❤ You earned a like for the donut alone.

Wow that sucks that you blew the CVT belt. Good thing they're ready and available at a moments notice. On that note, I can't wait to see that little Kubota pushing the Insight down the road. And maybe add a little propane injection in the future? 😉 Would be cool to see how it would react. Nice work Jimbo!! 💪🔥

Sometimes the tuning process feels like stepping on a rake but eventually you start to get the results you’re looking for. Also I’m super excited about the diesel insight.

Well, seems we finally have a name for the Renault project!

I’m going to need to see a drag race between these two masterpieces 😊

Yessss, give in, forgo the CVT, put a motorcycle chain and sprockets on there instead of the pulleys.

Such a calming voice and easy to understand as a german. Nice project, can‘t wait to move on with my own project after watching this Video.

Another great video. I'm looking forward to seeing the Kubota diesel engine in the Honda Insight. Thanks for sharing 👍.

The way this thing sounds is just 10/10. It sounds SO good.

YESSSSSS.... ROBOT CANTINA .... my morning just got better...

Now I'm reallt stoked for the Kubuta Insight. It just makes too much sense!

You can’t win for losing. Can’t wait to see the insight again.

V8 swapped in just to film the into... Good job, Jimbo!!

My goodness does this channel have me excited for the weekend lol

I’ve been thinking about Jimbo’s backyard as a nice place to have some fun… seems like we share the very same thought! You broke the car but you had great fun, 200% worth it!

Thanks for the help jimbo ❤ But I have seen some water cooled engines run at 10:1 afr.

One of the few channels that get better, and better. Thanks Jimbo.

Ahhhh… thank you Jimbo for another wonderful episode!!!!!👍😸

Hi Robot Cantina, I have Kawasaki KLR650 with a CVK40, common mods for this carb/bike are larger jets, KLX Needle, also there is a mod to drill the slide vent to 7/64ths to quicken the slide opening, this may fix your richness in the lower rpm. The CVK 40 has a bunch of aftermarket support since Kawasaki and Harley Davidson used these carbs in their bikes. Might be a nice upgrade too. if you need one LMK I have a stock spare for free99.

Remember, "Lean of peak" (aka LOP) is also a tuning method available for air cooled cruising. Toss the EGT gauge on it, and you'll see as you go lean of 14.7:1 EGTs will initially go up, but come back down. Between 16.2:1 and 19:1 is where you should find cool lean running and maximize economy. *but* it should also be noted that lean mixes burn slower, so you'll need more advance to counter that.

Always looking forward to sunday morning for another video, i love the lighthearted experimental nature of your projects. It really shows that this is all just for fun. Can't wait to see the diesel insight!

I have been working on bikes since I was a preteen and my father thought if I rode a dirt bike I should be able to work on it. He taught me everything I needed to know back then. I have been building bikes since I was in my early 20s (Now 57) and racing and tuning carborated, and FI bikes since 2000. With that said the needle valve on the CVK (As well as the VM and tm) controls off idle throttle, piolet jet off idle to about 1/2 throttle, main jet 3/4 throttle to WOT. The way I would have fixed your problem would have been to raise the snap ring on the needle valve 1 or 2 groves. leaning out off throttle, and going up 3 jet sizes on the main (2 1/2 numbers per size) as I seen in other comments check the float level.

It still trips me out that a little rubber fanbelt is all it takes to move an entire car. And even do donuts!

I love these experiments. The automotive industry should watch this. Learning from other people is what makes progress!

Lol. Your donuts in the gravel reminded me of my 5 speed 84 Celica GTS coupe. I used to love to take it out on wide gravel backroads and play rally driver (in the mid 90s when we still had gravel roads here in East Tennessee). Unfortunately I also had the experience of leaving parts behind on the highway afterwards- but mine was actual metal bits. I blew a hole in the side of the 22RE block, and it still ran. Not many people can blow up a 22RE. It takes skill! I put another 22RE in it and drove it for another 100k miles fwiw. I think the previous engine's timing chain jumped off. I already had a new timing chain kit but hadn't done it yet. Oops. I miss that car... it was made to be worked on. Everything was easy to take apart, fix, put back together. No stupid plastic clips that break. I should never have sold that car.

"Oh Robot Cantina, you've done it again..."

I _think_ the first-gen Insight might also share the speakers from the S2000. Not certain though. Fun fact: The first-gen Insight's combustion is so finely tuned that the spark plugs need to be turned (indexed?) the right way for optimum engine function. So there are FOUR spark plug variants (A, B, C, D) available for its 3-cylinder engine, and they stamp which plug each cylinder uses on the head. (Mine takes three B's, which I've read is typical.)

If anyone is interested, the SA publication Super Tuning and Modifying Carter Carburetors - Dave Emanuel is a hoot of a read. Forget the book is about Carter carbs. It first takes the reader on a journey into carb principals from basic to advanced and uses Carter carbs to show the concepts in pictures. Then it applies specifics to tuning them - that's the Super Tuning part. It shows the inverse relationship between manifold vacuum and Venturi vacuum and how and why carbs are load sensing. It also explains emulsion tube concepts and how they pertain to idle mixture circuits. Strictly speaking this may or may not apply to a $30 Keihin 32 CVK rip off but it might. It is often the case the idle mixture screw is not actually an idle mixture screw per-se. Thing is, the fuel in the idle circuit is pre aerated by the emulsion tube and the emulsion tube's size varies the ratio of pre aeration in the idle mixture circuit. What the idle mixture screw actually does, is basically act as nothing more than a tap for pre aerated fuel. This means you're adjusting the volume of premixed air and fuel in the mixture circuit. It then follows that you can't do with volume of fixed ratio pre aerated fuel what you need to do with a different ratio of pre aerated fuel. It seems like a mute point however, this has consequences when you factor in throttle stop screw position of the butterfly - the air leak it induces a) directly reducing the signal in the idle mixture circuit and the transition between idle and main metering circuit and b) diluting the the premixed idle circuit fuel. There must be an overlap of the two circuits to avoid stumbles/flatspots etc.

G'day mate great vid as always I still think adding runner length between the carb and the boot attached to the billet block even an extra inch will help low down torque production maybe add a 90 degree Elbow between the carb and the billet block for ease of installation. Would be an easy test to just keep adding runner length to see if it helps overall acceleration. Thumbs up mate

I wonder if that dip in AFR is engineered into the carb to act as an accelerator pump.

Another great episode. Love the Renault, they were great in Rally in the past, so your donuts were appropriate! But I do live the little Honda, can't wait for more on that car as well. Thanks Jimbo! Cheers, Robert

Still sounding good! And now you can say that it really shreds.

And we start with a power slide!!🤘

I went through this business with the CV carburetors when I hopped up my Honda CM 450T. My solution was to leave it all standard and only change the needle. I did not have a ready supply of blank needles to modify but I found that they were the same as a small box nail, and so I purchased some at the local hardware store and started turning them down. What worked for me to get a punch off the line and smooth acceleration was a very blunt needle. This keeps the emulsion tube out of play a little longer. I found it playing with the diaphragm Springs did not help at all. Mind you, that in those days I was not working with a wide band sensor. I had the narrow band eardrum sensor and the wide band butt sensor, going.

YES! Diesel insight! Love the channel!

I love these videos! The cars, the data, the diagrams, the tests.....

Worthwhile keeping a spare belt for those cvts. The circle work in the yard was epic

Mr Magoo you've done it again!

The first thing that I thought was the belt when you lost your speed. Good video Thanks for sharing such interesting videos 👍

I don't recall if I mentioned it on the last vid or was just thinking about it, but quite a long time ago I assisted a local hot rodding team fine tune their mechanical fuel injection system on a project car, and they operate almost exactly like old performance bike carbs in that they work great at WOT (and almost exclusively will not function well anywhere else!) as they were more or less made for racing applications where off-gas maneuvers are short blips; I believe the really early systems were adopted from hulking airplane V12s that chugged fuel even at partial throttle. The mention of the Keihin carb made me think that some kind of hybrid system between it and the mechanical system would have been fantastic for getting some kind of usable street performance; getting them to idle correctly even at pit lane speed was a nightmare as you'd basically have to bump the throttle with the clutch in to keep the engine going. Ha, glutton for punishment memory lane! Add: Ah, I remember where I was going with that now. If the Renault has a fuel door on the right side, that'd be a great spot to shoehorn in a NACA duct for feeding air to the engine filter if you don't mind taking a cutting wheel to the old fill port. They make everything look cool anyway but are wonderfully effective aero aids in both scooping (and run backwards, removing!) air to/from your desired location from inducing a low pressure entry/relief area. I have several of different sizes that one day I'll get the courage to chop up my hood or right at the front fender for a pseudo ram air to graft on my daily ride.

Fuck i love this series. In no little part to the awesome presentation and narration from Jimbo.

Your theme music is a real treat.

I like your sleepy little town. 👍

Those gauze air filters are only effective if oiled. The oil is the actual filter. The gauze is a labyrinth that forces the dirt to make hard turns and hopefully get stuck on the oily strands.

Congratulations on your best video yet, Jimbo! So packed full of fun and drama! It was great to see the Insight again and the excitement of your breakdown odyssey added spice. The doughnuts was a fun start too! You’re excelling yourself 😁

Great intuition and superlative knowledge added to meticulous patience. You are the man.

100+ mpg Kubota diesel insights I'm excited to see the progress this project makes

Better than any TV show on now

I can sympathize with the issues of getting parts from a "rural" area. I live in central FLA, and getting parts for my MG can be frustrating at best, since I always seem to need parts now, not in a week. Glad to see the Honda making a return, should be fun.

Two great projects there. The diesel in the Honda Insight would benefit from a few modifications learnt from its take one in the Saturn. Exhaust, turbo and intercooler mods especially. I think the Renault is only going to see success and perform to its full capability once it gets engineered to mate the Predator lump direct to the clutch and gearbox. All Jim needs then is a third car and someone to donate or help him find a nice 3/4 cylinder two stroke outboard/jet ski powerhead to do a two stroke project car. He'll have all bases covered then!👍

Yesss! Diesel Insight!

Excited to see the insight back in a video. Cant wait to see the performance of both projects.

Your videos always make me smile ☺ .. thanks Jimbo !

I'm already excited for the next video, and to see the Honda project take shape.

I almost commented on the air filter thing, but then I figured (correctly) that Jimbo was just trolling his viewers again 😂

The intro was perfect. 😄

Diesel in the Insight is probably the best thing I've seen this year. You're gonna have folks waving cash at you when you get over 100mpg.

a couple things to consider, shortening the slide diaphragm spring can cause the slide to lift too early which will also cause the fuel through the main jet to flow too early. for future reference when testing or trouble shooting rather than making a permanent non-reversible change by cutting the diaphragm springs, I either use small zip ties or thin stainless wire to temporarily shorten the spring that way i can try different lengths to find the optimal length. it is also possible that raising the slide needle is contributing to your off idle rich condition. because there is no direct link between the throttle and the slide CV carbs can be a real pain in the ass, with a cv carb the wrong float height can cause a lean or rich condition, but so can the wrong fuel jets, the wrong needle position, the wrong bypass jets, and on and on the best of all is like you made reference to in your video, all the reference charts refer to throttle position, 1/8, 1/4, 1/2, full throttle, ect. but there's nothing that relates to real world street application like cruising down the freeway at 80 mph and 6k rpm but where the actual sustain throttle position is less then a 1/4 throttle, like i said, cv carbs are a pain.......

Yesss! I always thought the diesel in the Insight would be a great combo. Looking forward to seeing that series. The red Saturn was a loyal test mule, the most honorable way to spend it's final miles. The Renault is such a great looking little car as is, patina and all. Simple chassis for modern small engine swaps. Hope it stays around long term too!

TURBO TIME FOR THE KEIHIN!!!!

Got me with the BIG BLOCC again😂

Hey Jimbo ! Doughnuts are fun, hard on belts, unless gnomes of gremlins are the culprits.

long time a go i have a bike with this carb... changed all parts... only thing save the carb i make a aluminium funnel at scape 38mm to 25mm to have high back pressure and make very high torque on low rpm from 4500 to 2500 rpm (better cruise)

I always thumbs up your videos, but today you earned it with that motorcycle carburetor demonstration. See you on the next one.

I waited since the beginning of the renault project for an intro like that... Keep it going, love your series

Tuning carbs with metering rods, we used to take a ignition points file a make a small flat on the taper gradually fattening up the mixture. 6:50

Another fun episode. Poor little Renault doing donuts in the yard. That'll show for for acting like a teenager. Can't wait to see how it acts when fully in shape and tuned more. Keep up the fun Jimbo!

Dooo del-doo deee-dooopteeee-dooooo ... love the outro 😁

Hi Jimbo. If you invert the electron flow in the flux capacitor and use quality plutonium in the power generation unit, you should achieve at least an extra ten parsecs per time unit. Love your work 👍

I wouldnt lose any sleep over the rich condition when the carb transitions from pilot jet to main jet........that is actually good for having good throttle response and pick up from idle when you want the vehicle to take off from a standing start etc but doesnt have a any real impact on fuel efficiency once the rpm picks up for normal driving. The main issue was overcoming the lean condition on the main jet.

Absolutely love this project. You cant get round the ovelapping intake pulses with a v twin like this. It will be easier to tune and faster if you just add another carb, one per cylinder. Google charge robbing. Alternatively, look at carbs for small HD Motors. They are already designed to cope with it.

Really excited to see the Insight back! My favourite of all the cars you've done.

Keihin d-slide is so much much easier to adjust. Best carburetor of all time.

Cant wait for the insight.

Another great video! Thanks for all of the insight into how the carburetor works and the results you got while testing it out. Shame about that drive belt! Hopefully you'll be able to get a proper replacement soon. What a great surprise to see the Insight coming back! I can't wait to see the diesel in there. I'm also very intrigued to see the electronic control of the fuel rack. I'm curious what aspects you will be monitoring and how you will change the mixture in response. Until next time!

Great thanks for this tiny week end candys

It sounds awesome with the new carb. Fun stuff.

Great job as always!

I think I may have some insight into that dip in air fuel ratio. A similar problem happens with Chinese 50cc carbs. Check the accelerator pump. On 50cc CV carbs the accelerator pump is unecessary with a proper carb tune and simply dumps quite a bit of gas every time the throttle is opened from the closed position. I've gone from 85 mpg in the city on my Chinese 50cc all the way up to about 110 mpg simply disabling the accelerator pump. It also helps prevent oil dilution which is a known problem with these bikes but no one has enough old school carb tuning knowledge to figure out that the extra fuel making it into the oil is from the accelerator pump. This is why no matter how lean a pilot you're still getting the dip. Check the accelerator pump circuit, possibly see if disabling it helps as this will make the CV carb purely vacuum metered.

Going rich on tip in is by design, it's like an accelerator pump, it prevents stumble when suddenly increasing throttle.

Great Work, Jimbo. This is fun! I love each auto series that you've produced.

Is it just me but that exhaust sounds great. Almost like a motorcycle.