Mach 1 Stock Carb Tuning

[Bevel bob]

I am using a 60 slide. Something is telling me that the mixture screw on the SSI works the opposite way to normal , out is richer . I got rid of the fixed float bowl . A remote is so much better.

[Dave354]

According to the service manual, the screw is turned in for rich out for lean, however the opposite on carbs over 30mm?
For some reason I can’t post a pic of the page, but I’m guessing you have the service manual.
Regards

Dave

[blaat!]

So I decided to put a temporary air/fuel ratio gauge on and tune the Dellorto proper. I had to bungee a 12v battery on as the bike is 6v and the gauge needs 12v. I welded the bung into an extra pipe for the sensor and the whole thing worked fantastic.

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I was running way rich and corrected that by moving the needle clip to the top slot and putting a smaller main jet in. Now I'm between 12:1 and 14:1 through most of the throttle and it is much smoother with more power. Not breaking up hardly at all.

One other thing that surprised me is that the choke lever seems to do absolutely nothing to the AFR

[Bevel bob]

Hi Jim, I am very interested in your AFR set up , I have a spare pipe with a bung welded in, what else did you purchase ? . The slide stop on the top of the carb can be used to give an idle but is not easy to access. The "choke" is no such thing at all. It was intended to slightly richen up the mixture at higher speeds to help with setting up . Makes no difference for starting . This carb is a copy of the Amal TT race carb. My 60 slide works .

[blaat!]

Hi Bob,
After researching and looking at reviews, I settled on the Innovate brand, but I suspect the other big name AEM is similar and it is a little more affordable. Part of the reason I spent the extra is that I knew I would make it portable and use it on multiple projects. I opted for the analog version since I like looking at a gauge needle waving rather than a number, although most have guage-like LEDs to simulate a needle.

Anyway, I bought a "kit" which comes with the gauge, oxygen sensor, and a wiring harness to connect everything together. The harness also connects to 12v DC of course to power it. The harness can also tie into other systems, car computer or PC if you are so inclined. I just kept it simple and connected the sensor to the gauge and 12v positive and negative.

The model I bought was the Innovate MTX-AL

I called the manufacturer and they told me it draws 3 amps so I bought a 12v 10 amp hour SLA battery and that has gone a couple hours no problem. I understand the sensor has a heating element in it. I recharged the battery after that so no idea how long it would actually go. You may want to do some amp to watts calcs if you are hooking it directly up to a 12v single. If you don't connect it to the ignition you will need a switch to turn it on/off.

My idle is a bit lean but it is strong and I don't idle for any length of time so not worring about that. Before doing this I was consistently down around 10:1 to 12:1 and after I adjusted the needle and main I'm more like 12:1 to 14:1. If I punch the throttle it goes rich briefly as expected but then catches up. If I twist the throttle steady though, it stays above 11:1 and feels great. I took the gauge off for the MotoGiro but I plan to put it back on (a 20 min procedure) and do some more tuning.

Before I was listening for popping in the exhaust, sluggishness, looking for running better cold, looking at the plug color, etc. It was like flying blind. Now I just look at the needle and I know what is what.

I hope that helps!

[graeme]

Agreed,,,
I bought the AEM brand.
Best money I have spent !
Highly recommended

Graeme

[Bevel bob]

I am curious what settings you have found to be the best , although this will alter with camshaft types.Did you buy a sort cable seperately?.

[themoudie]

Aye Blat and Graeme,

With a nasty flat spot that I so far have been unable to remove from the '74 450 MKIII, with AMAL 32mm carb and homemade exhaust, would you be so kind to list the product reference numbers for the AEM brand equipment that you recommend?

Being a bit of a "Luddite", my ignorance about these bits of kit has been blissful! But, if it will help me rid of the carbie gremlins and doesn't require permanent fitting or a laptop/mobile phone app to use, then I might give it a go and use it on the rest of the "fleet".

Thank you for your time.

Good health, Bill

[Bevel bob]

Hi Bill, Its a very usefull kit ,but needs a "bung" welded into the exhaust pipe ,usually an old spare as its a bit ugly . You also need a bit of !2v power to heat up the sensor so a good bike battery that may run down on a Ducati single ! ,so the "KIT"may need to be on for a shortish time (a switched supply ) You dont need to be an expert to interpret the reading as you will gain experience on the way. I had lots of problems trying to set up the mixture on a brit twin and eventually found a long steep hill where i could hold a set throttle position for a good distance ,then cut the ignition and do a plug inspection . This soon showed where the rich and weak sections of the carb range was. The only downside is my mates want me to fix their bikes so they can keep up.!!.

[blaat!]

Hi Bill,
If you search Google for "AEM air fuel ratio kit" you will have several options to buy from. Summit Racing and Amazon are two good options. Just make sure you buy the kit which will include the gauge, sensor, bung to weld in the exhaust, and the wiring harness. The model number of the kit I just looked up was 30-4110 by AEM


The whole thing currently costs about $170 - $190 USD. If the price is significantly lower then you are only buying one part and not the whole kit. Most of the variations you will see are just gauge color, LED color, etc., but they all do the same thing. You can get whatever dial appearance and LED color you like.

They will all be "wideband" which is what you want. Some will specify "Bosch 4.9LSU" which is the current Bosch sensor that every kit uses, and even if you were to get a previous generation sensor it would still work just fine so really nothing to think about there.

Mine came with photo copy instructions that were very clear. All the kits can hook up to fancy car computers, phone apps, etc., but you don't need to pay any attention to that. I was intimidated by that too, but you just need to plug the sensor and gauge into the harness they provide, and hook up 12v positive and negative. Then just zip tie everything to the bike.

I will put all my findings for tuning on here shortly Bob.

Thanks!
Jim