Av7 Airsal 74CC AKA Tuning Satan's Son

Hey all.

I have a thread in moped repair where I got a lot of the issues from my build dealt with.

I'd like to create one thread for my 74CC Kit Tuning here.

I've read all the threads on the miserable life of owning the Airsal 74CC kit. I've been able to compose a list of things to tune in order to keep my temps down.

Here is some background on my set up.

Av7 Cases- Mild Case Match

Budget Race Crank and Bearings- Here

Airsal 74CC Cylinder - Here

Custom 47mm head- here

Doppler pipe

Sha 15.15 running a 72 jet "feels about right" 76 is too rich from what I felt.

Bh7S plug

I put a 1mm base gasket, and the piston still doesnt fully clear the exhaust port at BDC.

The head gasket is the aluminum one, with some high temp RTV (i know i know).

Stock Vairiator

Treats CDI

1.2mm Timing

Running 50:1 Lucas Oil Here

It's been OK weather last few days here in CA around 76F I'd say when I ride.

The moped runs OK until I get to 35-40 for a short distance. IT picks up heat and stays heat soaked until I slow down for a good while. I've hit 43.3mph, and get temps of 398F. I stop as soon as I hit that.

I'm usually in the 370-380 riding long distance hitting WOT 40 then slowing down to 30 etc. I'm concerned with the warmer weather coming.

Is it safe to say I should stay under 400F?

I need to check squish and am planning on ordering a PHBG 19mm or 21mm.

Which one should I get? I want to move away from the SHA.

IMG_0518.jpg

Thanks

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

EH 📣FCC of the QCB /

Did you try a 74? Any screens on the SHA? You could even try bumping the timing down.

Oh quick question....did you run the head gasket that came with the kit?

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

Totally normal JBOT /

I'm amazed no one sells a moby wc head yet. I made one and it's been cool. Haha get it

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

> EH FCC of the QCB Wrote:

> -------------------------------------------------------

> Did you try a 74? Any screens on the SHA? You could even try bumping

> the timing down.

>

> Oh quick question....did you run the head gasket that came with the kit?

I realized I made a typo. I tried 72 74 76. 74 was a little too rich (from the sound and feel of the ride).

I plan on going on a long ride tomorrow, so will try the 74 again. I was messing with the crappy dellorto sha filter. Depending on how much filtering yahdooo it will mess with the jet. I have it set for now.

I'm running the alumin head gasket. Not the one that came with the kit. (edited)

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

> JBOT Admin Wrote:

> -------------------------------------------------------

> I'm amazed no one sells a moby wc head yet. I made one and it's been

> cool. Haha get it

lol! nice one.

So why does a 74CC heat up more than a 50CC?

My Vapor says I was around 8k RPM when doing 43. It can't be the RPM, the added friction from the piston going up and down so many more times? The 50CC's hit higher RPMS I think. Is it because the piston is bigger and has a larger explosion?

Would getting the PHBG 19 or 21 cool it down if I can jet it higher on the top end?

I alwmost want to make a head in CAD and pay out the wazooo for fat fins and have it machined.

Thanks,

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

Incelforlifebaby!hotandhorny69 646260 /

Treat sells a 47mm head with no de-compression

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

> Barack Obama Wrote:

> -------------------------------------------------------

> Treat sells a 47mm head with no de-compression

yeeee, check out the link up there. That's what I'm running.

My body hates starting it, but I'm using it.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

Unless you stalk Frenchie eBay for 10 years

B1EE7FA9-791C-48E0-8951-2BCD3FE8369A.jpeg

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

EH 📣FCC of the QCB /

Shit^^^^

Ya dude you might need to bump the timing back a touch. Glad you got the real head gasket. The fiber one leaks like crazy after like a mile.

Have you looked into the slide mods for SHAs. Sometimes they are rich low to mid but lean on the top end.

Jbot is right tho. Such a common kit for AV7 a LC Head would be cool to see in production.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

I don’t know why but Airsal decided to neuter the fin situation on those 74’s that probably doesn’t help. From my experience it’s the long pipes that kill large bore av7s. Doppler, Ninja, giannelli ect. Higher rpms, and more heat.. the tiny cases.. not good. If it’s not the cylinder that gets cooked, it’ll be the seals. Circuit pipes or modified stock pipes with those 70-74 kits. Low rpm with a shit load of torque. If you want it to last. I’ve got my wife’s bike set up with a molossi 62, matched av10 head, airsal stuffed crank, 15mm sha and a modified stock exhaust doing a quick and easy 50. Anything beyond that is av10 territory. I really wish there were more 50 and 60cc kits for av7 being made, And beefier aftermarket cases.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

EH 📣FCC of the QCB /

Your doing it wrong then.....AV7s can be high RPM rippers if built right. This dude has a good setup. He can bring the temps down.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

Totally normal JBOT /

15in carb with a 74 kit is too small.

I'd go 19phbg at least.

Yeah and what did you set the squish to? Maybe wanna go bigger with squish/less compression. You don't need much compression on a 74cc kit. Extra compression just makes it run stupid hot

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

> EH FCC of the QCB Wrote:

> -------------------------------------------------------

> Your doing it wrong then.....AV7s can be high RPM rippers if built

> right. This dude has a good setup. He can bring the temps down.

Thanks for the positivity!

Spent a lot of time on this guy. I appreciate it.

I'm at the point where I rather get the PHBG versus modding the SHA.

I looked into that when you posted the suggestion, but I rather get a PHBG at that point :) lol! (edited)

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

> JBOT Admin Wrote:

> -------------------------------------------------------

> 15in carb with a 74 kit is too small.

>

> I'd go 19phbg at least.

>

> Yeah and what did you set the squish to? Maybe wanna go bigger with

> squish/less compression. You don't need much compression on a 74cc kit.

> Extra compression just makes it run stupid hot

Yee yeee. I think the 15 is OK in terms of feeding the moped but the issue is the restriction in jetting unless you slide mod- that's what I'm understanding.

On the low end it's OK but once I get to top speed it could prob use more fuel down the gullet.

I read the tuning guide for PHBG. Seems quite intricate so I will need to re-read a few times.

I couldn't determine the main difference with the 21mm and 19mm other than the hole size for the intake. I think I will go with 19mm. I saw someone post about a mikuni 24 but that's massive.

I'm pretty stoked on playing with a new carb though. It's also pretty damn impressive they came up with variable fuel delivery from nothing but a damn metal box with air passages and fittings haha. Quite brilliant when you think of it. (edited)

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

EH 📣FCC of the QCB /

I prefer PHBG over everything but they can be harder to tune if your new to tuning. V18 is almost as good and easier to tune for most people. I helped my friend with that exact setup with a SHA 15. He ran it for years then upgraded to a VM18.

http://outofcontrolmopeds.blogspot.com/2012/03/dellorto-sha-boring.html?m=1

Skip to the part about slide modding. It is a game changer. The jist is It changes air speed to control your lower range and run a larger jet to not be lean up top.

Also check for a leak on the intake where the carb clamps to the intake. They usually always leak. I have done the oring Rick it it seems like it never works. So I usually take the shin out. Take a small small small small small amount of gas resistant RTV and use a q-tip to apply it when the clamp part of the carb is then I slide the shin back in. Wiping all the excess off with another q-tip. Making sure not to get any in the pool it hole.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

I would suggest to go for 19mm multi circuit carb and drop the compression a bit by properly indexing the cylinder. With the index right it will not just give you more top end but knocking a few points off the compression will help keep the heat down in the combustion chamber by putting the parasitic potion into the pipe where it will work for you not against you. Also with the extended duration of the exhause event with the proper indexing there will be additional stuffing from the pipes reversion wave so you will have a more robust power band. The transfer event will also be extended which will supply more fresh cooler charge.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

🇮🇹💦 Of the Loin /

SHA is not a good carb to use on an overbore kit in a variated bike, period.

Even less so if it's single variated and not dual

The only moped head that has the appropriate amount of cooling for strictly passive air cooling is a stock MB5 head, let that sink in.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

Hi Guys,

Thanks for the replys. I went on a long ride this weekend. 40 or so miles.

Moped runs fine at 25-30 until I take it to 40 then it's heat soaked and I gotta slow down for a long time.

I'm now hesitating between the PHBG 19 and the VM18. Seems like the VM18 will make my life easier??

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

I think I will also buy the ER3 variator. Why the hell not.

I see this guy is running a VM18

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

You can try the basics, first. Get a colder plug and run a richer mix. Try a castor-based oil like klotz.

In my experience running Opti 2 at 100:1, it was awesome for cruising around town, but blew pistons racing with it. Not a big fan of synthetic super oils anymore.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

EH 📣FCC of the QCB /

I always feel that a VM18 is an easier carb to tune if you are learning about carburetors and tuning. It is more of “I got it pretty close and it runs great.” With PHBG you can control the fine tuning easier. I want to say with a similar setup VM18 were at like 90 main and 25 idle. If you go VM18 I would just order a range of jets around that and then dial it in to you bike.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

Totally normal JBOT /

If you go phbg get spigot mount.

Clamp mount is the worst

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

I hate making decisions whaaaaaaa.

I'm tempted by the VM since I see a lot of good reviews. I'm a perfectionist though and if I can do more with the PHBG19 I want it. But then again, I know mopeds, and do I really wanna go and make my life harder with the PHBG.

Tough decisions. Must decide tonight so I can get my Treats discount :)

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

Is the Mikuni 18 big enough?

If it is, I will go with Mikuni. F it!

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

French Moby /

VM18 it is order is placed.

Gonna try and sell my sha 15.15

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

I've built 3-4 using the fiber head gasket (sprayed with Permatex copper), one has been on 3 30+mile rallys and zero issues, torque to 12 ft.lbs, and re-torque 2-3 times after heat-up/cool-down. Also, what Rebel said about spacing/compression. (edited)

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

EH 📣FCC of the QCB /

Huh..Interesting, I wonder if the copper spray kind of bonds the fibers. I still like replacing it with the aluminum one. Less mess and proven results.

Re: Av7 Airsal 74CC AKA Tuning Satan's Son

> Rebel Moby Wrote:

> -------------------------------------------------------

> drop the

> compression a bit by properly indexing the cylinder. With the index

> right it will not just give you more top end but knocking a few points

> off the compression will help keep the heat down in the combustion

> chamber by putting the parasitic potion into the pipe where it will work

> for you not against you. Also with the extended duration of the exhause

> event with the proper indexing there will be additional stuffing from

> the pipes reversion wave so you will have a more robust power band. The

> transfer event will also be extended which will supply more fresh cooler

> charge.

I don't know if you caught this but this is the most important thing. If the port timing is wrong the engine has to work a lot harder, and the piston absorbs a lot more heat at BDC because it's exposed to the exhaust gases and not getting quenched by the cylinder wall. All the aftermarket heads are wrong, too much area on the squish band, you're almost better if with a stock av10 head. Ignore the squish band clearance and just focus on the exhaust port floor even to the piston at BDC. Also it will be easier to start.

The carb and pipe have to be matched. If you are running a stock pipe, the Sha is fine but on a big pipe you need to be able to add a ton of fuel up top. I normally like VM over phbg but French bikes will break the mount clamp on the vm18 because of the swinging engine vibrations. The clamp is weak, and the VM carb is heavier. Spigot moung phbg is the way to go here.

Timing is the only other lever at your disposal. I would say that a le partie with a jog box timed at 1.3 is mandatory with a big pipe, but you can get away with points as long as your timing is like 1.1mm btdc max.

I've also had a lot of these heads come in warped like a potato chip. I think it's because of the extra material on one side for the engine mount, acts like a heat sink and causes it to expand unevenly. If you've overheated the snot out of it a couple times and suspect head leaks, dress it with glass and sandpaper.

Having built a couple French bikes over the years there's really only 2 ways to do it: either use the big, low rpm kit with stock exhaust, Sha, and tune for torque with a relatively mild setup. OR start with after market cases, 50cc high rpm, and lube up for dropping like 2k into vario, clutch pulley, the whole 9 yard. Anything in between just breaks stuff and will never get you to true blaster stats. But that's like, just my opinion, man.

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