Nice write-up! I had one of those a couple years ago for a back up when I ran out of Co2. The wiring shorted out the second time I used it and I had to rewire it like you did (I also tore mine all apart for the hell of it). It's an okay compressor if you have smaller tires and your not airing down super low, but it's real slow if you have larger tires. It would take almost 20 minutes to air up one of my 35x12.50x15 from 8 psi to 30 psi.

Also, you will eventually want to get rid of the air hose and chuck that comes with the compressor. It drove me crazy and the chuck never seemed to work right, I would install a standard coupler and air hose (like you talked about) with a nice clip on air chuck.

The MV50's were on sale for around $40 just before xmas so this write up is perfect timing for me. Looking forward to a job I can do indoors - it's been cold in CO! Thanks for taking the time to document and share.

i can confirm the cold in colorado...
looks like it's time to open up my compressor and upgrade a few things
better to do it now before trail season kicks into high gear
thanks for the write up!

Thanks, Jeremiah. I'm working on that last part, but you wouldn't believe how hard it is to track down a 1/4 NPT tap around here. Lowes and Home Depot were a bust... I went to Ace/Tru Value but they were closed. Next time I get some time off I'll go to the shop where I got the 1/8" NPT tap and be done with it.

No problem man. I actually did this write-up to answer your request. I saw your comment in my build thread and until then I had it on the back burner. My Wife went out of town for the weekend w/the baby and I was on graveyard shifts, so I had a couple hours each day before work to knock it out.

Glad you found it helpful, and that I could send a favor back your way.

You're welcome. It's a fun project man, good luck.

So I've been meaning to follow up on the intake reed valve fix. I replaced the reed valve and ran the "3-minutes from 15 PSI" test again, using the same tire guage to check before/after pressures.

After modifiying the compressor, the test results were:

-Ambient temp: 40 degrees F
-Compressor connected to spare deep cycle battery, out of vehicle
-Tire: 285/75r16 Goodyear Duratrac, E-Load Range
-Starting tire pressure:15 PSI
-Compressor run time: 3 minutes
-Ending tire pressure: 30 PSI

So, 15 > 27 before (+12 PSI), and 15 > 30 after (+15 PSI)... That's a 3 PSI increase increase over the 3 minute period, which my simple math tells me is a 25% increase in air up speed from 15 PSI. Not too shabby for $10 and a couple hours.

Last, I took a few pictures of the install of the new intake reed valve...

I had a set of feeler gauges that I haven't used since I rebuilt my Supra engine, so I decided to cut the end off one of them and use it for my new reed valve.

The factory installed reed valve was 0.004" thick based on my comparisons to the feeler gauges. I went with a 0.005" thick replacement reed. I wanted a little extra thickness so the reed would hold up to the pressure on the exhaust stroke, while retaining enough flexibility for the reed to easily open on the intake stroke.

I used a small machine screw to make a tap by cutting notches into the threads on opposite sides with a narrow cutoff wheel. After I drilled/tapped the hole, I cut the same screw down to a shorter length and used it to secure the new reed. I applied Red Loc-Tite to keep it in place. Also, I put a slight bend in the new reed with the inside of the bend facing down. This makes the reed like a spring and applies some pressure to help it seal quickly and completely on the exhaust stroke.

The new reed is also thicker, leaving more material sitting around the lip of the intake port, which along w/the extra thickness, should prevent the reed from getting pushed into the intake port. Note the size of the old reed (visible to the right) vs. the new reed.





Side view of the screw head. You have to use a low profile screw here, otherwise you may have interference issues w/the piston on the exhaust stroke.



The piston on my compressor actually had a small indentation cast into it at the very spot where the new screw was installed (visible top center in pic below), as if they intended for the reed to be secured with a small machine screw in the first place.



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In summary, with:

- Enlarged intake & exhaust ports
- Upgraded intake reed valve
- Upgraded relay
- Upgraded power wire & circuit breaker
- New pressure guage

I was able to net a measured 25% performance increase in the pressure range where the compressor will be used most often. I also believe that I've greatly increased the durability and reliability of the compressor w/these mods.

Tonight I aired up all 4 tires consecutively from 20-37 PSI, running the compressor off a spare deep cycle battery, and it performed flawlessly. It was sufficiently speedy for my needs and I look forward to getting more use out of it on the trail.

That is pretty sweet, nice job!

Huh, I never thought of upgrading mine. I figured I'd just get a new one when it crapped out. My only gripe so far has been the useless pressure gauge... I just carry another gauge in the compressor's tote bag :/

BigFishAllDay: Your detailed breakdown is really great. I got my SuperFlow yesterday and worked exactly once before the Intake reed valve disintegrated into shrapnel.

So now I will follow your path to repairing the intake valve, but have a few questions:
- on your repair on the intake valve, does the machine screw protrude through to the other side of the cylinder head?

- on the intake valve, did you include an o-ring or other cushy landing surface for the reed? On mine - the exhaust valve came with an o-ring.

- lubrication: when I took my Superflow apart, there was evidence of oil in the cylinder chamber and the crank area, but not much. While cleaning out the left over bits of the broken reed shards, I wiped out the shards along with all the oil. What sort of lubrication do you think needs to be applied and where?

Any info you have is much appreciated!

UPDATE:
I rebuilt my intake valve, it took a few tries using different material for the reed.

I created a reeds to the shape of the original with these materials:
- beer can. Yeah, duh, the first thing that is of abundance in my fridge. This did not work. The aluminum is not springy enough to continuously snap back into place with out bending out of shape.
- cat food can. The material is too thick and provides too much resistance from the incoming air from the cylinder.
- tomato can. Same as cat food can.

I was running out of ideas. Finally I took apart an old tape measure that was sort of busted anyway. Deep at the end of the inner coil, there is some flatter material that worked - and plenty of it - I'd say around 24 inches. It works because its thin but springy. It took a few tries to get the right shape, but eventually got a good reed in place.

I used the advice by BigFishAllDay and used a machine screw and some locktight to hold down the new reed. The screw that I used was too big in that the head stuck up too much and the other end of the screw poked out too much on the other side. I used a dremel tool to grind off excess material.

After re-assembly and a few test inflations, I'm fairly satisfied:
-it's much louder now. But I've borrowed these same compressors before while out on the trail, and those were loud too. I'm not too much worried about that.
- There is a marked improvement in the performance, although I didn't measure exactly like BigFishAllDay did. I'll chalk up the performance to the little bit of porting I did to the intake and exhaust holes mentioned by BigFishAllDay.

I've yet to do the electric upgrade, but will look into that another time.

Hope this helps you with your SuperFlow compressor!

Thanks buddy - I appreciate it!

The air fitting on mine looks like a standard 1/4" fitting. Any hose should connect - am I missing something?

i spent time this weekend working on mine and have some observations
i've used mine maybe 6 times before taking a closer look at it
the first thing i noticed was that the fuse, fuse holder and some of the wire insulation had melted.
i had no idea it got that hot.
next i noticed that all the wiring, soldering etc was horrible
wires were corroded, solder contacts were barely attached or only half the wire was touching
no wonder these things burn out or break quickly

i had the parts on hand to fix the wiring issues so i'll check it after each use for problems

i also had the parts to replace the pressure gauge and hose fitting.
the holes drilled on the head are metric and require drilling and tapping for our 1/4" npt parts to fit.
the actual hose connection is our normal 1/4" but the threads are not
this is where i messed up. i cracked the head while tapping one of the holes.
i have a ton of pipe thread dope in there so i'll see if it holds
otherwise i'll order another one and take my chances again.

so even if you guys don't tackle the drilling and tapping, fixing the wiring issues will definitely help

and i'm an idiot, i have no pics