Building own TwinMax
 

Hi,

I am toying with the idea to make my own twinmax type meter. Does anybody have an idea what the vacuum pressures are on the throttle bodies?

Regards
Mike

Home-made Twinmax?
 

Mike:

I have a similar idea. I have a Fluke 40 mhz 2-channel portable scope so I thought I could use this as my readout. Found a couple of differential pressure (vacuum) transducers at Newark El, they are Freescale units (p/n MPX2100DP) with a max pressure rating of 14.5 psi (100 kPa), about $20 ea. I think these should work OK based on using my simple mercury unit. I bought them 3 months ago and they are sitting on the corner of my desk. I just need to wire them to a power supply (could use the bike's battery, but I think better to have an independent supply as the bike's system would be fluctuating w/rpm.

Anyway, this would be the high-priced option as the scopemeter costs about $1200!

In the meantime I'm too busy with my work and travelling, leaving for China this Sat, etc., etc. AND getting my "S" ready for the ride from Phila down to JAX for the Iron Butt Dinner on March 10. I am building a custon wedge-shaped aux fuel celll that will replace the seat cowl. Will hold about 3 gal, constructed from 16 ga stainelss steel. My previous bike was a K1200LT for 3 years and 62,000 miles, and I had mounted a 3 gal fuel cell on that to give me a 410 mile range. Hmmmmm.

Stuart Ostroff --> check out last year's IB dinner on my website www.stuartostroff.com

20ft clear plastic hose, yard stick, fluid of choice.

'20ft clear plastic hose, yard stick, fluid of choice.'
what he said. I use ATF. My twinmax got sold after the '$2.00 manometer' got built. works like a CHAMP:)

Do you have a diagram of how this goes together. I don't trust my twinmax anymore since I've bounced it off the garage floor a couple times.

except under load at actual roadspeeds.
Depends on how accurate you wanna be :)
Also, on how much you tolerate cumbersome liquid filled setups.
But if you want cheap, and still pretty accurate, you can't beat that piss-in-a-pipe method :)

I just use a slack tube manometer in differential mode. I have been convinced to give up my long treasured mercury carb stix due to the dangers of handling mercury.

By differential mode I mean one leg connects to the left cylinder, one to the right. This way, absolute vacuum is unimportant, you only see the difference between the cylinders. I got mine from Dwyer Instruments, Google will find them for you. If you feel you need a gauge, the same company sells a device called a Magnahelic that you can get with a 15 - 0 - 15 gauge face, center needle, that works just pefectly. You can even bungee it to the top of the tank for on-road, under load, evaluations. It's about 60 bucks which compares quite favorably with the cost of any of the gadget type critters.

Hey ED!!!!
I don' see no steeenkin ZX12 listed in the 'my bikes' section? wass-ammaa-U? eh? blow 'er up already:) :)??

No, and I haven't, for reasons of shear laziness, updated the sig line to show the '01 Honda Blacbird. I'm in love. The poor S is over in the corner of the garage snivilling. I actually feel sorry for it and will take it out for a nice 600 miler this Saturday. Just have to wipe the damn chain lube off my hands before I ride. :o