Zdz-140

[Terryscustom]

Kind of makes me curious what JMB can would best suit a DA70...they have a long and short one for that displacement I believe. What is the preferred source in North America for them?

DA Y-header with M-80-L.

[Machzx]

8.5 is header length?

[Terryscustom]

8.5 is header length?

That's correct. It's a smallish canister made for a 140-150cc size and you shorten the header to get the best performance. Same thing if you use the 3W L70 (almost identical can to the JMB 70's) Same concept. http://www.aircraftinternational.com...derLength.aspx

The concept is a nice breathing exhaust and unless you shorten the header you get a pipey non linear throttle.

[Machzx]

i think im around 11 in on a gp 123
i know there is a ton of guys running the chart they came up with
i have es composites in a 3dhs slick an 123 gp i think the lengths are different again on the comp pipes .
they did a ton of run time to get the numbers .
is it possible to try longer lengths ?

[Machzx]

That's correct. It's a smallish canister made for a 140-150cc size and you shorten the header to get the best performance. Same thing if you use the 3W L70 (almost identical can to the JMB 70's) Same concept. http://www.aircraftinternational.com...derLength.aspx

The concept is a nice breathing exhaust and unless you shorten the header you get a pipey non linear throttle.

Single can?

[Alberta1]

Too much back pressure causes excess crank case pressure and blown base gaskets.

Not to derail the tread. I am kinda curious how you would determine this. Does the smaller bores prevent the exhaust from leaving from the exhaust system prior to getting partially scavenged back into the cylinder on the down stroke of the piston, causing a compression concern that would blow out a gasket.

[JDaly]

Terry,

Where can you get JMB Exhaust in the US or are you ordering direct from the Chezc Republic?

[Always Flying]

Terry,

Where can you get JMB Exhaust in the US or are you ordering direct from the Chezc Republic?

Jim,

You can order JMB from AMR-RC I inquired about one for my Da 70cc

Mannyh

[Carlisler]

Dying to hear how this 140 compares to the GP123!?

Is it worth the possible replacement effort...?

What are your numbers like Jack?

(my guess is cost -10%). LMAO!

[wingburner]

Dying to hear how this 140 compares to the GP123!?

Is it worth the possible replacement effort...?

What are your numbers like Jack?

(my guess is cost -10%). LMAO!

I just called John Craven........NEVER-NEVER did I think I would be talking to him....man did we laugh!!! Great guy, he's coming around!!

Far as numbers go??? Mine are good, John's are good so we're both happy!!

Replacement will be a larger engine anyway!!