Anyone running 38's

x2ryder

x2ryder

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Aug 23, 2004
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Moline, Illinois
I am thinking of maybe trying to get my hands on a set of 38 tmx carbs from a mach z. They would be for my 780 I am building. Anyone runs these carbs before? If so do you have some jetting specs or feedback on these carbs?
Thanks
 
PM sent. As for jetting, you're on your own. I can tell you that I used to run staggered jetting on mine, around the 310,320,330 range for mains, 45 pilots. That was with stock pipes, and very basic ported 780 cylinders.
 
valin said:
PM sent. As for jetting, you're on your own. I can tell you that I used to run staggered jetting on mine, around the 310,320,330 range for mains, 45 pilots. That was with stock pipes, and very basic ported 780 cylinders.
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How was the throttle respons and mpg. vs. the 33's? Did you dyno it with that setup?
Asking beqause i just bought a 780 kit (cpr) and maybe will upgrade to 38's!
Thanks!
 
Well, I went on a trip last year, and averaged 15mpg. That is in Canadian mpg, with 40.5mm carbs. My sled is excellent on fuel. The throttle response is still very good.

I dyno'd mine with 38's. It peaked of 181hp, but it also doesn't have your typical 780 porting. I'm also running Bender big bore pipes, and Delta 3's.


On the 780's, the 38's are a good investment.
 
valin said:
Well, I went on a trip last year, and averaged 15mpg. That is in Canadian mpg, with 40.5mm carbs. My sled is excellent on fuel. The throttle response is still very good.

I dyno'd mine with 38's. It peaked of 181hp, but it also doesn't have your typical 780 porting. I'm also running Bender big bore pipes, and Delta 3's.


On the 780's, the 38's are a good investment.
Click to expand...
Ok! 38's it is then =) 181 hp is good numbers but you have lakerace porting or? I'll be happy if i pass 160 with my stuff, thats the goal anyway. And phazer intakes is used instead of stock,right?
Big thanks for your help valin!
 
No. I run stock intakes. I tried running Vmax 500 intakes, but I did not like the angles of the boots.

160hp is an excellent goal to have, and you should be happy when you end up with a bit more, depending on the rest of the setup, and porting.
 
valin said:
Yes. You will need to run a different thottle cable, or build a bracket to run the stock cable.
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Ok good! I think it was mrviper ho recomend xcr 800 throttle cable (with stock oil cable) and mach z choke cable.
But i work at the right place to build me a bracket so maybe i do that.

Also was told not to use the earlier (780) mach z carbs,do you know why?
 
yamalars said:
Also was told not to use the earlier (780) mach z carbs,do you know why?
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I believe the early MachZ 38s had the power jets[additional jets for above 1/2 throttle] They are much harder to set up and really unnecessary.
 
800vmax4 said:
I believe the early MachZ 38s had the power jets[additional jets for above 1/2 throttle] They are much harder to set up and really unnecessary.
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But can't you just plugg the power jets and up the mains then or is the nozzels and needels different to?
 
valin said:
I ran an XCR800 cable in mine before. They work fine.

Get yourself a set of MachZ 800 carbs.
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I hear you! If the 780 carbs worked i guess someone here would know,right?
Will look for 800 carbs then. Thanks!
 
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