38mm Carb 780 Help

S

SRX it is

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I've read the threads and got the phazer boots part covered. Now what about the choke and throttle cable, I have the MachZ ones.

Mostly, how about the jetting?

I have opened up airbox 160, 157.5X2 and 50 pilots with 35MM bored carbs. Does anyone have a recommended starting point for this combo?
 
What pipes? Case ported or no? Compression ratio? What year are your carbs from? What nozzles and needles are in them? We need more info in order to help you fully.

You need a Mach Z choke cable. As for a throttle cable, if you build yourself a throttle cable bracket, you can run the stock SRX cable. That will give you a nice, easy pull. If not, you can use an XCR800 (and i'm sure many others) throttle cable, but the pull will be hard and it will annoy you.

I don't like the phazer boots. I use stock boots, but I hone them out with a die grinder a bit so they don't impede flow.

As for jetting, give us some more info, and we'll be glad to help you.
 
Thanks Alot Valin

I will open them up tomorrow and let you know. I was told they were off of a 98 Mach. My compression is 120 to 125, heads opened right up by a hack because high comp heads were removed when it was sold. I really could use a decent set of heads that are matched not eyed.
My pipes are stock with newer Hauck growlers and it's a Hauck kit.

I will re post all this tomorrow with the rest of the info. Again, thanks.
 
Provided you are running the stock o-2 nozzles, and 8ady1 needles in those carbs, I'd throw 45 pilots, and 400 mains, and bring it down from there.

If I remember correctly, I believe I was running 340 mains and 45 pilots with my old Hauck ported 780 cylinders, on stock pipes. That's not to say that your cylinders are ported the same as mine were, so I would still start up around the 400 range, and come down from there.
 
The carbs I got were junk

Ok so now I have another set with the 03 nozzles and 8ADY1-40 needles. A bit richer than the 02s. I'm guessing that I should start with the 380 in this case. I also want to keep the airbox. Should I use the 600 inlet boots for the airbox? I know it's an old subject, but when trying the boost bottle did anyone jet down to compensate for the additional fuel going into the motor instead of the airbox? Richer circuit would account for the HP loss.
 
Do not run a boost bottle. You will lose alot of hp. I was still on the lean side when I had the boost bottle installed, and was down alot.

Don't mess around, and start with 400 mains and bring it down from there. Run the stock intake boots. I didn't like the angle of the carbs with the phazer boots. Remove the top shelf in the airbox, and ensure there are no lower dividers (if you have them). As for airbox boots, you can just modify the stock SRX boots to work. Pull the boot out of the airbox. You will see that the inside of the boot is rounded. Turn the boots around and face the rounded portion toward the carbs so they will slide over the bell of the carb. The amount of potion that now sticks out of the airbox is very thin. Don't worry about this because the carbs are much longer, and will fit in there nicely. Cut the remaining part off the carb boot, so that both sides of the boot have the same depth. Therefore, when you are done, the boot is only about 1/2" wide.......with just the portions remaining that allow it to stay into the airbox. When you install the airbox, pull the airbox apart completely and install the bottom onto the carbs, then bolt the top shelf on.
 
Excellent

Cool, that sounds easy enough to me. Yep I will start with the 400s then and the stock boots. Properly tuned should I be around 170? Should I put in a 2000 up stator?
 
The 98 stator will be fine.

Your hp will depend on the amount of porting in your engine. I would guess that you will not be more than 170hp.
 
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