let the fun begin, tuning to commence

hello all, it is now 5:30am in SD and i have been cleaning a set of carbs for a 82(?) XJ750 since the 11 hour shift ended at 11:30pm, i am a little tired.

i have located a source of high temp (400*) silicone hose to build my yics tool tommorow, i have located the yics port, i have a vaccum rig set up with clear tubing, a restictor valve, a fuel filter for a dampener, and a vaccum gauge,

1) at what RPMs do i want to fine tune the vaccum? what psi am i shooting for? or am i just reading the 3rd carb vaccum and balncing from there?

2) does it matter where the idle adjustment screw between the 2nd and 3rd carb is set at when i bench sync this thing? or when i get to adjust ing the vaccum?

2) seeing as this is a hitachi (sp) 32 series carb how far out do i turn the fuel enrichment screws? the ones that steal your sanity? is ther any way of tuning the mixture without a colortune? or just set it and leave it be?

this is all i can think of right now, but if you all have any thing to add feel free, i've been up since 6 am yesterday and i know i missed something, (no i'm not missing parts i made a checklist, and santa ain't even this thourgh :lol: )

thankyou all for the help, maybe tommorow (no work yay ) i can have this thing idling smooth and below 2-3K.

aaron

gonna crash now, figurativley

 

ps how do i measure the float hight, what are they suppose to be set at and if needed how do i ajdust them? thansk and goodnight

 

You set them at idle. That should be around 1000 rpms. Sometimes your side cover will have your idle speed listed on the sticker Yamaha puts on there.

Yes, measure number three and set the rest to that... sort of. Set four to three. Set one to two. Then set bank 1 (carbs 1 and 2) to bank 2 (carbs 3 and 4).

You'll need to adjust the idle periodically while you're doing this because the idle will change as the engine comes into synch. You may even need to restart your synch procedure as you dial it in because it was so far out to start with. It's just a little of this, then a little of that. Make sure you have fans to cool the engine while you work.

The simple answer is 2-1/2 to 3 turns out. After you synch in the carbs, you'll want to start watching your plugs. Adjust as necessary. After you get them where you like them (colorwise), recheck your carb synch to make sure nothing changed there. One adjustment effects all adjustments.

Probably not a bad idea... seeing as how you've got two number twos in your list above. :wink:

 

To adjust float height, you'll need a clear 1/4" ID hose so slip on the nipple coming out of the base of the float bowl. Slip it on and hold it up along side the carb so that you can measure the fuel level in relation to the side of the carb.

You'll need to make a rig that hold fuel so that you can fill the carbs. After you have that hooked up to the carbs, open the bowl drain screw and let the fuel flow into the clear tube. It should be about 3mm below the carb body's lower edge (where the bowl mates with).


(h/t Nick for photo.)

If the level isn't correct, you have to drain then remove the bowl. There's a tab on the float that must be bent slightly to make your float level adjustment. This is an extremely tedious and time consuming process, but you must do it.

 

ok I'M AWAKE and knda well rested !@#$% ankle biter next door waking me up at noon!!! :lol:

thankyou for all the help yea i forgot to mention the fans, i'm gonna go buy anothor one today so i should have 3,
and for the floats if i find they are off how do you adjust them?

thanks gamaru, the savior boble headed avatar

Aaron

 

Floats are adjusted by bending the tang where the needle hooks to. Bending it towards the needle valve will lower the fuel level, away will raise the fuel level.



I found this picture on the interweb. This float looks similar to the ones found in Hitachi carbs. The tang that you'll be bending is arrowed to and marked as 'tab'.