About to jet, need some guidance.

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Unknownz24

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So I'm about to jet for my pod filters and straight through exhaust at the same diameter. I picked up a few up size jets from xs650direct and also have my colourtune in hand.

I'm going to start with 2 sizes up on the mains and one size up on the pilot. I've yet to see if I need washers or it's just a clip for my needle.

First big hurdle...any tips on getting the pin out that holds the floats in place?? They won't budge!
 
They must be corroded,as they usually almost fall out.They could be stuck in the holes by some old gunk. Don't try to beat them out,as the little holders will break!. lha:yikes:
 
I use a punch to remove my pins, but I only need to tap them very lightly with the end of a small screw driver. Definitely do not try and force them out. Use some penetrating oil or wd40. You could also apply heat, but you need to be very careful and brief with it. Aluminum melts lower than brass, but the very thin pieces of brass might heat up quicker.

What size jets did you buy? I would use 2 up on the pilot, but others with similar setups use 1 up. I just don't like being many turns out on the idle mix.

For mains, start with 5 up or more.

If you experience flooding and wet plugs, but your float height is set correctly try lowering (leaning) your main jet needle.

I will be posting my experience once my jets come in early next week. I definitely want to compile more specific information in regard to pods and exhaust and how to tune these carbs.
 
Main jets I bought 145, 147.5, and 150.
Pilot I only picked up a 45.

The american/canadian models came stock with 135 mains and 42.5 pilot.

I installed the 147.5 main and the 45 pilot and raised the needle by one step (4th groove from top) but I haven't cut the exhaust yet so it's not a fair assessment right now. I'll keep you guys posted on what my colourtune ends up telling me. Probably won't get to tuning until sunday though. Have a wedding to go to tomorrow.
 
my own bike had 125 mains
mounted pods and straight exhausts, started off with 150 jets but was way too high...
i now have 140's and it seems to work (cant ride the bike yet, so havent been able to truly test it

also raised the needle 1 step, pilots are atm stock
 
I am swearing by leaning the main jet needle with these mods, but please correct me if this is not a problem for any of you. So far I have pulled and adjusted my carbs exhaustively; 100 or more times before I have come to this conclusion.

More information is great. At some point we could make a sticky to quickly help anyone looking to for this information in the future. It is always hard to find follow-up information and longer term follow-up information for mods like this.
 
ive read but dont know real world that cutting the headers shorter than stock can creat some tuning problems
 
yes your cutting them at the stock leangth,iam not sure but if you was to put some slip ons from there you might not have to rejett. personally i did what your doing and put some 3/4 washers with small inner hole to get some back pressure back. it does help and the sound is not that diff just more quite at idle
 
I'm going to get mine on the dyno when it's complete. Trouble is, there are so many permetations with parts and types of fuel, that i don't think there will be a definitive answer.

A ball park figure would be great for future builders
 
Okay, so I popped in the colourtune this evening and have some updates. With oiled pod filters and stock pipes, the following settings gave me blue flame (ideal mix) at all rpm both in nuetral and under load (3rd gear rear brake full on.) Under hard snaps of the throttle the flame is orange (rich) with just a quick flash of white flame (lean) when letting go of the throttle. I took some video and I'll post it here when I get to a proper computer. (On my android phone right now.)
 
Hey guys, I just recently became a proud owner of a 1981 XS400. Picked it up for $240 with a cracked/leaky crankcase cover. Picked up a new old one a local bone yard, gave the bike some TLC and "viola" she runs. Well, shortly after it running I have decided to switch to pods, rejetted carb, and hacked off the mufflers. And now its back to not running.

I based my rejet roughly on this thread, have 142.5 main jets, 45 pilot jets, 2 turns out on mixture screws. I noticed some people mentioned changing the needle position. This one I am lost on. Where/what do you do to set a different needle position? And any suggestions or ideas why I am having trouble starting?
 
So I have been chasing similar problems with my carbs and my bike also has pods and straight out headers. I got a jet kit and changed the main jets to 150's, raised the needle one notch, and now have a total of three needle shims shims as well. After doing all of this, I noticed the tips of the needles on the mixture screw had been broken off (could be me, maybe previous owner, not sure). I got those out, bought new needles, and reinstalled the carbs.

The bike started up on two kicks, which was awesome, considering this was the first carb I ever worked on. What is also awesome is that the initial problem seems to be fixed: at high rpms, I was getting a bunch of sputtering, limiting my top speed to about 70-75 mph and adversely affecting performance, but now, I can easily hit 8 or 9 k rmps with no problem.

Unfortunately, now I am getting a similar sputter, but now at about 4-6 K RPMs. The bike has no problem accelerating from stop to about 4K, sputters up to about 6K, and then almost "breaks free" and takes off like a bat out of hell.

I'm stoked about the "bat out of hell" part, but am looking for advice on the new sputtering problem. Any thoughts?
 
I got a jet kit that had (2) 150 jets and (2) 145s. I went straight for the biggest jets, which seems to have cleared up the sputtering top end. But it seems to be lean at the 4K-6K range now. Will using the smaller 145 jets "richen" up the mid range? Or is it possible I need to go even BIGGER than 150?
 
drewpy said:
I'd try altering the needle height down again first
Click to expand...

Nice. This is exactly what I was thinking.

Side question- the bolts that hold the carb "boot" to the head, do they have a torque spec? If so, how does one get a socket on it? I can't even get a box end on them let alone a socket.
 
I didn't do anything more than snugly tighten the carb boots and I have no problems.

FYI with stock airbox and tiny free-flowing mufflers I am running 1 size larger pilot, 5 sizes larger on mains, and I raised the needle all the way (dropped clip all the way). Currently I have no running issues at all other than some light popping on deceleration likely due to excess fuel. I have driven for 200 miles with this setup so far and it drives great. My brass floats are set to 23mm from the top lip (not the gasket surface).
 

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