I'm having trouble jetting my tb 28mm carb on my pitster x4.. it has a yx 160 bottom end.with a 177 bbk. Stock head.daytona type outer rotor.chp coil.I'm at bout 4365 feet elevation..iany help thanks
jetting on tb 28mm carb on yx 160
bigbirdklx
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I'm having trouble jetting my tb 28mm carb on my pitster x4.. it has a yx 160 bottom end.with a 177 bbk. Stock head.daytona type outer rotor.chp coil.I'm at bout 4365 feet elevation..iany help thanks
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what jetting do you have now?
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44 pilot 100-105 main should get you close
make sure you have the nipple on the right side of the carb plugged . 85% of the people that have trouble with that carb . do not have the nipple plugged
make sure you have the nipple on the right side of the carb plugged . 85% of the people that have trouble with that carb . do not have the nipple plugged
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I remember you telling me that. When I bought it..its still plugged..I think I tried those jets..but I tryed so many differant ways..can't even remember what I tryed..but ill give it a shot again.and see what happens...
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I tried running those jets matt and still runs the same as the jets that came in it...I tried differant jets all the way down to an 89..doesn't seem to get any better for some reason...
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I'm gonna try running a 102.5 main and a 44 pilot..I had a 50 pilot and 125 main..so ill keep updating...
depends where the problem area is in the throttle range..
idle to 1/4 throttle is pilot, 1/4 to 3/4 throttle is needle and obvious the rest is mainjet..
changing the mainjet will have a small effect in the lower rev ranges, but an engine that size and your altitude should have at least a 100 main and pilot will be around 40-50. tune the pilot till you have around 1.5 - 2 turns out from closed on the mix screw.
tune the pilot first then set the needle height.. and its best to do plug chops for mainjet setting.
idle to 1/4 throttle is pilot, 1/4 to 3/4 throttle is needle and obvious the rest is mainjet..
changing the mainjet will have a small effect in the lower rev ranges, but an engine that size and your altitude should have at least a 100 main and pilot will be around 40-50. tune the pilot till you have around 1.5 - 2 turns out from closed on the mix screw.
tune the pilot first then set the needle height.. and its best to do plug chops for mainjet setting.
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Ya the 50 pilot is good from idle to 1\4..but boggs down there after..tried 100 and 102.5.and it will rap out at bout 1\2 throttle..as if it was hitting the rev limiter..but only at 1\2 throttle..so I put an 85 main in..and it doesn't really get any better...I mean from that kind of jump in sizes I should. See some kind of differance..but nothing really changes...
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Ok when I put the 85 main jet in to try it I put the needle all the way to the top..and no differance..it was in the middle..what I don't understand is where it rapps out at half throttle
85 mainjet seems way too small for a pe28 clone carb..
which brings your next problem, the needle is providing more fuel that the main jet.. bounce it up to 100 and see what happens..
also your doing this all backwards..
forget your main jet settings till you can get good throttle response from idle to half throttle, this will be the pilot and needle setting..
best way to tune the pilot is to find where it idles best with the mixture setting..
1.5 turns from closed is spot on but youll get away with 1 to 2.5 turns..
but anyways theres heaps of good advice in here already which should have you going good..
on another note... have you just done all the work to your engine in one go?
checked your valve clearance?
checked your cam timing?
is it a stock cam or modified cam with stock springs?
which brings your next problem, the needle is providing more fuel that the main jet.. bounce it up to 100 and see what happens..
also your doing this all backwards..
forget your main jet settings till you can get good throttle response from idle to half throttle, this will be the pilot and needle setting..
best way to tune the pilot is to find where it idles best with the mixture setting..
1.5 turns from closed is spot on but youll get away with 1 to 2.5 turns..
but anyways theres heaps of good advice in here already which should have you going good..
on another note... have you just done all the work to your engine in one go?
checked your valve clearance?
checked your cam timing?
is it a stock cam or modified cam with stock springs?
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Ok well I was out ridding this weekend.and my cam chain tentioner came out while I was ridding... and you get the idea.so now I just bout a v2 head and a 184 bbk.and a s35 grind cam.from tb..so before I try 200 differant jets..any body suggest..what I should start with on this tb 28mm carb.thanks a lot...
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Soon as I get my bbk ill try it. And get back to you thanks for the help
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Ok well back at it..I have a yx 160 bottom end... tb 184 bbk... s25 grind cam..tb v2 head..tb 28mm carb I have the 125\50 set up in there now but doesn't seem to work I tryed moving the needle 2nd from the bottom not really much of a differance.I'm at 4365 feet. When I hit a jump and give it throttle in the air it boggs down even worse wen in the air.. matt at pitster sugested to move the flot but up nor down really helped either..lol..but hopefully someone can point me in the right direction...thanks
ok tb28mm is a pe28 copy right?
125 main at yr altitude seems a shade to big.
i would install a smaller main (probly 110 or even 105) until you tune the bog spot out..
some of the these carbs have issues with too big of main jet influencing the rest of the throttle range..
your pilot might be ok, but only you will know... mixture screw must provide best idling @ 1.5-2 turns out from closed (sometimes 1- 2.5 turns is fine)
if its any more than 2 turns then you need a smaller pilot and obviously any less and you need a bigger pilot..
while tuning the pilot leave the needle clip in the middle, once your happy with the pilot and idle quality then move onto the needle setting..
now basically you just have go 1 needle clip at a time. and given your engine size and mods it will need to go down on the needle (richer).
you should notice a small increase in throttle response at each needle clip until its good.
in some cases i have had to put a thin washer under the needle clip to hold the needle up a little.
also remember you can do plug chops to see if you need to go richer or leaner
also please only change one thing at a time or else it will play mind games with you..
see how ya go
125 main at yr altitude seems a shade to big.
i would install a smaller main (probly 110 or even 105) until you tune the bog spot out..
some of the these carbs have issues with too big of main jet influencing the rest of the throttle range..
your pilot might be ok, but only you will know... mixture screw must provide best idling @ 1.5-2 turns out from closed (sometimes 1- 2.5 turns is fine)
if its any more than 2 turns then you need a smaller pilot and obviously any less and you need a bigger pilot..
while tuning the pilot leave the needle clip in the middle, once your happy with the pilot and idle quality then move onto the needle setting..
now basically you just have go 1 needle clip at a time. and given your engine size and mods it will need to go down on the needle (richer).
you should notice a small increase in throttle response at each needle clip until its good.
in some cases i have had to put a thin washer under the needle clip to hold the needle up a little.
also remember you can do plug chops to see if you need to go richer or leaner
also please only change one thing at a time or else it will play mind games with you..
see how ya go
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Ok well the way it seems to run now..I'll try setting the air fuel srew at 1.5 turns and put a 110 in and try it...but when I start it it sits and idles fine..just when I'm out ridding....ill try and see what happens there thanks a lot..seems like this things getn the best of me......
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just change 1 thing at a time. otherwise you'll have no idea what worked and what didnt. i like to start with the pilot i'll try 1 size if i dont like it i'll go up 1 or down one depending on how its acting. once i get that part of the throttle worked out i move on to the next thing.
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