Carby / Jetting settings for your bike.

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thump*140

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Bike model: Mikilon D8 125

Engine Model and capacity:155z Zongshen

Engine Spec - stock or modified - list mods: 32-42 exhaust pipe. Standard other than that.

Carby model and Internal Diameter: OKO 26mm Flatslide

Jetting specs and Jet Type used (Keihin or Mikuni) : K40 pilot, JJH needle on middle clip, K100 main

Area you live, and general altitude (sea level, desert, highlands etc): Adelaide
 

thump*140

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Bike model: RevMX TTR175

Engine Model and capacity: 175Z Zongshen

Engine Spec - stock or modified - list mods: Standard

Carby model and Internal Diameter: OKO 26mm/ OKO 28mm Flatslides

Jetting specs and Jet Type used (Keihin or Mikuni) : K40 pilot, JJH needle middle clip, K100 main (26mm) K42.5 pilot, JJH needle, second clip from bottom, K102.5 main. (28mm)

Area you live, and general altitude (sea level, desert, highlands etc): Adelaide
 

sean01

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Bike model: custom crf50 style bse

Engine Model and capacity: yx160

Engine Spec - mods: yx150 head, no base gasket (approx 12:1 comp), akunar 7.2mm cam and H/D valve springs, H/D clutch springs. yx outer rotor with standard cdi and pickup mod

Carby model and Internal Diameter: OKO 30mm with 2 inch velocity stack with uni filter

Jetting specs and Jet Type used (Keihin or Mikuni) : DHZ 36 pilot, 105 hex mainjet, N80F needle fully raised with an additional 1mm washer, mixture 2 turns out

Area you live, and general altitude (sea level, desert, highlands etc): burpengary (north side of Brisbane), sea level
 

DvDRip

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interesting thump
40 pilot now huh? 36 seems to be the golden jet for the 26mm oko.... any reason why you're using a 40 pilot now?
 

thump*140

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guessing the 175 breathes a bit better, cause anything under a 38 pilot, and it was backfiring like a mofo on deceleration.... heaps responsive, too responsive actually, but yeah, a bit lean...
Kinda strange that the Blitz 250 was perfectly happy with a 36 pilot, but the 175 rather dislikes it..

If memory serves, the 160HO and the 175 run bigger valves than the old 155 dont they? could have something to do with it i spose... increased breathing ability, plus the diameter of the RevMX exhuast and lack of muffler "restraint" means she breathes pretty hard....
 

wogtaz ryder

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I think it was just +1 exhaust valve? but there has been alot of stuff that where supose to be in the new HO.. so pull one down for the hell of it thump lol
 

topguntravis

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Have you tried a 102.5main and 40pilot on the 175z thump*140??
I'm looking for something a bit richer and not quite as responsive as you make yours sound. If you've tried this or something richer that WORKS let me know please :)
 

thump*140

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I think it was just +1 exhaust valve? but there has been alot of stuff that where supose to be in the new HO.. so pull one down for the hell of it thump lol
lol CBF'd... plus i havent pulled down the old 155z version, so i wouldnt really know what i was comparing it too... Can say the 160HO is a piece of piss to kick over and fire up, the 175 is not... no decomp cam in that one, i'd bet money on it... already done a set of starter gears, but that was my fault cause i got "impatient" when i stalled it in deep sand... *oops*
Have you tried a 102.5main and 40pilot on the 175z thump*140??
I'm looking for something a bit richer and not quite as responsive as you make yours sound. If you've tried this or something richer that WORKS let me know please :)
Yeah Topgun, i tried a 42/102.5 combination, and if you want something a bit less punchy, and richer for the engine's sake, that one works quite well... I like big punch down low and crisp response, so all my motors are bordeline lean... but you can crack the throttles on all my bikes as quick as you can, and none of them bog...
You could try a 105 main, but much bigger than that, it starts making a doughy spot in the midrange that the needle cant tune out...
Much bigger than a 42 pilot, and you'll have trouble with starting it, and will bog if you crack the throttle too quick. :D
 

DvDRip

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if you don't want that bottom end punch wait til I try out the pe26...... around the same price as an oko and should be a good performer just without insane snappyness of the oko.... ordering one soon so stay tuned on the nitrous thread ;)
 

topguntravis

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I was ganna get a PE26 on my new bike but would of cost me $140 extra from Ed's supplier...But DHZ has em for $99 at the moment? not genuine? I'm ganna try the 100main & 40pilot and if I can find a 102 and 42 i'll see which I prefer. but my carby tuning skills are rather poor lol
 

thump*140

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topgun the TTR comes with a jetting kit, and the 42/102.5 combination can be found in the spares kit. Dont even bother riding it with the stock jets, whip em out, and go straight to the 42/102.5 combo..
Rip is right though, the PE-26 or 28 will be a slightly "tamer" carby... outright power will be similar, and it will offer a good spread of power, just without the brutal snappiness of the OKO...
Sneezy's lil bro is running a DHZ PE-26 on his shitpro 140, the quality seems quite good, and when jetted correctly, offered pretty good all round performance. Sneezy is running an OKO26mm in an identical bike, both bikes are as fast as the other, but the OKO-fed bike is much snappier...
If you are still concerned about the 175 being a bit to keep hold of, try using an older style 1/2 turn throttle... The throttle that comes with the TTR is closer to 1/8 turn than 1/4, and with an OKO26 tuned properly is half the reason for the brutal throttle response... An old style 1/2 turn throttle may not look like porn, but it will keep the front tyre on the ground a bit more, and will lighten the throttle pull..
I've got a couple of different carby options coming up for the TTR bikes, they'll be posted in the review thread as i make my findings. :)
 

ando

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and for that reason and that i'm up to a 118 main on my molkt i'd be wondering why the oko cant run a larger main jet than a 102.5....

tho with that said i know there is a fair difference in the sizing of keihin and mikuni style jets ie. 125 keihin to 110 mikuni... so i get there will be some difference but just going on the two carbs and settings i know currently running on the 175 i'd be thinking that a 102.5 would be lean up top.

it would be interesting to find out how large the main jet can get b4 there is noticeable problems in the midrange. obviously the needle setting would be good to know as well.
 

sean01

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yeah mikuni jets are measured in flow and keihin is in size of the hole (mm)

and too big of main does effect the middle range..
i put a 110 main in my 30mm oko and the middle to top end was rubbish.
went back to a 102.5 and was really responsive but run out of legs up top.
then settled on the 105

on a 175z i would be starting at 110, and then youll probly find it needs to be dropped to about 108..
125 main sounds very big.. we use 110 in 196cc engines with 28mm oko's

Yeah I pulled the post to allow myself more time to check things out thoroughly after finding new info in the below Vintage Dirt Bikes forum thread :

Searchable Knowledge Base • View topic - Mikuni specs for MT250

The two jet conversion charts give conflicting comparison specs ... The ONLY real way to know for dead certain is to buy a set of jet drills and use them to measure the actual sizes of various Mikuni and Keihin jets ... maybe Mikuni changed the way they size their jets at some point in time over the years ?

----------------------------------------------------------------------------------------------------------------------

Here's my original post ...

Mikuni jets are rated a cc/minute of flow and Keihin jets go by size in mm ...

I've read where Keihin pilots are #36 = .36 mm / #37 = .37 mm / #38 = .38 mm etc ... and #100 main = 1 mm ... #102 = 1.02 mm etc

I haven't found a Keihin to Mikuni pilot jet conversion chart yet ...

I've had this main jet conversion chart saved for a while ...

Width------Keihin # -- DynoJet # -- Mikuni #
0.0350---- 92.5--------- 92---------- 86.3
0.0360---- 95----------- 94---------- 88.1
0.0370---- 97.5--------- 96---------- 90.0
0.0380---- 100---------- 98---------- 91.9
0.0390---- 102.5------- 100---------- 93.8
0.0400---- 105--------- 102---------- 95.6
0.0410---- 107.5------- 104-----------97.5
0.0420---- 110--------- 106-----------99.4
0.0430---- 112.5------- 108--------- 101.3
0.0440---- 115--------- 110--------- 103.1
0.0450---- 117.5------- 112--------- 105.0
0.0460---- 120--------- 114--------- 106.9
0.0470---- 122.5------- 116--------- 108.8
0.0480---- 125--------- 118--------- 110.6
0.0490---- 127.5------- 120--------- 112.5
0.0500---- 130--------- 122--------- 114.4
0.0510---- 132.5------- 124--------- 116.3
0.0520---- 135--------- 126--------- 118.1
0.0530---- 137.5------- 128--------- 120.0
0.0540---- 140--------- 130--------- 121.9
0.0550---- 142.5------- 132--------- 123.8
0.0560---- 145--------- 134--------- 125.6
0.0570---- 147.5------- 136--------- 127.5
0.0580---- 150--------- 138--------- 129.4
0.0590---- 152.5------- 140--------- 131.3
0.0600---- 155--------- 142--------- 133.1
0.0610---- 157.5------- 144--------- 135.0
0.0620---- 160--------- 146--------- 136.9
0.0630---- 162.5------- 148--------- 138.8
0.0640---- 165--------- 150--------- 140.6
0.0650---- 167.5------- 152--------- 142.5
0.0660---- 170--------- 154--------- 144.4
0.0670---- 172.5------- 156--------- 146.3
0.0680---- 175--------- 158--------- 148.1
0.0690---- 177.5------- 160--------- 150.0
0.0700---- 180--------- 162--------- 151.9
0.0710---- 182.5------- 164--------- 153.8
0.0720---- 185--------- 166--------- 155.6
0.0730---- 187.5------- 168--------- 157.5
0.0740---- 190--------- 170--------- 159.4
0.0750---- 192.5------- 172--------- 161.3
0.0760---- 195--------- 174--------- 163.1
0.0770---- 197.5------- 176--------- 165.0
0.0780---- 200--------- 178--------- 166.9
0.0790---- 202.5------- 180--------- 168.8
0.0800---- 205--------- 182--------- 170.6
0.0810---- 207.5------- 184--------- 172.5
0.0820---- 210--------- 186--------- 174.4
0.0830---- 212.5------- 188--------- 176.3
0.0840---- 215--------- 190--------- 178.1
0.0850---- 217.5------- 192--------- 180.0
0.0860---- 220--------- 194--------- 181.9
0.0870---- 222.5------- 196--------- 183.7
0.0880---- 225--------- 198--------- 185.6
0.0890---- 227.5------- 200--------- 187.5

There are several different types of Mikuni jets ...

mikuni pilot jets

mikuni jets
 

ando

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i've seen that chart b4 seano helped a fair bit lately but i don't get what the 'width' is related to is that a measurement in inches?? diameter?? seems like it to me...

i know coolie with his keihin pe26 running a 125 is unbelievable and i'm still tuning and running 118 on the molkt and its got no problems from middle to top... my drill bits unfortunately dont have anything between 118 and 131 so i'm a little stuck.

my pilot does need work obviously it dont have numbers but it looks like a mikuni 'm28/1001' type and i'd guess a 35 but unfortunately the keihin main and mikuni pilot presents me with the problem of getting the size of the hole right.
i think i got it figured out tho, cross referencing a wire gauge size to inches/mm diameter to get a 40 pilot i think i need a 78 gauge which is .016 inch or .406mm as long as i'm completely mistaken and its a keihin pilot not mikuni, thankfully i have a spare pilot out of a junka molkt to test it on. plus i'll test the spare main somewhere between 118 and 130.

i know i could have just bought new jets but since running into the problem of what 'type' they are i figured it'd be easier to test since i had access to some drills. plus in doing this with the molkt maybe i'll eventually get a bit of info compiled to help some peeps out :p

hey thump do you know what mains sneezy's running in both his keihin and oko on the 140 should be interesting to see if there is a big difference in size... or maybe i just want to know what type the jets oko's run keihin/mikuni/other??
 
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thump*140

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Hey Ando, yeah SNeezy's lil bro's 140 with the PE26 Keihin is running a 36 pilot and 97 main, and Sneezy's 140 with the OKO26 is running, wait for it, 36 pilot and 97 main....
Both carbies run Keihin style pilots and mains... Not sure on the needle of the PE26, but both seem to run quite well. The PE doesnt have the response or sting of the OKO, but that's to be expected....
I've got a 28mm KOSO with PowerJet coming this week, so that should be interesting again to see what sorta jetting the 175 likes with it, and how much difference the powerjet makes...
Going by the pics on ebay though, i have a sneaking suspicion it has the shallow float bowl and is running round head mains... wait and see..
 

sean01

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yep all koso carbs run small round mains jets...
im not a fan of the koso carb as there extremely hard to tune, harder than the sht copy pwk with small round jets..

having said all that tho, i had to run a small round in place of my hex jet in my 30mm oko and it works fine. no hesitation at all

i recon the copy pwk and koso need the OKO emulsion tube and bowl so you can run the hex mains..

thump, ya should of went the 30mm oko on the 175, bigger valves or valve would of made it nice
 

thump*140

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all in the name of research sean... :)
Have tried a 28mm OKO, mid range was still a tad tricky to get perfect...
28MM KOSO wiht powerjet is next, then i'm thinking PE-26 and PE-28...
Curiousity may even get the better of me, and i might try the PE-24 just for the hell of it...
Pity i dont still have that 30mm Pumper Mikuni floating around...
I really need a job, too much time to play in the shed... :)

Yeah not sure about the KOSO, as it *looks* like the float bowl may actually be the deep one, but it shows the carb as coming with a few spare round mains and pilots...
If it's the deep bowl, then i'll yank the emulsion tube from another carb and run hex heads.. Plus i've got a busted 21mm OKO with powerjet bowl, and that runs hex heads, so i've got a few options...
I'm keen to see if the powerjet adds sting up top, plus the effect of the 28mm as well..
I'd try the 30, but that means pulling the Blitz to bits.... CBF'd...
 

sean01

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lol thump...
the trick with the midrange on the 28mm oko is to use a 26mm slide... iv done it several times now and dvdrip verified it too.

but anyways youll sort it out.. its wat tuning is all about ;)
 

aus_yzman

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Bike model:Motovert pro 09

Engine Model and capacity: Lifan 150cc

Engine Spec - stock

Carby model and Internal Diameter: stock Mikuni carb bore size??

Jetting specs used: #20 pilot jet, #105 main jet, needle circlip on 2nd lowest groove
low speed mixture screw 1 1/4 turn (located underneath)

Area you live, and general altitude Brisbane just above sea level
 

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