150cc T-rex Daytona motor - photos

[sean01]

was it only glowing when idling?
and did it start to go back to normal colour with a heap of revs?
if so then pilot is way to lean..

40 pilot doesn't sound right

as for the main id start from 110 and work up.. id imagine 132 is way too big

 

[krazed0451]

I have a K45 from an OKO, will that slot into it? It's yours if you want it

I also have a 112 main...

 

[grnman]

Remember that Keihin jet sizing is different and is not directly the same as the OKO's that you are tuning. so 110 is just stupid for this engine. i ran a 125 main in my old modded daytona and it was about right.

yes the pipe was also glowing at 5,000 rpm not just idle. it would not idle buy its self even with the idle turned all the way up.

What pilot does sound right then?


Width------Keihin # -- DynoJets # -- 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

 

[sean01]

mix screw screwed all the way in and still no idle means too small of pilot jet unless it will idle when screwed nearly all the way out.. PE carbs like around 50/55 pilot jet from memory..

start with tuning the pilot then tune the needle and then finally tune the main..

oko and keihin jets are the same
pretty sure fiftyboy tim just finished tuning his BBK V2'ed z160HO fitted with a PE28 and he ended up with a 110 main.
a stocker 160 runs a 102, and our old 190 odd cc engines ran 110/115 so you can see why im suggesting a 110

but regardless if there's sizing differences or not i would start lean on the main (start lean and work up) because too fat in the main will effect the pilot and idle quality

 

[grnman]

Ok thanks heaps for your help Sean. sounds like i might start in the 50's range for the pilot.

Funny how the kit only comes with a 35 and 40 pilot then.

 

[sean01]

not unusual for china kits to come with the wrong jets...

its just trial and error mate.. keep trying till you get some response on the mix screw..

and just out of curiosity have you tried the 35 pilot..

 

[fusedminis]

start with tuning the pilot then tune the needle and then finally tune the main..

Thats an interesting comment as I always thought you got the pilot dialled, then the air/fuel screw, then needle then main.

Could somebody clear this up as I am about to tune my new bike and have dont have a solid memory on how to tune. (used to, but havent used this info for about 2 years now)

 

[sean01]

pilot and air screw is dialed in together..
its the air screw that tells you what pilot is needed..

ideal mix screw setting is @ or around 1.5 turns from shut, now this ideal setting must also be the best idle quality @ a little more rpm's than normal idle speed..
if the best idle quality is more than say 2 turns then a smaller pilot is needed, if its less than 1 turn then a bigger pilot is needed..

 

[fusedminis]

Yep I know that one, my question was the order next, needle then main or otherway around, I also remember something about throttle position coming into it.
Last time I tuned a bike it took me a while to get it right, I was following a walkthrough that I downloaded from somewhere, it was really helpful and I believe I got everything right in the end thanks to the info, but since then I have lost it and forgotten what it said exactly, thus the questions.

 

[SGONE]

TBolt USA, LLC Tech Database - Simple Guide to Jetting

 

[grnman]

not unusual for china kits to come with the wrong jets...

and just out of curiosity have you tried the 35 pilot..

Its not a china kit. this one came straight from japan.

yes i tried the 35 first and it was a mofo to push start. the pipe was massively red hot after 30 secs. The 40 went better but still got hot closer to the header. it bumped started better as well. so the answer in the first instance is go bigger than 40 on the pilot first.

 

[sean01]

ok

pilot / air screw first
then needle
then main jet..

a lot of ppl do it the opposite way round but since the main can muck up everything if its too big i start with the pilot / air screw..

after a while you tend to know what jets to use without even doing all this with specific carby's.

i go by engine size and then by internal mods (like comp and cam shaft)
like my yx 160 runs 13:1 comp and a 7mm cam and 30mm oko, i use 38 pilot 102 main and needle all the way lifted + raised with a 1mm washer

but a stocker 160 runs a 36/38 pilot 100 (102 max) main and needle raised one clip

also tune to 1 specific octane level and keep it at that.. the higher octane you use the leaner you can tune because it burns cleaner

 

[fusedminis]

Not to thread-jack but could you tell me what I should be running on a 155z stock, with a 26mm molkt, running on premium unleaded (not the top stuff, mid range)

 

[sean01]

oh pooo molkt..

102/104 main (try each) and i think they have the same pilots as mikuni so around 20/25 pilot... dont quote me on the pilot tho as the only 155's with molkt's iv tuned were factory fitted in the bike and it was only the mainjet that needed playing with..

usually molkts get the bin

why not use that vm28 you had in the for sale thread?

 

[fusedminis]

I would love to use the Vm28 (really only a 24mm for some reason) but its not going to fit in my frame, thus the molkt as it is the only carby I have come across that clears, I have tried oko flatslides without any luck too.
So I either find another carby that wil fit (expensive just buying them to try out)
Or I get this molkt working (from what I have read they arent so bad)

 

[sean01]

molkts suffer from poor top end... good down low tho.. mainly due to there size..

most molkts are 24mm also..

so the vm28 is actually a 24mm..
you had this listed in your add

7. Mikuni 28mm Roundslide carb $80 (I just measured the opening and its actually 28mm not 24mm as stated before)

 

[HACKMUNCH]

we run on our 160 dohc, pe 28, daytona spec needle (richest position) 35 pilot and 122 main. runs tiptop at 800ft above sea level 65 degree f.

 

[pbk]

we run on our 160 dohc, pe 28, daytona spec needle (richest position) 35 pilot and 122 main. runs tiptop at 800ft above sea level 65 degree f.

dunno wether you realied but Australia is like other side of the world mate so clearly jetting specs are gonna be different...

and running richest needle postion dosent that mean you need a bigger main jet?

 

[sean01]

dunno wether you realied but Australia is like other side of the world mate so clearly jetting specs are gonna be different...

and running richest needle postion dosent that mean you need a bigger main jet?

basic jet specs will be the same and its a good start for grnman.

richest needle setting doesnt have anything to do with the main as its at a different throttle opening..
tho you could probly get away with installing a richer needle like i need in my carb..

 

[grnman]

yeah well Hacks jetting is pretty much what the kit comes with, but mine obviously needs bigger. mine is ported from the daytona japan factory so that may be the difference in jetting. and not to mention i live next to the water and the nights here are at 10 degrees or so at the moment.