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hahahaha under pressure not wanting to get passed by a pitbike, nice

May as well try old trusty VM26, mine works ok, no flat spots, just power alllll the way till i run out of valve springs. Mines dunno what idle jet and 107.5 main, clip second from bottom. To be honest, i cant read what's written on the idle jet, hahaha.
 
I took the bike out today, so after the installation of the v2 and hi-comp piston i installed the trusty oko 26mm that was on the stock 155z, i ride trails and could not eliminate this low end bog that is a pain in the arse, after playing with the oko a bit and changing some jets the best i could get the low end bog to was at a minimum but still there and warranted that low end unusable, a 34 idle jet and a 98 main jet actually worked well, but was below the jetting that the stock 155z with out tb goodies was running.

I then put a new 30mm mikuni on and the power was lacking a tad but not heaps and was better down low but as i got used to the 30mm again the low end bog that it still had creeped up again to the noticable point and something needed doing again, not sure if this is the s35 cam or big valves coming into play.

Anyway i have had this 28mm KOSO carby which came standard with a 133 main and a 44 idle jet, to big for my combo, and knowing how 28mm flatslides can be buggers at tuning i put it away, today i put it back together and put the 26mm oko 102 main and 36 idle jets in it, this carb also has a power valve feature, a hose from the top of the bowl runs to a jet on top of the carb intake on the air filter side, and at med to high revs it draws fuel thru and drops it straight in the carb before the slide, to cut a long story short the 28mm worked an absolute treat and the low end bog is there still but is at a point where it can be controlled thru a slightly higher than normal idle, idle does sound high when idling but i can live with that, i still have a idle jet prob as the mixture screw is basically all the way in, the bike did not miss a beat and was the best its been so far.
20130105_225112.jpg

here is a couple from either side tonite when i tidied up the wiring and routed the cable to come straight down on top of the carb.
20130105_225037.jpg

20130105_225056.jpg

I am installing a black steel rim tomorrow as the alloy rims especially the fronts cop a beating from the exposed rocks.
 
must be a ***** to ride with no seat!
 
Have you tried running a 38-40 pilot jet?
What brand needle are you running in both Carbies?
Is that a stock manifold? A Tb manifold would make a huge difference and make sure all your manifold ports line up perfectly.
The bottom end flat spot can be a real pain in the neck to iron out. Remember that when its lean it gives the same signs as been too rich.
I had a 28mm oko that i could not get that bottom end flat spot out of no matter what. I think it must of been a venturi casting problem
 
Thanks Damo, I have a 36 and 40 but no 38. Gonna order one now. I'm using the OKO needle. I'll check later and compare the 2 for any difference. I'll check the plug when I get home for signs lean or rich. This is the first time I have had the 28 run so good but am concerned about the mixture screw being almost in all the way . It is a stock manifold I will also order the TB manifold today. Going out again this arvy, I'll let ya know mate how it goes. Cheers bud:)
 
A 38 and needle in the middle should solve ya problems. The performance gain form the Tb manifold will be well worth it.
Make sure your running a jjh needle. Will be written on it.
 
Cool mate. Hope it sorts you out. You will love the difference the manifold and a bit of port matching does
 
The 40 didnt work out so well, was back to its usual self, but i do have a 38 on the way and that may be my saving grace.
 
Got my tb intake and associated parts today, hopefully on the weekend I can install the goodies, also got the 38 idle jet to try in the KOSO carb:)
uploadfromtaptalk1357732345907.jpg
 
Got a bit of time today to install the tb intake and the 38 idle jet. This pic here shows how the rubber adaptor and the tb intake perfectly match, where the previous setup left a big gap from where the carb stops in the rubber adaptor and where the adaptor joins the intake.
20130113_151825.jpg


Here you can see the length difference in the 2 setups, there was a little difference in the angle of the intake on the head resulting in the carb sitting quite close to the frame, but now means the carb can sit straight and the throttle cable runs up the side of the tank nicely.
20130113_152050.jpg


And this is how it looks all attached,
20130113_154152.jpg


That pic shows the KOSO 28 with the 102 and 38 jet setup, On trying to tune the 28 to the new setup it just did not want to play the game like the 28s never do, i tryed changing the needle setting but with the bike only running with the mixture screw all the way in i wasnt happy with that, i went back to the OKO 26 and installed the 102 and 38 and had the clip on the lowest setting on the JJH slide needle and the mixture screw at 2.5 turns, its idling but doesnt like a lower idle and wants to stall, but in saying that i didnt take the bike out, and really need it under load to work with the tune and adjustments on the needle. I had a freshly cleaned air filter on the carb but will let yas know how it goes when the bike gets taken out next time.
 
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That vent that comes out the carbie and goes back to the bowl is that how its meant to be??
I know some carbies have a similar set up and its for road going bikes with pollution laws on them.
What happens if you block them 2 off??
 
motovert24 said:
much better manifold that tb one. sits abit close for my bike but so much better then the stock ones
Click to expand...
Yeah it matches beautifully harry, just over tuning carbies haha, might get a PWK or PE if this keeps happening haha(prob PE for trails)

DHZ_XR8cing said:
That vent that comes out the carbie and goes back to the bowl is that how its meant to be??
I know some carbies have a similar set up and its for road going bikes with pollution laws on them.
What happens if you block them 2 off??
Click to expand...

Yeah damo, from my understanding its a power valve, and at high revs it pulls fuel up and drops it directly thru a jet(small tiny jet) into the carb, did not try and block them but the 26 does not have that option and i may feel a better topend now or worse topend as i have the 26 back on. Ill keep trying till i get it right and even out of curiosity the KOSO may go back on and try other things, it all leads to more knowledge of my own little special ways of tuning haha(very special), i had the oko JJH needle in the KOSO where the KOSO needle was not a JJH. Really what carb would you recommend for my setup or just keep percervering with these 2, im always open to other options, so let me know ya thoughts lad.
 
The PE28 is a realy nice allround carbie. Make sure you get the genuine Honda and not a knock off. If you get it from Classic honda 50's it comes with a full rebuild kit which is handy to have in the toolbox.
The 28mm oko pe has a vent at the back of the carbie like your koso and it gets blocked off but im not familiar with the koso or the tube running to the bowl.
 
Another little tip too Mick. If you look in your manifold it will be rough and have casting marks. Polish them out with wet and dry. It helps with air flow.
 
will do mate, i have dealt with classic honda 50s on quite a few occasions and has always been a positive experience and will do so in the future, ill get onto a carb once the bloody aircon in the ute is fixed lol
 
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