For Those about to Rock... buying OKO Flatslides..

[kinlonpower]

thought i would work my way down from main.(Im prob doing it backwards)As usual i researched after tinkering.I also ditched the pod..power vs noise vs traffic rideability..noise was winning.muffler only has one baffle it seems.siliconed up join in exhaust tamed the popping.
i will get one bigger and one smaller pilot(Has a K36 i think) and move the clip up or down one and see what i get i suppose.is bogging when snapping the throttle usually too rich??thanks again for help!!!!

 

[sean01]

always start with a smaller main jet as it will effect the rest of the rev range if its too big

 

[krazed0451]

Hey guys, a bit of an update on straight top vs angled top carb plates... I bought a 26mm OKO with a straight top on it and was surprised I didn't need to cut the cable down to fit after reading this thread.

On it's first run it was sticking wide open due to something (I believe the slide). I have since pulled the slide and rubbed down the area's in the carb that I could see wear on, then reassembled it with a touch of grease. Since then I have run the bike again without a single problem.

I did order an angled cap but it turned up the Monday after I took the bike out so I don't really need it... I was going to fit it anyway as the turn directly out of the carb on a CRF50 style frame is fairly tight but on inspection realised that it's the angled cap that requires the cable cut down.

I'm going to keep running with the straight cap for now and see how it goes, but I'll keep you guys up to date. Hopefully all runs smoothly and I don't need to bother with the angled cap

(I run a braided cable too... Not sure if this contributes to this issue as mine was thoroughly lubed from day one.)

 

[brad123]

would theoko carby go well with a 140 dhz dpro crf70 stock engine

 

[TyD]

yes.. Wasn't that answered in your thread?

Get one from dhz and the jetting should be spot on.

 

[sean01]

100 main will be a shade too big.. ask ken from dhz to supply it with a 96 main jet

 

[nikkerz]

hi i have a 140 with a flatslide 26 mm i have mild to wild engine work i got stage 3 cam heavy valve springs big bores kit and when i open the throttle above half i dies and farts coffs and wont rev i had it dyno tuned and it still does it what do u think? cheers

 

[krazed0451]

hi i have a 140 with a flatslide 26 mm i have mild to wild engine work i got stage 3 cam heavy valve springs big bores kit and when i open the throttle above half i dies and farts coffs and wont rev i had it dyno tuned and it still does it what do u think? cheers

What jets are you running? Can we have a complete run down of engine mods please?

Start here: http://www.miniriders.com.au/carby-tuning/25033-carb-jetting-tuning-dummies.html

Good comparison info here: http://www.miniriders.com.au/carby-tuning/24570-carby-settings-your-bike.html

 

[sean01]

hi i have a 140 with a flatslide 26 mm i have mild to wild engine work i got stage 3 cam heavy valve springs big bores kit and when i open the throttle above half i dies and farts coffs and wont rev i had it dyno tuned and it still does it what do u think? cheers

good dyno tune hey... bet they still charged you for it..

anyways yeah as above post your full specs of the engine and the sizes of the jets installed in it now and what position the slide needle clip is set at...

 

[nikkerz]

its a 140 lifan bottom end with ceramic 150 big bore kit and ceramic top piston stage 3 race cam . heavy valve springs. stainless steel bige bore exhaust system. 28mm flatslide carby with standad jets i dont have the carby with me at this time from memory their around 35 slow and 105 main i can get exact on thursday . i did have a adjustable cdi on it but it was more problems then what its worth i think the slide needle was at the top


yea as u said good dyno tune

 

[nikkerz]

the carby has a 130 main and 39 slow ther the numbers on the jets what do u think

 

[krazed0451]

That will be way too big... You're probably better off with a ~100 main and possibly a smaller pilot (stick the smaller main in and see how that goes first)

No wonder it bogs coming onto the main!

 

[Barnesd09]

Try a 38 pilot, needle on the middle clip and a 105 main.
Will be a good starting point to work from.
Remember to tune the air screw too to get it idling correctly.

 

[sean01]

id start low in the main so it doesn't muck the pilot up..

38/100, needle in middle to start with.. id recon 105 is miles too big..

probly end up with the needle raised a bit if the cam is pretty big..

 

[eagle]

Hi folks!
I just finished a bike project where I also replaced the old YX140 with a 155ZS and a OKO28mm carb.
I did some test riding but wasn't able to do some serious riding yet, however I'm not satisfied with it's setup so far, although the new engine/carb combo seems to be pretty impressive.

From what I read so far in this thread seems like I should approach setting the carb up like that:
1)Find correct main valve by spark plug checks at full throttle
2)Find correct pilot valve by checking mixture screw setting at fastest idling (the more the screw is in the higher the likeliness I'll need a bigger valve (or by checking spark plug at "zero throttle" /idle?)
3)Find correct needle height by checking response and behaviour when opening throttle from 25 to 75%
Correct?

As far I did 2 test runs... First one was pretty impressive, however it was kinda hard to start and it bogged sometimes and also... how do you call it?... "backfired" a lot... when unburnt fuel ignites inside the exhaust and causes little explosions. It even blew out a piece of grill inside the exhaust thats supposed to dampen that effect haha
On second test run it was hard to start too (choke wouldn't make much of a difference if at all) but I might heaven't given the engine a proper warm up period. It backfired a lot and seemed to have a lot of failed ignitions since it ran very.... unpredictable... sometimes it was near dieing and then were also these sudden "power thrusts" that sometimes where close to kick me off the bike ^^

I was able to ride about 200m or more at full throttle to check for spark plug color and found it to be on the lean side. It's not that white it would make me feel the electrode would turn to dust by touching it but it's got a white tint.
Also it's still quite cold outside. -1°C when I did the 2nd test run, maybe about 4-5°C when I did the first.

Edit: did a testrun again today and also checked carb setup. I did carb chops at near idle, 25%open, 50% open, 75% open and 100%open (while riding!). I started at idle and worked up. Tendency was rich (dark spark plug) at low trottle and the higher opened the leaner (grey to white tinting).
Behaviour of bike was overall pretty good, maybe a bit hesitating and backfiring a little. Unfortunately I can't compare to other carbs running well on this engine but the increase in power compared to the old YX140Z40 is notable.

Carb setup is as follows:
Pilot: K48
Needle: 1notch up (richer), JJH type
Main: 130 (!?)

Well, if I heaven't read through that thread I'd no doubt get a one step bigger size main, but from what I read here I'd better start with needle center notch and a Keihin 97,5 main.
Again, engine is a untuned Zongshen 155 used for dirttracks.

I guess that K48 means it's a Keihin valve, right?
Does anybody know which one is the main? it only says 130 and is lettered in a small bow on one side of the hexagon towards the end that sticks out at the bottom. (is that clearly? ^^)

Martin

 

[eagle]

I ordered 95 98 and 100 size main jets and 35 39 40 pilot jets, I hope jets fpr best setup are wihin these 6 jets...

Another question, that I can't remember beeing asked here before, what's correct float hight of those 28mm flatsides?
I noticed that after riding there was a serious amount of fuel pissing out of the overflow until I closed the fuel tap. Not always but most of the time if I remember correct.
I can't really tell if this also would happen during riding, I checked a few times but heaven't really noticed any fuel comin out there...
Any help on how to set correct float height on these carbs? (if thats the problem...)

 

[sean01]

19mm is the float level height.

sounds more like you have something floating around in there jamming the float open.
make sure you fit a fuel filter..

 

[eagle]

I'll check that. And, yeah, I've got one. But I can't tell how well this device works since it came stock with the bike...

Those 19mm, is this measured when turning the carb upside down so springs are compressed slightly by the float bowls weight, or when turning it to the side just before float bowls start to compress the spring?

 

[sean01]

on the side mate.. they get measured when the float is only just touching the needle

 

[eagle]

Hmm... something's not right here, I dismanteled my carb and float high seems to be far from 19mm. Its 19mm when I compress the needle spring, and about 22mm when its in neutral position turned to the side. I can't image how it would be that far off... I also heaven't found a way to adjust it so I'll leave it like it is. I gave it a good clean with hot water.
Jets already arrived but weather s*cks at the moment so I won't be able to do any testing yet =/

turned to the side with no stress on spring

completely depressed

caliper set at 19mm on both pics