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Post by jackthefuzz on Dec 7, 2006 22:39:23 GMT -5
Ok today the OKO 30MM slide carb came in along with the correct throttle cable. Straight forward installation, just remove the keihin and old throttle cable and install new cable and carb into the previously installed aluminum intake.
The OKO is quite a bit smaller in both length and width so there is alot of room to work round it. so far I have had only run it to adjust the idle and initial mixture and 1 around the block test ride.
the OKO has Instant throttle response compared with the CVK. The OKO seems to have more low end torque. I havent done any measurements yet and it may be an illusion due to the quick throttle response ,I dont know. It flattens out on top and this may be due to jetting or the fact that my test ride was done sans any airfilter. but I am getting the same top speed and it feels quicker. IT SOUNDS ALOT DIFFERENT. Much lower pitched intake noise. In a blind test you would'nt be able to tell the difference between this and a CRF450 and for me thats not a bad thing.
also its half the price of CVK, something to consider . just over 100 dollars incl cable and aluminum intake
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Post by jackthefuzz on Dec 8, 2006 12:23:08 GMT -5
ok day 2 observations. this things runs great wihtout an airbox on it but I cant seem to get enough air flow with the airbox attached or even only a hose attached to the front of it. the only way I can get it to run right is to leave the carb completely open. if anything is attached to front of the carb it chokes for air at anything above mid throttle. will have to work some more on that.
this carb running open is quieter than the CVK carb running through the airbox.
So far fuel economy appears to have suffered quite a bit, but I have been doing wide open blasts to see where adjustments have to be made.
there is almost no engine braking when letting off the throttle so brakes are getting quite the work out
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Post by Admin on Dec 8, 2006 13:25:15 GMT -5
I don't know anything about those carbs but it sounds like you are running rich. You will eventually need to get an air filter on there. Hopefully, you can adjust the mix but you may need to down-jet.
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Post by jackthefuzz on Dec 8, 2006 19:06:32 GMT -5
yeah it was way rich, I was trying to make it run with the idle stop set too low. I fixed it
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Post by jackthefuzz on Dec 10, 2006 10:59:28 GMT -5
well here is my conclusion after riding about 100 miles with the OKO carb. Its coming off and the keihin CVK is going back on. While the OKO produces a smoother idle and smoother acceleration and is quieter than the cvk, it uses way too much fuel and top end is too flat. I think its too much venturi area for a 160cc machine. if one is going to opt for a slide carb on a GY6 I think the 26 or 28MM carb is better than the 30MM.
Just my humble opinion your results my vary
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Post by Admin on Dec 10, 2006 11:42:15 GMT -5
Good experiment.
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Post by jackthefuzz on Dec 10, 2006 12:08:56 GMT -5
it was a worth a try and I'll be able to recover my costs by reselling the carb on ebay. so no loss. it would probably work very well on a GY6 powered ATV/Cart/Buggie as there is much better low end response
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fastnfurious
Big Dawg
Broom...Broom....Brooooooooom
Posts: 28
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Post by fastnfurious on Dec 10, 2006 20:03:05 GMT -5
O.T.
Hi jackfuzz,
How did you install the OKO 30MM flat slide carb to your bike? When I tried to install the OKO carb to my BKM sauron bi2type it hits the crankcase. Could you post a pics and tell for the adjustment you did during installation of OKO carb falt slide?
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Post by jackthefuzz on Dec 10, 2006 21:13:05 GMT -5
hey fast. it fit right in and didnt hit the crank case at all. Are you using the aluminum high performance intake??. the clearance between the bowl and crank case was very minimal but it worked. I'm sorry i didnt take any pictures of the isntall. the adjustment was simply finding the best balance of mixture v idle stop settings.
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fastnfurious
Big Dawg
Broom...Broom....Brooooooooom
Posts: 28
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Post by fastnfurious on Dec 11, 2006 0:16:23 GMT -5
hey fast. it fit right in and didnt hit the crank case at all. Are you using the aluminum high performance intake??. the clearance between the bowl and crank case was very minimal but it worked. I'm sorry i didnt take any pictures of the isntall. the adjustment was simply finding the best balance of mixture v idle stop settings. Hi Jack, that time during am trying to fit OKO carb im using the stock intake, maybe it's the stock intake causing of hitting the crank case. Thanks for the info. BTW, is this the carb did you use cgi.ebay.com/ebaymotors/GY6-OKO-28mm-24mm-Carburator-Vento-Scooters-POWER-JET_W0QQitemZ170037335310QQcmdZViewItem#ebayphotohosting
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Post by jackthefuzz on Dec 11, 2006 1:19:32 GMT -5
yes thats the carb only mine is a 30MM. you will need to change the intake to get the carb to fit. anyway the stock intake is crap, you need to change it if you want to see any performance increase
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Post by jackthefuzz on Dec 11, 2006 17:14:00 GMT -5
The Clear winner in terms of overall performance and efficiency when installed on a 150CC GY6 Scooter is the 30MM Keihin CVK. The CVK loses a little in performance on the low and mid range, its little louder , it produces a rougher idle and its slow throttle response. what the CVK loses there is completely made up for in its excellent fuel effeciency and better top end power. On the big 2 strokes or the GY6 powered ATV's I am certain the OKO 30MM Slide ( Keihin PWK) would be the winner. They each have advantages better suited for different machines
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Post by sussexscooterhead on Dec 11, 2006 17:46:29 GMT -5
I had thought the accelerator pump on the 30mm CVK would offset the traditionally slow throttle response of a CVK carb, is this not really the case?
Out of curiosity, were you running the OKO with one of the aftermarket pipes or the stock pipe? And were you using keihin main and pilot jets in your efforts to tune the carb for your engine? I didn't see any mention of the jetting changes you made.
Thanks for the info.
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Post by jackthefuzz on Dec 11, 2006 18:47:51 GMT -5
sussex yes the pump sure does help but you are always at the mercy of that damned slide opening up when it gets around to it. They remind me of those damned solex carbs on my MGB on the OKO. No I didnt open it up to check what jets were in it. I went with what it came with. my opinion is the 30MM OKO has too much venturi area for this engine and as vacuum drops it leans out on top. One of the clues to me was the carb was spraying fuel out of the front of the carb at wide open throttle. that tells me that manifold vacuum was 0 or very close to 0. it wasnt being sucked into the carb. maybe jets would change this? ? I dont know, I dont think so. all I know is the jetting is enough that it was only getting around 40MPG. The test was done with a blown out PFS v8 exhaust. a 164CC cylinder, head and crank. as I noted earlier this carb has fantastic throttle response low and mid range, huge power in the mid range, but then it quickly tapers off after about 3/4 throttle and start to bog down. The Idle was extremely smooth and its a very quiet carb. I think a 28MM would have worked, but thats just a guess
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Post by Admin on Dec 11, 2006 21:03:54 GMT -5
Downing the main jet size may have helped. Before you put the OKO on ebay see if anybody here wants to buy it and tinker with it a little more.
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Post by jackthefuzz on Dec 11, 2006 21:49:11 GMT -5
Downing the main jet size may have helped. Before you put the OKO on ebay see if anybody here wants to buy it and tinker with it a little more. absolutely Dawg.
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Post by jackthefuzz on Dec 13, 2006 22:28:21 GMT -5
allright I am going to take another shot at the slide carb now that I have an exhaust on. Now maybe I can actually hear whats happening. Has anyone got a slide carb to work on a scooter yet? ?
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Post by sussexscooterhead on Dec 13, 2006 22:45:00 GMT -5
I'm running the Mikuni TM24 flatslide. It works well but requires frequent adjustments for weather and temperature - generally just needle clip placement and air mixture screw adjustments. I'm glad to hear you're going to take another stab at the OKO. I'll be interested to hear how things work out.
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Post by jackthefuzz on Dec 13, 2006 22:52:33 GMT -5
thats a 24MM and thats why I am still thinking the 30 is just too big. Nice carb BTW I like those mikuni's. I have a 26 on a YSR50 with a big head 110cc engine
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Post by sussexscooterhead on Dec 14, 2006 9:11:07 GMT -5
You might find the 30mm is too big but I think it's worth jetting it properly and finding out.
One thing I meant ask before, does that carb have the power jet? And if so, is their a small jet that can be changed for it, too? Just curious.
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Post by jackthefuzz on Dec 21, 2006 20:33:56 GMT -5
I put the 30MM oko carb back on tonight and have been playing with it. this time I didnt attempt to play wiht it until I had the air box hooked up and the carb breathing through a filter. Running with the airbox cover off, it now runs perfect. with the cover on it, it goes over rich at anything over 3/4throttle. I have been drilling 3/4 holes in the box and it gets better after 2 holes, I think 2 more holes and it will be good to go
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Post by Admin on Dec 21, 2006 21:35:41 GMT -5
If you can get enough air in there you are fine. You are better off running a little rich than too lean. I'm sure you knew that. I just wanted to hear myself talk.
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Post by jackthefuzz on Dec 21, 2006 23:10:53 GMT -5
yup dawg I agree. a little rich is ideal. I went back to the proper procedure for setting these things up and started out determining high speed first then working back towards idle. I have enough air now for top speed now. the main jet that came with it works. I then moved the needle to full lean, clip in top position. It gained a smooth transition off the slow circuit but lost some power through the mid range so stepped the clip down one notch and set the slow circuit and now it works very good. I still believe that if anyone wants to go to a slide carb the 30MM is too large a 26 or 28MM will work better. Its interesting to note that the Keihin 30MM CVK works well except the pumper turns the thing instantly rich everytime you twist the throttle so its very difficult to set up the slow speed mixture. You think uyou get it perfect then rev it a couple times and the thing is spraying black clouds of carbon out of the exhaust.. Which brings me to my final comment tonight. WOW that V150 exhaust is really really put together nice.....
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Post by Admin on Dec 22, 2006 0:02:56 GMT -5
Wow, fuzzman, I never had those problems with the 30mm CVK carb. I did change out the main jet but the low speed was fine. There are just a lot of variables and each scooter seems to have a personality of it's own.
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Post by jackthefuzz on Dec 22, 2006 0:52:46 GMT -5
you know dawg, I keep doubting myself. I just dont know what is up with this engine. I think it should be producing more power than it is with the mods I have made. Oh its fast alright, but I still think it should be faster and stronger. I keep going back to the cam timing and thinking maybe I didnt get it right. everytime I look at it , it appears to be spot on but I dont have a really good veiwing angle to verify it. I have a Trailtech Vapor computer coming next week. trailtech.net/store/vapor.html It has probes for both cylinder head temp and tach and I ordered a water temp probe that I will put on a switch to monitor oil temp. maybe that will finally answer the question of if its just a case of expecting too much from a 150cc machine??? you know what they say. building an engine to 90% of its potential is easy, its the last 10% thats hard, very hard
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Post by jackthefuzz on Feb 4, 2007 1:33:41 GMT -5
tonight I decided to correct the compromised situation with the OKO slide carb. From day one I knew I had a main jet that was too large. I opened it up and found a 139 main and 39 idle jet. the 30MM CVK had a 129 Main and a 40 idle jet. I had been running the OKO with the needle full lean to get it to run and even then it was rich, Rich enough that after running through a tank full of gas there would be carbon on the license plate.
I switched the main jets, centered the needle jet , the result being the engine wouldnt transition off of idle, It would immediately lean out. I had to choke it past the transition. I then put the needle jet at full rich and it would cough a little in transition but it would stay running. It being 1 am and the streets empty I decided a test run was in order. HOLY COW! Huge difference in mid and top end power, but still slightly lean even with the needle jet full rich. A 132 or 135 main should get us where we need to be and allow for needle jet adjustment either way.
Ok the test. this is unreal for a 150. Wide open throttle I got 8260RPM at a crazy 73 MPH verified by the calibrated trail tech. this was on level land, actually facing a slight headwind/crosswind. I got out of the tuck and was able to cruise at 65MPH .cheeks flapping speed.
Now to find those jets!!!!
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Post by ddillon on Feb 4, 2007 7:30:48 GMT -5
Fuzzman,
It sounds like your getting closer and closer to "handgrenading" that engine. 73mph! What do your neighbors think when they see a grown man on a scooter buzzing around @ 73MPH in a full skiing tuck at 1AM with his cheeks flapping in the wind? ;D
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Post by jackthefuzz on Feb 4, 2007 11:43:20 GMT -5
ddillon, for sure the engine doesnt sound like it can take much of that and neither can the neighbors. I go real real slow till I get to the guard gate , then I stand on it.
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Post by jackthefuzz on Feb 4, 2007 13:44:51 GMT -5
well, I think thats it for the engine, this afternoon I went to start it and got a nice cloud of oil smoke. It went away after a few minutes, but I can tell a tear down is necessary. I think it was just too lean
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Post by jackthefuzz on Feb 4, 2007 18:00:59 GMT -5
metal transfer around the valves, it didnt hole the piston but it was melting, and the top ring is wasted
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