Jetting Problems on my 30mm OKO

[JohnSwitch]

I was trying to do the plug test today so that I could determine if my main jet is the right size. I start by setting the air screw and checking if my pilot jet is right and from what I could tell it looks good. I then warmed up the bike and I I put a new plug in for the test. I tried to run the bike though all its gears to 6th @ wide open. This is where I had a problem because I could not get the bike to wide open. When I was in 4th to 6th and I had the throttle wide open the bike would just loose all power (not straight away after a few seconds on wide open). I don't think it was splattering it sounded like it was just getting no fuel.

What I think is wrong is that the flout bowl is running dry, could my flout level be wrong and cause this or is it the pep weiner not supplying a enough fuel or am I on the wrong track. Could it be that my main jet is to big or small?

Can any one shed some light on this please or has anyone had a similar problem?

I am running a OKO have read that on the 30mm OKO carb people have had problems with the bowl running dry but that was on modified Banshee's.

Here is the link to my build if you want bike specs
http://www.blasterforum.com/full-rebuilds-128/kilowatt-monster-42969/

 

[mmajay]

My opinion is its to big on main but you must tell us what it is to be certain along with all your mods you have.

 

[Blaaster]

Did it sound like it was 4 stroking or did it sound the same as it should and just loose power.

4 stroking usually means too rich and vice versa.

I dont think you would pull all the fuel out of the bowl unless you have a blockage in the fuel line, or needle and seat assembly, or the float is set to an extreme level.

 

[Blaner]

ive experienced this..main is too big, and it slowly chokes out the combustion as the crankcase accumulates fuel... what main are you running?? what pilot ?? what needle?? what clip?? list your mods here too

 

[brandoz28]

So what's the plug look like? Im also betting rich given the info here

 

[Blaner]

http://www.blasterforum.com/carburetor-138/what-size-keihin-pilots-do-you-run-44181/#post551579

http://www.blasterforum.com/engine-13/oko-no-go-41056/#post514619

http://www.blasterforum.com/engine-13/oko-go-go-41817/#post523311

http://www.blasterforum.com/engine-13/another-pwk28-jetting-thread-41193/#post516028

http://www.blasterforum.com/engine-13/oko-30mm-carb-owners-jetting-40969/#post513354

 

[Blaner]

these OKO's are impossible, some work perfectly, other are rubbish, cheap carb, cheaply made, when they work they work well....

PS, the wonders of search button!

 

[Blaner]

unlikely to be the pet weiner, it takes some serious flow to over demand the supply, your float level may be wrong too, should be 19mm

 

[JohnSwitch]

My motor has been ported and has a 3mm stroker. The head has been skimmed and reshaped and has a stock size piston. I am running a FMF fatty with the power core 2.

I put the biggest jets in that I had to start with. The main is a 160, pilot is 50 and the needle is on the middle clip and it is the needle that comes with the OKO.

Ok let me try tell you about the plug but please bear with me because I dont really know what its meant to look like except from what I have read on the forum. This was going to be my first plug chop. As I tried to ride the bike though the gear to 6th and WO with no luck I still did have a look at the plug and it looked like it was running rich. The ground electrode and the centre electrode where not brown but slightly black hard to say. The centre electrodes inoculater was definitely white.

I am also going to check the float level again.

The next size down on the jets that I have are a 152 main and 48 pilot will try that tomorrow if I get a chance and will take a pic of the plug.

Thanks for the feedback guys!

 

[Blaner]

where is your fuel screw set? does it bog out in mid range? mine was bogging in the middle then lighting up on main...was quite scary!

the needle is a N80F, closest match in genuine keihin parts is the JJH, which is a little richer which a sharper taper.

for the plug chops, its best if you cut the threads and look at the smoke ring.

Are you premixing? which oil at what ratio?

 

[Blaner]

what degree of porting are we talking here? have you made sure your port timing figures place power within useable RPM range? has it been matched to the 3mm crank?

what are talking RE: reeds and airbox?

 

[slickerthanyou]

My motor has been ported and has a 3mm stroker. The head has been skimmed and reshaped and has a stock size piston. I am running a FMF fatty with the power core 2.

I put the biggest jets in that I had to start with. The main is a 160, pilot is 50 and the needle is on the middle clip and it is the needle that comes with the OKO.

Ok let me try tell you about the plug but please bear with me because I dont really know what its meant to look like except from what I have read on the forum. This was going to be my first plug chop. As I tried to ride the bike though the gear to 6th and WO with no luck I still did have a look at the plug and it looked like it was running rich. The ground electrode and the centre electrode where not brown but slightly black hard to say. The centre electrodes inoculater was definitely white.

I am also going to check the float level again.

The next size down on the jets that I have are a 152 main and 48 pilot will try that tomorrow if I get a chance and will take a pic of the plug.

Thanks for the feedback guys!

I would say that jetting is not rich enough to cause this problem may need to back down a few. Definetly check and adjust (if necessary) the float level before making any new jetting changes. No way it's running out of gas unless your tank screens are clogged or obstruction with the float valve preventing it from opening.

I agree with Blaner these carbs are a biotch to jet, took me a while! I ended up 165 and 58, 2 turns out on the air screw, those carbs really like a fat pilot for some reason, I too had agressive port, +3 crank, CFM air box uni filter, power pros pipe, Vforce2 cage, then went to Rad valve cage.

This sounds like a possible reed issue to me, what kind of cage and petals do you have? Oh ya please tell me you have done a leak down and compression test before ya fire it up. If not I would do each before I did anything else to take that out of the equation. and the compression test will give ya a baseline to work with. When i had my motor work done, My compression was 150 after break in and a tank of gas it went up to 157 and is now two years later at 152. I say do this that way when you get to that 10% drop from which you started at you'll know it's time for new rings!

 

[JohnSwitch]

where is your fuel screw set? does it bog out in mid range? mine was bogging in the middle then lighting up on main...was quite scary!

the needle is a N80F, closest match in genuine keihin parts is the JJH, which is a little richer which a sharper taper.

for the plug chops, its best if you cut the threads and look at the smoke ring.

Are you premixing? which oil at what ratio?

Ok the the air screw is at 1 1/2 turns and the idle screw well I dont know because when I turn it, it has no effect on the bikes idle non that I can notice.

I am pre mixing and running 36:1 fully synthetic Castrol, Power 1 2T JASO FD

The porting on the bike was done by Tim Bosson and I know he ported for the stroker and he is know as one of the best in Cape Town. So I dont think he would have port it to place power within an unusable RPM range.

I am running stock reeds with the airbox lid off and No Toil filter.

 

[JohnSwitch]

I would say that jetting is not rich enough to cause this problem may need to back down a few. Definetly check and adjust (if necessary) the float level before making any new jetting changes. No way it's running out of gas unless your tank screens are clogged or obstruction with the float valve preventing it from opening.

I agree with Blaner these carbs are a biotch to jet, took me a while! I ended up 165 and 58, 2 turns out on the air screw, those carbs really like a fat pilot for some reason, I too had agressive port, +3 crank, CFM air box uni filter, power pros pipe, Vforce2 cage, then went to Rad valve cage.

This sounds like a possible reed issue to me, what kind of cage and petals do you have? Oh ya please tell me you have done a leak down and compression test before ya fire it up. If not I would do each before I did anything else to take that out of the equation. and the compression test will give ya a baseline to work with. When i had my motor work done, My compression was 150 after break in and a tank of gas it went up to 157 and is now two years later at 152. I say do this that way when you get to that 10% drop from which you started at you'll know it's time for new rings!

Hey Slick
I have not done the compression test but will find out if the guy how built my motor did the test. I don't have the tools or know how to do the test my self but will have to look into it. I also don't think that its running rich it really feels like fuel just gets cut off.

I am running standard reeds it might be that but I cant believe that the effect would be so much.

I am going to check the seal on the reed block and check the float and then if that does not work try the 152 main and 48 pilot just to see what happens.

 

[JohnSwitch]

I have checked my float level and from what I have read on how it is done, it looks right at 19mm. I attached a pic showing where I measured from. I tilted the carb to +-45deg so that the tang just touching the needle and then measured.

Some people say you should measure to the heights point on the flout and others say to the lowest point. The sizes I got on the pic are as follows, size 1 = 19mm and size 2 = 24mm. So is the level right or 5mm out?

I also check the reed block spacer. There was fuel between the reed spacer and the intake boot mating face so I am assuming that might be an air leak so I took the reeds out cleaned all mating surface and seal it with a silicone gasket maker and the standard reed gasket.

I will not get a chance to test the bike again till next weekend but will let you know if resealing the reed spacer helped. If this was the problem would I feel it all over or just on top end on WOT.

Thanks for all they help guys!

 

[Larry's Shee]

If you have checked the pet weiner and tank vent to eliminate that continue with jetting. Try a google search for OKO carb repair. Seems I saw someting as to drilling out the fuel inlet on BHQ. I'd search for you but the search function on BHQ sucks. As to mention of use on modde Banshees causing the problem, a modded Blaster isn't that far behind one cly on a shee.

Also I would suggest only changing one thing at a time.

 

[mmajay]

Try those other jets you have. 152/48 should be much better. 160 main is way to big for your mods . Your plug is probably covered in fuel and oil.

 

[JohnSwitch]

Ok cool will try the 152 and 48 next weekend. Attached is a photo of the plug. I could not get to WOT in 5th and 6th but this is what it looked like anyway.

 

[mmajay]

Ok cool will try the 152 and 48 next weekend. Attached is a photo of the plug. I could not get to WOT in 5th and 6th but this is what it looked like anyway.

That plug dont look to bad really. Really you need more jets than what you have because 152/48 might be lean for you. Most of us with your combo end up at 155/48 or close. If you try the 152/48 and it helps then make sure your not to lean but you should be close.

 

[slickerthanyou]

I have checked my float level and from what I have read on how it is done, it looks right at 19mm. I attached a pic showing where I measured from. I tilted the carb to +-45deg so that the tang just touching the needle and then measured.

Some people say you should measure to the heights point on the flout and others say to the lowest point. The sizes I got on the pic are as follows, size 1 = 19mm and size 2 = 24mm. So is the level right or 5mm out?

I also check the reed block spacer. There was fuel between the reed spacer and the intake boot mating face so I am assuming that might be an air leak so I took the reeds out cleaned all mating surface and seal it with a silicone gasket maker and the standard reed gasket.

I will not get a chance to test the bike again till next weekend but will let you know if resealing the reed spacer helped. If this was the problem would I feel it all over or just on top end on WOT.

Thanks for all they help guys!

Number 2 is where u measure 19mm from. Fix that FIRST! As far as the reedcage goes are u running the factory reed stops too for got to ask that? If not I'd put them stops back on.
Looking at that plug, looks to be lean to me even if ya couldn't get it WOT it should have some color to it on the porcelin after riding, (actually looks a little grey) but if ya didn't ride long like less than a few minutes i'd say that is a normal outcome. Looking at your mods stock air box/reed cage maybe a little fat on the main, but i'd still leave that 160 in there for now. For sure fix that leak or your new top end won't last long!I:I

Oh just read that the idle screw is doing nothing for you right? This sounds like the slide isn't adjusted properly, with no tension on the cable there should be 1/8" opening between the slide and the carb body. I actually had to increase mine to get it running ok, but I'd start at 1/8". You then need to make sure your cable slack free play is adjusted properly 4-6mm!