Please ID this carb for me

[sicivicdude]

That is a 28mm Keihin carb!

That's a 28mm something carb.... LOL

I've never seen a Keihin with a powerjet on it but I have seen an OKO 28 with a powerjet.

The OKO 28 and 30 mm carbs are directly knockoffs of the Keihin carburetors however.

My humble opinion is that a stock carb is SILLY undersized for even a mildly tuned blaster. A 28-30mm carb is ok for a mildly tuned blaster. You really need at LEAST a 33 and preferably a 35+ mm bore carb to feed a well tuned big bore kit with a high end pipe on it.

The most common modification is a PWK series keihin carburetor. You'll find the most support and troubleshooting running one of those but there are a lot of choices as far as what carburetor you can go with. Mikuni makes some fine carburetors in the TM series (34-38) or you could go about finding a used carburetor off a dirtbike or other ATV, you just have to be VERY careful about what carburetor you decide to go with and its actual condition.

Be warned, when you upgrade carburetors you will need to either reem out your stock intake manifold (risky!) or buy an aftermarket intake manifold (pricy), you'll need a different throttle cable (one "for TORS delete"), and you'll probably need a reed spacer depending on what intake you end up with. Once the carburetor fits on the engine side, you'll need to modify the intake "snorkel" coming from the air filter by adpating to a larger diameter incoming ari horn connector tube.

 

[BlastrMastr240]

just put the 28mm carb on and realized the air intake end is too big for the stock rubber manifold.

 

[slickerthanyou]

just put the 28mm carb on and realized the air intake end is too big for the stock rubber manifold.

The intake end is the same size as a stock carb 1.378inches loosen the clamp more!! I:I

 

[BlastrMastr240]

The intake end is the same size as a stock carb 1.378inches loosen the clamp more!! I:I

It wont work, even with the clamp off, the reed valve/engine side fits 100% perfect same as stock, but the larger air filter side is too big for the stock parts.

 

[BlastrMastr240]

Work hours are late so im going to try to modify the air intake in some way or simply put a boot around the carb and intake.

 

[super noober]

what guys normally do is cut teh intake a little ways back and add a small piece of pvc and use the corect size rubber plumbing adapter to contect it to the carb

 

[Larry's Shee]

Some also boil the boot and use something big enough shoved in there then let it cool

 

[BlastrMastr240]

Work hours are late so im going to try to modify the air intake in some way or simply put a boot around the carb and intake.

I worked all day on my blaster; new 28mm carb, air filter right off the back of the carb, no boot, new exhaust gasket for a minor exhaust leakage up against the cylinder, just 1 problem now, when it runs it STILL billows white smoke, and i put a cinder block behind the silencer for the smoke to hit and as i expected that spot is black and wet, like oil, and smells of octane. when I 1st put on the carb it ran 100% awesome but minutes later with no changes it started to idle lower and put out more smoke than it had a minute ago, still running acceptably i gave it a lil throttle it does not have a very good response time and you can hear the low end bog.

Can u please answer the oil spitting and bog issue? :-/

 

[sicivicdude]

I worked all day on my blaster; new 28mm carb, air filter right off the back of the carb, no boot, new exhaust gasket for a minor exhaust leakage up against the cylinder, just 1 problem now, when it runs it STILL billows white smoke, and i put a cinder block behind the silencer for the smoke to hit and as i expected that spot is black and wet, like oil, and smells of octane. when I 1st put on the carb it ran 100% awesome but minutes later with no changes it started to idle lower and put out more smoke than it had a minute ago, still running acceptably i gave it a lil throttle it does not have a very good response time and you can hear the low end bog.

Can u please answer the oil spitting and bog issue? :-/

You have a major air leak. You need a leakdown tester to find the leak. White smoke generally means clutch side seal leaking oil into the crankcase but it can also mean that the case could be broken between the crankcase and transmission.

 

[BlastrMastr240]

You have a major air leak. You need a leakdown tester to find the leak. White smoke generally means clutch side seal leaking oil into the crankcase but it can also mean that the case could be broken between the crankcase and transmission.

So eh.... if its just a seal/gasket, can i just buy a new one and toss it on?
You just burst my bubble man, this screwed the whole thing.

is it safe to ride?!?!!?!????:-/

 

[sicivicdude]

So eh.... if its just a seal/gasket, can i just buy a new one and toss it on?
You just burst my bubble man, this screwed the whole thing.

is it safe to ride?!?!!?!????:-/

Is it not safe to ride. A lean condition on a 2 stroke is particularly dangerous because the piston is exposed to an explosion every single stroke. Do not ride it suspecting a major air leak or you'll end up scoring the piston to the cylinder wall and ruining it, a set of rings, and most likely, a bore size.

If it is a gasket or seal, you can disassemble the engine (provided you have all of the proper tools) and change the gasket or seal. If it's a broken case, you either need to get the cases repaired or replaced.

Generally internal breaks come from a broken piston skirt due to excessive piston to cylinder clearance. If the piston is currently broken, you'll need to replace it and, chances are, bore the cylinder to to next available oversize.

 

[BlastrMastr240]

:-/ ........... crap

 

[sicivicdude]

:-/ ........... crap

Sorry to be the bearer of bad news.

Use a leakdown tester to find the source of the problem and go from there.

 

[BlastrMastr240]

Well, it fits all symptoms.

Does that mean oil is leaking into the firing chamber and then being spit out the exhaust? Or is that air escaping the cylinder head into the crank/trans case and then the blaster only firing on a little air and mostly gas and oil?

 

[sicivicdude]

Well, it fits all symptoms.

Does that mean oil is leaking into the firing chamber and then being spit out the exhaust? Or is that air escaping the cylinder head into the crank/trans case and then the blaster only firing on a little air and mostly gas and oil?

You may need to go back to 2 strokes 101 and see what the problem could be.

The crankcase and combustion chamber are connected while the transfer ports are open. If the crankcase is leaking to the transmission area, it's pulling transmission fluid in while the piston is going up (crankcase is under vacuum) and then blows fuel/air charge into the transmission case while the piston is falling.

Whether it's the seal leaking or a hole in the crankcase, the engine will by pulling transmission fluid into the crankcase and then up into the combustion chamber to be partially burnt and then spit out of the exhaust pipe.

 

[BlastrMastr240]

This is ridiculousness. All the symptoms are gone, but i still have a bog in the low end, it just does not feel like it wants to.. gOOOOO.... everything runs and works, even the white smoke is 90% gone, just looks like running emissions now. Should i take a video and post it or?.... i mean.... this thing is spinning me in circles, and if it helps any, after i put the new carb on and put new gas in the billowing white smoke dissipated. i put my hand behind the silencer and NO moisture, no spitting it was just a little hot XP . shud i still leakdown test it? or what.

 

[BlastrMastr240]

Tomorrow is fine tuning day, if ANYTHING relating a leak is going on, Sunday may be tear down day. Then we see whats wrong, and fix it.

 

[sicivicdude]

I think you have consumed the transmission fluid to the point the crankcase stopped sucking it in but rest assured, a leaking seal is still leaking even if it's not sucking in transmission fluid.

Build/buy a leakdown tester and figure out if you actually have a leak and then use the tool and some soapy water to find the leak. Fixing it now is a LOT less expensive than fixing it later!

 

[BlastrMastr240]

alright, ill try to find one for sure. I defiantly dont want to replace the whole cylinder assembly and all. Well, lets see what happens, so i may not post on this thread till i find one and by then i may start a new thread.

Thanks for all ur help I:I

Vitos 240
VF3Reeds
28mm OKO
Pod filter with pre-filter
FB exhaust + silencer
Kenda Klaw rubber on Douglas rims
Sprocket to compensate tire size

 

[BlastrMastr240]

You goto tell me if this is bad or not, the main jet is a 330...... :-/