TRX250R.ORG
Workshop => Carburetor, Intake, and Exhaust => Topic started by: countryboy9799 on April 09, 2015, 11:21:35 AM
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Here's my problem
As far as I can tell the carb is a stock Keihin. I finally got my motor back together and it runs. I have been battling this carb from the beginning and I am ready to just scrap it. The problem is the float hangs up and will overflow randomly. I even ordered a new float and its the same thing. I have tried adjusting the float to where it should be and even lower than it should be but I always run rich.
The plug is wet and black and it sputters like its rich too. So I thought I would test my theory by shutting the fuel off and after that 10 to 15 seconds it ran like it should until it leaned out so that tells me the motor is running great and the carb is not working right.
Just looking for thoughts on whether I should keep wasting time with this carb or look at a new one. I would like to keep things close to stock so let me know whats recommended and what I will need like a throttle cable, intake boot and whatever else I would need.
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Here's my problem
As far as I can tell the carb is a stock Keihin. I finally got my motor back together and it runs. I have been battling this carb from the beginning and I am ready to just scrap it. The problem is the float hangs up and will overflow randomly. I even ordered a new float and its the same thing. I have tried adjusting the float to where it should be and even lower than it should be but I always run rich.
The plug is wet and black and it sputters like its rich too. So I thought I would test my theory by shutting the fuel off and after that 10 to 15 seconds it ran like it should until it leaned out so that tells me the motor is running great and the carb is not working right.
Just looking for thoughts on whether I should keep wasting time with this carb or look at a new one. I would like to keep things close to stock so let me know whats recommended and what I will need like a throttle cable, intake boot and whatever else I would need.
You are missing something real basic and do not need to replace the carb.
Remove the float bowl and turn the fuel on and move the floats up and down. Does the fuel shut completely of when the floats are held in the up position?
The problem is probably with the needle. The rubber seat on the needle probably has a grove, or line that is keeping it from sealing or the needle is not moving freely in the socket in where it slides up and down. Remove the floats and rotate the needle in the seat socket. Move the needle up and down to make sure that the needle does not have the slightest bind. We replace a lot of needles and seldom have to replace the floats.
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The problem seems to be the float is hitting the bowl and hanging up with the float that came with the atv and the new float kit I replaced it with. That is why I suspect it will overflow randomly. Fuel even ran out the this air vent today.
(http://forums.trx250r.org/vbulletin_imports/1262_5079_2017-04-18_9309.png)
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The problem seems to be the float is hitting the bowl and hanging up with the float that came with the atv and the new float kit I replaced it with. That is why I suspect it will overflow randomly. Fuel even ran out the this air vent today.
(http://forums.trx250r.org/vbulletin_imports/1262_5079_2017-04-18_7083.png)
A lot of fuel has to be getting past the float valve for it to run out of one of the top vents.
If the floats are hitting the float bowl, it should be a simple fix.
Do you have the correct float and float bowl?
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I highly doubt you need an entirely new carb, but it's possible.
I wouldn't waste your money on a new one until you've eliminated all other possibilities
Did you adjust the float tab so far out that it pulls the plunger too far out of the seat, therefore it gets stuck?
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I would install the float without the bowl on, and post a pic of you measuring it, to make sure you have the float height set properly.
I don't know your knowledge level so I don't want to come across as insulting, just trying to nail down the issue
Also post a pic of the old and new float side my side. The more pics the better so we can help you out
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first off do like jerry said. inspect the needle tip for any kind of groove or hardening of the rubber. if it doesnt have rubber then maybe it has a wear groove. after that check if the flow stops when you push the floats up. if both of those things ckeck good then maybe your floats are bent and rubbing the side of the bowl and hanging up. i dont recall if the keihin flots can be installed upside down but maybe have a look. i installed some lectron floats upside down once and it took me a few minutes before i figured out why it was pissing out the over flows
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I am pretty sure the carb is stock, the bowl fits on good but don't know if it's stock. I will get some pics posted on Saturday when my son can take pics.
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properly sealing float valve and proper float height setting should cure your issue. really cheap parts from jetsrus.com remember if it is stock that little rubber tip on the float valve needle is almost 30 years old.
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I did a little work on the carb and am just getting frustrated. I really question if this is the right carb. I have 2 floats that came with my R and one I bought new and something just isnt working right. I am seriously thinking about just getting a new carb. I can get a 38MM Air Striker for 203 or a 35MM for 184. I think it might be a good investment. What else would I need? New throttle cable?
I have also thought about just getting a new PJ, they are cheaper. I can get this one for just under 140.
http://www.amazon.com/Keihin-016-039-PJ-34mm-Carburetor/dp/B00C178IZ4/ref=sr_1_1?ie=UTF8&qid=1428933656&sr=8-1&keywords=keihin+pj+34
I need to get the choke/idle speed knob anyways and they are 30 bucks right there.
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I should mention too that I have a FMF gold series pipe. So would a bigger Air Striker be better?
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If your getting a new carb, go with a keihin 38mm PWK AS. You won't be disappointed with it.
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http://www.jetsrus.com/carburetor/carb_keihin_PJ_carb_exploded_view_parts.html (http://www.jetsrus.com)
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So with the 38AS would I need a new intake boot or can I stretch the one I have?
Will I need a new throttle cable?
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you can stretch your intake boot with some heat. But you will need a new throttle cable, the motion pro part# 01-604.
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I am not having a lot of luck with that throttle cable. Duncan racing the only one that sells that one?
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There's other places to find it but i had a hard time finding it too when i was looking for one. You could get the carb and cable from Duncan racing, i believe they have a package deal on them.
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#01-0604******
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http://www.amazon.com/Motion-Pro-01-0604-Black-Throttle/dp/B000GZP9KA
http://www.amazon.com/gp/offer-listing/B00C178JY4/ref=dp_olp_new_mbc?ie=UTF8&condition=new
Looks like those 2 should be what I need. Anything else I would need? This will attatch to my thumb throttle?
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Yup that should be all you need. Yes it will connect to your thumb throttle.
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you can get it all from the same place. dont forget to put in the online discount code for extra 10% off.
http://www.eddie-sanders-racing.com/category_s/37.htm
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Thanks, will get an order in now. Hopefully I will have it by the weekend. What should I start with for my main and pilot jet? I just bored the cylinder over .020". The pipe is a FMF gold series Fatty.
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Whats the discount code?
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onlineorder
^ that is the discount code. also eddie includes a jet set for your given motor size that comes with the carb so you can begin jetting.
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Looking at getting this carb as well! I have a similar setup. .020" over with a fmf "rev" pipe and vforce 2 reeds. Should we be changing our pipes if we go with the A/S or will the FMF's be fine until more motor work is done?
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Looking at getting this carb as well! I have a similar setup. .020" over with a fmf "rev" pipe and vforce 2 reeds. Should we be changing our pipes if we go with the A/S or will the FMF's be fine until more motor work is done?
I am hoping are pipes should be better with a bigger carb, hopefully someone will know.
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Getting ready to place my order, I see at ESR there is a 20 dollar machining option, I am guess that is for machining it so it fits in the intake boot better. Is that a good option or could I do that with some sand paper? Or just skip it altogether.
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its up to you. like stated it will press tight into the stock intake manifold without machining, but the boot on the air box side i do not know, it may need machined on that side, that is if you are running stock boot between airbox and carb. perhaps someone else can chime in.
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its up to you. like stated it will press tight into the stock intake manifold without machining, but the boot on the air box side i do not know, it may need machined on that side, that is if you are running stock boot between airbox and carb. perhaps someone else can chime in.
I think I am going to get their airbox eliminator kit because the boot I have has shrunk down and I could use a new air filter anyways.
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Hey guys,
just an update and question. I got my carb and cable. I was able to put the carb in the intake boot but the boot from the air filter box has shrunk down and shortened. I am thinking about just replacing that boot and air filter. Whats my best option for this? I did run it and it made a world of difference. Its not jetted perfectly but it runs way better and no fuel overflowing.
The only thing I am concerned with is the idle speed is to low. I have the adjustment all the way up, maybe I will need to get it warmed up and make sure the pilot jet and air screw are right to.
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I am having the same problem with my stock carb that countryboy is/was having. I bought a carb rebuild kit and have adjusted the float and replaced the needle. (shindy carb kits are of terrible quality). It is still leaking. Carb was thoroughly cleaned and inspected. I even installed a hose and put it to my mouth, blowing air into the carb with the bowl off and would move the float manually up and down...it worked great. However, it still drips when gas is running through it.
Part of me wonders if the ethanol in the gas has done something to the carbs, but I don't know.
I thought in order to run a 38 a/s carb you had to remove the airbox or at least the lid....Is that not the case?
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I think I am going to get their airbox eliminator kit because the boot I have has shrunk down and I could use a new air filter anyways.
If you ride where there is any water puddles or mud you should keep your air box.
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I am having the same problem with my stock carb that countryboy is/was having. I bought a carb rebuild kit and have adjusted the float and replaced the needle. (shindy carb kits are of terrible quality). It is still leaking. Carb was thoroughly cleaned and inspected. I even installed a hose and put it to my mouth, blowing air into the carb with the bowl off and would move the float manually up and down...it worked great. However, it still drips when gas is running through it.
Mine acted like it had some mismatched parts for some reason. It was like the float was not designed for the carb I had. I put my 38AS on and it took some modification to get it to fit but it runs much better now.
Part of me wonders if the ethanol in the gas has done something to the carbs, but I don't know.
I thought in order to run a 38 a/s carb you had to remove the airbox or at least the lid....Is that not the case?
The only problem I am having is now I have some major kick back when I try and start it. So much so that my shin is finally healing after 3 weeks and have just pull started it with another quad. I got an OEM used CDI box and it does the same thing so I am going to take the flywheel off to make sure the flywheel didn't spin on the crank. Any other suggestions?
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If you ride where there is any water puddles or mud you should keep your air box.
I decided to use my air box but I had to do some modifications to get the air box boot to go over the carb plus it had shrunk down because it was not as long as it used to be.
I do finally have a few hours on it so at least I can break it in without it being way over to rich. Hopefully I can get to the point soon that I can start dialing the carb in.