JustRandy

Rocky Mountain ATV sold me an oil filter they said would fit the 250EX, but I looked all over the engine and couldn't find where it goes. I looked in the service manual and engine diagrams and couldn't find anything about a filter. So I guess it just doesn't have one. I still have the filter like a souvenir lol. It might have a screen or something to keep the chunks out of the oil pump but not sure since I've never had it apart. It's also a pushrod engine. Can you believe it? Honda redesigned everything from the 250X to the 250EX using computers and decades of knowledge and what they came up with was a pushrod engine with no oil filter lol

So a broken jet was the problem? Awesome you fixed it but seems strange a jet would suddenly break on the trail with the guy that sold it to you lol Turn the idle speed back up some then adjust the mixture until it idles at the speed you want and the stumble should go away. Often a stumble is found in the transition between the pilot circuit and the needle circuit (see pic below). Turning the idle speed down as far as possible while adjusting the mixture is a good way to create a stumble if the carb isn't absolutely perfectly designed.

If the carb has to be tuned so far away from stock then something else is wrong.

Yes, I posted the link to your tool thread. https://www.quadcrazy.com/atvforum/topic/16053-carby-adjusting/#comments Call it what you want but it devolved into a perpetual disagreement that didn't get anywhere. In spite of that there is a lot of priceless info on that thread about carb tuning.

Sorry. I did consider the readers. Here is one: I had positive feedback and I didn't know anyone was objecting to content. I thought everyone was objecting to the drama. My thread at atvconnection has 2.25 million views. What's the ad revenue for that? I guess I'm confused on the goal. I thought you'd like content. If you're wanting to generate a database of solutions like quora then it seems like it's defeated by the fact that people routinely won't devote the time to look up answers. That has always been a problem on forums, even before smartphones. Often the first reply to a question is "Did you do a search?" Dispensing answers to repetitive questions without chatting and having some fun sounds a lot like employment. Then it's not really about helping people for the fun of helping people but inflating the solution score. In light of my thoughts please advise how you'd like me to proceed and I'll decide if I want to participate further. Thanks and sorry for the confusion.

Mech made a post about that a while back https://www.quadcrazy.com/atvforum/topic/16053-carby-adjusting/#comments I told him it was a good idea but it resulted in a fight nonetheless.

Is the quad fixed now? What was the solution?

Banter increases the content, which is what you want, right? Also I've received at least 2 compliments on the thread for the content and the suggestion to "keep it up". What is unwanted is the off-topic snide jabs and ridicule out of jealously that starts fights. That is the element that needs addressed.

Most threads I'm on get really really long. Don't know what it is about me. That one on atvconnection is 12,699 replies long lol

This is what happens when mods don't want to get involved. Moderation means calm things down. It's like cops showing up to a crime scene and saying they don't want to take sides or get in the middle of it. Someone here is doing something wrong and it should be pointed out by a person of authority or 2 or 3 members in agreement so we can learn to get along better. We could produce a lot of interesting content if we could find harmony.

If you get some downtime while waiting on parts or something you can do the diff-lock in any range mod and the start in gear mod. Should be easy to find on google. It was 12 years ago so I forgot how to do it or I'd just tell you. And if your pump looks like that I bet your brake cylinders don't look much better. You can disassemble and hone them out with a dremel rotary tool with some sort of brush or buffer bit. They sell rebuilt kits too.

If the pump wasn't pumping enough to the carb it's weird that taking the airbox lid off helped lol If you want more fuel into the carb just blow into the tube on the gas cap. It will pressurize the gas tank and force fuel to the carb. I have to do that once in a blue moon when the tank is low.

I learned something new. Evidently they changed fuel pumps in the middle of 1998 because they list 2 of them: 19B11 is same number as the 1997 one. 19B02 must be the one I have.

What about the little one-way valve?

Wow that's odd. The plastic is what seals the pump from the engine vacuum. Do you know what years your are? Mine is 1998.

And where is the clear plastic membrane? And the valve? I don't see them here:

But you do see the ridicule, right? That's what started all the fighting.

I told you it's worth your time to tear the pump down because of the corrosion I found in mine. Mech ridiculed me for it.

The only screws I'm aware of on any carb are the idle mixture screw (#14) and idle speed screw (#28). The main jet is #17 on the diagram and isn't adjustable. The pilot jet is #15. I guess as long as the voltage doesn't go over 15 the CDI should still function. I guess we can rule out the regulator as the cause of the problem, but because the idle voltage is so low I'm not sure we can say the regulator is good.

To me that sounds like it ran well when the battery was dead. It seems like it would be really easy to hook up a voltmeter to the battery and observe the voltage while you rev it up like in the video. That would officially rule out the regulator. The screw you're turning only affects the idle, so if there is any improvement it's only a coincidence. It could be that the engine is getting warmer or the weather is changing.

Yep that's what I was thinking in the beginning. If adjusting the needle up and down doesn't change anything then it's something else. I'm watching and waiting until a valve check is finally performed. Intake valve and regulator are notorious faults on these quads and should be ruled out first thing. These engines have such a long stroke compared to the bore that even a low compression engine will still run good. A friend had a 250s, which is the exact same piston but shorter stroke, and the kicker would just about fall under its own weight it had so little compression. It smoked like a tar pit but ran like a raped ape. If the intake valve is open the loss of compression wouldn't affect it much except for it firing back into the cv carb. If he had a mechanical carb the symptoms would be less dramatic. Also removing the airbox lid would relieve some of the backfire pressure and keep the slide from fluttering as much. And running better with a dead battery implicates the regulator. I'd hookup a voltmeter and be sure the volts never exceed 14.4 at any rpm. Swapping regulators with another used one wouldn't necessarily rule it out since both could be bad. I swapped in a LT4WD regulator when my king regulator failed. Not long after the one I swapped also failed.

Stop pouting.

That's a good policy, especially for a professional working on other people's carbs. And I would probably buy genuine OEM needles for something I really cared about. But I've used Shindy kits in the past without a noticeable issue. And a Shindy kit with needle, jets, float needle and seat, and gasket costs about what an OEM needle costs. I wouldn't fault someone for using one. $16.74 at Amazon https://www.amazon.com/Shindy-Carburetor-Repair-Kit-03-209/dp/B003CK89TE

I don't know. Ask Shindy.

If there's no number on the needle it's probably a really cheap needle. I think I've seen them like that before. Or they have some weird numbers that don't correlate to Mikuni. The Shindy kits have always been ok for me. https://www.shindypro.com/ I think the important thing is that they come from Japan. Our jet needles are stamped with our unique code to make it easier to differentiate from the OEM part when repairing the carburetor kit. Other makers stamp using random numbers or the same numbers as OEM, creating confusion. https://www.shindypro.com/carb-kit-info Now I see.