Try to go easy on me since this has been a nightmare for me to try and diagnose. A little background on the story. I bought a pretty much OEM 1987 trx250x that ran but had some top end noise so I figured it needed a camshaft and rockers. Opened it up and it already had a new camshaft and rockers installed with zero wear and the valves were also nice within the clearances in the manual.

Side note(the top end noise all along ended up being a stretched cam chain)

Ordered a Honda OEM Camshaft rockers, did a Namura piston and rings and gasket kit all around while I was in there. And this is an entire different story but I also changed the Cam chain to a brand new one at this time. Set it to TDC and also pulled my plug and double checked piston was up. Got the timing set perfect with the dots lining up with the head. Installed the tensioner after springing it back in. Since I went this far and my old pipe was rusty. I bought a full FMF exhaust system. I did some research on here and found out I should change my jets. So I cleaned my entire gas tank, took the in tank filter out and cleaned it. It was sooo nasty. After tank cleaning I opened/cleaned the carb and changed the main to a 130 and pilot to 40 set a/f screw to 2.5 turns out.(UNI filter with airbox lid on and 3x 1/2" holes drilled in it)

Got the entire thing back together and it started instantly with about half a kick of the kickstarter, compression seems noticeably better with the new piston/rings and gaskets, The FMF system sounds so nice and loud! It revved good and seemed responsive, But then it didn’t want to idle and slightly popped/sputtered. But what I really noticed was THE STAINLESS FMF EXHUAST GETS SO HOT WITHIN ABOUT 30 SECONDS YOU CAN BURN YOURSELF. Its heating up so fast the top end doesn’t even have a chance to get hot to the touch.

I did some more research on this forum and others and most people seem to think it can be 1 of a few problems.

1. ITS RUNNING TOO LEAN…I also ordered a 42 pilot and a 135 and 140 mains. Putting these into the mix seem to make things worse, and the plug is black/wet so im sort of thinking its not this.

2. TIMING IS OFF…I checked the timing again with the plug out and both side cover plugs off the left of the engine. Set it to TDC also checking the piston is up by sticking a small wire in the plug hole. First time I did it I think I was off one tooth, beacause when I opened the head back up again and re-timed it I just had to move it one notch. I had the tensioner out and made sure the front slack was taught, and the lines were perfectly in line.

3. VALVE CLEARANCES ARE OFF…Again since it was at TDC I took the valve covers off and checked the clearances to make sure one set of valves weren’t opening/closing when they aren’t supposed to. The play is almost perfect inside the manual specs of .0047

At this point it starts right up first kick still and seems to run ok for about a minute but the exhaust gets super hot. It then sorta chokes itself to death and slowly stalls out since it doesn’t like to idle as of now. I have noticed when I romp on the throttle sometimes a little black smoke comes out of the brand new FMF system. Like maybe oil or gas is getting in there.

Im frustrated with checking the same 3 problems over and over so im asking the pros here to see if any response is even remotely helpful. Ive put about $1500 worth of mods into this thing including the entire 400ex front end swap and 660 rear shock, and since then I have not been able to ride!!

Help me out

It won’t come off.

The little black thumb thing is pointed towards lock, turn it to open it still will not come off. I have pushed down on the cap trying so but it is on there.

How do I get this thing off? I am guessing it is broken and needs to be replaced?

Are these good machines ? We just purchased this from the original owner.

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Just picked up a really clean 2007 trx 250ex.

It has the popping on deceleration, so I started reading up on rejetting. At first I only plan to ad a uni filter and change the spark plug. From that what kit or jets do I need to not run lean? Change out just the main or the pilot?

What are the differences between uni filters? I see stage 1 and stage 2. Red and pink. Are they universal fit or is there a certain size I need?

Just picked up a really clean 2007 trx 250ex.

It has the popping on deceleration, so I started reading up on rejetting. At first I only plan to ad a uni filter and change the spark plug. From that what kit or jets do I need to not run lean? Change out just the main or the pilot?

What are the differences between uni filters? I see stage 1 and stage 2. Red and pink. Are they universal fit or is there a certain size I need?

i just purchased this quad and the only thing wrong is the tail light doesn’t work and i only have one setting for the lights. I think the po changed the wiring because the lights are controlled by an illuminated rocker switch on the left front fender along with a toggle switch used for the kill switch. The key switch is the only thing on the handle bars. The starter is hidden under the gas tank but easily pushed. So i need to try and fix these two things. I dont have any power to the pig tail for the tail lights but i do for the break lights, where am i suppose to get power from for these? I will have to get a hi lo switch for the lights.

i just purchased this quad and the only thing wrong is the tail light doesn’t work and i only have one setting for the lights. I think the po changed the wiring because the lights are controlled by an illuminated rocker switch on the left front fender along with a toggle switch used for the kill switch. The key switch is the only thing on the handle bars. The starter is hidden under the gas tank but easily pushed. So i need to try and fix these two things. I dont have any power to the pig tail for the tail lights but i do for the break lights, where am i suppose to get power from for these? I will have to get a hi lo switch for the lights.

I have a 07′ trx250ex i’m having problems with it when I go down the road it shuts down. I have gas in it and once it stops I have to put the reserve on for it to start back up. I read that it could be the fuel filter.. I’m not sure if it is or even how to check it out. Is anyone else have this problem before if so how do I fix it. if you could please give detail, I never had to fix my four wheeler..only done work on my car…thanks:stupid:

I have a 07′ trx250ex i’m having problems with it when I go down the road it shuts down. I have gas in it and once it stops I have to put the reserve on for it to start back up. I read that it could be the fuel filter.. I’m not sure if it is or even how to check it out. Is anyone else have this problem before if so how do I fix it. if you could please give detail, I never had to fix my four wheeler..only done work on my car…thanks:stupid:

When hitting a small (one foot deep by 8 feet long) puddle my 2001 400ex will sputter and basically runs like crap for about 20 seconds. It seems once it dries out it runs normal again.
I believe this has to do with the spark plug/boot and how it sits down in the front of the engine in a socket where water will collect until it is boiled out of there. Seems like a poor design because dirt could build up and every time you pull the plug some falls into the engine.

Anyone’s suggestions are welcome!