Couple Questions

[03pete]

I have a 1985 LT250r with the mods in my sig. I went out today, and after a little while, it was running good at throttle 0-.75, but whenever i put it past that, it would bog, and slow down instead of speeding up. It was raining outside a little, and i went through a couple puddles, but slow. I'm not sure if I got water in the carb, or i need new jetting.

Also, I am going through spark plugs like crazy, and dont know what to do. I was running at 32:1 and after 15 minutes or so, i would pull it, and its completely black, sometimes wet. I figured it was fouled and tossed it. and it would do the same thing. So today i switched to 40:1, and im not sure if the bogging is the ratio change, jetting or water in the carb. Is 40:1 too high to run? or was that a good switch due to the spark plugs going black. I am running NGK's too.

When i was out riding, the spark plug came a little loose and when i went to screw it in more, the top of the engine had a little oil on it, which is what made me run 40:1

Sorry for the wall of text, I hope someone can help out.

[LTandRaptorider]

What brand oil are you running in it at 40:1? Only use a good brand for that ratio. I would recommend going back to 32:1. You are trying to cure fouling plugs by leaning out the oil mix- not good. If you have black plugs, especially after running at full throttle, that tells you the main jet is too rich. You have a stock carb on it? If so, the jets have probably been changed. I can't remember the stock jet size for a stock LT250R carb... 2?? something. Take the carb off, good time to give it a cleaning anyways... Take off the bowl and see what size main jet is in it. Get the next couple sizes down. Yes, you will get jets you may never use, but you have to try other sizes and see how the engine runs. Good to have some different sizes anyway to re-jet for weather changes. Check the pilot jet size while you have the carb apart. How does the engine idle? You may have to change the pilot jet too. Good luck, post back how it works out. :cool:

[03pete]

Thanks for the detailed explanation. Im not very good with engines, but I took the carb off, and everything was very clean. The bogging problem was water in the carb, but I still need new jetting anyway. I ran into a bigger problem, my top end went out. It just went out while i was in 4th gear, and the compression was very low. I could turn the kicker easily with my hand. After getting it home and getting the pipe off and looking at the piston, i need a new one BAD. its all cut up. I pulled the spark plug out, and the metal rod on the tip where the spark happens, broke off and went down into my cylinder. I will be ordering a new piston, rings and gasket, but I don't even know how to install it:blah: . I heard it was easy, buy I will see. Also I was told that after this happens, I should get my cylinder bored...Is this true? I really wanted to keep it STD but if needed I will have it done.

EDIT: I will also go back to 32:1.

Thanks
Alex

[LTandRaptorider]

Yes, sounds like you def will need to have the cylinder bored. So don't buy a piston yet. If the cylinder isn't scored, boring over one size should be good. Otherwise it may need bored over 2 sizes. the shop you take it to will get the piston to match the overbore size.

also, how did water get in the carb? cap not tight or leaking carb boot? you will want to check into that also.

I just re-read your post. You said the spark plug electrode broke off. The piston had to smack it... Was it the right size plug? i.e. too long... And if you took the pipe off and looked at the piston from the side and saw damage, you will def need at least bored 2 sizes over.

[03pete]

I was riding like two weeks ago, when it stalled in the middle of a cornfield. After kicking it for a half hour, it finally fired up and i drove it right home. The first thing I did was check the spark plug, and when i pulled it out, that metal piece was missing...but it still ran. I changed plugs, and have been riding it for the next 2 weeks which makes me think that it may not be the metal piece that caused it, and maybe just that time for a new top end. I will try to snap pics of the piston; I haven't opened it up yet.

For the water in the carb, I am running a open airbox, ( How it was when I bought it), so water must have sprayed on the filter. (K&N)

Yes I am sure it was the right size plug. NGK.

[03pete]

I tried to snap a few pictures, but its a little too close up for my camera. I got a couple, but their not very clear.

[03pete]

You can see the nicks in the edge of the piston a little.