90 CR250 won't start

[joh9356]

:laugh: yeah, I'm startin to feel like it too.....

Theres lots of good thoughts there. I really just don't know what to think. I probably would be better off to check the full compression on it, it seems ok, but that;s the key word....seems. Will get a compression tester tomorrow. Do you know what the compression should be on this model?

Maybe it is the top end..........

To answer other questions:

1) As long as I keep giving it gas, it will run forever. As soon as I let off, it dies and won't start back up, so definitely not a seizing issue. It turns over fine.

2) Push starting will also get it to run, but again, it won't start again after that, I am not going to keep doing that, it takes the fun out of riding, and is not a permanent cure..... ;)

The more I read these responses, the more I am considering a new top end. that will cure any question. I have the speccs for my piston from Wiseco, so that may be the next step.

It is really hard to think the carb is causing it to flood. A carb will only give an engine how much fuel it asks for, if not majorly malfunctioning, which this one certainly does not seem to be.

Thanks guys will let you know.....

Jim

 

[The_STiLe]

um im not insulting your craftsmen ship but did u put the piston in the right way??

 

[nickyd]

You know I assumed this whole time that you did the piston....at least open her up and check to see what is happening. I rebuilt a PW50 and had a very similar issue. My bore gauge didn't go that small so I winged it - put a stock piston back in (old one was burned up but cylinder was fine) - anyhow she started right up and died....then would not start...next day, same thing....so I pulled the cylinder and went to a shop to have it measured and bored - the guy randomly had a brand new PW50 cylinder there - so I picked that up and threw it in on - low and behold she ran.

 

[joh9356]

OK, yes, I did install it the right way. I do know that.

And I took the piston and cylinder to someone to make sure and they said there was nothing wrong with it. I had some scuffing on the exhaust port side, but other than that, It looked fine.

I think I may just go ahead and replace the piston and ring set anyway. The cylinder looks brand new.

Thanks guys,

Jim

 

[nickyd]

was the piston/cylinder measured? or just visually inspected?

 

[joh9356]

OK guys, you may just be a bout right on the cylinder.

Here it is. I have been fumbling with this thing now after the rebuild. Here is what is going on at this point.

I can kick it and start it the first kick now. However, I can't let it die, or it won't start back up. I rode it around my property for about a half an hour yesterday. If I try starting it after I let it die, it won't start back up, it floods. However, if I wait until the next day, it will kick right up and run fair, and so on and so forth.

Now, here is the catch. When I first kick it over and start running it, like I said before, it runs great and the throttle response is perfect. But after exactly 10 seconds of running, the throttle will bog if I give it gas and I have to crack the throttle a little higher each time to keep it at an idle. I would say about 8% throttle to keep it idling.

Now if you go through this entire thread, you will see that it was running exactly like this before any repair work was done to the engine in the first place. Folks, the only thing I have not done is replace the top end, it looked ok, but I am thinking about taking it in to have a pro top end done to it.

What do you think?

 

[nickyd]

I assumed that you did the top end from the start. I would at least take it apart and check it out (measure it, etc).

 

[joh9356]

Yeah, I feel bad, I should have done that first, but, this is my first experience rebuilding two-strokes, so it was definitely just that, a learning experience ! :)

 

[nickyd]

yeah, sounds like you didn't just get your feet wet - you jumped right in head first!!! nothing wrong with that at all!!!! I am betting that the cylinder/piston are worn - I could be wrong - but check it out! Like I did with that PW 50 I had - sucked taking it all apart since it started right up then died....but I had no choice

 

[joh9356]

I heard that.

I will let you know what happens after it's done. I gotta get some more money now ! :)

 

[nickyd]

sell that bike!!!! haha. just kidding

 

[nickyd]

john, where are you located? If you happen to be in my area I will help you with the top end. let me know

 

[joh9356]

sell that bike!!!! haha. just kidding

I completely plan to!!! :laugh:

Nah jk, I'll hang on to it for fun, and all the work I put into it. I live in South Carolina.

I tell you what my plan is, is to get a WR250F next for my leisure trail riding. It's between the WR or the CR250X.

I really appreciate the offer. If you are close by, then I will take you up on it, if not, I have already talked to my tech and he is only going to charge me 200 to rebuild the top end.

Thanks for the offer, that is very kind of you.

Jim

 

[fadingfastsd]

Hey guys how do you kick the engine from TDC? How do you tell its at TDC when you start the kick?

 

[Triver]

What Happened?

I am having problems starting my 79 Honda XR185 and have been following this story which has been alot of help even though the bikes are different but now I have to know if JOH ever got this thing running?

 

[Wyld Bill]

Boy your having as much fun as I am rebuilding my 1990 CR250. They are a money/time pit. I finally sold another toy so I could buy a 2004 CRF450. I'm still trying to get my 1990 CR250 running though. See my post in this section.

 

[shepherdblake]

Did you ever get your problem resolved?

I just fought a similar battle with a 2 stroke arctic cat snowmobile. The thing would not rev past 2000 rpms, or would not start at all. The problem ended up being the wires that come out of the stator. The insulation on them was fine, but the wires were brittle and cracked. I replaced all the wires and now she runs like a champ.