2005 rm250 is a nightmare to start

[Lewis duffield]

Right so here goes I have a 2004 rm250 I bought off a friend cheap. before I bought the bike my friend said he had a new high comp piston and con rod installed he just didn't have the time to put it back together. So I took the bike to a mechanic to check the full bike over he did say it had a new piston and con rod but the old crank bearings had been used. So I replaced the main crank bearings oil seals and gaskets also the stator plate was nackerd so I got that rewound back to new. I got all the bike together put new gas in with ratio 25m/1l fuel went to start it and nout happened. So I cleaned the carb all the jets checked fuel line new air filter also inspected air boot and reeds for damage all looked good put it back together with a new br9es spark plug checked for spark fist it was nice and blue so I attempted to start it after about 3 kicks it started i stopped it and it started straight back up I took it for a little spin through the woods and wasn't running very good with no bottom end power just bogs when it should be screaming. We did a compression test what came up at 180psi witch is good we tried to start it again with nout also tried to bump start it with the car the bike sort of started but sounded very crapy just bogging down with no pull and back firing. We took the spark plug out and it was oily black cleaned it up checked for a spark still nice and blue. What else could it be anyone help me out here ?:)!!!!!

[Lewis duffield]

Someone must be able to help out.

[Family Man]

What jets are in it? Br8es is the plug you want you want not br9es.

[Naeve44xu]

Check piston is in right could be something like that just missed it. Sounds like everything is good. That's the only thing that I could think of. I got a bike real cheap because someone did that on a fresh rebuild.

[Lewis duffield]

Ok mate that is what my local mx shop give me for the bike has he got this wrong. Not sure on jet size will find out in the morning and get back to you.

[Lewis duffield]

My mechanic has had the block apart at least twice now and had a look over everything so I am sure the piston is ok.

[AddictedToBling]

25:1. Which oil? Fully Synthetic?

 

Has to be one of three things.

 

#1. Mechanical

 

#2. Electrical

 

#3. Fuel

 

Process of elimination.

 

#1. Engine's been to a mechanic so should be right ? .

 

#2. You have good spark. Say no more  ? .  

 

#3. I'll go with fuel/gas. Is it getting fuel? Is the fuel getting through the system? You have an oily plug so it must be. Has to be the actual fuel then. 25:1 is a bit rich, even for break in. Hence the oily plug.The bike/carby/jets won't/shouldn't be setup to run 25:1   . 

32:1 should be a starting point.

Edited November 1, 2015 by AddictedToBling

[78SuzyQ]

Did you get any water moisture in the motor ? any condensation in the motor is an enemy of combustion maybe a woodruff/timing key ? i know that causes backfire when it gets sheered off

Edited November 2, 2015 by 78SuzyQ

[Lewis duffield]

Ok I will change my fuel mixture and see what happens there. What's the best way to check the woodruff key as somebody else had mentioned this to me.

[AddictedToBling]

Ok I will change my fuel mixture and see what happens there. What's the best way to check the woodruff key as somebody else had mentioned this to me.

 

You'll have to take the fly wheel off.

[Family Man]

Try the br8es. Again what size jets are in it

[Lewis duffield]

178 main jet. 55 pilot jet. Needle clip 2 nd from top. Float level around 16mm it's a keihin pwk 26 carb. It's not the screw on top it's the bolt on one witch has a metal spring loaded leaver that sits on top of the slide. I also got 2 br8es spark plugs nice blue spark but did not start.

[Lewis duffield]

What should I set my air/ fuel/ idol screws at.

[Lewis duffield]

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[Lewis duffield]

<iframe width="480" height="360" src="http://s1078.photobucket.com/user/Lewis_duffield/embed/Mobile%20Uploads/story"></iframe>

[Lewis duffield]

The bike

[Lewis duffield]

Carb the slide and needle spring loaded arm that sits on top of slide up spring loaded arm that stirs on top of slide down

[Lewis duffield]

Spark is this strong enough. http://i1078.photobucket.com/albums/w491/Lewis_duffield/Mobile%20Uploads/th_trim.EA8E5D97-218D-4113-B0B4-280EEE52FEB3_zpsifylsipt.mp4

[Lewis duffield]

When you give it a big kick it backfires what could be the problem the bike was starting fine few days ago

[Lewis duffield]

So I pulled the motor apart so you guys can take a look. Head Cylinder wall . Piston and rod . Look around the power valve why is it oily black.