I need help with a 250x motor

[RichM1983]

I'm having trouble getting this motor to run. I purchased it in pieces and had to put the whole quad together and now I cant get it to start.

The motor is a 88 250x motor, I think it is because the oil seal by the output shaft of the tranny has a circlip there and the newer motors dont. It also has a high compression big bore piston from JE but Im not sure exactly how big its or the compression ratio. I know its getting spark, it has good kicking compression, and I konw its getting gas BUT im just using regular octane gas because I was told it would start with it but maybe not run that great.

When i kick it the motor hits and acts like its going to start but doesnt. I even tried pull starting it with a truck for a short distance but gave up so I wouldnt tear anything up.

I really need some help from you guys and Im completely lost. Thanks.

[pimpin330ex]

check your valves and clean the carb.

[bwamos]

Posting the obvious first..

Double check all of your grounds and connections in circuit and out of circuit, you may not be getting good spark.

[RichM1983]

Well I'm pretty sure I'm getting good spark. I think my problem is with the carb. I dont really know anything about jets and all that stuff so I really dont know. I do know that the bore is a lot bigger than stock and that it would need to have things in the carb changed and I don't think the carb I'm using has had anything changed from stock. I would think even with a stock carb and the bigger bore that the motor would still run but maybe badly. I cant even get it to start. If it helps the motor has also had some head work supposedly and I'm using some aftermarket header with a White Bros. E-Series and a K&N filter. Im pretty sure the head doesnt have stock valves and springs and things from looking at a stock head i have.

[2muchquad]

Maybe your cam is out of time.Make sure when the piston is at TDC(a T will be on the flywheel under the plastic cap on the stator cover) the lobes on the cam will be DOWN.Make sure any slack in the timing chain is on the carb side of the motor.;)

[GPracer2500]

Originally posted by 2muchquad
Maybe your cam is out of time.Make sure when the piston is at TDC(a T will be on the flywheel under the plastic cap on the stator cover) the lobes on the cam will be DOWN.Make sure any slack in the timing chain is on the carb side of the motor.;)

Checking the cam timing never hurts...but with the piston at TDC the cam lobes could be either up OR down. It depends on which stroke you're on--compression or exhaust. Remember, there are two TDCs. For checking the cam timing it doesn't really matter. You look at the indexing marks on the cam sprocket and make sure they're even with the top of the head.

I'd remove the carb, remove the main and pilot jets, clean everything thoroughly with carb cleaner and compressed air, and note the sizes of the jets. It could be something simple like a clogged jet or a fuel screw that's screwed all the way in or...

[RichM1983]

Thanks for the help guys. I know that when the motor is at top dead center that the cam lobes are pointing down. On my motor, an old X motor, there is a T mark and an F mark. When the T mark is lined up with the case mark the lobes are down.

Could I have the whole thing messed up so that when the motor should be on the stroke when the motor fires its actually on the stroke where the exhaust is opening and thats why it just hits but wont start? I dont know if thats even possible.

Thanks again for the help.

[RichM1983]

Ok guys I took my carb apart and cleaned it and it wasnt really all that dirty. I checked the numbers on my jets and I have a 28 Pilot jet and a 35 Main jet and a needle that has 7Jb on it. Does this sound right atleast for a stock bike? Im running a full exhaust and a piston thats around 84mm but I'm not sure exactly what the measurement of the piston is because I dont have a calliper. Im going to put the carb back and try it. Thanks for the help. Oh and its a Kehin carb to.

[PYF]

Originally posted by RichM1983
Ok guys I took my carb apart and cleaned it and it wasnt really all that dirty. I checked the numbers on my jets and I have a 28 Pilot jet and a 35 Main jet and a needle that has 7Jb on it. Does this sound right atleast for a stock bike? Im running a full exhaust and a piston thats around 84mm but I'm not sure exactly what the measurement of the piston is because I dont have a calliper. Im going to put the carb back and try it. Thanks for the help. Oh and its a Kehin carb to.

Don't remember for the pilot, but 35 on the main is completely impossible.You should be running in the 1xx...

[DieselBoy]

how did you make out with it?

[wilkin250r]

Take off your air filter, and spray a bit of starter fluid in your airbox boot (like a half-second burst). If it starts and runs for a couple seconds, then dies, then you have a fuel-delivery problem. It will run off the starter fluid, then dies when the starter fluid runs out, because it's not getting any other type of fuel.

If the starter fluid still doesn't start, you have a spark, compression, or other issue that is NOT fuel-related.

Try some simple stuff. New spark plug (don't just check the old and say "It looks good" Put a new one in anyways). Check your compression, things like that.

[RichM1983]

Well when I went back and checked the pilot and main jets the pilot is 128. I guess I couldnt really see the 1 in from of the 28 but Im positive that the main is a 35 unless the 1 is just completely gone for some reason. I know that fuel is getting into the motor because I can smell it on the plug when I pull it out.

Also when I kick it and give it some throttle to get it to start it makes the compression jump up insanely and my leg feels like its breaking.

Im also using a new spark plug.

I think my problem is wiring because I think that the bike would atleast have sputtered and done something when I was pull starting it.

I'm going to try and find a wiring diagram on the internet but if anyone has one or could scan me one and send it to me I would really appreciate it. Thanks everyone

[RichM1983]

I also read on the site that the reverse wires need to hooked up for the bike to run. If they arent hooked up it will spark but not run. I dont know if this is true but could someone confirm it for me? Thanks.

[wilkin250r]

Originally posted by RichM1983
I think my problem is wiring because I think that the bike would atleast have sputtered and done something when I was pull starting it.


You said in your first post "I know its getting spark", so how can it be a wiring issue?


Did you try the starter fluid? Did you check all your ground connections?

We are trying to help, but it doesn't appear that you are doing YOUR part. We are giving suggestions, but it seems that you're ignoring them.

By the way, these ATVs spark on BOTH upstrokes of the piston, both compression and exhaust. The spark on your compression stroke obviously does the work to ignite your fuel. The spark on the exhaust stroke is called a "phantom spark", and it does nothing, there's nothing left to ignite.

Why do they do this? Because it's easier to design, and more reliable. The spark just fires on every revolution. But more importantly, what does this mean do you? It means that you don't have to worry which is the exhaust stroke and which is compression stroke. The spark plug fires on each, so you can't be out of phase on your ignition timing.

I have a 250x wiring diagram, but I can't scan it. I can answer questions for you.

[300ex_#387]

A 35 main should be about right with the motor work..

[RichM1983]

Well actually I've checked everything you people have said and appreciate the advice. I checked and made sure my timing was right. Made sure the motor was getting gas and checked the jets. Made sure it was getting spark. Its getting spark but I read on this website that IF you dont have th reverse hooked up on the older X's then it would get spark but not run so I tried to figure that out and I ended up buying a manual but still no luck.

Im not a mechanical genious but I have had many motors apart and many motors all the way down to the tranny and I built this one from the tranny up and thought I had everything right but wanted to make sure. It turns out I do have everything right so far except maybe the compression and something possibly wrong with getting a week spark.

I still cant get it run so now I'm waiting on a compression tester because I may be getting a low compression number.

As far as the harness goes I'm working with one thats been hacked all to peices and I pieced enough together that I thought it should work.

Thanks for the help guys.

[Sjorge450R]

are you sure that the two wires on the right crankcase are connected? That could be a problem. Also check the ground behind the coil.

I would take the spark plug out, put it in its cap and have someone hold it to the frame while you kick it to see if its gets a good spark.

[RichM1983]

I checked the spark like you said to. I went and purchased a compression tester and I ended up only having 40-50lbs. I changed the top end, put new head, cylinder and piston, it was used but I thought it was in good shape and it turned out that it only had 60 lbs of compression so I guess Im gonna have to get a new cylinder and a piston or bore the one I have out.

I was pretty sure it was my compression because when I would kick it over the piston would actually keep spinning after my foot hit the peg so obviously its low on compression.

Anyone have a get cylinder and piston for sell. haha

Thanks everyone. I appreciate it.

[DieselBoy]

bore her out, hone, new rings, piston 'n gaskets, and your away to the races.

are your valves seating good? it may be worth the extra bit for valve lapping.