spark compression fuel still wont start

[mud runner]

iv got a 84 200x with a xr200 cylinder and head and what it looks to be a high compression wiseco when i got it it ran like crap for 5 mins and smoked like crazy pulled the topend off timing chain was streched and eating into the case so i put a new one on and the cylinder looked go and the the piston to cylinder clearence was good so i just put rings after it was honed put it toghter it has spark (new plug and the harness and coil off of my 85 200x) has enough compression to bluw your finger off the plug hole but it wint start me and my buddie kicked it fir 2 hours re checked the timing it was perfect kept hicking qoasionaly you could hear it like it srying to start but it wont start off of carb cleaner i am out of ideas any suggestions

[barnett468]

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check the cam timing and the valve clearance, then check the cam timing and the valve clearance, then check the...

[John Tice]

How many pounds of cranking compression have you got? Did you check the new ring end gap? How much skirt clearance does the piston have? You honed the cylinder? Did you hone it or only break the glaze? If the timing chain is sloppy, the sprockets will have as much wear as the chain; maybe replace all of them?
The other guy’s would know how much cranking compression that your engine usually has? The few questions above can make the difference between a good job & a So-So job.
JT

[yaegerb]

Blowing your finger off the spark plug hole isn't an adequate test. Invest in a compression gauge to ensure its within spec. How do you know you are getting adequate fuel? Is the plug wet?

[jerkin]

Blowing your finger off the plug hole is meaningless, you need a real number. Case in point, I bought a lt50 for my boy a few years back thinking it just needed a coil, guy said it would run for a while then shut off and wouldn't start until it cooled down, classic symptom of a bad ignition coil. So I pick up a new coil for it but still can't get it to start, even while spraying mixed fuel directly into the cylinder. Compression reads 90psi, I couldn't find anything online but assumed that should be plenty for such a small engine. Still couldn't get it to run so I start posting on a few boards and find out it should be more like 110psi. I yanked the cylinder and found out whoever bored it never chamfered the ports and the rings were cracked. Hit the ports with a Dremel, ran a hone through it, new rings and gaskets and it fired up in a few pulls.

Put a compression tester on it, open the throttle all the way and kick it until the gauge stops going up, that is your compression. Now you can look around online and see where you should be, or at least where it needs to be to run. You can't really get a hard and fast number on these old engines because you don't know what's been done to them, high compression piston, shaved head, different thickness gaskets, etc. Any of these will change the compression. Anytime you rebuild and engine do a compression test on it after you get it broke in, that gives you a baseline so you can keep an eye on things and know when it is getting to be time for a rebuild.

[mendoAu]

In my experience carb cleaner is for cleaning carbs but does a poor job of starting engines. Ever notice when you spray carb cleaner into the carb while running you have to throttle up or your engine dies? Use an old spray bottle like a windex bottle with gas instead of the carb cleaner and see what happens.
I don't know if that engine has a chain tensioner (my 200es does) but perhaps someone left it out on the rebuild which would certainly make it appear to have a stretched chain. If it does did you adjust it with the bolt on top of the engine block?
Check the pulse rotor. I found out that you can install it 180 degrees out. It should have a stamped line on it that should line up with the O on the cam sprocket.
I'm no expert, HA! thats why I know what can be put together wrong.

[mud runner]

How many pounds of cranking compression have you got? Did you check the new ring end gap? How much skirt clearance does the piston have? You honed the cylinder? Did you hone it or only break the glaze? If the timing chain is sloppy, the sprockets will have as much wear as the chain; maybe replace all of them?
The other guy’s would know how much cranking compression that your engine usually has? The few questions above can make the difference between a good job & a So-So job.
JT

i just broke the glaze iv rebuilt a few fourwheelers and dirtbikes and if i rember right the piston to cylinder clearence was 3 thousants its been a couple months synce i mesured it. im gonna get a compression tester im pretty sure my brother broke the one i had so ill have it this weekend but i did rember somthing on the fly wheel for the timing marke there is a dot with a f and a dot with a t i used the dot with the t because i assumed it ment tdc thanks for all the help

[onformula1]

If you don't have a manual, here you go-

http://www.oscarmayer.net/atc/manuals/

Double check all the timing marks, do a compression test, the best spray to test an engine IMHO is starting fluid.

[John Tice]

You can get a 50cc syringe at a feed store; measure the volume of the combustion chamber at TDC. Divide the engine displacement by the Head volume & bingo your compression ratio. Multiply the compression ratio by 14.7 & you will get what the approximate cranking compression should be. Then you can estimate if the bore or rings are bad.
JT

[John Tice]

You can get a 50cc syringe at a feed store; measure the volume of the combustion chamber at TDC. Divide the engine displacement by the Head volume & bingo your compression ratio. Multiply the compression ratio by 14.7 & you will get what the approximate cranking compression should be. Then you can estimate if the bore or rings are bad.
JT www.smallenginemachineworks.com