So I'll start with I bought this quad as a mechanics special. The piston had completely shattered off the connecting rod and bent the rod as well as scored the cylinder. This also bent the valves.
I took the engine out and split the case and thoroughly cleaned all the metal shavings out.
I got a used replacement crankshaft assembly and reassembled the case.
I replaced the cylinder with a good used one ( measured it out) and got a new piston and rings.
I also re
Fresh gaskets and seals top to bottom
i thoroughly cleaned the carb (twice now to be sure) , put new valves and seats, lapped them, adjusted the valves to spec
got a new battery however the push button start does not work but jumping the starter relay does crank the engine

ok so now to the issue. When I jump the posts on the starter relay it cranks the engine but wont start. I blew out all the vent lines for tank and carb. I'm getting good spark and good gas flow to the carb bowl however my spark plug is dry after cranking the engine. I have got it started a couple times by putting gas directly into the spark plug hole. It wont idle but I can keep it running by holding the throttle.

Hoping you guys can shed some insight on what to try here. Thanks in advance

 

First thing is check compression, should be well over 100psi on a new engine, try another spark plug, double check you got cam timing right. If that doesn't work, blow the jets and passageways through the carb out with compressed air. Check you can see through the jets before putting them back. Also find out why the bike isn't turning over "on the button" you need that fixed anyway, and it is just possible it has a bearing on why it isn't running.

 

Spark plug is new. I will try another new one. I did check all the bearings while I had it apart and all felt good, no play and rolled smooth. I did blow out the carb very well multiple times with compressor and carb cleaner as well as blew out every hose on the bike.
when I did the timing I put on a new chain and spun the crank several times after I set it to make sure it was good. I dont have a compression tester but it passes the thumb test and it gets plenty of suction to the fuel pump when I pull the starter cord. Also since I can get it to run after pouring gas in the head make me believe it has decent compression but maybe I'm wrong.

 

Update if anyone is following this thread. I figured out why the push start button wasent working. I had the gear position sensor upside down so it wasent reading that it was in neutral. Maybe that will help someone in the future. Also figured out that I wasent getting fuel to the spark plug because I had set the timing out 180. Once I flipped it that fixed.
however I'm still not getting it to start. My compression reading is only coming in at about 90 which I suspect just isnt enough. I tried the oil in the cylinder trick and it came up to 105 so I suspect my cylinder/piston isnt in spec. I had measured the bore out at 66.07 and the piston was a 65.97. From what I read thats .02 over acceptable range. I know the rings havent seated yet and it would improve once they did but I cant get it running for that to happen. Maybe a learning lesson for others to avoid. Ive re ordered a 1mm oversized piston and having the cylinder bored to fit. My next question is will I have to change my jetting or cam to accommodate the big bore change?

 

The engine would start fine on 90psi. Don't know the 230 but many quads have an automatic decompressor which drops the compression at cranking speed anyway. You had something else wrong. Ring end gap matters a lot more than piston to bore clearance, if those new ring gaps were OK (under 0.020") the engine would run fine, sloppy pistons just rattle a bit. Regarding 180 degrees out, when the crank is at TDC on the exhaust stroke it will be 180 out on the valve timing mark.

 

This quad does not have a automatic decompression, it does have a lever for it though. The manual states to only use the lever for pull starting but not when you use the starter motor. I had fixed the timing being 180 out already and that's when it started pulling gas into the spark plug correctly.
as far as rings went I kinda just assumed the kit had the proper gaps and didnt really check them in detail. I assume I should have does this with some feeler gauges at center bore.
it only will start when I pour gas directly into the cylinder and even then its hesitant to do so and I gotta keep mid to open throttle to keep it going.

 

I would be looking at carb again, particularly idle jet and choke. It is possible previous owner had been messing with it before it seized. Be sure you can see through the jets. Not something I normally do, but it could be a candidate for a rebuild kit, this ensures that clean, correct jets are in it. Or a Chinese carb, if available and cheap. Pot luck if it has the right jets and is set right, but you could be lucky and get one "right first time"

 

I'm 100% the carb is clean. I soaked, sprayed, ran a brush wire thru, and blew with compressor. Twice actually cause I wanted to be sure it wasent that. I can see a clear round hole in all of them when held to the light. I did not verify they were the correct size but the PO had it running before the piston blew up so id assume they are close enough for it to run. I'll check them in the morning. I also took off my head to verify my valves were sealing and they passed the water test perfectly. I checked the ring gap as suggested and I think they may be too high. Top ring measured .25mm gap and bottom at .48mm (measured 1 inch below top of cylinder) . I think it may just be my cylinder needs to be bored

 

0-25mm is fine, not sure why there should be that big a difference between top and second ring, but I bet the rebored cylinder would have a ring gap something similar to 0.010" on it's new top ring.

 

From what I read the 2nd ring is spaced bigger to allow combustion that passed the first ring not to get trapped between the two causing back pressure on the top ring which makes it unseat itself.
I have the 1mm oversized piston coming tomorrow and gonna take the cylinder to be rebored as soon as it comes. I'll update this thread with outcome of compression increase. I'm still in the dark if I need to change my jets to accommodate the overbore increase.