Is it really this easy to warp a stock head? Or Why wont my bike run?

[extremeodd]

Long story short, I had a head gasket blow out the other day and it got replaced with a solid aluminum one yesterday. I put maybe 5 miles on it between 3 rides without checking the head torque and when I went to ride it again after it cooled off it wouldn't run. After messing around I noticed that if I put my hand by the front of the motor when dropping the clutch at speed, my fingers would get covered in fresh oil/fuel. All 4 of the nuts required about a half turn but that didn't fix the issue, so I pulled the head and the mating surface appears flat when resting a file on it but sadly I don't have any good straight edges to double check. Since the gasket looked fine, I reassembled using a bit more torque than I normally would and still had the fuel/oil spray when trying to start. I'm assuming because I forgot to retorque after the first (and second, and third) rides that the uneven clamping pressure combined with heating/cooling caused the head to warp.

To be safe, I went ahead and ordered another stock head (only item on Amazon I could get delivered tommorow, on Sunday)

Amazon.com : CDHPOWER Cylinder Slant Head Cover Set - 80cc/66cc Gas Motorized Bicycle : Sports & Outdoors

Amazon.com : CDHPOWER Cylinder Slant Head Cover Set - 80cc/66cc Gas Motorized Bicycle : Sports & Outdoors

www.amazon.com

Figured while I was waiting, I'd do a quick sanity check on my diagnosis.

 

[JerboaJohn]

you do have a flat surface, , put the head against a window. take a slip of paper and try to slide it in every corner and side. you can find high and low spots like that.
but milling it flat is another thing. you need a horizontal, absolutely flat surface like glass or a marble kichen cutting board
sure it's not coming from the exhaust?

 

[extremeodd]

The intake and exhaust were the first thing I checked for leaks. In the past when the exhaust vibrated loose it didn't stop it from running, just made it ungodly loud and weak. The new stock head came in and it's been installed, eventually got the bike to run but it was VERY hard to start. Once I got it started for the first couple of mins I couldn't let it get below mid range rpm otherwise it would stall and be an utter bastard to get started again.

Would this be indicative of a flooded motor? To even start it I had to pedal up to over double the rate I would normally go to get her to pop off and it would only fire one to three times, requiring me to get back up to speed. Had to do that about 4 times before it started, once it started it was 4 stroking hard and smoking like crazy for a few seconds then it went back to 2 stroking and had full power. Every hard pull it was smoking something fierce. I'm currently running a touch oil heavy at 16:1 for my break in but it wasn't smoking like this at first. I do have a terrible habit of leaving the petcock on, so I'm making sure to close that now as this issue seems to occur after riding it and letting it sit.

Either way, shes running (for now...) and now I have a spare head to play around with, I want to try increasing the compression ratio.

EDIT: Since I don't want to create a new thread, if I were to get a vm18 carb https://www.ebay.com/itm/Mikuni-Gen...rb-Carburetor-VM18-144-1002-0046/331509558390 can it work with the stock intake? How about a 40mm cnc intake?

EDIT 2: After letting it cool down, I retorqued the head nuts (about 1/4 turn each) and tried going for a ride. Same issue, could only get the occasional pop if I got it up to a stupid speed, was unable to get it started before I was completely exhausted. I'm at a complete loss on what the problem is, the spark plug only has maybe a dozen miles on it and looks fine, the carb seems to be working fine (I have a spare NT that I'll try swapping once I catch my breath), the intake and exhaust are firmly attached/not leaking. The CDI has literally only a dozen miles on it (but I have a spare just in case). No wonder so many people love electric bikes, literally plug and play!

EDIT 3: Checked for spark which it is getting (at least unscrewed from the head), fuel bowl is full, exhaust and intake are still tight. Swapped plugs and managed to get a back fire when clutching in after trying to start but no luck on actually running. To say that this is frustrating is an understatement. Like I had this running perfectly earlier other than some smoke in the exhaust, all I did was park it until it cooled off!!

EDIT 4, the final edit: For ****s sake, it was the CDI. I came across a post saying that the CDI firing without being attached to a plug/grounded can fry it. When I had the head off (with the cdi still plugged into the coil) I cycled the engine a few times while inspecting it. Either that or it was just a s**t CDI, swapping my ratty one from my previous ebay build made the bike fire on the very first try. Faster than it's ever started before.

So here is where the entire thread shifts again: What's a good, high quality CDI that I could get? I'd hate to have this be an issue again and as tempting as it is to buy a bunch of stock CDIs, I'd rather buy once and forget about it.