fresh built top end, bike wont start

[cbrooks118]

Hey guys, I have just put togethor the wifes 300ex, bored 10 over with an 11:1 wiseco, but the bike wont start. I put everything togethor according to my manual, but it wont fire up. The timing was set with the tick mark straight up, with the horozontal tick marks following the head... This is my first four stroke rebuild and i was wondering if i might have missed something. The motor cranks just fine, sounds great, no mystry sounds or anything, battery went dead though, so i thought i would take suggestion while its charging.... 11:1 should crank fine with regular starter shouldn't it? If the timing is off, wouldnt i hear something irregular? should i try to pull start it?

[ZeroLogic]

Is it getting gas from the carb? When you reinstalled the cam, did you put the lobes facing downwards or upwards? They are soppose to be facing downwards. 11:1 pistion works with the starter. Did you try different gas? Different spark plug? When you installed the pistion, did you install it facing the right way? I believe on a Wiseco pistion the arrow should be facing the exhaust side, but don't take my word for it. Hope this helps a bit.

[zeppelin]

the position of the piston wont prevent it from starting, but you are correct the arrow points to the front of the bike. right now im guessing that your problem is either electical or your timing is off. it being your first four-stroke rebuiled it would be understandable to be off a tooth or 2. did it back fire or make any blurble like it came close to starting?

[ZeroLogic]

I would double check your timing also. There should be one line verticle and two lines left and right that line of with the top of the head. And when setting the timing up you have to have the machine on top dead center.

[cbrooks118]

yes, tdc, tick mark on top, also two ticks aligned with head, piston is in correctly with arrow toward exhaust. I will again doble check timing tomm but i am pretty sure it was right. I did scotbright the valves to remove carbon builup on bottom of head,maybe i should try a new spark plug..... has 93 octane in tank.....

[cbrooks118]

It did not act as if if was going to fire up, did crank really smooth though? no backfire

[GPracer2500]

gas getting to the float bowl? check for spark?

[bud394]

if all above doesn't work
run a compression check
you said you removed carbon from the valves maybe a valve is stuck open and your not making compression.

also if no compression
since is your first four stroke did you install piston rings correctly(the gaps dont line up)

[cbrooks118]

Piston rings were put in correctly, however in restrospect i do thin i check the T mark on the flywheel to adjust the timing... i will break it down tonight, and thanks to my new manual, hopefully i wont have anymore problems... thanks for the input guys

[jwick07]

Please post what the problem or the cure to the problem was. Good luck!!

[cbrooks118]

well i broke it down tonight, seems as if my timing was off, forgot to align with t mark on flywheel, however i thought this would fix my problem, put it back togethor smoothly, aligned t mark on flywhell when piston was at tdc, aligned cam sprocket with one tick mark up, other two aligned with the head, however this bike still will not start.checked carb, spark plugg, take spark plug out and man am i getting compression. When i put it in gear, even with clutch in it seems hard to move forward.... is that normal on 1a new piston 11;1 from stock? Any suggestion why it wont start?? SHould i try to pull start it? Do you think i bent a valve while just trying to crank it if timing was off the first time?
Wouldnt it start and just run like crap ? Valves looked fine! Running out of ideas fellas' would appreciate any feedback!!!!:confused:

[Z-Racer-5c]

It has compression. Did you check the plug to see if it is sparking? Pull the plug and connect it to the wire, touch bar to a good ground on the bike turn over like trying to start it. ( it will not bite you as long as the end is touching metal ground, however!! it will if you just hold it in your hand!) it should spark visibly! if it does put the plug back in the bike. If it doesn't then try a different plug(even if that one is new) If still no spark it will probably be the coil or could be the trigger.


If you have spark then I would go for the fuel part of the equation. use carb cleaner or brake clean. remove the air filter and spray into carb throat during starting. if it fires stop spraying and clean the carb. probably a clogged pilot jet. Hope this helps!

Dennis