250F Gettin pissed off

smerch69

smerch69

I got a 2005 Yz250f. I changed the head gasket a while back because it was burning water and im having a bitch of a time getting the bike operational again. At first i had the timing totally wrong, then i fixed it. The bike still wouldnt start. I then realized my piston was at BDC when i timed it so i re did the timing again, Checking that the piston was at TDC with a wire down my cylinder. Now the bike stilll wont start, just sits there and backfires if i have the choke on. I watched a youtube video and it showes the guy using the punch mark or "eye" on the flywheel and lining it up with the marks on the stator cover to set the timing, and on another video they used the H to set the timing. Any ideas?
 
PALMER84ONE

PALMER84ONE

It is always better to be pissed off than kissed on. So, let's start with this. Leave the YouTube crap to easy stuff and the manual to bike specifics. Do you have a manual that you can refer to for the assembly and timing? If not, get one (OEM) and go from there.
 
smerch69

smerch69

PALMER84ONE:
It is always better to be pissed off than kissed on. So, let's start with this. Leave the YouTube crap to easy stuff and the manual to bike specifics. Do you have a manual that you can refer to for the assembly and timing? If not, get one (OEM) and go from there.
Click to expand...

I have a downloaded one but its not very detailed and i couldnt find any info. Also when i took my head off to change the gaskets i set it down upside down and all the lifters slid off. I just realized now i might be missing shims so thats a cunt and a half. I didnt notice anything though so hopefully im wrong
 
smerch69

smerch69

Another thing i should add is when i was trying to start it i had the bike on full choke and it would only backfire if the choke was on. I did notice some fuel comming out of the over flow on the carb, but it wasnt much
 
O

ossagp

if you had the valves out of time and kicked it over there is a good chance that they made contact with the piston and now they are bent. check for that. you dont need to play games with wires in the spark plug hole to find tdc and that still wont tell you if it is on tdc on the compression stroke, which is the stroke you are concerned with. apparently youtube doesnt either. bent valves or valves which are still out of time will make one back fire. with two cams you have more chances to be slightly out of time.
 
2strokesteve89

2strokesteve89

I would check for bent valves as well, like Andy said. I do not know if that bike is an interference engine, but if you have a leak down tester just make sure the valves are in the closed position and see how much leakage you have, if you've bent a valve it will be obvious.
 
P

PawPaw

What were the valve clearance when you checked them after the head was reinstalled?
Did you have all the correct sized shims back in place?
Are you sure the cam's are phased correctly?
Have you done a leak test to be sure the valves are not bent?
How long was the bike apart? If more than a week, then you may have a clogged pilot jet.

Paw Paw
 
smerch69

smerch69

PawPaw:
What were the valve clearance when you checked them after the head was reinstalled?
Did you have all the correct sized shims back in place?
Are you sure the cam's are phased correctly?
Have you done a leak test to be sure the valves are not bent?
How long was the bike apart? If more than a week, then you may have a clogged pilot jet.

Paw Paw
Click to expand...
How could the valves be bent, i havent ran the bike in a few months
 
Top