I'll have to agree with the others, that you have not listened to the best advice. VALVES!!!! Firing means is it popping at all, or just rotating in its compression/decompression stroke? Revolutions, and no popping...
250F Why Won't My 2007 Yz250f Start?
- Thread starter AKmotorider
- Start date
Oh, I've listened. I'm just making 110% positively, absolutely, completely, totally mega super-duper sure. I also haven't been able to do it yet, only got to work on my bike for 10 min today, kinda pissed. I will report back again, probably tomorrow, whether it was the problem or not.
Wow, what great idea! I'll be sure to give a try right away. That way I'll know for sure!
Was it only hard to to start when cold or was it hard to start after it was warm?
Alright guys, I have an update! On a 2007 YZ250F the intake valve clearance is between 0.10 and 0.15 mm. The exhaust is 0.17 - 0.22. I measured mine and it came up as exhaust taking no more than 0.06 and the intake wouldnt even take the smallest, 0.02, feeler available. That means the side of cam lobe and the valve bucket is probably touching...not a good thing I'm guessing. That is quite obviously off spec...so what size shim do I need?
Also wanted to mention that when trying to get it to TDC I had some issues. When the two dots on the camshafts were lined up perfectly, the mark in the timing cover down near the crankcase would be off by about 1-2mm . Align the mark, and the dots on the cams were slightly eskew. My instructor said it is too small of a difference to matter, but then again, he works on cars, not finnicky high performance motorcycles. Maybe this is why it is backfiring? Also, which one matters more when checking the valves? Aligning the cam dots or the timing mark? Thanks.
Also wanted to mention that when trying to get it to TDC I had some issues. When the two dots on the camshafts were lined up perfectly, the mark in the timing cover down near the crankcase would be off by about 1-2mm . Align the mark, and the dots on the cams were slightly eskew. My instructor said it is too small of a difference to matter, but then again, he works on cars, not finnicky high performance motorcycles. Maybe this is why it is backfiring? Also, which one matters more when checking the valves? Aligning the cam dots or the timing mark? Thanks.
You have to pull the old shim out first, to determine the size that's needed.
Edit:
Check the how to's, and get err done.
https://www.dirtbikeae.
ddicts.com/threads/adjusting-valve-clearances-2005-kx250f-rmz250.4214/
Edit Edit: Get a manual, and follow it to the letter. On my '07 450, all the marks fall into the exact place they are supposed to be at.
Edit:
Check the how to's, and get err done.
https://www.dirtbikeae.
ddicts.com/threads/adjusting-valve-clearances-2005-kx250f-rmz250.4214/Edit Edit: Get a manual, and follow it to the letter. On my '07 450, all the marks fall into the exact place they are supposed to be at.
Got a manual. Told me the timing mark and cam dots are supposed to both line up at the same time for correct timing. I might not worry about it though, its barely off.You have to pull the old shim out first, to determine the size that's needed.
Edit:
Check the how to's, and get err done.
https://www.dirtbikeae.
Edit Edit: Get a manual, and follow it to the letter. On my '07 450, all the marks fall into the exact place they are supposed to be at.
Btw, thanks for the link. It's a huge help.
I always go the cheapest and easiest way first. Old Blue was having trouble starting on me, when it did it had shitty throttle response and died after a short ride. the day it died on me after i thought i had everything figured out it was running and seemed ok. Then the trouble started, my buddy got a flat and headed back for town, i followed in case he had trouble. It turns out he should have followed me 
. I lost my throttle, no response what so ever and the bike died on me. That was a long ass walk back to town.
Turns out the bolt that holds the slide to the throttle had came loose and that was my problem with everything, good thing the top of my carb is sealed off from the rest. Put some lock tight on the stupid thing cleaned the carb and the bike runs perfect now. After you get done with the valves go through and tighten everything in the carb and clean the shit out of it. carefull with the throttle its self, that thing is a bitch to put back in.
Little long, but its midnight here, I dont have to work tomorrow and there is nothing on the telly. So.... enjoy
. I lost my throttle, no response what so ever and the bike died on me. That was a long ass walk back to town.Turns out the bolt that holds the slide to the throttle had came loose and that was my problem with everything, good thing the top of my carb is sealed off from the rest. Put some lock tight on the stupid thing cleaned the carb and the bike runs perfect now. After you get done with the valves go through and tighten everything in the carb and clean the shit out of it. carefull with the throttle its self, that thing is a bitch to put back in.
Little long, but its midnight here, I dont have to work tomorrow and there is nothing on the telly. So.... enjoy
Dammit. With my limited one hour time to work on my bike every day this is gonna be a pain....is there any vids or write ups that you know of on how to adjust the timing?
And you know what I just realized? That damn bike shop caused the timing to be off. They were the ones who took it apart last. Funny thing is, I notice no difference in performance whatsoever between before they worked on it and afterwards. And I know they took all this stuff off, they had to get to the cylinder.
Hahaha and he never bothered to turn around and check on you? Isn't that just dandy. I will check the carb and clean it since I have never looked at it before. What you described is def not my problem though because I dont have bad throttle response, just starting. Cool story too.I always go the cheapest and easiest way first. Old Blue was having trouble starting on me, when it did it had shitty throttle response and died after a short ride. the day it died on me after i thought i had everything figured out it was running and seemed ok. Then the trouble started, my buddy got a flat and headed back for town, i followed in case he had trouble. It turns out he should have followed me
Turns out the bolt that holds the slide to the throttle had came loose and that was my problem with everything, good thing the top of my carb is sealed off from the rest. Put some lock tight on the stupid thing cleaned the carb and the bike runs perfect now. After you get done with the valves go through and tighten everything in the carb and clean the shit out of it. carefull with the throttle its self, that thing is a bitch to put back in.
Little long, but its midnight here, I dont have to work tomorrow and there is nothing on the telly. So.... enjoy
We were with two other guys, I think he thought i went with them. But I got about half way to town (which is a long ways) and a guy on an XR650 picked me up. I had to ride bitch for the next 5 miles hahaha. But the old girl is running great now and is ready to rock and roll.
the reason your bike wont start is your valves are out of spec giving it less vacuum threw the carb causing a lean condition. your timing chain marks aren't lining up because your timing chain is stretched you will never get the marks to line up perfect. i always replace the timing chain every rebuild. some say there weak and are known for being a problem