wont start W/button untill warm. runs great once pulled

[bchessel]

hello folks,
i have a pred 500 tld with a 560 BB kit, tuned carb, powermaxx exaust, cams, port & pollished, open air intake
heres my problem:
when cold or after sitting over night it will not start with the button . it just turns over and sputters somtimes , we can pull with another atv and fires right away and runs fine , it takes about 5 min of running till it idles without shutting off . after that it will start with a slight tap of the button everytime till it sits about 45 min
when i turn it over with the filter off it blows alot of fuel out the back of the carb as if the carbs sneezing . every once in a while it will pop and back fire and somtimes it does start but more often it will not

what ive tryed :
new plug, ive tried a hotter plug carb cleaning (all jets),

any input will help Thanks

[bchessel]

another pic

[LE Nick]

Your intake valves are tight.

[predatoradam]

Intake valves are tight, and possibly your intake valve faces are worn out. Both of these can cause the whole "It won't start when cold, but when pull-started, will fire right up" thing.

I have an 05 TLD, and I just put new intake valves in this winter. If you search on this forum, you will see that I have a thread talking about EXACTLY the same issue. My intake valve faces were worn out badly. I had the EXACT same issues you are talking about. Removed the head, installed and lapped in new valves, and she fired right up!!!

Good luck. This is definitely where I would look though, as it seems more common on these quads than I realized. And, from reading through your mods, you seem experienced enough to have checked every other possible easy thing ahead of time that could cause these symptoms. All I know is, I was lost, called a tech at a local shop and described the problem. He said, "change the intake valves", so I did. She runs great now, haha!!

[bchessel]

I thought they were suppose to be tight . I spoke with an authorized dealer and they want $100 to do a seep test and compression test .. should I do it? I can do the compression test myself, as for the seep I sent it just pulling the head off and pouring fluid on closed valves to make sure they seat tight. I hate to pay for things I can do myself in my own garage. I have had issues in the past with "authorized dealers", now I no longer trust in them. If anyone can offer insight to my situation, please let me know. Thanks!

[bchessel]

ok looking into the valve thing a little more! (i havent looked at my head yet. im not with it ) if its light damage , is it posable to adjust or have a shop mill them to fix it or do i need to replace the head and valves ( if damaged of corse)

[dcc1089]

It is possible to adjust the valves to get them back into spec, but first you need to find out how far out they are. It's quite simple to check them. Pull the front fenders and gas tank. Remove the valve cover and slide a feeler gauge between the cam shaft lobes and the valve buckets. Your clearances should be .006" intake and .010" exhaust. You can only adjust the valve clearance so many times, then you run the risk of dropping a valve and associated damage. As stated above, your symptoms point to tight intake valves.

[predatoradam]

As others have said, they should be "tight", but this simply means that they should have little valve lash: ideally, 0.06". If that are tighter (less than 0.06" lash), then you have to think about why this has happened. The shims didn't wear, the cam didn't get bigger, and the bucket hasn't worn. The only other thing to cause this would be for the valves to sink up into the head. For me, this was caused by the intake valve faces getting worked over by debris and other things, causing the valves to sink up into the valve seat in the head.

I would definitely start with valve lash to see where it is at currently. If that doesn't check out, you could always try to simply shim the intake valves appropriately. If this works, it will probably only work for so long (I did this, and got one riding season out of it before I had hard start issues again). I then found that the valves had again gone "tight". I removed and replaced my intake valves, and all is well again. Starts like it's brand new!

As far as a seep test, is what you were describing what the shop said they would do? When I removed my head to see if my valves were bed, I sprayed WD-40 into the intake ports, and could see it coming out around the valve face between the face and the valve seat in the head.

Also, as long as you don't have any damage to the head, there is no machine work needed. I simply bought new valves, bought valve lapping compound and valve lapping tooling from O'Reilly Auto Parts, and lapped them in myself. Doing this helps to mate the surfaces between the new valve face and the original valve seat in the head. BTW, the compound and tools for lapping the valves cost me roughly $20.

Good luck. BTW, I know I went in depth in talking about what to do to replace intake valves, but I would highly recommend checking and resetting the valve lash to see if that works for now. If it doesn't work, then I would probably remove the head and look at the valves.

[bchessel]

THANKS GUYS .. i went to pick up my pred from my riding buddy house today to work on it this week. ive followed your links and looked more into this tight valve thing (lots of good how-to's )and im excited. i was so lost and reboult the card like 3 times thinking i missed somthing lol . it only took 1 day asking you guys to find a great and logical answer ... its amazing that such a little adjustment on a valve can be the differance.
once agian thank you and i will let you know how it comes out

[bchessel]

this is what i found when pulling the head off