Bike wont start and yes I checked the valves

Ok so heres the deal, the bike has a fairly new top end, Athena 280 kit 2008 fast heads head and i have riden it a number of times but not enough to warrent any adjustments. Yesterday when ridding I was clearing some trail so I shut it off then it was harder to start then normal but it started, then a little further down the trail shut it down again and again it was hard starting. after I started it i was doing a lap around my 2 mi. practice coarse and it started to loose low end power, but fan the clutch and gas it and of it went. This got worse and worse until it stalled and I couldnt start it. Got ti home and first checked the valves, and wile they might have been out very slitly they wernt bad at all. I ajusted the shims put it back together and it still wont start. Checked for spark and thats fine. Pulled the plug and it was wet. Now what????:thumbsup: Should I take apart the carb or take the whole top end apart???

do a leak down test on it.

I checked the torque on the head and it was fine. How do you do a leak down test?

Pull your oil filter ASAP and check for copper/bronze shavings.

OK so we have some small shavings. Does this mean my $1000.00 head sucks.

Never had a problem with the stock one.

I think he is refering to the copper coming from your crankshaft.

What color are the shavings and i hate to sound like an ass, but does the bike have oil?

Yes ass. Just kidding. I'm a 49 year old and been riding since i'm 11. I get a new bike just about every year. This one I have had for 3 years (times are tuff)

I change the oil before it's needed and with the proper oil. I'm pretty sure it's a valve now that I saw the shavings, But I just don't know why. It's a fast heads head that cost me over $1000.00 and if it has 2 hours on it thats a lot. And yes I know how to shim the valves.

Nope, not the head. If you've got copper/bronze shavings on the filter then your crank is shot. Sorry dude.....

Don't even try to kick it over. Time to split the cases.

I've never done a crank on one of these but Charlie C and a bunch of other experts here will chime in.

How many total hours on it out of curiosity?

I will be taking the top end apart today. I think it's the head because it doesn't seen to have a lot of compression.

OK so I took the top end apart. After reading the response I was dreading the splitting of the cases. Took the head off and the valves looked great, took the cylinder off and no visual damage to the cylinder, put it up on the bench and walked over to the bike to start looking at the crank, took a look at the top of the piston and there's a hairline crack right down the middle.I have never been so happy to see a broken piston. No damage to the cylinder. Let see if Lucks racing stands behind what he sells.

Do you also have brass shavings in the oil filter? I read through the posts and you mentioned something about finding shavings and thinking that it's the valves. Valves are not going to cause brass shavings or any other type of shavings. That's going to be the crankshaft if thats the case. The cracked piston is a new one on me specially on the top. Usually if they crack, they break and it's usually a skirt and it takes out a bunch of other expensive stuff on the way. You're real lucky it didn't blow apart and do more damage.

How can I check the crank? I usually just wiggle it and if it doesn't wiggle i'm good to go.

You should have no up and down pay in the lower bearing at all. If you can twist it and get play, it's not going to last. It will slide side to side, but not an excessive amount. I don't have my book handy to give you the side to side tolerances, but it's not a lot. What type of riding has this bike seen? MX puts a lot more stress on a lower end of an engine than a guy riding through fields just cranking it up once in a while. I get 30 hrs out of a crankshaft because my kid runs hi-level MX. If it goes any longer than that, I have a bomb waiting to go off at any time. It's not worth sacrificing his health and safety for $225. 100 hrs is a pretty good run on that crank.

Then my crank is good. I ride mostly trail but i'm a fast b rider. Wiseco now makes a big bore kit so i ordered a piston from them. They said it is the same size.

If you've got copper/bronze shavings in your filter then your crank is definitely going. It might still pass the wiggle test....

It would suck to rebuild everything else and have your crank blow completely 5 hours later...

If you've got copper/bronze shavings in your filter then your crank is definitely going. It might still pass the wiggle test....

It would suck to rebuild everything else and have your crank blow completely 5 hours later...

110% correct. The brass in the filter is a sure sign of lower bearing failure. The bearing cage goes bad and takes out the thrust washers. The thrust washers are are the brass washers on each side of the connecting rod at the crankshaft.

the brass shavings could also be from the top end. all of the plain bearings have brass under the top layer. IMO

I just replaced the crank in my had brass shavings in the oil.....I put a new crank in.....and the old crank...the cage for the bearing was starting to wear down....I feel I caught it just in time........You have half of the engine apart.....just a little more time and you could replace the crank.....I think your taking a big risk if you dont replace it it will cost you more money the next time around........good luck on your project.......

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