400 ex, wont start after new head.

[85lt250r]

The bike was running prior with a jammed decompressor sound coming out of the right front of the head. So I changed the head with an lrd head with a webcams 450/451 cam and put it all back together and adjusted the valves. I cannot get it to start. It backfires through the carb and it sparks.
I line up the index with the head and the "t" mark and the lobes are down and it will not start.

Any input would help.

1999 426ex, lrd head, web cam

It ran on a stock head and hot cam stage 2. But sounded like it had a jammed decompressor. Even though there is no decompressor.

[SHADETREE101]

you could be a little tight not letting them close, or the timing is a tooth off. sounds like the plug is firing before the valves close. also changing to a ported head, your jetting could be way off now.

[bwamos]

Your cam timing is off.
There are 3 timing marks on the cam sprocket. 2 should line up with the case, the other should point up when the flywheel timing mark is lined up.

If you did that.. perhaps your cam chain wasn't on the lower sprocket on the crank, and it's slipped out of time. You intake is definitley open when your engine is firing.

Or you're rockers have no clearance and are way too tight.

[85lt250r]

The carb was jetted for a lrd built 440 that blew. It was then replaced with this 426 with the same fcr 39mm that was origonally with the head. I found the intake boot has a crack also. But the timing is off I think.

Could it be a bent valve maybe?

I will check the lash again. The intake looks off to me, the adjuster is flat with the nut. While the exhaust sticks up atleast to where you can see one thread.

[Buffalo400]

Originally posted by SHADETREE101
or the timing is a tooth off. sounds like the plug is firing before the valves close. also changing to a ported head, your jetting could be way off now.


Probably what he said.....

get a new head


and a brain for it

[YFZ#426]

your a dumb ***

[85lt250r]

Why even post if you are an idiot?

I got it running. I fixed another ported head I had laying around and cleaned it up on the mill. The lrd head after closer inspection had a slightly bent valve.

So now I will rebuilt that one with some new hardware. Thanks guys.