Went And Did It Now.

762 Views 16 Replies 8 Participants Last post by pondy, Mar 24, 2009

Crash450

Discussion Starter · Mar 21, 2009

So I decided I needed more power. I bought and put on the Athena 478 BB kit. everything was going smoothly until I tried to start it. ZERO compression and no combustion. Sounded like the only thing moving was the starter. Pulled it all back apart. Checked everything. rings, torques, .etc no problems. Put it all back together and decided my timing must have been off. But in my head that didnt explain the zero compression. well timed it again. turned it by hand and waaalaaa tons of compression. torqued everything down and threw in the plug. sounds like its not getting fuel. Although it is. everytime you goose the throttle it backfires like a SOB. So my question is. which is more likely to be. Out of Time? or Valves need adjusted. Engine only has about 35 hours of riding MAX. Or is there another issue that I am overlooking? Any help would be awesome. Thanks :wtf:

1 - 17 of 17 Posts

SyKo450

· #2 · Mar 21, 2009

Well if it runs, your timing must be ok

What kind of fuel are you using?

Crash450

Discussion Starter · #3 · Mar 21, 2009

thats the thing... it doesnt run. Only backfires like a fool. turns over a few times then boom flame out the tailpipe.

yfzrider69

· #4 · Mar 21, 2009

Sounds like your jetting is off. Like the pilot is to small that's why it's hard to start.

Crash450

Discussion Starter · #5 · Mar 21, 2009

180 pilot.

yfzrider69

· #6 · Mar 21, 2009

QUOTE (Crash450 @ Mar 20 2009, 11:11 PM) index.php?act=findpost&pid=760303

180 pilot.[/b]

180 isn't the pilot that's the main. That doesn't even effect anything until about 3/4 throttle. The pilot should be around a 48 to 50, maybe a little bigger with a big bore kit.

Crash450

Discussion Starter · #7 · Mar 21, 2009

my bad. long night. the piliots im not sure of but im almost certain they are 50+. But the engine does not do anything but turn over until the throttle is fully cracked open. thats when the backfire ocours.

SyKo450

· #8 · Mar 21, 2009

Then your timing IS off

prospecdc

· #9 · Mar 21, 2009

ok first off, if you have spark, fuel and comperssion you should be firring up and running without touching the throttle (this assuming your timming is relatively clsoe) , either your off on your timing which it sounds like the culprit to me, or you need to actually test your compression , watch to make sure you are getting fuel in through the carb, and test your ignition system (which by the sounds is ok).

Here is how i came to this conclusion, at first yuou had no compression and your timming was way Muffed up right from the start, chances are you are probably going by the wrong marks or not setting TDC. I am willing to bet your timing is still of 1 or more teeth on the intake, or possibly both cam shafts. Or still have them 180 off. I would suggest double or tripple checking them.

Crash450

Discussion Starter · #10 · Mar 21, 2009

will just one tooth being off the intake not let it run at all? and yes the fist time I can almost promise i had the timing way jacked up simply because everything else was put together correctly and confirmed corect by a builder.
Its just that I work on airplanes. This is my first go round with timing of this sort. Im kinda teaching myself as I go along. I keep getting frustrated and thats really not helping me any. should my timing marks look like two L's but facing away from each other. the Intake cam being L? Hope that makes sense lol?

srxboy

· #11 · Mar 21, 2009

look up the cam mod. It gives great pics of the timing marks and where they should be.

TTMRACING

· #12 · Mar 21, 2009

check your valve shims, sometimes if you get the shim tight and then torque the caps down it will open a valve just a little and this will cause 0 compression.

sandslinger79

· #13 · Mar 21, 2009

There are basicly three marks on the flywheel there is a H and a I you need to time it on the I mark. You also need to keep all chain slack on the tensioner side, other wise when you release the tensioner it will roll everything and you will be off. Wish I could explain it better for you but im a doer not a teacher.

prospecdc

· #14 · Mar 21, 2009

not sure what you are talking about "L" shape, but the marks on the cam gears should be lined up with the head surface and should be pointing to the out side. and yes one tooth on the intake cam could cause it to not run, if the engine doesn't get the amount of fuel and air it need at the time it needs it, you will have a no start condition.

Crash450

Discussion Starter · #15 · Mar 24, 2009

Got her all figured out and running good. thanks for the help everyone.

yfzrider69

· #16 · Mar 24, 2009

QUOTE (Crash450 @ Mar 23 2009, 10:02 PM) index.php?act=findpost&pid=761370

Got her all figured out and running good. thanks for the help everyone.[/b]

So what was the problem? I'm sure everyone would like to know.

pondy

· #17 · Mar 24, 2009

QUOTE (Crash450 @ Mar 20 2009, 10:42 PM) index.php?act=findpost&pid=760309

will just one tooth being off the intake not let it run at all? and yes the fist time I can almost promise i had the timing way jacked up simply because everything else was put together correctly and confirmed corect by a builder.
Its just that I work on airplanes. This is my first go round with timing of this sort. Im kinda teaching myself as I go along. I keep getting frustrated and thats really not helping me any. should my timing marks look like two L's but facing away from each other. the Intake cam being L? Hope that makes sense lol?[/b]

if it was just one tooth out on the intake it wont start well, i did this, would not start unless you held the throttle open for a bit, and would not idle
i use a steel rule on the head to make sure the dots line up correct

1 - 17 of 17 Posts

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