Question about 2004 Yamaha YZ 450 F

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This could be a number of things, none of which will be solved without revisiting the motor again. Give some thought to the following:
Check cam and gear timing. Did you repace the cylinder and or hone it, bore it? Did you gap and offset your rings correctly? Have you checked the valve train to see if you have a valve not closing?
You see there are a number of possible causes for will have to go through one at a time and eliminate them.

Posted on Oct 05, 2009


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What causes motor not to have compression

Blown head gasket, cracked head or block, broken or jumped timing chain, severely worn piston rings to name a few.

Mar 06, 2015 | 2007 BMW 320i E90

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I have a 1990 trailboss 4x4 polaris i put new rings and pistons in it started for a minute then quit its getting fire what could be wrong

everything could be wrong, wrong size piston, rings, but most likely you have a timing issue. since it ran at first and I don't know how well or long it could have jumped time or broken the tensioner for the chain. but if it was slightly off you probably bent a valve an it is staying open slightly preventing compression. pull out your plug and put your finger over the plug hole to check the compression. if no compression then you bent the valve.

Dec 09, 2014 | Garden

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Run my yamaha yfz 450 2007 with no water as it leaked and i didint realise now the quad wont start and i have no compression any ideas?

A bunch of things could be the problem >> valves scalded and stuck partly open, Rings seized to the piston, scored cylinder walls blown cylinder head gasket and warped cylinder head.

Mar 22, 2011 | Yamaha YZ 450 F Motorcycles

1 Answer

I have a `994 chevy 2.2l engin. the timing chain broke. put new chain on lined marks up. eng. is missing on 3and 4 cylinder

Have you checked compression in those cylinders? I would bet they are low and the probably cause is bent valves from the broken timing chain.

Oct 23, 2010 | 1994 Chevrolet Cavalier

2 Answers

1990 318i engine no compression yet timing chain ok cam and lifters working pistons going up and down has spark 0 compression wont start

I suggest you bring the pistons to TDC, one at time on the comprssion stroke and do a "cylinder leakage test". Put compressed air into the spark plug hose and try to detect where the air is going. If you have the piston exactly at TDC, it will stay there when you put conpressed air in the hole, if it's off a little it will push the piston down. If you have the valve cover off you can watch the valves to determine if you have the pistons on the compression stroke. You should be able to buy a fitting from an auto parts store that will thread into the spark plug hole. If not take an old spark plug and bust the guts out of it and weld a pipe fitting to it to adapt your air compressor hose.

Mar 07, 2010 | 1996 BMW 318

1 Answer


By "all timing marks seem to be right", are you talking about the timing marks on the alternator rotor or the camshaft timing marks? A 1985 model is a pretty old bike. If it has never had a timing chain or the adjuster guides replaced, you may need to address this issue. Not only do you need for the ignition timing to be correct, you need the camshaft timing to be correct as well.

In your problem line, you stated that you had fuel, and spark. You need three things to get any engine to run, fuel, spark, and compression. Do a compression check on the engine. If the compression is low, it won't start either. Three things can cause low compression. Bad rings, improper camshaft timing, and valves not seating properly.

If you want to get the bike running again, I would suggest you do a "top end job" on the engine. Pull the head and cylinder. Measure the cylinder for wear and bore for a new piston if necessary. Replace the rings. Have a valve job done on the head at a local machine shop. When you put it back together, do so using a new timing chain and adjuster slides. You'll be surprised at what a "New" engine feels like. Good Luck!

Jan 31, 2010 | Honda XR 200 Motorcycles

2 Answers

Had a 360 stop due overheating and then rolled a crankshaft bearing. Initially thought we had dropped a timing chain as we found links in the sump these we discovered were from an earlier problem before...

Is this a 360 v8 engine?
Timing chains rarely fail to the point that they fall apart, generally the gears wear and the chain stretches out and the engine won't run properly before the chain itself comes apart. Finding links in the pan tells me something really bad previously happened in there.
In spinning a bearing, metal is transmitted throughout the entire oiling system and without a total rebuild, the engine will never be "right". During a severe overheat the timing chain can relax and not be tight enough to keep cam timing in phase, additionally the piston rings can relax and not be giving you sufficient compression.
Timing is set by bringing the engine up to TDC at the crankshaft at which point the distributor will either be pointing to the #1 tower on the dist cap or it will be pointing 180 degrees away from #1 in which case, just turn the engine one more time again stopping at TDC. If then the rotor is not pointing to #1 you need to move the distributor one tooth over to get that corrected. I am assuming that you did check the alignment of cam and crank gears when you had the chain out. Regardless of if the timing is set correctly, you should be getting spark at all cylinders. If not you need to find out why.

Jan 14, 2010 | 1983 Jeep Cherokee

1 Answer

How do you set the timing chain on a 2006 yamaha yfz 450

1st set piston at top dead center, which is the top of its travel. after you have verified top dead center, and you are 100% sure its at top dead, install the cams. first the exhaust cam, with you facing the sprockets, with the cam lobes facing up and away, about the 10 o clock position. once set there, you should see a refrence on the sprocket, with lines that will be parallel with the cyl. head surface. then install the intake cam, with lobes facing in the 2 o clock position. once again, you will see refrence marks on the cam sprocket that should be level with the cyl. head surface. after the cam caps are installed, and the cam chain tensioner, turn the engine with the flywheel bolt to verify you have no piston valve contact. after you turn over a few times, recheck timing.

Dec 23, 2009 | 2004 Yamaha YZ 450 F

1 Answer

Installed new cylinder, piston and rings on my 03 kx80. I drove it around for a half a day and it quit. It acts like it will run but dies out. took the carb off and cleaned it and no signs of carb probs.

When u put those new things on the motorcycle, u go easy with the motor, u shouldn't had driven it half day. Do a compression test. check your timing again, change your spark plug, was your timing chain properly tensioned

Jul 25, 2009 | kawasaki KX 125 Motorcycles

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