valve timing
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1st Gear
Joined: Feb 2008
Posts: 5
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valve timing
howdy all, i have put an 85 evo back together after someone else pulled it apart ,i put anew cam in and when i went to start it it would turn over fine with no plugs in it , but put plugs in and she struggles to turn over , i definitely lined timing marks up ,with plugs in it sucked through exhaust ,i pulled cam out and had it checked that the gear was pressed on correctly and it was , i got told to turn motor over one more revolution and reinstall cam, does this sound right , i'm confident that they are correct but just unsure in my mind , any help would be greatly appeciated as i am pullin my hair out tryin to find a solution!
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1st Gear
Joined: Feb 2008
Posts: 5
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RE: valve timing
just 10" over pistons and barrels , the new cam is crane , had cam gear put on by harley w/shop , no noises , the only thing that really gets me to make me think i stuffed up is that when you crank it with plugs in it and put hand over exhaust it sucks through it and that doesn,t seem right , its not a hi torque starter but i,ve had it off and had it checked and all ok, with no plugs it turns over sweet , with pl7ugs it gets maybe a revolution and a half then bogs down and goes again ,we've had light truck battery on it and it does the same thing
Road Warrior
Joined: Nov 2007
Posts: 1,984
Likes: 7
RE: valve timing
Well there is no majec in these things. Well sometime, maybe a little. Check compression. Testers not too expensive probably at WM or Auto Zone. If this cam is causeing real high cranking pressure may need compression releases. You would know your cam specks.
Cruiser
Joined: Nov 2006
Posts: 193
Likes: 1
From: Arnold, MO
RE: valve timing
If you have the marks lined up it is correct. The crank rotates two revolutions for every one by the cam. The pistons don't know where they are in the firing cycle. The cam determines it.
Run a compression test to get a cranking pressure. Autozone will loan you one with a small deposit.
Run a compression test to get a cranking pressure. Autozone will loan you one with a small deposit.
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Thread Starter
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1st Gear
Joined: Feb 2008
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RE: valve timing
checked compression ok , this might sound really stupid ,but here goes can it rotate the wrong way ? looking from points /carby side it rotates anticlockwise , is this correct direction of rotation? i definitely had timing marks lined up and thats what i thought that is the valve timng and then u just slip the pushrods in and adjust and everything should go
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Tourer
Joined: Feb 2008
Posts: 383
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From: Richmond BC.
RE: valve timing
Yes looking at the cam it will rotate counter clockwise as it is opposite to the flywheel rotation. You mentioned points. First off set the gap on the high point of the narrow lobe .020 gap. for the timing put the timing mark in the center of the hole T:F which is the advanced mark front cylinder. Make sure the points are close to the narrow lobe or you will have to rotate it 180, turn the breaker cam against the springs and adjust it so they just start to open I use an ohm meter and want it so the needle just flickers. You could use a test light if you like with battery voltage the light will be out with the points closed and just flicker on when they start to open. For checking the cam you need the specs they should include the opening at TDC you can use a dial indicator to check this 0 the indicator on the heel of the cam then rotate it in the running direction till you read on the dial indicator the TDC lift acording to the cam specs and check to see if the TDC mark is in the timing hole on the flywheels this will tell you if the gear is on right. The other method is with a degree wheel which will give so much lift at so many degrees of crank rotation again from the cam specs chart. Either method will make sure the cam is degreed in properly. The starter won't turn the bike over in reverse as there is an over running clutch plus a bendix that are designed to only work one way. As was mentioned before check the pushrod adjustments carefully and allow lots of time for them to bleed down before rotating the engine otherwise you could end up with some bent valves which might be your problem now.