TDC with heads on and timing belts off ???


Information and questions on GL1100 Goldwings (1980-1983)
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velvetrider
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Motorcycle: 1983 GL1100 Interstate

TDC with heads on and timing belts off ???

Postby velvetrider » Sat Sep 12, 2015 2:59 pm



OK,,,I am not positive that I have TDC. and the heads are back on. I have installed the cam and rocker arm assembley, but the pulleys do not match same position in which I removed um. Honda book says not to rotate pulleys with the belts off, as it may cause bent valves or damage pistons.
When I removed the belts I marked both tooth locations on the belt at TDC.

A lot has transpired so no I am not sure if I have TDC or TDX.?? I suspect either way the pulleys are not going to line up as they should. I never removed the cam from the carrier, but am not sure that the cam did not get turned. Do I have to pull rocker and cam out and spin to correct place?
Even still I have to be certain about TDC. I have loosened rockers all the way out, but feel I could cause some serious problems if not careful. I have written so much on here about my head gasket/valve job that I am certain I will qualify as the village idiot. Backing off 90* on the crank should eliminate any possible damage as all pistons will be lower. I guess I just have to put crank where I think TDC is, adjust the valves and see, I got a better than 50-50 chance I am right.,,lol


Last edited by velvetrider on Sat Sep 12, 2015 5:44 pm, edited 1 time in total.

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spiralout
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Re: TDC with heads on and timing belts off ???

Postby spiralout » Sat Sep 12, 2015 5:11 pm

If you're that worried about turning the cam pulley to get it lined up, back the motor up 90 degrees first, line up your cam pulley, then bring the motor back to TDC.

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velvetrider
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Re: TDC with heads on and timing belts off ???

Postby velvetrider » Sat Sep 12, 2015 5:36 pm

yea I got that part figured out,,90* takes the problem away. However, when I go back to TDC how do I know if it is not TDX? The valves have been completely unadjusted so the usual "#1 rocker should move" will not apply. Thanks for the help though.
you guys roc.!

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spiralout
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Re: TDC with heads on and timing belts off ???

Postby spiralout » Sat Sep 12, 2015 9:18 pm

You went back and edited your first post after we both replied. Don't make this more confusing!!!
This is why you mark the crank pulley and case before pulling the belts :P
If you're on the T1 mark on the flywheel, the #1 and #2 pistons are both going to be at the top of their stroke. Just back the crank off from there so that the valves aren't going to hit when you turn both cam pulleys in to place then turn the crank back to T1. The crank doesn't determine TDC, the valve train does. Apologies if this doesn't make sense, but after all it's Sat night and drinking time ;)

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velvetrider
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Re: TDC with heads on and timing belts off ???

Postby velvetrider » Sun Sep 13, 2015 7:16 am

Cheers Spiralout, thanks. You be right, But If I happened to rotate crank and lost track of TDC,
(I do think I got the rotation right) but for argument sake, Is there any other way to determine TDC?

indianakid
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Re: TDC with heads on and timing belts off ???

Postby indianakid » Sun Sep 13, 2015 11:46 am

spiralout was correct in his first post. and a little off in his second. the crank determines Top Dead Center (TDC on mark T1). with the crank at TDC and belts off turning the cams will damage the valves. that is why the crank is turned back approximately 90 degrees to move the pistons away from the head / valves so the cams can be rotated to their correct position with the words UP in the up position and timing marks aligned. now the crank can be rotated back to the T1 mark with out damage to the valves. now the belts can be installed.

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spiralout
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Re: TDC with heads on and timing belts off ???

Postby spiralout » Sun Sep 13, 2015 12:19 pm

indianakid wrote:spiralout was correct in his first post. and a little off in his second. the crank determines Top Dead Center (TDC on mark T1). with the crank at TDC and belts off turning the cams will damage the valves. that is why the crank is turned back approximately 90 degrees to move the pistons away from the head / valves so the cams can be rotated to their correct position with the words UP in the up position and timing marks aligned. now the crank can be rotated back to the T1 mark with out damage to the valves. now the belts can be installed.

Sorry, I should have said TDC on the compression stroke of the piston, (how often do you refer to TDC as the top of the exhaust stroke?) which is all that matters here, is determined by your cams and valves. Of course the #1 and #2's pistons highest point in it's travel is going to be T1 on the flywheel. What determines whether that highest point in it's travel is going to be compression or exhaust strokes is your cam timing and valve position. OP's problem is determining whether #1 is at the top of it's compression or exhaust stroke. I'm trying to say that it doesn't matter. That will be determined by the camshaft position.

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velvetrider
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Re: TDC with heads on and timing belts off ???

Postby velvetrider » Sun Sep 13, 2015 1:34 pm

Soo,,,I guess there is no TDX, (exhaust stroke) as long as T1 mark is aligned as the valves can now be set as a compression stroke, regardless of which rotation is. As long a TDC is backed up 90* and pulleys are set in the up position. I did all this,, both pulleys set at 90* then back to TDC and set the valves,,or tried to. #1 intake & exhaust, #3 exhaust & #4 intake. Then tried to rotate 360* and do the other side. Problem is crank will not rotate but about 240*, I am at a loss as to why this has occurred. ?? Needless to say I have adjusted these valves, oh I guess 7/ 8 times. It is not like I just got this bike I have put over 65K on it. I obviously have done something wrong. any suggestions. ??

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702scottc
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Re: TDC with heads on and timing belts off ???

Postby 702scottc » Mon Sep 14, 2015 1:21 am

Make sure you are using the correct marks on the cam gears, sounds like you have one side on the wrong Mark.

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velvetrider
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Re: TDC with heads on and timing belts off ???

Postby velvetrider » Mon Sep 14, 2015 9:43 am

Scottc, Thanks,, you were right. Pulley on 1 & 3 was not preloaded before I put the belt on. I thought I had it because I had marked the belt before I removed them. I did it because I wanted to be sure belt was in same teeth. I am not changing the belts and it seemed like the "right" way to go.
As you obviously know, where the belt is on the pulley is not nearly as critical as where it is on the crank. I was one tooth out.. Thanks.

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702scottc
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Re: TDC with heads on and timing belts off ???

Postby 702scottc » Mon Sep 14, 2015 10:09 am

Good to hear you figured it out. I always did the left side first, keeps the crankshaft from turning when you are setting the rh belt over the cam gear. It's under some spring tension but it's an easy job once you've done it once or twice. Be sure and recheck your marks in relation to the crankshaft mark before you put the belt covers back on. Should be good for many miles.




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