replacing timing belts


Information and questions on GL1000 Goldwings (1975-1979)
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ntintruder
Posts: 66
Joined: Tue Jun 28, 2011 9:07 pm
Location: Willoughby,OH
Motorcycle: 1976 GL1000
1972 CB750K2
1977 CB750f

replacing timing belts

Post by ntintruder »



Pulled the heads on a gl1000 and replaced gaskets and seals. I took the timing belts off to replace them as well. Before replacing the camshaft assys., I put no. 1 cylinder on TDC and then rotated the crank 90 degrees so as to avoid piston and valve contact. What I want to be sure about is what to do next. Should I line up the two marks on the cam drive gears with the "up" sign up and rotate the crank to the TDC for no. 1 cylinder and then put the new belts on? The manual does not say exactly what to do and I am a little paranoid about bending a valve as I know this is an interference engine and you can easily bend a valve if you don't get it right.


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Hoosier Jack
Posts: 419
Joined: Thu Oct 02, 2014 4:21 am
Location: Terre Haute, IN
Motorcycle: 1982 GL1100 Interstate

Re: replacing timing belts

Post by Hoosier Jack »

Here is the very nice write up from Wing Admin. As for me, I have a guy that does them for me. Last time I did it the timing was off 180. Call me whatever you like, but the bike does not run well at 180 degrees off and I have no idea how I did it.

viewtopic.php?f=14&t=9774
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newday777
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Joined: Tue Jan 11, 2011 5:21 pm
Location: Milford NH summer/fall & Oceanside, CA winters(N San Diego) with lots of miles riden between
Motorcycle: 2008 Cabernet Red. Level 4

1983 GL1100A Wineberry 36,000 miles

1975 CB750 K5 Planet Blue 7,800 miles

1976 CB750 K6 Anterris Red 25,000 miles

Past rides
1999A Restored from PO neglect & sold at 19,000 miles

1999SE Totaled by cager at 105,000 miles

Re: replacing timing belts

Post by newday777 »

Properly done would be to set the motor up at tdc before you pull the heads and not move the motor position with the heads or belts off as you can end up 180° out, you won't know where it is until you try to fire it up.
180° out is fixable by swapping the coil blue and yellow wires.
ntintruder
Posts: 66
Joined: Tue Jun 28, 2011 9:07 pm
Location: Willoughby,OH
Motorcycle: 1976 GL1000
1972 CB750K2
1977 CB750f

Re: replacing timing belts

Post by ntintruder »

Both the Honda shop manual and the Clymer manual say to set the engine to TDC for cylinders 1 and 2, then rotate the engine 90 degrees before replacing the cams, otherwise you run the risk of bending a valve when you torque the cam holders into place. The cams are in and torqued, the cam drive gears are aligned with the proper timing marks and I need to get the crank back to TDC before replacing the belts.
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DenverWinger
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Location: Denver, CO
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1980 GL1100 STD Vetter (2005-)
1993 GL1500 Aspencade (2017-)
1983 Trav-Lite Camper (2010-)
Past rides
1972 CL350 (1980-1988) sold
1978 Suzuki GS550 (1985-2005) sold
1977 GL1000 (2002-2006) sold

Re: replacing timing belts

Post by DenverWinger »

An interesting thing is that you can put one of the cams 180 degrees out and the motor will run.

The normal timing is that when cylinders 1 and 2 are TDC, one is on compression stroke, the other between exhaust/intake. The coil sparks to both simultaneously, a wasted spark on the exhaust/intake cylinder.

But with one cam 180 degrees out, at TDC both #1 and #2 are either on compression or between exhaust/intake at the same time. Same with #3 and #4.

The end result is the four cylinder engine runs like a two cylinder, with #1 and #2 firing simultaneously, #3 and #4 also firing simultaneously.


♫ 99 Little Bugs in the Code, ♪
♪ 99 Bugs in the Code. ♫ :(
♫ Take one down, Patch it around, ♪
♫ 127 Little Bugs in the Code. ♫ ♪ :shock:

~Mark
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