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Just had to break down the motor on my 84 GL1200. The bike seemed to be running fine then all of a sudden it would not crank. After recharging the battery and several (more than a few) tries the bike started but had a loud ticking sound from inside the motor. If I turned the bike off it would take several tries before the bike would even crank.



Decided to pull the motor (video on-line came in real handy) could not see any problems so I split the cases. What I found was #1 rod was bent. Piston, heads, and crank all look fine, I can't seem to see any reason why the motor would lock up the way it did, no coolant in motor, was not running hot, and as I said no damage to the piston.



I obviously need to replace the rod and figured I would go through the whole motor. According to the previous owner the bike only has about 20,000 miles on it but I can tell the motor has been out before.



I wanted to know if anyone knows what the piston and bore measurements should be for the standard bore. I want to make sure has not been bored out previously.



Thanks in advance!
 

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From the GL1200 Service manual. I hope this helps.



Units mm (in)







[align=left]ITEM STANDARD SERVICE LIMIT[/align]

[align=left]Cylinder compression pressure
1,100-1,500 kPa 1,000 kPa[/align]

[align=left](11-15
kg/cm2 , 156-213 psi) (10 kg/cm2 , 142 psi}[/align]

[align=left]Cylinder Cylinder 1.0.
75.500 75.515 (2.9724-2.9730} 75.60 (2.976}[/align]

[align=left]Out·of·round
- 0.15 (0.006}[/align]

[align=left]Taper
- 0.05 (0.002)[/align]

[align=left]Piston Piston 0.0. {at skirt}
75.470 75.490 (2.9713 2.9720) 75.35 (2.967)[/align]

[align=left]Piston pin hole 1.0.
19.010 19.016 (0.7484-0.7487) 19.03 (0.760)[/align]

[align=left]Piston to cylinder crearance
0.010-0.045 (0.0004-0.0018) 0.15 (0.006)[/align]

[align=left]Piston pin Pin 0.0. (at sliding surfaces)
18.994-19.000 (0.7478-0.7480) 18.98 (0.747)[/align]

[align=left]Pin·to·piston crearance
0.010 0.022 (0.0004 0.0009) 0.05 (0.002)[/align]

[align=left]Pin·to·rod interference
0.015-0.039 (0.0006-0.0015) -[/align]

[align=left]Piston ring End gap Top and second
0.10-0.30 {0.004-0.012} 0.60 (0.024)[/align]

[align=left]Oil ring side rail
0.20 0.90 (0.008 0.035) 1.10 (0.043)[/align]

[align=left]Ring·to-ring land clearance
0.015 0.045 (0.0006 0.0018) 0.12 (0.005)[/align]

[align=left]Crankshaft, Aunout (at center journal)
0.05 (0.002)[/align]

[align=left]connecting rod Rod side crearance
0.15-0.30 (0.006-0.012) 0.40 (0.016)[/align]

[align=left]Crank pin bearing oil crearance
0.020-0.044 (0.0008-0.0017) 0.08 (0.003)[/align]

[align=left]Main bearing oil crearance
0.020 0.044 {0.0008 0.0017} 0.08 (0.003)[/align]

[align=left]Main and Taper
- 0.004 (0.0002)[/align]

[align=left]crank pin[/align]
journal Out·Qf·round
- 0.008 (0.0003)
 

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Discussion Starter #3
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First thanks for the quick response.



I hate to sound stupid but what is the second set of numbers on the cylinder.



Cylinder Cylinder 1.0. 75.500 75.515 (2.9724-2.9730} 75.60 (2.976}



I'm assuming the 75.500 - 75.515 is the factory spec but what is the 75.6?



Regards,
 

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Junior Grue
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sajobob wrote:
I'm assuming the 75.500 - 75.515 is the factory spec but what is the 75.6?
Service limit. If exceeded re-boring is needed.
 

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It had liquid in a cylinder (gas, water or coolant) and when cranked it bent the rod.
 

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1987 GL1200 Interstate
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Just a bit of debris in the float needle seat, a weak float needle or a float that doesn't, is all you need. Then sit back and wait as a plugged gas cap, or even gravity, pushes the fuel past the pump, through the carb and into the cylinder.

This pic is of my head, #2 cylinder. What do you figure would have happened had I tried to start the motor?
 

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I did notice that 2 of the intake ports were full of fuel when I pulled the motor but I guess I was hoping it had something to do with fuel lines being disconnected. I guess I better order a set of carb kits before I put it back together.



Was hoping I would be riding it now, not rebuilding more parts.:?



Thanks again for all the help!
 

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I don't believe Mother left a lot of room for re-boring, even if you're able to find OEM pistons/rings in + sizes. Check-measure the bore carefully for damage from the bent rod. You might just luck-out and only need the rod and bearings for 1 cylinder...



You may also want to contact the PO to verify the mileage, as 20+k miles is nothing for a 1200... :gunhead:
 

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1987 GL1200 Interstate
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sajobob wrote:
I did notice that 2 of the intake ports were full of fuel when I pulled the motor but I guess I was hoping it had something to do with fuel lines being disconnected. I guess I better order a set of carb kits before I put it back together.

Whoa!...cease and desist. Chances are someone already bought carb kits, and that's your problem.

Go to your local Honda dealer and buy only OEM parts. Or, if you must, buy on-line from a reputable dealer like Western Honda.

OEM gasket kits are cheaper, and of course, much better than the aftermarket guys. Where you are going to get hurt is with the float needles and seats, and the jets if you need them.Any reputablemechanic will tell you to use OEM, though.
 
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