bhendron
Well-known member
I posted recently about an '06 for sale that the PO's mechanic claimed had low compression due to glazed cylinders (post here: https://www.fjrforum.com/forum//index.php/topic/168306-glazed-pistons/). They claimed to have performed a leak down test and determined air getting past the pistons.
The bike has ~50k miles on it and was offered for $1,000. I took the leap and bought it.
I have sourced a 'new' motor from an '07 that has 34k on it for $600 shipped. It supposed to arrive no later than the 14th of June.
Meanwhile, I thought I double-check the trouble and see if I come to the same conclusion. It seems to me that a bike of this mileage is due for valve clearance check #2 and that would be the most likely culprit for low compression. The mechanic said all the valves were in spec and even gave me his numbers. With the valve cover all ready off, it was an easy decision to check them myself. I checked, double checked, and triple checked. Here's what I came up with.
My service manual (2002 shop manual) gives spec of Intake 0.15-0.22mm and Exhaust 0.18-0.25mm,
Cylinder 1:
In: .203 .203
Ex: .330 .305
Cylinder 2:
In: .203 .203
Ex: .279 .279
Cylinder 3:
In: .203 .203
Ex: .330 .330
Cylinder 4:
In: .229 .229
Ex: .279 .279
Our numbers don't match and his are a little tighter on some. All of the exhaust are out of spec on the loose side and Cylinder 1 intake out of spec on loose side. Could it be that since the exhaust valves may not have been opening far enough that the gasses were forcing their way past the rings and causing the subsequent pressure issue?
I bought a leak down tester from Harbor Freight however, none of the adapters will fit the plug holes on the FJ. I've ordered a proper adapter.
All thoughts and suggestions welcome! The bike in the shop:
The bike has ~50k miles on it and was offered for $1,000. I took the leap and bought it.
I have sourced a 'new' motor from an '07 that has 34k on it for $600 shipped. It supposed to arrive no later than the 14th of June.
Meanwhile, I thought I double-check the trouble and see if I come to the same conclusion. It seems to me that a bike of this mileage is due for valve clearance check #2 and that would be the most likely culprit for low compression. The mechanic said all the valves were in spec and even gave me his numbers. With the valve cover all ready off, it was an easy decision to check them myself. I checked, double checked, and triple checked. Here's what I came up with.
My service manual (2002 shop manual) gives spec of Intake 0.15-0.22mm and Exhaust 0.18-0.25mm,
Cylinder 1:
In: .203 .203
Ex: .330 .305
Cylinder 2:
In: .203 .203
Ex: .279 .279
Cylinder 3:
In: .203 .203
Ex: .330 .330
Cylinder 4:
In: .229 .229
Ex: .279 .279
Our numbers don't match and his are a little tighter on some. All of the exhaust are out of spec on the loose side and Cylinder 1 intake out of spec on loose side. Could it be that since the exhaust valves may not have been opening far enough that the gasses were forcing their way past the rings and causing the subsequent pressure issue?
I bought a leak down tester from Harbor Freight however, none of the adapters will fit the plug holes on the FJ. I've ordered a proper adapter.
All thoughts and suggestions welcome! The bike in the shop: