new FJ owner carb questions

holes41 · March 03, 2014, 09:26:16 PM

I replaced my filter with an OEM one from Yamaha 2 weeks ago, it looks like the one from rpm. Is it comparable with California gas or could it have caused my problem ?

movenon · March 03, 2014, 11:54:09 PM

I have had no problem with the stock filter that I had on and so far no problem with the Fram filter I have on now. As a note I do think if you were running straight gas and converted to ethanol then there is a chance of the ethanol cleaning out some varnish from your tank and filter. Just an opinion.
I your repair you might also consider new fuel lines.
George

holes41 · March 05, 2014, 11:20:33 PM

I have an update, mechanic did a "dry" and "wet" compression check because I wanted him to go over things while he's in there and cylinder #2 was down by 15 or 25 psi I don't remember . all others were in the 140s, he said all cylinders went up 15psi when he added oil to them and we are hoping it is a valve issue. I've got my fingers crossed , if it was rings would #2 have jumped differently than the other 3 ? I appreciate your help.

movenon · March 06, 2014, 12:18:35 AM

I am sure he will, but I would check the valve clearances on #2 first. 140 is great on the other cylinders. Higher than mine....
Let us know how it comes out.
George

Pat Conlon · March 06, 2014, 12:53:12 AM

Spot on George. Low compression? Not the rings? No head gasket leaks? Then it's the valves...

As George recommends, check your valves. If you find a tight valve (typically exhaust) on the #2 correct that first, then retake your compression test and see if you get lucky and the compression number comes up....if you are lucky....you just had a valve that wasn't fully closing and the problem is fixed.

If you are unlucky, and the compression number does not improve after the valve adjustment, you can bet you cooked a valve.

A Painful Le$$on: That's why valve adjustments are so important on our large displacement air cooled engines.

BTDT

holes41 · March 06, 2014, 06:25:40 AM

Quote from: Pat Conlon on March 06, 2014, 12:53:12 AM
Spot on George. Low compression? Not the rings? No head gasket leaks? Then it's the valves...

As George recommends, check your valves. If you find a tight valve (typically exhaust) on the #2 correct that first, then retake your compression test and see if you get lucky and the compression number comes up....if you are lucky....you just had a valve that wasn't fully closing and the problem is fixed.

If you are unlucky, and the compression number does not improve after the valve adjustment, you can bet you cooked a valve.

A Painful Le$$on: That's why valve adjustments are so important on our large displacement air cooled engines.

BTDT

I have never had good luck, I hope this is an exception, or I may be parting it out

movenon · March 06, 2014, 08:14:36 AM

Don't panic. Even is one cylinder is low, I would say ride it for a while. You might be surprised. It's not a new bike. All of my cylinders are on the low side and the plan is just to ride it and do a top end later or wait until a good deal comes up on an engine, whole bike, or set of cylinders and a head lots of options.
Hang in there.
George

Pat Conlon · March 06, 2014, 11:07:47 AM

Yep, don't panic. I rode my bike for years with compression in the 120's.

Those FJ's engines are stout.

holes41 · March 06, 2014, 06:59:13 PM

good news, I have 4 valves that are tight and 2 of them happen to be in the #2 cylinder, looks like I am Lucky for once

Pat Conlon · March 06, 2014, 07:03:23 PM

Redo the compression test. Let us know what your new numbers are....

holes41 · March 06, 2014, 09:40:46 PM

Quote from: Pat Conlon on March 06, 2014, 07:03:23 PM
Redo the compression test. Let us know what your new numbers are....

Will do once proper shims are installed. Its been 5 days since my last ride and the withdrawals are killing me!

holes41 · March 08, 2014, 05:13:27 PM

One more question guys. My diaphragms have no tears or holes, but they are wrinkled up , is this normal? can I add new diaphragms at a later date from the top without a tear down? My budget is the issue, thanks

FJmonkey · March 08, 2014, 05:41:08 PM

If you have no holes then they are OK to use, and yes, they can be replaced from the top without removing the carbs. As the slides move up they have to wrinkle, then smooth out when they are down. Some creases will develop and that is where the holes will eventually develop. Many have used liquid electrical tape and a Q-tip to paint both sides of the holes to keep them diaphragms going longer.

holes41 · March 08, 2014, 11:29:16 PM

Out of curiosity, what are all the hoses and T fittings for coming off the front of the gas tank for? It is a california model if that makes a difference.

FJmonkey · March 08, 2014, 11:53:06 PM

Quote from: holes41 on March 08, 2014, 11:29:16 PM
Out of curiosity, what are all the hoses and T fittings for coming off the front of the gas tank for? It is a california model if that makes a difference.

That sounds like what I saw on CA FJ's. It is a vapor control system that uses two charcoal canisters, check valves, bunch of hoses and a solenoid. It controls what direction the vapors go depending on if the engine was running or not.

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new FJ owner carb questions