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A few questions for the experts

Started by codell, July 25, 2021, 11:10:46 PM

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codell

Hi folks, first post, I would like to pick your gray cells on a few matters.

1. I am familiar with fuel injection and gravity fed/vacuum carb systems, but I do not understand this fuel reserve thing. I notice the pump is louder when first turning the key on with the reserve on, but exactly how does it work? Is the fuel sender involved with the computer to increase fuel pump output? Does the fuel pump stop working or is it underperforming when fuel is low in the tank? I finally figured out how that steampunk rear shock works, but this one has got me.

2. On valve adjustment. I checked the head torque first (no backing off) one loose between 2 and 3 exhaust side. Compressions with engine cold WOT/ 160-170-165-165. All of the valves were on the looser end and #1 all were at max recommended settings. Basically, the rest were all over the place some at max and some mid-range. My question is should I bring them all back closer to minimum and should they be more uniform?
I purchased this bike as a semi project about a month ago, a 1989 with 20k miles. Good plastics and clean tank. Quite frankly I didn't know what I was getting into. Second gear is strong and it pulls great up to 120mph. I haven't pushed it any further yet. The only thing besides basic maintenance (mostly cleaning, lubing and torquing everything plus dielectric paste on that dreaded red plug), it has needed are a chain slider, front/rear wheel bearings and steering head bearings (zealously overtightened).

You guys are spot on about those stock front brakes. The rear is good.

I have spent many enjoyable hours reading your posts and have learned a lot. Thank-you.



red

Quote from: codell on July 25, 2021, 11:10:46 PMHi folks, first post, I would like to pick your gray cells on a few matters.
You guys are spot on about those stock front brakes. The rear is good.
I have spent many enjoyable hours reading your posts and have learned a lot. Thank-you.
Codell,

Front brakes may not be what they should be, if still using the ancient OEM rubber hoses.  I'd suggest getting braided stainless hoses made up, either by a decent hydraulics shop locally, or get a tailored set from an aftermarket supplier.  If you do, you may not need any other brake parts.

You can now get banjo hose ends that can rotate as needed (hydraulic hoses do not twist).
You can now get bleeder-screw banjo bolts, to make it easy to bleed the hydraulic lines (~US$20 each at the right shops).
You can get hose sheathing in clear or translucent colors, if desired.
Cheers,
Red

P.S. Life is too short, and health is too valuable, to ride on cheap parade-duty tires.

Motofun

Just my opinion, others may disagree.....For a street bike I like the valve lash to be on the loose side but within spec.  If things are going to change they will only get tighter with time though with 20k they are probably fixed in position.  Compression is good, no need to worry.
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Pat Conlon

Quote from: Motofun on July 26, 2021, 06:49:06 AM
Just my opinion, others may disagree.....For a street bike I like the valve lash to be on the loose side but within spec.  If things are going to change they will only get tighter with time though with 20k they are probably fixed in position.  Compression is good, no need to worry.

+1 on this ^^
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

codell

Just got back from a 200 mile shakedown cruise. Bike is awesome. I like it much more than my old Kaw C-10 and VFR.

Thanks for the valve info. I was comfortable with them being on the loose side, but I wanted someone with more experience with these to confirm this.

Also, thank-you for the brake info. The rear brake already has a s/s brake line, that is probably why it seems good. I will convert the fronts over to s/s and maybe go for those blue dots too, plus some other stuff. Winter project. But for now the engine braking is so good on this bike I can adjust for it.

On the fuel reserve thing, the fuel light came on and the world did not end. I rode it for another 30 miles without putting the reserve on and nothing happened. So, I am still confused as to what this switch really does.

Pat Conlon

There are 2 fuel sensors in your tank.
1) A float for the fuel gauge and fuel level warning light...and
2) A separate fuel sensor for the reserve function. When this sensor gets uncovered by fuel (low fuel level) it sends a signal to the ignition box and thus interrupts the current to the fuel pump which in turn interrupts fuel to the carbs.  This gives you the engine studders .
By manually flipping the reserve rocker switch from run to reserve, the power is restored to the fuel pump and the bike returns to run normally.

You can follow the logic on Cutter Bill's excellent Current Flow Diagrams.
http://www.fjowners.com/index.php?topic=18991.0

Cheers.  Pat
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

codell

Thanks Pat.
I was riding in the mountains when the light started coming on in long sweepers, then it would go off. That makes sense. The excellent schematic tells all. All mysteries at this point are resolved and I can ride in peace. Thanks again.