DIY technical writeup. Sat, 18 Apr 2026 05:17:06 +0000 Sat, 18 Apr 2026 05:17:06 +0000 XJBikes - Yamaha XJ Motorcycle Forum https://xjbikes.com/forums/forums/xj-diy-how-to-instructions.21/ Thu, 16 Apr 2026 19:07:46 +0000 https://xjbikes.com/forums/threads/how-to-convert-to-leds-and-still-have-everything-work.14068/ https://xjbikes.com/forums/threads/how-to-convert-to-leds-and-still-have-everything-work.14068/ invalid@example.com (SQLGuy) SQLGuy
Since I was trying to save power, I didn't want to add load resistors; that would have been counterproductive. Instead I needed to make some flasher and computer changes to accomodate the LED's while still maintaining stock SECA functionality....

How to convert to LED's and still have everything work]]> 122 Tue, 24 Mar 2026 01:20:13 +0000 https://xjbikes.com/forums/threads/clutches-101-part-1-the-400-550-600s-with-pics.29541/ https://xjbikes.com/forums/threads/clutches-101-part-1-the-400-550-600s-with-pics.29541/ invalid@example.com (bigfitz52) bigfitz52
CLUTCHES 101: Part 1, the 550 and its brethren:

First item of business: a quick note on the differences between the 400, 550 and 600s and their world-market cousins. They seem to differ a bit in the number and placement of "clutch boss springs" which is covered in detail here: http://xjbikes.com/Forums/viewtopic/t=22927.html so we won't repeat that discussion...

CLUTCHES 101-Part 1: the 400/550/600s with pics]]> 101 Sat, 21 Mar 2026 02:35:45 +0000 https://xjbikes.com/forums/threads/rebuilding-the-yamaha-vacuum-fuel-valve-w-pics.25058/ https://xjbikes.com/forums/threads/rebuilding-the-yamaha-vacuum-fuel-valve-w-pics.25058/ invalid@example.com (bigfitz52) bigfitz52
Rebuilding Yamaha Vacuum Operated Fuel Valves (Petcocks.)

THEORY of OPERATION: The way these things are supposed to work is this:

When the petcock is in the ON or RES positions, fuel flow is held "off" by a spring-loaded diaphragm seal. When vacuum from the intake manifold is applied to the smaller port (see pic below) the diaphragm lifts the valve seal off the seat and fuel flows (out the larger port.) When the valve is...

Rebuilding the Yamaha Vacuum Fuel Valve w/pics]]> 79 Tue, 02 Dec 2025 06:47:00 +0000 https://xjbikes.com/forums/threads/winterizing-my-xj750.7065/ https://xjbikes.com/forums/threads/winterizing-my-xj750.7065/ invalid@example.com (tinwakr123) tinwakr123
What must I do to winterize/store my bike?

Thanks,
Chuck]]> 9 Fri, 28 Nov 2025 12:31:04 +0000 https://xjbikes.com/forums/threads/happy-thanksgiving.133329/ https://xjbikes.com/forums/threads/happy-thanksgiving.133329/ invalid@example.com (Ronnie208) Ronnie208 1 Sun, 09 Nov 2025 14:36:39 +0000 https://xjbikes.com/forums/threads/how-to-fix-miss-firing.133316/ https://xjbikes.com/forums/threads/how-to-fix-miss-firing.133316/ invalid@example.com (Blaž Podbevšek) Blaž Podbevšek
I have recently rebuild the YAMAHA XJ500 1981 (bassically a rare European version of XJ550, seca, etc.), picture bellow:

The rebuild took time, my battery died (before rebuild and during it motocycle ran like a dream).

I connected electricity to start it up from a running car and without battery in the...

How to fix miss.firing]]> Tue, 28 Oct 2025 13:03:51 +0000 https://xjbikes.com/forums/threads/clutch-rattle-fix-xj550.117514/ https://xjbikes.com/forums/threads/clutch-rattle-fix-xj550.117514/ invalid@example.com (LarryMc) LarryMc Simply remove the gear and press part of a roll pin around the protruding section of the dowel, reassemble, done. You'll...

Clutch rattle fix (XJ550)]]> 5 Wed, 22 Oct 2025 16:28:13 +0000 https://xjbikes.com/forums/threads/why-you-need-to-replace-original-brake-lines-w-pics.41400/ https://xjbikes.com/forums/threads/why-you-need-to-replace-original-brake-lines-w-pics.41400/ invalid@example.com (bigfitz52) bigfitz52
"why do I need to replace my brake lines, they look fine?"

Why indeed.

FIRST REASON: YAMAHA said they were only supposed to last FOUR YEARS. Four. Not thirty.

Check your date codes.

Sometimes they're easy to see:




Sometimes you really have to look (this one says 5/82)...

Why You NEED TO REPLACE Original brake lines w/pics]]> 75 Sun, 19 Oct 2025 12:03:30 +0000 https://xjbikes.com/forums/threads/tci-rebuild-thread.38234/ https://xjbikes.com/forums/threads/tci-rebuild-thread.38234/ invalid@example.com (darkfibre) darkfibre http://www.xjbikes.com/Forums/viewtopic ... rt=15.html
tumbleweed_biff has sent me his dead TCI to (hopefully) repair.



So we have this:




The already diagnosed blown driver transistor:...

TCI rebuild thread.]]> 45 Fri, 10 Oct 2025 11:40:49 +0000 https://xjbikes.com/forums/threads/charging-system.133280/ https://xjbikes.com/forums/threads/charging-system.133280/ invalid@example.com (Jomo35) Jomo35 14 Wed, 10 Sep 2025 00:26:34 +0000 https://xjbikes.com/forums/threads/1982-yamaha-xj650-seca-wiring-diagram.117580/ https://xjbikes.com/forums/threads/1982-yamaha-xj650-seca-wiring-diagram.117580/ invalid@example.com (XJ650SECATAY) XJ650SECATAY 15 Sat, 30 Aug 2025 23:53:24 +0000 https://xjbikes.com/forums/threads/bleeding-the-xj750-seca-front-brakes.124736/ https://xjbikes.com/forums/threads/bleeding-the-xj750-seca-front-brakes.124736/ invalid@example.com (k-moe) k-moe
What I do to bleed the system.
1. get a...

Bleeding the XJ750 Seca Front Brakes]]> 18 Sun, 10 Aug 2025 06:29:35 +0000 https://xjbikes.com/forums/threads/how-to-reshim-valves-on-a-1986-maxim-x-700.133191/ https://xjbikes.com/forums/threads/how-to-reshim-valves-on-a-1986-maxim-x-700.133191/ invalid@example.com (Donglord) Donglord 12 Fri, 08 Aug 2025 21:25:08 +0000 https://xjbikes.com/forums/threads/shim-under-bucket.133197/ https://xjbikes.com/forums/threads/shim-under-bucket.133197/ invalid@example.com (Donglord) Donglord 7 Mon, 14 Apr 2025 23:45:07 +0000 https://xjbikes.com/forums/threads/how-do-i-go-about-tuning-my-carbs.132979/ https://xjbikes.com/forums/threads/how-do-i-go-about-tuning-my-carbs.132979/ invalid@example.com (Donglord) Donglord 2 Sat, 29 Mar 2025 00:57:01 +0000 https://xjbikes.com/forums/threads/intake-boot-repair-bicycle-inner-tube-bandages.132815/ https://xjbikes.com/forums/threads/intake-boot-repair-bicycle-inner-tube-bandages.132815/ invalid@example.com (hogfiddles) hogfiddles
1. Get a bicycle inner tube
2. Cut 4 sections just the width of the intake boot
3. Use a paper hole punch to create a hole for the vacuum port-- obviously measuring how far in from the edge you need to be....
4. Slather the whole boot exterior with the rtv
5. Slide the inner tube onto the boot to create a
"Bandage"
6. Do the other 3

Now, re-install the carbs and see if there's any difference.

DFox]]> 1 Wed, 12 Mar 2025 08:16:45 +0000 https://xjbikes.com/forums/threads/removal-of-xj-900-anti-dive-top-piston-brake-plunger-piston.132887/ https://xjbikes.com/forums/threads/removal-of-xj-900-anti-dive-top-piston-brake-plunger-piston.132887/ invalid@example.com (co.dirtbiker) co.dirtbiker
View attachment 51141
View attachment 51147

The problem here that the piston shaft sticks up in the middle of the hex recess, so you can't get a standard hex wrench in it. A "tamper proof" hex wrench would...

Removal of XJ-900 Anti Dive top piston Brake Plunger Piston]]> 1 Wed, 26 Feb 2025 00:32:54 +0000 https://xjbikes.com/forums/threads/1985-xj700n-carb-fuel-and-vacuum-line-routing.132862/ https://xjbikes.com/forums/threads/1985-xj700n-carb-fuel-and-vacuum-line-routing.132862/ invalid@example.com (FuerstorLast) FuerstorLast I'm just going to start this off with this is my first bike, and quite an adventure so far. It was a barn find and was in rough shape. I've gotten to the point of having to route the fuel and vacuum lines to the carbs and have no idea where to start. I've been following the service manuals for the things I've addressed before, but there is little to nothing on this subject. If you could please help I would greatly appreciate it.]]> 3 Mon, 24 Feb 2025 19:50:41 +0000 https://xjbikes.com/forums/threads/how-to-repair-plastic-side-covers.130812/ https://xjbikes.com/forums/threads/how-to-repair-plastic-side-covers.130812/ invalid@example.com (Dan Gardner) Dan Gardner
When you go out and start searching the internet for guidance on repairing plastic side panels, there isn't too much to be found. You probably end up with the guy who uses super glue and baking soda to build up and shape a peg - it may be a perfectly good repair, I...

HOW TO: Repair plastic side covers]]> 10 Fri, 17 Jan 2025 18:15:53 +0000 https://xjbikes.com/forums/threads/carb-slide-does-not-have-the-same-speed.132817/ https://xjbikes.com/forums/threads/carb-slide-does-not-have-the-same-speed.132817/ invalid@example.com (Frederik Thomsen) Frederik Thomsen
I took the carburetor off the motorcycle to clean it (the tank was full of rust), and now it’s running again. I noticed that it’s slow to return to idle after giving it some throttle. I took the carburetor off again and saw that the carburetor slide doesn’t drop at the same speed. However, when I take it apart, I can’t see why. Could it just be that the spring is old? Any tips?

Also,...

Carb slide does not have the same speed]]> 2