'79 xs400 rough>reliable>cafe 'Scarlett'

[xschris]

Don't waste your money on these crap kits!!!!!! Jets are cheap and can be found all over the place. The shims can be found at any hardware store also for a few cents.

 

[jthiessen]

Jets are cheap and can be found all over the place. The shims can be found at any hardware store also for a few cents.

So a local motorcycle or ATV style shop might carry jets? And what are the shims for?
Also where would be a good place to start (jet-wise) with Pods on the H-stack?

 

[xschris]

Start with stock first. Turn out the idle mix screws to 3 turns and go from there. Yamaha sells jets. If you carbs have adjustable needles ( for the mid range) you wont need shims.

 

[jthiessen]

So here is my petcock.

In the background you can see some fuel in the vacuum line after a 22 km drive. Is that a sign of a bad diaphragm? If so from this picture, can you tell if this is definitely a petcock from a '79?

Here is another pic of my rear calliper. I don't really know what I am looking for in regards to "pitting". Can I just buy a new dust jacket and plop it back on?

Also,

Since I've owned the bike, this ground has never been attached to anything. What is it for and where should it go?

 

[jthiessen]

And my VIN is 2L0 - 070784. Theres a 10/78 as well on the tag.
Can somebody please confirm the model of my bike?

 

[Requiem]

The top of the brakecylinder looks pretty rough, though that doesn't necessarily say much about the rest. You'd really have to bleed the brake system and take out the cylinder to be able to judge it correctly. Doing so isn't a bad idea at all as you can see how the brake is doing and give it all a good clean.
The rest I can't really help you with I'm afraid

 

[nickso]

I would clean that caliper piston up a bit....looks pitted close to the seal area.

That earth wire looks like the earth from the rear lights.

 

[xschris]

That petcock is off a 76-77 xs360/400. http://www.ebay.com/itm/1977-YAMAHA...Parts_Accessories&hash=item3a91b44f1b&vxp=mtr Make sure the nipple for the vacuum line points up. That ground wire is to be attached to the frame. It is the wire harness ground.

 

[jthiessen]

That petcock is off a 76-77 xs360/400.

That is good to know. But with an older petcock and with a VIN 2L0 - 070784, is this bike even a '79 like the PO told me?

 

[xschris]

Vin is correct for a 79 bike but at some point the petcock was replaced with one from an older bike. It happens a lot and with a 35+ year old bike

 

[jthiessen]

My after market signals aren't flashing so hot. They seem very irritate. Sometimes they are fine, sometimes they simply stay on, sometimes they blink very quickly.

Could it be that the load isn't sufficient on the relay even though they are not LEDs?
Can I use a LED flasher while not using LED lights?

 

[16VGTIDave]

An LED flasher should be fine with incandescent bulbs.

Sounds like you have poor connections or bad grounds.

 

[jthiessen]

Might be a dumb question, I want to replace the diaphragm of my petcock without taking it off the tank, but I have a full tank and no jerry can. Can I take off the diaphragm without loosing fuel? Or am I able to invert the tank without loosing fuel through the cap?

 

[xschris]

Gas with come out with the diaphragm off. It you turn it upside down it will come out the cap. The best way is to get most of the gas out of the tank.

 

[jthiessen]

Went for a ride today and noticed a few things.

1. There was some white smoke out of my right exhaust that got more blue with more throttle.

2. When gearing down to first and stopping at a light, my RPM stuck up around 4k when my idle is set to 2k. It would stay up even when adding some rev's.

There was a fair bit of vibration as well.

Any thoughts?

 

[xschris]

Your burning oil. The bike is running lean on the pilot circuit or dirty. Have you synced the carbs?

 

[motoTrooper]

White smoke? Sounds like a coolant leak in your head gasket!

Really though, could be that your right cylinder may need checking with a compression test as oil may be getting past the rings.

As far as your high idle -maybe check the choke on the carbs to be sure it opens/closes properly? More carb cleaning possibly (Yay!)

And vibration, parallel twins have it but it can be worsened by carbs not being synced or one cylinder having more compression than the other.

Hope it helps. Best to think of it as an interesting mystery puzzle and you are the brilliant investigator. If you look hard enough all the answers will appear.

 

[jthiessen]

Haven't done a carb sync yet. Or a compression test.
I guess those are my next to steps.

Would the smoke, idle or vibration be a symptom of bad valves? The valves sound funny. Maybe the rocker arms need attention?

 

[xschris]

Valve adjustment?

 

[jthiessen]

Did a bit of maintenance the other day.
- Reset my valves.
- Checked my points gaps, they were good. A bit of pitting on my points.
- The nipple on the petcock between the carb manifold and diaphragm was upside down, might explain the fuel in the line.
- Painted up my seat hoop.

Next I want to get new tires. My current tires are F 100/90/18 R 110/90/18. Is that stock for a '79 with mags? I am looking at Shinko 712's, Kenda K657 or K671. I'm just not a big fan of how the corner between tread and sidewall flairs out on the K657. Does anyone have experiences with these tires?