Got myself an xs400, new to the forum

[berend2712]

Hi everyone!

My name is Berend, originally from the Netherlands but I moved to Vancouver, BC last summer.

I got myself an xs400 in november last year, it's my first bike and I've been loving it so far. I have silently been getting a lot of information from the forum for the past months and all the information has been of great help, I thought it was about time I introduced myself and said hi .

About the bike, it's one of the later models. If I did the identification correctly it's an XS400-K, but in more practical terms, it's a DOHC from 1984 (nobody seems to remember that they made them until that year).

This is also my first experience doing work on motorcycles (I had a 50cc moped, but that had like 3 moving parts, so it doesn't really count), and I have been learning a lot. So far I changed the oil and filter, cleaned the air filter box, flushed the brake system and unseized the caliper, changed the plugs. I just finished adjusting the valve clearance. Also my engine got really hot which I think was because there was fuel in my oil (that is a reason for overheating right?). So I decided to clean my carbs and I found out that my float valves weren't closing properly anymore, so I'll pick up some parts tomorrow to fix that. All in all a lot of basic maintenance which has been fun, but I haven't gotten to ride it much yet, but I hope to change that this week as the weather has been awesome!

Anyway, you might all hear more from me in the future when the next thing breaks. Thanks a lot so far everyone, you have been a great help!

Cheers,
Berend

[EDIT] I was convinced I put this in the right section, but it seems all went wrong. Maybe one of the mods can move this to the right forum section for me? Thanks!

 

[drewpy]

welcome Berend seem to be doing the right thing

 

[xschris]

Welcome to the forum Post a few pics of the bike.

 

[berend2712]

This is from when I bought it last October, not the best looking one in the world but it runs and I am happy .

While I'm on here anyway though: is there anything else but the float valves in these carbs that can create drips of fuel leaking out of the air intake? I have mine suspended and hooked up to my fuel tank out of my bike so I can see what's going on. When I put my tank on prime, fuel starts to drip out the air intake, I thought that was what caused the fuel in the oil. So I cleaned everything thoroughly and got some new valve seats and needles today, installed those but I just checked and I see a drip again. The float valves are of course not meant as a fuel shut off device but they shouldn't let any fuel through anyway right? Is there something else that could be leaking?

Cheers,
Berend

 

[Wolfe_11B]

Bad floats?

 

[berend2712]

I don't know? I took them out today and they float just fine in a cup of gasoline. They also look fine (no holes or damage or anything). I decided to bend the metal lip a bit and give it another go. To be fair it was only a very small drip that never even made it into the bucket below. I will let you guys know how this turns out .

 

[drewpy]

should never leave the tap on prime, there's a reason that the taps were made that way

 

[berend2712]

Well this was just to check wether it was leaking or not, because that seems hard to verify while the engine is running, or is there another way to do it?

 

[BBS360]

Are the float heights set correctly?

Welcome btw. The more Canadians the better.

 

[berend2712]

Yeah I checked, it seemed fine. Anyway, it now went from drips to moist, and that is only with the tap on prime so I suspect this will be about as good as it gets. Hope I can take it for a test ride tomorrow!

 

[Wolfe_11B]

Just looked at the 84 needles.... They don't have viton tips? No wonder it leaks a bit. So long as your petcock closes everything up, I wouldn't worry about it too much.

 

[berend2712]

No they don't, thanks for the confirmation, I'm putting everything back together now, I'm assuming all is well. Thanks for the help!

 

[berend2712]

Just went for a ride and it's working great! No problems whatsoever. Checked the plugs when I came home and it seems the bike is running really lean (see photo's). I don't get this? The setup is completely stock (except for a small leak in the right exhaust but I don't expect that to have that much influence). I tried WD40 around the intake boots and carb, but no reaction to the idle rpm whatsoever. Also there was no popping at deceleration and generally the engine was running really smooth. Any suggestions anyone?

When I took out the diaphragms on one of them there appeared something that might evolve into a small tear, but the slides made a nice "wooshing" sound when pushed up. Would that show up in the WD40 test?

I'm not really sure what to do about this, especially since the engine runs great.

Cheers

 

[berend2712]

So I just went for a ride, and the engine runs a bit less great than last time, now the engine doesn't die down when I don't open the throttle and engage the clutch. It hangs at about 3k rpm and then slowly dies down to idle speed. This seems typical for a leak somewhere, but I can't find one spraying WD40 over the intake, carbs and airboots. Does that mean it might be the diaphragms?

 

[xschris]

If you push the slide up and cover the venturi on the carb with a finger it should stay up and close very slowly. If it closes fast you may have a vacuum leak in the diaphragm. Another way to test a diaphragm is to hold it up to the light and look for holes. I would also get the exhaust leak fixed and make sure the carbs are synced with a manometer. What are the idle mix screws set at?

 

[berend2712]

I tried that thing with the slide. The diaphragm with the damage on it goes down in about 7 sec, the other in about 10, but it doesn't seem like a very significant difference. I did a temporary fix on the exhaust, it seems a little better now, but still after about 20 min of riding the revs go down really slow. Other than that, very smooth ride, no backfiring or popping on decelleration.

I don't know what the idle mix screws are set at. I'll try to figure that out tomorrow.

 

[xschris]

Make sure the carbs are synced

 

[berend2712]

Before I did that I thought I'd check the idle mix screws like you suggested, and I found the left one was only set at 1.5 turns out, so I'm assuming that might have something to do with the issue. Annoying thing is that the thread on the right one is completely stripped so I hope I can get it out with a screw extractor or something. That brass is really soft, I hope it'll work.