Hi all, I need help 1977 not starting

Your valves sound very loud ( tappets). Make you adjusted them correctly. There are threads on this in the forum and specs in the manual. Fix any and all vacuum leaks then sync again. Make sure the oil is 20w-50 for wet clutch bikes. Check your oil level with the bike cold and on it's center stand. It's the only way to make sure it's full.

they sounded strange to me too, I planed on looking at them again. Oil is valvoline 20/50 wet clutch, and seems full. Any suggestions for a more permanent bond and seal for the manifold barb?
I’m going to pick up the throttle spring and new vacuum hose from the dealer tomorrow.
 
Some high temp epoxy will work. Are those manifolds from yamaha? I never had a barb get loose on any of the ones I have used.
 
Every set of aftermarket boots Ive had, the barbs always come loose. When the bike is hot they will be loose enough to pull out with your fingers.

I use a pair of needle nose pliers to hold the barb while I put the caps back on.
 
Barb is bonded with jb weld, works fine for now, doesn't seem to leak.
I did the valves again, broke the valve cover plug, had to wait for a new one
got the throttle spring for the carb
replaced the vacuum hose


It seems to run nicer, a little quieter, fewer vibrations, and maybe a better pull in the mid-range. I did the valves 3 times, the last time i was using a fixed wrench (that i didn't have the first couple of times) and not a ratchet, i feel like the ratchet didn't allow me to stop exactly on the spot (needing to change directions on the ratchet to hold the crank from wanting to spin).

We had a nice weekend high 60s low 70s, so i had 0 starting issues after doing the valves and adjusting the idle and air screws. This morning was a little cold, about 45 degrees, it didn't want to start, not even with starting fluid. Is this going to be a summer-only bike? or not a morning bike?

The right side was a little richer than the left, I am going to look into it.

I think i am also going to check what its like with smaller jets, ill go back to 142.5 main, and see how it feels
 
I am still having a hard time starting it in the cold, it starts, but it takes some work (starting fluid and many kicks). When it's warm, it starts fine, when warmed up it starts on the first kick.

It seems like my main issue is cold starts. When it starts, it rides nice, pulls strong and maintains a somewhat consistent idle speed, not sure if it is masking other issues, but i hear some of you guys saying it starts on the first kick cold or warm and I want that :)

I changed the mains to 142.5 (from 145), it seems like i was running a little rich, synced the carbs, the bike felt great, i could idle it on 1000-1500 and it sounded good. Rode great (no freeway tho), ill do the spark plugs reading after riding it a little more and see what's going on there. (no change on the cold starts)

My choke dust seals are loose, got them new but i guess its the wrong part. Do they have any effect on the vacuum? are they just dust sealers?

Also, I keep reading about the mix screw washers/selas, from what i was reading, I do not have them and do not need them, could anyone confirm that some models do not have them?

Last, my mix screws springs look too short, at 3 turns they almost have no pressure on the screw, at 3.5 they are loose. Could i just stretch them a little ?

Thanks again
Nir
 
Difficulty start in cold weather is the nature of the beast. It can run crappy until its warmed up. This is what old machines do, its all they do. You need to prime the bike before you start it every time unless the bike is hot. Put the choke on and kick it 3 times and then turn the ignition on and start it.
 
I used to get that on a CB650 I had. I synced the carbs and replaced the tired old coils. Sometimes it's two or three little things going on at the same time taking you down the rabbit hole. Have you had any recent carb work?
 
Hi everyone, I'm a new member and owner of 1977 XS400. The previous owner had the mike xs pwk carbs on it, the owner could kick start it every time he tried, I couldn't :( it was idling very high (around 3k), I got it home, and decided to change the carbs back to BS34. I got a pair from a member here, cleaned them, got new jets, gaskets and some other parts, put it back together, and I can't start it (kick start only). There is a new battery in it, new plugs, I've tried push starting it, and you can the engine trying to start, it gest a few strokes and die, not enough to even respond to the throttle.

* right after I installed the new carbs, fuel was leaking from the air filter. I removed the carbs, changed the float height, and it seems to be fine.
* It has a 2 into 1 exhaust and pod filters

Any suggestions? if the carbs are not clean enough will it not start at all?

It was running before the carb change, just not so great, and was very difficult to kick (for me anyway)

Thank you
 
Hey Niro, I'm going through almost the exact same problem right now. I got a stock air box though. One thing that I learned about pod filters is that you should go up about 15 stages from the stock jets. Also one cylinder will be your base cylinder with primary coil. That cylinder is typically jetted a couple stages higher than your secondary cylinder. Reason being is that the primary requires a bit more fuel for intial start up. The air pods reduces all resistance to your carbs giving you a ton more air than what's required, hence needing bigger jets to off balance. You will likely have to experiment with different stages of jets to get 'er bang on. Hard learned experience
 
Difficulty start in cold weather is the nature of the beast. It can run crappy until its warmed up. This is what old machines do, its all they do. You need to prime the bike before you start it every time unless the bike is hot. Put the choke on and kick it 3 times and then turn the ignition on and start it.

Priming it helps, starting in the cold is slowly getting better, or the weather is getting warmer lol
 
Hey Niro, I'm going through almost the exact same problem right now. I got a stock air box though. One thing that I learned about pod filters is that you should go up about 15 stages from the stock jets. Also one cylinder will be your base cylinder with primary coil. That cylinder is typically jetted a couple stages higher than your secondary cylinder. Reason being is that the primary requires a bit more fuel for intial start up. The air pods reduces all resistance to your carbs giving you a ton more air than what's required, hence needing bigger jets to off balance. You will likely have to experiment with different stages of jets to get 'er bang on. Hard learned experience

Hi Big Al
Thank you for your feedback. Im pretty happy with how it rides, I dont have any hiccups or dead spots on the throttle, it still needs fine-tuning, but works well for a 43 year old :)
my main issue is cold starting, I am experimenting with jets now.
Thanks
 
No worries bro. One good thing is that in colder weather I find my xs400 better than my inline 4 bikes I've had lol. Once it warms up you'll be able to get a better idea whether or not the jets are at the right stage. Unfortunately for most older carb bikes the outdoor ambient temperature has to be around 15 Celsius and higher, to get it right. Least ways in Canada anyway where I'm at in the centre of British Columbia
 
Just an update, apparently I had a dying coil which made starting more difficult. It finally died the other day. I ordered one to test and be sure it is the coil, and sure it was. The bike now starts SO EASY, it also got a little warmer here, but I think the dying coil didn't help the cold starts. Should I replace the other coil too ? is it one of those things you do in pairs? I also got a new spark plug wire and caps.

Im back to original jetting seems to work best this way, running a little rich on one side, but i am still fine-tuning it. Overall running idling and starting much better than when I got it.

My next issue is that it feels like the clutch is slipping a little on WOT and high rev, or maybe its something else that feels like a slipping clutch.

Going to finish tuning the carbs this weekend and look at the clutch wire adjustments (I changed the handlebars so maybe i messed up something there).
 

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That's good news that there's progress. Your clutch plates might be done in. What kind of oil are you running?
 
Coils can be tested with ohm meter. The specs are in the manual. Make sure your new ones are the correct spec for points model bikes.
 
Coils can be tested with ohm meter. The specs are in the manual. Make sure your new ones are the correct spec for points model bikes.

Yes, it was tested with a multimeter. I only got one, should I replace the other as well even if still ok? Is this common practice?
 
I usually replace (coils) in pairs and keep the single as a spare. Motorcycle clutches can and will slip when theyre cold. It takes a good 30mins before everything is really warmed up.
 
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