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Hi all, I need help 1977 not starting

Discussion in 'The Garage' started by Niro, Nov 3, 2019.

  1. Niro

    Niro XS400 Enthusiast

    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
  2. Gra900

    Gra900 XS400 Addict

    You will need to look at the plugs. Take them out, wire them to earth with the caps on and check for a fat blue spark.
    Then put them back and try starting again. If no joy take out and see if you have gas getting into cylinders x none (no smell), some (smells of gas and plugs are dry) or too much (plugs are wet).
    If you get a spark and some, it should go. Otherwise you need to adjust carbs.
    I’d also recommend working on your kicking technique
  3. Niro

    Niro XS400 Enthusiast

    Thank you, I have a spark, cleaning the carbs again. Hopefully it’s that.
    Gra900 likes this.
  4. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    The factory carbs are the best option with these bikes.

    Are you pulling the throttle when you kick it over? Are you using the choke lever?

    The float height could be keeping the needle valve closed. Did you get new needles and seats? What parts kit did you buy? Are you using the factory vacuum petcock? Are you getting gas in the carbs and in the combustion chambers? Were the carbs bench synced before you mounted them?

    The BS34 carbs you have came off a good running engine that is installed in my bike.

    Have you checked the ignition points and verified they are in good shape and timed correctly?
  5. xschris

    xschris a lifestyle not a trend Top Contributor

    Are you using stock H-pipe and uni pod style filters? Post some pics of the bike so we can see your setup. Once plugs get wet with gas they will be very hard to start the motor. What's your compression on each cylinder?
  6. Niro

    Niro XS400 Enthusiast

    I did some kicks with open throttle some without, same with the choke, not even close to starting with a kick.
    I did not get a kit, I purchased original Mikuni jets, new float bowl gasket, and new washers for the seats, I cleaned them very well, they look new. They were bench synced, and i believe i am getting gas in the chamber, it smells like it a little.

    I didn't check the points yet, I'm thinking it worked before, should it not at least start and idle/run bad?

    Thanks again
  7. Niro

    Niro XS400 Enthusiast

    No H-pipe, no room for it with the current setup, I am using the mike xs filters, I am ordering UNI today but again, should it not at least start, or start badly? I've tried no filters too, no luck. I don't have the compression numbers with me, but it was about 135 for both, I could have probably kicked a few more times and got a higher number.

    I attached a few images of the filters and exhaust

    Thank you

    Attached Files:

  8. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    You didnt mention new needles and seats? Its definitely worth it to make sure that the points are gapped correctly and they are clean and static timed. Might as well check the valve lash too. Its always helpful to eliminate potential issues that are easy to check and/or otherwise known as regular maintenance. The coils could be reversed, simple stupid stuff is all it takes.

    A bench sync is good enough to get the engine idling and worthy to go around the block. With the carbs installed, loosen the drain plugs to make sure the bowls are filling with gas.
    Gra900 likes this.
  9. Niro

    Niro XS400 Enthusiast

    no new needles, do you think it is necessary? you said it was running before, so again, I'm expecting it to at least start. Same with the points, it was running and starting, not perfect, but worked. The previous owner said he did the points, I have invoices showing he got the parts. I intend on getting into all of these, timing, valve clearance, and some other maintenance, but I first want it to start.

    I also didn't mention new mix screws (the pointy ones) and washers, as one of the originals was bent a little.

    I checked when I removed the carbs yesterday, and both bowls had fuel in them. I will check again when i get home today and reinstall them. I gave them another good clean last night.

    What's there to bench sync other than the air screws, balance, and idle?
  10. xschris

    xschris a lifestyle not a trend Top Contributor

    77-79 xs400 carbs only has needles and springs for the pilot mix screws. Does your intake manifold boots have air barbs for syncing? It will be important they do later on. Your bike looks to be a 78 2-E. Kick only bikes need to be kicked over fast enough for the bike to start. If you go too slow it will flood the motor and foul the plugs. With your intake and exhaust setup it will make things much harder for starting. Going back to more stock setup will be a great performance and starting improvement.
  11. Niro

    Niro XS400 Enthusiast

    I believe my intake manifolds do have the barbs, is it where the vacuum from the tank goes?
    The thing that drives me crazy most is that the thing worked and kicked, I just want to get to the point where it's running, even running bad, before I go back to stock.
    I was also reading that some people say the mike xs filters are ok, is it this model? or should I definitely switch to uni ?

    Im goinig to replace the fuel lines and filter today when i reinstall the carb, you never know, lol
  12. Gra900

    Gra900 XS400 Addict

    Bike looks nice, I have the same 2 into 1 pipe set up. I’ve not got it going just yet = front brake! Tyre etc to finish.
  13. Niro

    Niro XS400 Enthusiast

    Thank you, hope you'll get yours running quickly :)
  14. xschris

    xschris a lifestyle not a trend Top Contributor

    The mikes filters are garbage. In the trash they should go. I had a set for a xs650 and 400 and they stink. What ever filter you go with , stock or uni's the H-pipe is critical for good tuning. Looks like you have an emgo slash cut muffler. Those are a poor option for tuning also. The mac 2-1 headers are ok when you have the mac muffler to go with it.
    Spiffarino likes this.
  15. Niro

    Niro XS400 Enthusiast

    Installed the carb after cleaning again, nothing, kicking dose nothing! push starting shows some signs of starting, but not really starting, just a few strokes again. I really suspect it is something in the fuel delivery (besides the kick issue, which also might be me not knowing how to kick start a bike).

    @xschris Assuming I would like to go back to the original exhaust, what years will fit?
  16. xschris

    xschris a lifestyle not a trend Top Contributor

    I think all sohc 77-82 setups would fit. But with your square head motor I would think you would need to have those type header shims.
  17. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    Are the spark plugs coming out wet or smelling like gas?

    What ever the previous owner said means nothing. All of these components are vital to make the engine run. They arent a "set it and forget it" thing. Points need frequent maintenance. Things like that degrade over time and need constant checking. These are things you need to know and verify for yourself, for your own safety and to make sure the bike runs at its absolute best.

    So far you havent checked timing or points.. You have fuel at the carbs. You say youre getting a spark too.

    If the plugs are wet, you are not getting a spark. If they plugs are dry, timing is off. I cant imagine how fuel would not be going in the engine if theres gas in the carbs. Theres a lot of passages for gas to flow. You should have SOME kind of evidence of fuel or spark.

    Air mix screws are lightly seated and then turned out about 2.5 full turns. Bench sync adjusts the butterflies to make sure they are evenly opening together. Bench syncing mainly evens out the idle and equalizes the carbs during throttling.

    Pour gas in the spark plug holes and kick it over.
  18. Niro

    Niro XS400 Enthusiast

    I agree, its on my list, I will definitely check the points and the timing

    plugs smell a little like gas, will a vacuum leak make starting the bike a problem?

    How much fuel should I pour in the plug hole?
  19. NewHavenMike

    NewHavenMike 1976 XS360C Top Contributor

    Pour in a squirt of gas, like a soda bottle cap full in both sides. If you still have nothing, you cant possibly be getting a spark. If you get popping but no quick idle, then you need to look at the points and verify static timing. If it starts and theres an idle and responds to throttle before it dies, then the problem could be in the carbs.

    A vacuum leak will cause problems yes. No matter what, if you are getting fuel and spark, you should eventually hear a pop or a backfire of some sort when you kick it over, even if the coil wires are reversed and timing is 180 degrees out.

    Its totally a possibility that your battery has no juice.. These bikes need to have a battery to operate and it has to have good volts.
  20. Niro

    Niro XS400 Enthusiast

    Going to try this as soon as I get home!
    My vacuum line from the gas tank comes out of the manifold with the nipple/barb, ill take care of it later.

    Cant be the battery, brand new and fully charged, was one of the first things I did.

    Thanks again, hoping for some progress, at least a diagnostic progress

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