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"Damineding" Carb rebuild kit

Discussion in 'The Garage' started by franticvike, Jan 30, 2023.

  1. franticvike

    franticvike XS400 Enthusiast

    I've got fuel leaking out of my float bowl like a sieve and I'm pretty sure the carbs could use a rebuild. Having a tough time finding a rebuild kit. I see the one at Mixes, but shipping to Canada is absurd ($40+ for an $18 part).

    I searched around and found this one from Damineding. Never heard of them, but the parts look right to my very untrained eye. My gas tank also developed a couple massive rust holes while it was in my garage for two years so the bonus petcock repair kit sounds useful. Anyone have any experience using these?


    My bike is an 82 DOHC Maxim.
  2. CaptChrome

    CaptChrome XS400 Addict Top Contributor

    Fuel leaking from the bowls definitely means you need to replace the float valve and seats in each carb. So, you are thinking about this the right way.

    I don't have experience with the manufacturer of that kit, but I have tried to stay clear of the stuff from Taiwan. I bought and used some rebuild parts from Keyster, which is a Japanese manufacturer and they fit and seem to operate well. Parts might be available from Yamaha as well and you can trust them.

    Regardless of what you buy, I don't think that you need to replace the jets, needle or needle jet unless your bike was showing fueling issues. Taking those things out, cleaning everything well and reusing the hard parts works and you will probably save a bunch of money as well. You really need to get just o-rings, bowl gaskets and the aforementioned float seat and valve.

    My two cents anyway....
    franticvike likes this.
  3. Lakeshadow

    Lakeshadow XS400 New Member

    Looks like a decent option to me
  4. CaptChrome

    CaptChrome XS400 Addict Top Contributor

    FYI - I just looked up some Keyster kits. For your bike they have #K-1526 which includes a float valve, a float seat and o-ring and a bowl gasket. You would need one for each carb. They can be sourced from Sirius Consolidated which I believe has a presence on both sides of the border, so less shipping costs. The incremental way of doing your carbs is to drop the float bowls and clean and replace this stuff in the float bowl as a first step. This solves the problem at hand, gives you some familiarization with the internals of the carb, lets you assess what condition the rest of the carbs are in and limits your cost outlay and scope.
    franticvike likes this.
  5. franticvike

    franticvike XS400 Enthusiast

    Thanks Capt. I pulled apart the float valves and could see some wear on the "needle". The screen part on both also looked quite banged up. I did some searching for the Yamaha parts but couldn't find stock at Partzilla or any similar site. Found what could be the parts on ebay but that's always a gamble. I'll check out the Keyster kit. Cheers.

    IMG_0248.jpg IMG_0242.jpg
  6. franticvike

    franticvike XS400 Enthusiast

    The Taiwanese kit in the mail today. Snapped a couple side by side shots of the float valve and seat, I'll upload them here in case anyone is curious. Swapped out the float valve and seat. Blow tested and seemed to be a good seal. But still getting a leak when I bench test it. Looks like the leak is coming directly from the fuel inlet on the second carb. I put a red circle on that in the last photo. Not obvious to me how to resolve that. Before I tear into it, can anyone point me in the right direction? Thanks.

    edit: I found in another thread that the o rings on the fuel inlet are the likely culprit. Separated the carbs (argh) and swapped all 4 o-rings. The were all hard and dry. For reference the o-ring size is "R-03" according to the kit I have. Quickly put them back together and fuel leak is way way down if not gone. Will try to mount up the carbs over the weekend.

    Note: see update below re o-ring size. R-03 is not correct.

    Attached Files:

    Last edited: Mar 8, 2023
  7. CaptChrome

    CaptChrome XS400 Addict Top Contributor

    Looks good. Remember to check and set the fuel level in the float bowls also (didn't see that mentioned). Hopefully you got the fuel supply leak with the new o-rings.
  8. franticvike

    franticvike XS400 Enthusiast

    I put the carbs on the bike to try and check fuel level with the tube method, but not sure I did that right. Levels look close, but not equal (left looks a bit low, right looks a bit high). Carbs also still leaking and I think from the inlet port. Going to take them back off and reassemble and adjust the tang. For reassembling the two carbs in the rack Is there a trick besides "lay it on something perfectly flat"? Also, is there a way to bench test the float level with fuel? I have an aux tank set up so I can get fuel to the bench, but manual seems to indicate that bike has to be run before checking level with tube method.

    edit: I found a PDF online for rebuilding the Mikuni BS32 - 36 carbs. It says for Suzuki GS but the BS32 looks identical to what is in my DOHC. The tutorial was linked in another thread but the link was dead. I think this is the same file. Here is the link (https://thexscafedotcom.files.wordpress.com/2014/06/mikuni_bs-cv_carburetor_rebuild_tutorial.pdf) and two screenshots that show how to bench set (before verifying with fuel on the bike).

    IMG_0389.jpg IMG_0387.jpg

    Attached Files:

    Last edited: Feb 12, 2023
  9. CaptChrome

    CaptChrome XS400 Addict Top Contributor

    I don't know any special tricks to gang the carbs up. I always just used my third hand.

    Yes, definitely do set the fuel level on the bench now that you will have the carbs un-ganged. It makes it much easier to set the levels correctly. See post #83 in this thread for a pictures of the setup: https://www.xs400.com/threads/81-xs...usty-back-into-rusty.20444/page-5#post-187064
    The correct level from the manual for your bike is 3mm +/- 1mm. Here is the picture from the DOHC manual of how you determine the measurement point.
    I put a dot with a sharpie on the float bowl 3mm down from the flange to make the required level easy to measure.

    Mikuni made BS34s for a lot of bike models from Yamaha, Suzuki and Kawasaki and while the carb bodies were pretty much the same, the internal jetting, the way they were ganged up, the throttle linkages, the fuel piping, the choke and even the float bowls and floats were a bit different. While the general rebuild procedures are good to follow, because of the differences, don’t follow the float setting method for another bike just because the carb is a BS34. Follow the setting method in the factory manual for your bike and model year.
    franticvike likes this.
  10. franticvike

    franticvike XS400 Enthusiast

    Thanks Capt.

    That other thread is helpful. I tried setting fuel level with the carbs unganged, only to realize that the fuel inlet for the second carb is a different size (6mm plastic too small and the black fuel line I have is too big). Just ended up with gas all over. Will have to find a hose size adapter if I want to try that again.

    Despite failing to set levels individually I ganged them back up on a plate of glass. I wanted to check if the nipple / inlet between the two carbs would stop leaking. No luck, pouring a ton of gas from the nipple. I have to think that my generic o-rings are slightly wrong dispite looking identical. The Yamaha dealer here wants $12 per O-ring. Partzilla is $4 each, plus $15 shipping. That price plus the two weeks waiting seems crazy to me. Is there a technical spec on this O-ring that I could take to somewhere like a hose or auto supply store to get a better fit? That rebuild manual that I linked above (I know Suzuki) appears to show something that looks like a spec (I think the size he's listing is 010). Anyone know if that is the same spec as for our DOHC bikes?



    Option 2, I'm not going for a restoration here (PO chopped the rear of the subframe off), so is there another way to pass fuel from the first carb to the second?


  11. CaptChrome

    CaptChrome XS400 Addict Top Contributor

    The SOHC bikes just have a piece of hose between the carbs as each carb has a hose nipple mounted up. I don't know if something like that can be adapted for use on the DOHC carbs (maybe the engine intakes are closer together making this impossible). But, if you can finagle installing a small section of tubing in the left carb with some epoxy and then use a bit of hose, that might work.
  12. CaptChrome

    CaptChrome XS400 Addict Top Contributor

    Also - I just searched on the o-ring part number and then looked at photos in the results. This came up from a Japanese retailer:
    Not that you want to buy o-rings from them, but they at least this might be a better way of figuring the o-ring size. It is not a straight-on photo, but it is better than nothing! Looks like 10mm OD and 8mm ID to me.
  13. franticvike

    franticvike XS400 Enthusiast

    Picked up another grab bag set of O-rings and this kit had the right size, so between new o-rings and the float valve and seat from the "Damineding" kit the leak is fixed. Got the fuel level set (or close I think) and back on the bike. Fires right up now when running from my shop gas tank, no choke (in a heated workshop) and seems to idle fine. Once I started revving it up though I quickly noticed it getting quite hot and saw some smoke developing in the exhaust and coming off the header pipes. I revved it again and it didn't want to come down, very slow to return to idle, so I hit the kill switch to avoid over heating.

    These symptoms seem contradictory. The easy start seems like a rich condition, but the hanging idle and hot running seems like it's lean. The oil has been sitting in it for a good few years so thinking I may just start with that to be safe then check for vacuum leaks.
  14. CaptChrome

    CaptChrome XS400 Addict Top Contributor

    Good you solved the fuel leak. What o-ring size was correct (that might help someone else out having the same issue)?

    Overly hot exhaust and hanging idle are both symptoms of a lean condition. If you have the pilot mixture screws adjusted, the most likely cause is an air leak from cracks in the carb holders or from bad throttle butterfly shaft seals.
  15. franticvike

    franticvike XS400 Enthusiast

    O-Ring appears to be "009" and about a 75 durometer (hardness)

    The carb holders (mount between carbs and engine) appear in very good condition. I've seen bad carb boots on my xt350. I suspect the previous owner replaced these.

    Throttle butterfly shaft seals sounds bad. I'll look into that.
    Last edited: Feb 26, 2023
    CaptChrome likes this.
  16. CaptChrome

    CaptChrome XS400 Addict Top Contributor

    After forty years the butterfly shaft seals are probably worth just replacing. If they aren't an issue, they will be shortly, and I would just replace them on any carburetor this old. It shouldn't be too big of an issue for you since you already know how to pull the carbs and un-gang them.

    Once un-ganged, you just need release the spring pressure on the shaft and an honest-to-god JIS screw driver and very even pressure to get the screws out and the butterflies off of the throttle shafts. You don't even have to open up the carbs. Just pull the shafts, clean everything up and check for wear, put in the new seals (concave side out), put the shafts back in, the butterfly plates back on (use some loc-tite on the screws) and tension the throttle springs. Then bench synch the throttle plates, re-gang the carbs and put them back on the bike.
    franticvike likes this.
  17. franticvike

    franticvike XS400 Enthusiast

    You're probably right about this. I noticed that the vacuum line to the fuel tank was looking dubious so I replaced that and immediately running much better, so that was probably a big part of the leak.

    Here's the bike running right after fresh oil and replacing the bad vacuum line. Doesn't drop to idle quite as fast as I'd like, but maybe good enough to get it on the road and figure out what else will need tweaking in the carbs before I pull them again. Happy for anyone's thoughts on how the bike sounds (non original pipes so exhaust noise makes it a bit hard to hear).


    Moving over to the clutch cable adjustment now. When I put it in gear the bike lurches and dies, like clutch isn't engaged. Cable felt tight though. PO seems to have just cranked the clutch lever adjustment all the way near to max (barrel adjuster all the way out). I removed the front sprocket cover before realizing the main adjustment was through the dust cover - hope I didn't mess up the steel balls when I pulled that off. Anyway, sprocket cover back on and I'm trying to loosen the lock nut but it just wants to push the cable up through the cable access port. Thinking maybe the lock nut is seized and that's why PO cranked the barrel adjuster. Planning to take the sprocket cover back off to soak the nut and then put it in a vice, but I'll search around first for any other options.
    CaptChrome likes this.
  18. CaptChrome

    CaptChrome XS400 Addict Top Contributor

    I think it sounds pretty good! I wouldn't spend any immediate time on the carb seals as a priority (I would eventually do them, but at a time when I might be pulling the carbs for something else). Just ride it and keep track of how the bike responds.

    Fix the clutch adjuster and have some fun.
    franticvike likes this.
  19. franticvike

    franticvike XS400 Enthusiast

    Broke the adjuster lock nut free with my impact driver. I've now adjusted it all the way in and out with no change in the behavior (started with it set to 1/6th turn back from contact). As soon as I put the bike in gear (clutch in) the wheel starts to move. I should add that that the cable action feels pretty good. Guessing this is stuck clutch plates.

    I see a video where a guy recommends just clamping the clutch lever into the bar and leaving it that way for a while to see if it will un stick. I'm going to try that, then maybe revving it up in gear and hitting the brake, as I've just put in fresh oil and don't really want to drain it right away.

    Edit: pinning the clutch lever in for a day with a clamp worked great. Clutch is now free. Found more pin holes in the gas tank unfortunately. Every time I patch the ones I can see and fill it up it seems new ones appear. Got a snow dump last night so a bit of time to wait before I can get it on the road anyway.
    Last edited: Feb 28, 2023
  20. franticvike

    franticvike XS400 Enthusiast

    Right cylinder still seems to be running very hot. After about a minute at idle I start to get wisps of smoke from the exhaust. When I shut it off more smoke wisps out. I took a couple short videos. I checked compression and both sides seem low (100-105), but very similar to each other. No noticeable change with a few drops of oil. Bike starts right up though and comes to idle nicely (which I thought unlikely if valves are way out of spec)

    I'm guessing it's the valves so about to open that up. Any other ideas appreciated



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