Carb/Exhaust issues

[rugbywarrior89]

Hello all. This thread is continued from: http://www.xs400.com/forum/showthread.php?t=11453

Finally got my new bike on the road tonight, but not quite satisfied with performance. I finally got my headlight working with another relay (Thanks for your help XSChris). The petcock rebuild was a nightmare after all new seals from mikesxs. I kept getting a gas leak from that little slot in the side. I think the configuration was just wrong and I had to take it apart 4 times before that worked. I'm still not sure if its leaking into the carbs, I'm just glad its not leaking onto the floor at this point.

I took the carbs apart and did some maintenance. I adjusted the floats to 26 (1.023 inches) after reading a bunch of threads about it. I also backed the mix screws 2 turns. One of them was completely tighted which I found very odd, I saw a lot of others with 3 but I'm looking for gas saving over power for now. I didn't mess with the jets at all because I'm not too familiar with everything just yet. I built a monometer with a barbell and some hose I had lying around but I had some issues getting it balanced. First off, it doesn't like to idle without choke. I changed the carb holders but no dice. Once it warms up it will idle about 20 to 30 secs before stalling. I also noticed it misfiring a lot. While syncing, I noticed a small flame from the right side every time it backfired. Lastly, there is also exhaust coming out where the pipe and header meet. Tried to tighten and reseal but that didn't work. Could that exhaust leak be the cause of the misfiring? Also when I rev it up, it doesn't always like to come back down to idle. Unfortunately, I don't have a tach to give you the rpms. I already know that I need to clean the carbs, Which I hope to do when the weather gets cold. I guess I'm just wondering If the exhaust leak is most likely the problem or if its the valve clearances that I haven't adjusted yet, or if the carb just absolutely need cleaned before I can start riding it regularly.

On a good note, it ran like a champ revved up and going down the road. Its just keeping it running at idle thats the hard part.

I'd like to here your thoughts...

 

[arfstrom]

I kept getting a gas leak from that little slot in the side. I think the configuration was just wrong and I had to take it apart 4 times before that worked. I'm still not sure if its leaking into the carbs, I'm just glad its not leaking onto the floor at this point.

Okay Look at this site: http://www.maxim-x.com/petcock.html This guy checking out my solution. HAP, Otherwise I am sure I have posted my pics at http://www.xs400.com/forum/showthread.php?t=8033&page=2

I took the carbs apart and did some maintenance. I adjusted the floats to 26 (1.023 inches) after reading a bunch of threads about it. I also backed the mix screws 2 turns. One of them was completely tighted which I found very odd, I saw a lot of others with 3 but I'm looking for gas saving over power for now.

On the outset, set it to 3. Its guaranteed to work. Once your have it running, then run set it when you ready to optimize. I have found that hasn't helped me. 26 sounds right. its been a while.

I didn't mess with the jets at all because I'm not too familiar with everything just yet. I built a monometer with a barbell and some hose I had lying around but I had some issues getting it balanced. First off, it doesn't like to idle without choke. I changed the carb holders but no dice.

I am in favor of the boiling, since I dont remember if you have or havent done it yet, You may be another one of the hundreds of us, that had to do it again. There are carb dips. Now my problem is I am really forgetful, I will sync, and balance, then put it all back, and forget to put the rubber air thing on the nipple.

Once it warms up it will idle about 20 to 30 secs before stalling. I also noticed it misfiring a lot. While syncing, I noticed a small flame from the right side every time it backfired. Lastly, there is also exhaust coming out where the pipe and header meet. Tried to tighten and reseal but that didn't work. Could that exhaust leak be the cause of the misfiring?

Nope, more proof that you need to clean your carbs again.

This link is awesome, If I would have followed his advise 2 weeks ago, at the bottom of this article, I might still be able to drive my bike this week, and he has rock solid info.
http://www.dansmc.com/compression_test.htm
http://www.dansmc.com/carbs2.htm

Also when I rev it up, it doesn't always like to come back down to idle. Unfortunately, I don't have a tach to give you the rpms. I already know that I need to clean the carbs, Which I hope to do when the weather gets cold. I guess I'm just wondering If the exhaust leak is most likely the problem or if its the valve clearances that I haven't adjusted yet, or if the carb just absolutely need cleaned before I can start riding it regularly.

Don't wait, just get it done. Alot of our bikes do that high idle. mine did, there are a few remarks on here that state they let out the clutch while sitting at a light, or what ever. I have seen everything from add a viton washer in the pilot screw hole. to keep cleaning the carb, resync, and lower the idle screw.

On a good note, it ran like a champ revved up and going down the road. Its just keeping it running at idle thats the hard part.

I'd like to here your thoughts...

 

[rugbywarrior89]

Yeah your right. I guess I will just bit the bullet and see about getting them cleaned tonight.

I do have another question. Do all the jets just get tightened down completely or do the all need some sort of adjustment? I know thats a newb question, but the only carb work I have ever done was on a 2-stroke atv. I have read the manuals ant they only talk about adjusting the mix screw so I would assume you don't but I just want to make sure. Also, when I boil it should I remove the jets or just leve them in the carb?

 

[16VGTIDave]

When you boil the carbs, strip them down, with the exception of the throttle plates and shafts. Have a look at an exploded diagram of the carb so you get everything else removed.

Tighten all the jets snugly when you are assembling the carbs. Be careful with the pilot screws. They should be very gently seated and then turned out 3 turns to get the bike started. There are plenty of threads here with tuning instructions.

 

[rugbywarrior89]

When you boil the carbs, strip them down, with the exception of the throttle plates and shafts. Have a look at an exploded diagram of the carb so you get everything else removed.

Tighten all the jets snugly when you are assembling the carbs. Be careful with the pilot screws. They should be very gently seated and then turned out 3 turns to get the bike started. There are plenty of threads here with tuning instructions.

Boiled the carb last night. Worked out pretty good... until the small sauce pan with all my jets and internal metal ran out of water and burned. It left black crap packed into every crevice of my internal parts. It must have taken 1.5 hours to clean everything. I reboiled and wired out the jets, carb cleaner and air. Got it all back together and it runs much better. Idles fine, got the carbs synced but now I have a new problem. I think the PO soldered around his float and i might have melted it off last night in the burn because I stopped for gas then went to the store. When I came out of the store there was a ton of gas coming out of the left carb air intake . I wonder if the float is getting gas in it and sinking instead of stopping the gas flow.

The other problem I have is taking off from a stop. Unless I take off at 4k rpms, it just spit and sputters and has no power. If my float theory is correct, then I wonder if its flooding out the cylinder until it gets revved then works fine. I think I'm going to buy new floats (and float needles while I'm at it) and see if that does the trick. Also, I haven't checked the valve clearence. Would that cause these issues?

 

[16VGTIDave]

Sounds like you are on the right track. See how it runs after you get the floats replaced and set properly. You should check the valves and make sure they are adjusted correctly before you tune and sync the carbs.

 

[rugbywarrior89]

Sounds like you are on the right track. See how it runs after you get the floats replaced and set properly. You should check the valves and make sure they are adjusted correctly before you tune and sync the carbs.

Can I replace it with the plastic floats on mikesxs? Is that recommended over brass?

 

[16VGTIDave]

As long as they will fit your carbs, there will be no real difference. The lighter weight plastic floats may bounce less when you hit a bump...

 

[rugbywarrior89]

thanks. unfortunately I have a 1982 SOHC which always seems to be missing from part fits lists. It always says maxim and SECA but never heritage special. Does my bike go by another name that I should be aware of. If not, should I look for parts under the 70-79 SOHC catergory or the 80-83 DOHC catergory. I'm kinda confused about that.

 

[xschris]

Most of the 80-81 stuff will work on your bike. Or ask one of us we can help

 

[xschris]

I prefer the brass one as they don't take up as much room in the carb bowl as the foam ones do. I think it was another emissions thing to limit the amount of fuel used I have one if you need one $12.50 shipped (This is another reason I don't boil carbs heat+ soft metal and rubber = bad)

 

[rugbywarrior89]

I prefer the brass one as they don't take up as much room in the carb bowl as the foam ones do. I think it was another emissions thing to limit the amount of fuel used I have one if you need one $12.50 shipped (This is another reason I don't boil carbs heat+ soft metal and rubber = bad)

You got a set of float needles/O-rings as well. I may as well take two of each if you got it. Also, how much for a working petcock? I used a rebuild kit from mikesxs but I don't think it worked, or could I send you mine to rebuild again cause I know petcocks aren't cheap? As of now, my form of OFF is a pair of vice grips.lol

Also, I need the pins that hold the floats. I kinday bent mine a little bit taking them off and on so many times.

 

[xschris]

Sorry no pins or o-ring or petcocks. Maybe take a pic of your petcock and we can see if something stands out wrong. These are my last two floats I have to sell $22.50 if you want them.

 

[rugbywarrior89]

Alright. I'll take them.

Also, would these be the correct float needle assemblies: http://www.mikesxs.net/product/48-1445.html
I was looking yesterday and there was no O-ring at all on the brass piece. I didn't look at the other carb but I would guess its the same way. I'm surprised the other one wasn't doing the same thing.

I was wondering if maybe I shouldn't get new main and idle jets as well at some point. The PO took off the stock exhaust and put on slip on mufflers. Keep in mind I don't know a whole lot about mufflers. The bike sounded like a rocketship which my wife and the neighbors didn't really care for when I was syncing carbs at 11:30pm. I took out the baffles and found that the end of the baffle wasn't closed off so the exhaust could go straight through the pipe without being redirected through the small holes of the baffle. So I put washers in the end of the baffle then I packed the muffler with stainless scrubbing pads around the baffle before putting it back in. That quieted it down significantly and the decibels are perfect for what I want now. However, I don't know what kind of impact that would have on the jetting. any ideas of what sizes I would want to get? Also I have Aftermarket air filters. Thanks for the help.

 

[xschris]

Those valves will work. I would start with 45 pilot just and 142.5 mains it would be a good start. The air filters you show are the worst ones to use because of the lip on the inside that blocks the pilot air jet. If you use them you need to use the stock H-pipe so there is no blocking.

 

[rugbywarrior89]

Those valves will work. I would start with 45 pilot just and 142.5 mains it would be a good start. The air filters you show are the worst ones to use because of the lip on the inside that blocks the pilot air jet. If you use them you need to use the stock H-pipe so there is no blocking.

Perhaps I can Macgyver a way to keep those air jets ope without the H-pipe. I will look. Also, does that nub in the middle there go to the tube sticking out of the crankcase? At the moment that tube is just sticking out of the engine. What should I doe with that tube? Should I close it off or put a filter on the end of that somehow?

 

[xschris]

The hose or "nub" is for the crank case vent. It is good to have it hooked up but you don't you should at least put a filter on it to keep junk from getting in there.

 

[Scorpio1963]

Rugby I recogmend getting a different kind of pod filters if your going to hook those up directly to the carbs.Spend a bit more cash and get a set of good quality filters.

 

[rugbywarrior89]

Thats what the bike came with so I don't have the OEM air box or h-pipe. What aftermartket would you recommend that goes straight to the carbs?

 

[xschris]

Uni filters are good they have no lip and can be oiled for great filtering. K&N Pods that use cotton gauze are good because they can be oiled or charged as some call it. If you can avoid the "gray or red mikesxs" style pods do it they can't be oiled well because they don't use cotton as a filter but a cheap synthetic material. If you want I can sell you the H-pipe that I showed you.