Pod Conversion - Help needed

freiesss

freiesss

XS400 Enthusiast
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Hello all,

Currently my bike (82' XS400 Maxim) is running great but I want to put air pods on instead of the stock air box/filter.

Everything is stock - including my exhaust.

What jets should I order?

If anyone has done this or knows what I should do, your help would be appreciated!

(Also - I think it's currently a little lean when I hit around 7000 rpm with the throttle all the way down)

Thanks!
 
Mixture: A lean mixture is felt as surging. The bike pulls, then doesn't, then does, then... Closing the throttle a bit makes it go away instantly. Many mistake a rich misfire as lean surging. I know I did.

Pods: Reconsider. Unless you are willing to invest many hours testing and tuning, or put up with a bike that doesn't run well, pod filters are not worth it. It has taken me 3 years of constant testing, adjusting, and learning to get my bike to run as smooth as stock. I had to remove the stock air box when I did my suspension modifications, so I had no other option than to use pod filters. Sure, it is now much louder, and may make the same power as stock, but it wasn't worth the effort.

I was speaking with a guy last week who is ready to sell a bike just because of pod filters. There were 3 other old-timers around, all nodding in agreement. They have all learned the hard way, and know better, now... CV carbs don't like pod filters.

If you aren't yet convinced, do a search here and read of the misery others have experienced. Also watch some Youtube videos and listen to how poorly the bikes run. Coughing, spluttering, misfiring... Still not convinced? Think you can easily accomplish what others can't? Then go ahead. Be sure to spend the $ to get good filters like UNI foam filters, or K&N. Then buy a box of quality (not the cheap knockoff) main jets, in pairs, ranging from 117.5 to 135. Consider making stacks to mount the filters onto. Then invest many hours testing, tuning, and taking detailed notes, rather than just riding.

Bottom line: Don't do it.
 
16VGTIDave said:
Mixture: A lean mixture is felt as surging. The bike pulls, then doesn't, then does, then... Closing the throttle a bit makes it go away instantly. Many mistake a rich misfire as lean surging. I know I did.

Pods: Reconsider. Unless you are willing to invest many hours testing and tuning, or put up with a bike that doesn't run well, pod filters are not worth it. It has taken me 3 years of constant testing, adjusting, and learning to get my bike to run as smooth as stock. I had to remove the stock air box when I did my suspension modifications, so I had no other option than to use pod filters. Sure, it is now much louder, and may make the same power as stock, but it wasn't worth the effort.

I was speaking with a guy last week who is ready to sell a bike just because of pod filters. There were 3 other old-timers around, all nodding in agreement. They have all learned the hard way, and know better, now... CV carbs don't like pod filters.

If you aren't yet convinced, do a search here and read of the misery others have experienced. Also watch some Youtube videos and listen to how poorly the bikes run. Coughing, spluttering, misfiring... Still not convinced? Think you can easily accomplish what others can't? Then go ahead. Be sure to spend the $ to get good filters like UNI foam filters, or K&N. Then buy a box of quality (not the cheap knockoff) main jets, in pairs, ranging from 117.5 to 135. Consider making stacks to mount the filters onto. Then invest many hours testing, tuning, and taking detailed notes, rather than just riding.

Bottom line: Don't do it.
Click to expand...

Thanks for the quick response!

The mixture is definitely lean... All the symptoms you listed are exactly what's going on with my bike...
What adjustment should I make? The mixture screw is out 3.5 turns currently.
@16VGTIDave
 
The Pilot (idle mixture) screw adjustment has no bearing on WOT fueling. Be sure that the bike is in perfect operating condition before trying to adjust the carbs. You can't jet for a bad spark plug or valves out of adjustment...

If the bike is in tip top shape, you should be checking the in tank filter, the petcock, then the filters at the float needle seats to ensure proper fuel delivery. Even a kink in the fuel line could cause issues. Then verify the fuel level in the carbs as instructed in the manual. I know you said 7000 RPM, but what RPM range is the surging occurring? If 7000 to 10,000 RPM, which would be getting worse as the revs increased, increase the main jets 1 size. Keep their sizes staggered, just increase to the next larger size. If ~4000 to just below 7000 RPM, check the diaphragms. If good, raise the needles 1 groove. If that is too much, return the needles back to stock and raise the fuel level 1mm.
 
16VGTIDave said:
Mixture: A lean mixture is felt as surging. The bike pulls, then doesn't, then does, then... Closing the throttle a bit makes it go away instantly. Many mistake a rich misfire as lean surging. I know I did.

Pods: Reconsider. Unless you are willing to invest many hours testing and tuning, or put up with a bike that doesn't run well, pod filters are not worth it. It has taken me 3 years of constant testing, adjusting, and learning to get my bike to run as smooth as stock. I had to remove the stock air box when I did my suspension modifications, so I had no other option than to use pod filters. Sure, it is now much louder, and may make the same power as stock, but it wasn't worth the effort.

I was speaking with a guy last week who is ready to sell a bike just because of pod filters. There were 3 other old-timers around, all nodding in agreement. They have all learned the hard way, and know better, now... CV carbs don't like pod filters.

If you aren't yet convinced, do a search here and read of the misery others have experienced. Also watch some Youtube videos and listen to how poorly the bikes run. Coughing, spluttering, misfiring... Still not convinced? Think you can easily accomplish what others can't? Then go ahead. Be sure to spend the $ to get good filters like UNI foam filters, or K&N. Then buy a box of quality (not the cheap knockoff) main jets, in pairs, ranging from 117.5 to 135. Consider making stacks to mount the filters onto. Then invest many hours testing, tuning, and taking detailed notes, rather than just riding.

Bottom line: Don't do it.
Click to expand...
I started mine just yesterday to check my voltage at battery while running, and while voltage looked good, the bike was running like crap, missing and sputtering. I then realized I had removed the air filters to get to some wires, and quickly shut her down. It runs good with the stock crossover and Uni filters.
 
16VGTIDave said:
The Pilot (idle mixture) screw adjustment has no bearing on WOT fueling. Be sure that the bike is in perfect operating condition before trying to adjust the carbs. You can't jet for a bad spark plug or valves out of adjustment...

If the bike is in tip top shape, you should be checking the in tank filter, the petcock, then the filters at the float needle seats to ensure proper fuel delivery. Even a kink in the fuel line could cause issues. Then verify the fuel level in the carbs as instructed in the manual. I know you said 7000 RPM, but what RPM range is the surging occurring? If 7000 to 10,000 RPM, which would be getting worse as the revs increased, increase the main jets 1 size. Keep their sizes staggered, just increase to the next larger size. If ~4000 to just below 7000 RPM, check the diaphragms. If good, raise the needles 1 groove. If that is too much, return the needles back to stock and raise the fuel level 1mm.
Click to expand...
@16VGTIDave
So, would I want to get two 117.5 and two 135? or do you think I should go bigger on the main if I want to try pods?
 
I'm not going to guess what jets you will need as there are too many variables. You will have to go through the testing and see what your bike needs. If you do decide to make your life difficult by switching to pod filters, you can match the jets. The stock jets are staggered to compensate for the airbox design. Don't waste your time or $ on cheap filters. Like most everyone else, I tried them and wasted many hours trying to tune the bike to run decently. And it never did. Also, ignore the jetting the SOHC guys use. The DOHC is a distinctly different engine with totally different fuel requirements.

For what it is worth, I'm currently running 120 mains, needles at lowest position (clips in top grooves), JBM Industries diaphragms, fuel level lowered 2mm, and 47.5 Pilot jets. That is with UNI filters on stacks and HD Sportster mufflers on the stock pipes. Will my jetting work for your bike? Probably not...
 
It may conflict with what your intentions with the pod filters but, if at all possible I would strongly suggest using an "H" pipe or some type of connection between the two carb inlets. This helped me drastically in making consistent pulls when I was tuning my DOHC with pods. By "H" I basically mean a small intake to help smooth air flow from the pods and some sort of cross member to help equalize pressure between the two cylinders. I made mine from PVC, JB Weld, and alot of body filer to smooth things out. However even if you do use such a pipe there will still be alot tuning ahead. Kind of sucks to do it in prime riding season.
 
Tggraff said:
It may conflict with what your intentions with the pod filters but, if at all possible I would strongly suggest using an "H" pipe or some type of connection between the two carb inlets. This helped me drastically in making consistent pulls when I was tuning my DOHC with pods. By "H" I basically mean a small intake to help smooth air flow from the pods and some sort of cross member to help equalize pressure between the two cylinders. I made mine from PVC, JB Weld, and alot of body filer to smooth things out. However even if you do use such a pipe there will still be alot tuning ahead. Kind of sucks to do it in prime riding season.
Click to expand...
Did you make a thread on your H-pipe build?...-would you do one? Or just maybe post photos and some pointers for those of us who are considering doing the same?
 
16VGTIDave said:
The 4th result from a search: DIY/Modded Stubby H-Pipe

You are welcome.
Click to expand...
I know this is am old thread. I've just bought one of these bikes with pods.,wish I hadnt but noticed the previous owner had a piece of fuel pipe running from the stubs where the carbs bolt on .bike ran ok .was told this set up is not the case and something is out of zinc .started Messing about .now the bike won't start .goes to show that some minor modifications work .
 
The carb system was designed from the factory to have independent signaling for vacuum from the cylinders so having them tied together can cause odd behavior. Best to cap both ports (or if you have a vacuum petcock, cap one and run a vacuum line from the other to the petcock). Then you'll want to reset the carb screws to defaults and readjust as needed.
 
thanks for your reply.ive checked the petcock its working fine .I put a temporary tank on ,had the bike idling good .messed about with the screws,capped each carb .I then put the tank on .connected to the petcock was working fine with the vacum..I put fuel in the tank and everything went haywire it wouldn't idle hard to start.took tank bk off set up temporary tank but still wouldn't start.checked filter in the tank it was clean. I've dismantled the carbs checked float height.going to fit ram air filters go up one size on the pilot and two sizes on the main jet.throttle needle up one notch .I'm just waiting on pilot jets arriving .its hard to tune bike with the main tank on .appreciate your advice.
 
Maybe the vacuum diaphragm on the petcock is leaking letting it suck fuel into the one side. I had issues with mine, even after trying a rebuild kit and just ditched it and grabbed a mechanical petcock off amazon.
 
when I bought the bike the previous owner told me to run it on super unleaded fuel and keep the petcock at prime.drove the bike home .never missed a beat but struggled to hit 50mph.there was a pipe coming from the petcock unattached. I msged the owner .told me it was a breather pipe?but found out it is the vacuum pipe .I'm now starting to think is it because I used normal unleaded fuel?the bike certainly ran with the 2 carbs connected and on prime ?
 
tstidham said:
If he said to run it on prime, then he knew the vacuum was broken and either not working or sucking fuel.
Click to expand...
hi fella.thought I'd give u a update. I put super unleaded fuel in .got my self a carb tune.fitted foam ram air filters readjusted float levels .bike started ,ran the engine for 10 minutes. I tuned the bike just listening to the engines behaviour. reckoned I wasn't far away.connected up carb tune .could not believe how much my tuning was out.right side of engine was barley getting fuel ,left side was getting far to much.plug on left was very suity, right plug very lean.i used the carb balancing screw and got them balanced perfect then adjusted idle speed.this also fixed one engine running hotter than the other.took the bike out. runs great up through the gears but between 8-9rpm it starts to kick ,splutter ,back the revs off to 8rpm and its fine .checked the plugs on return, right side perfect, light tan colour, left side quite white,lean.any ideas to why this is happening. I'd also raised the jet needle one notch ?previous owner had already dropped it one notch from stock settings. should I go back to where he had it set or raise the needle further or is the float level to low on the left side.thanks in advance.
 

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