Stupid pod issues/ decelerating issue.

[Nolanb]

Hey guys, I have 81 xs400 that has the battery box (if you will) chopped up so I can no longer use the stock air boxes and H pipe. It has 48mm emgo pod filters directly mounted. I have bigger mj's(150) and pj's(47.5) does good starting and idle. One issue I am having with it is the bike is not decelerating like it should when I am rolling or off the throttle. The rpm's stay up and hold sometimes for a good bit and other times for short time then rpms will come down slowly.. any help/knowledge is greatly appreciated. Hate that I had to start another pod thread.

 

[xschris]

Ditch them pods and get a H-pipe and put black foam uni's on the ends. Go back to stock jets and go from there. Is your exhaust stock or cut up? You can get a stock air box and battery holder if the frame has the stock mounts still.

 

[Nolanb]

Exhaust is still stock. Have H pipe still. Which I intend to use once I got it more dialed it. I have been considering doing pretty much what you suggested... just I feel made it so close. I'd hate to scrap it and start over. Currently googling the uni's, thanks chris.

 

[NewHavenMike]

When a bike runs well cold and gets worse as it warms up, this typically means that you are running too rich. RPMs that hang usually means theres an airleak, or your throttle cable is sticking. Make your throttle cable adjustments at the carb and leave the cable adjustment slacked at the throttle grip.

And dont even bother getting things dialed in until you have finalized your running setup. Youll just have to tune it all over again when you change something.

Anything that is changed in the engine, youll will need to retune and make adjustments.

Use the H pipe, and find a way to mount your filters on that. That will be the best non-stock airfilter mod you can do, and you will not see any true benefit other than the look.

 

[onekallo]

Not trying ti hijack but have a similar question.

I have a dohc with stock jets, stock air box and the Mac 2-1 pipes. I haven’t had enough time yet to see what it’s running like but it sure doesn’t seem right.

I toyed with the idea of switching to Uni’s or Pods and keeping the H pipe, and was thinking if I should be rejecting for the pipes, why not do it for the Pods at the same time.

My thought was that more free flowing aftermarket pipes would need more fuel, but would also need more air than stock air boxes too?

 

[NewHavenMike]

If you change anything at all with the engine, the first thing you should do is get new plugs and put a good 50-100 miles on. The bike must be in top running condition.

You need to read spark plugs. Plugs will tell you all about whats happening in the combustion department.

Sometimes you can tell right away. You should be able to narrow jetting down to 2, maybe 3 sizes. One of them will run the best, the other 2 will be OK.

There is NO exact formula for jetting based on what modifications are done. Theres just too many variables. It is not a “plus one, minus two” step process. At least thats what I believe...

Start tuning from full throttle redline, once you are satisfied with that, that will determine your main jet. You will adjust needle height and then onto pilots and then float height. All settings will start out as stock sans main jets.

 

[onekallo]

If you change anything at all with the engine, the first thing you should do is get new plugs and put a good 50-100 miles on. The bike must be in top running condition.

You need to read spark plugs. Plugs will tell you all about whats happening in the combustion department.

Sometimes you can tell right away. You should be able to narrow jetting down to 2, maybe 3 sizes. One of them will run the best, the other 2 will be OK.

There is NO exact formula for jetting based on what modifications are done. Theres just too many variables. It is not a “plus one, minus two” step process. At least thats what I believe...

Start tuning from full throttle redline, once you are satisfied with that, that will determine your main jet. You will adjust needle height and then onto pilots and then float height. All settings will start out as stock sans main jets.

Ok thanks for the help. Is there a certain style of cone filters you guys would recommend to use with the stock H pipe? I figure I get everything visually the way I want it all mocked up and then try and get it dialed in and running properly before tearing it down to paint and finish everything.

 

[xschris]

Not trying ti hijack but have a similar question.

I have a dohc with stock jets, stock air box and the Mac 2-1 pipes. I haven’t had enough time yet to see what it’s running like but it sure doesn’t seem right.

I toyed with the idea of switching to Uni’s or Pods and keeping the H pipe, and was thinking if I should be rejecting for the pipes, why not do it for the Pods at the same time.

My thought was that more free flowing aftermarket pipes would need more fuel, but would also need more air than stock air boxes too?

Your bikes look to be a sohc one. Black foam uni's are best for pods. If you still have stock boxes those will work even better.

 

[Nolanb]

Is it uncommon or bad to run differ size mains in the carbs or should I adjust my needle height.... Because before I put my current jet size in, I pulled plugs and the left side is rich and the right is lean.... I intend to use my H pipe after hearing see everyone on here recommend doing so. I had a hell of time finding a throttle cable for it. I got one from d2moto, and it was do not fit right going into the kill switch housing. I do not feel it sticking and seems to snap right back.

 

[NewHavenMike]

150 mains seem insanely huge. Did you check the valve clearance? Do you check timing? Did you get the carbs synced? If you havent verified all of this first, youre just going in circles.

Adjusting needle height is a secondary process.

 

[Nolanb]

I had 142.5's in and it could not get up past 6.5k rpms. Have not checked valves. Timing is good. The carbs were both benched and dynamic synced with the 142.5's. Not currently, literally just threw them in.

 

[NewHavenMike]

Youre wasting time.. CHECK the valves lol. Its something you need to do anyways. I adjust to .006 IN and .008 EX.

I run 360 carbs so the jetting is a bit different.. But I finalized at 130 mains, stock is 135.

Youll probably never get it good enough to where youre happy with the aftermarket filter set up, itll just run OK....Meaning that you wont be able to open up the throttle and youll just have to take it easy shifting at 6000 rpms. What did the plugs look like with the smaller jets?

Also, with modern fuels, reading plugs is much more difficult. They will always color light ashy gray and the porcelain will be a flat white when youre running well, it may appear to be running leaner than youd like. The easy indicator is if its all black and sooty for running too rich.

I put miles on spark plugs and get a reading based on how the bike feels in the entire RPM range and in combination with the plug chop. I also have a ColorTune so observe idling conditions but I barely ever use it. A real plug chop is you pulling over on the side of the "track" and changing in new plugs and then running the bike up to redline and cutting the off right there and coasting to a stop. Take plugs out and put the old set back in. Thats the most accurate way to get a reading.

Heres one of my chops I did for fun after one of the carb floats broke and the engine was acting up on my way home:


As you can see, the bike was running perfectly until the float broke, which is evident on the porcelain.

 

[xschris]

Valves should be closer to .004 intake and .007 exhaust (sohc xs400) cold. Plugs should be BP7ES with resistor caps Or I use BPR7EIX iridium's with non-resistor caps.

 

[NewHavenMike]

That photo is from my 360 block and explains the BP6s.

I always adjusted valves in the middle/slightly loose. Same thing with points. Honestly, it never occurred to me to try different settings. I just set them equally and didnt worry about it. Ill try the min settings next oil change.

Also, it is a very rare case that you need to use different size mains. There was a Yamaha or Honda that did this from the factory due to some airbox restrictions. I wouldnt recommend this unless you actually bring the bike to a tuner and run it on the machines and rare case you need to have different sizes.