Stinkin pod filters xj750 maxim

Alright everyone. I know you guys have been over this 5k times before but once I again I apologize. I have experience building trucks and tuned cars however this is my first bike.
I have a 1982 xj750 maxim
First build, stock motor.
I've seen hundreds of posts about why not to use pod filters and how bad "they suck"
Well before I became a member of this site or started this build I had already chopped the air box up into pieces so let's not go there.
I have 125 Mains and 43s below it in the carbs.
As a DoD employee and contractor for the Army I refuse to let a little 4 inch cone prevent me from finishing this build.
My spark plugs are sooty and black
I can get it to start with starting fluid after a long time of turning over with the choke on but it will not idle. It will stay running for as long as I rev the throttle
Tank is clean, carb rebuild kit is all brand new and I've tried 2 different jet sizes in every dang hole. Someone please tell me why I can not get the lady to idle and why it takes such a long turn over time and starting fluid to fire.
I had 125 fuels and 43 airs and it would start and keep running as long as I would stay on the throttle.
I went down to stock 40 air Mains and now IF it starts, it will only run for a second before it dies. Do I need bigger air jets?
Forgive me for my ignorance
I build M1 Abrams for a living but can't even get my motorcycle to run shame on me
Thanks guys

 

It sounds as if you have the AIR JETS (top side, under the rubber vacuum piston diaphragm) reversed.......the smaller air jet goes in the center of the three holes, the larger air jet goes in the forward (towards the engine) position.

On the bottom of the carb are the FUEL JETS, #125 is not a common main fuel jet size, they typically come in "2" size increments for the main fuel jets, i.e. 120 (1.20mm), 122 (1.22mm), 124 (1.24mm) etc. The PILOT fuel jets do come in 1-size increments, 40 (.40mm), 41, 42, 43, etc.

The #43 size is NOT an AIR JET (up top) size. The stock AIR JET sizes for your engine are #225 for the PILOT air jets, and # 80 for the MAIN air jets. By the way, the AIR JETS do not have the "mushroom head" like the FUEL jets do.............

 

Constant Velocity carbs do not work when used with pod filters. Physics and fluid dynamics trumps your experience.
If you have no intention of putting a stock airbox back in then you can get it to run, but it will never run as well as it should.
Return the air jets to stock (see pic below for corrrect placement)
Bump up the pilot and mains two sizes from stock as a starting point.
Get airbox intake boots to put between the filters and the carbs to somewhat compensate for the lack of an airbox (the airbox boots also act as velocity stacks)

The solution for running pods, and not have fueling issues, is to fit the bike with cable operated carbs, or build a FI system.

 

Ahh I just mean the smaller jet below the fuel main the airs are the 2 jets on the other end underneath with 1 open hole next to them yes?

 

I have the original boots from the air box connected to the carbs between the pods to attempt to suffice but she is still an angry she devil

 

I continously hear about how pods are terrible for these carbs but almost every single xj I see has pods for intake filters so I don't understand how it could've been so simple for them but not for me hah

 

Pods can make a bike hard to start but it should run ok once it's warmed up.
Pods will let in the air you need. The air goes in a little uneven especially going down the road but shouldn't effect it that much.
So if your plugs are black you must be getting to much fuel for some reason. It should run decent with the original jets.
You might try new plugs. if nothing else you would have a extra set

 

Go to factorypro's website and read how to tune constant velocity carbs, if you haven't done so already.

Second, prepare yourself to deal with the seven gates of hell.

Third, verify that your wallet is padded.

Then and only then, contact Chacal to order A LOT of fuel AND air jets. It took me months of trial and error to get my pods and carbs to play nice in Nevada. I have moved to a different part of the states since. And the trials began again.

I'd like to tell you that there is a silver bullet combination that will work for you. I just can't.

What I can say... work out the Max power with the main jets(fuel and air) then the midrange with the needle height. Lastly, work on your idle/low throttle cruise with the pilot jets(again, fuel and air) and properly adjusted with the idle fuel needle.

Have patience, drink a lot, and cuss frequently. Persistence is the key.

 

Some people care more about looks than they do performance.

http://xjbikes.com/forums/threads/new-pool-idea.81761/page-5

 

It will run lean with the original jets. Too lean for comfort.

 

Honestly if I wanted performance I'd get a bigger bike and it wouldn't be shaft drive like I said I've been building trucks and cars for my entire life. But I've worked on this bike with my 7 brothers and my wife so it's more sentimental than it is about performance. If I can get it to idle I can fix it from there.
This build started as 1. 82 maxim midnight special 750 horribly chopped up and not running by someone else and 2. A mint condition 650 maxim with a not-so-mint seized motor.
Then began the swap. The swap has been complete since winter so now I just need her to run.
If so many people say the bike won't even run with pod filters then why do so many maxims run with pods filters... for myself personally it's not about the looks 100 percent, or the performance at all for this particular bike, it's the knowledge learned from taking it down to nothing and building it how I want it

 

It is your bike after all. Just be aware that there will be a flat spot that you will have to live with.
Yes you can run pods. Yes lots of people do run pods on all sorts of bikes that have CV carbs. People do lots of things that aren't necessarily ideal.

Like I said earlier: airboox boots to join the pods to the carbs; bump up pilot and main fuel jets by two sizes as a starting point. Tune from there (get a Gunson Colortune plug to make things a bit easier when setting the idle mixture).

 

K-moe indeed we do like drink beer and smoke cigarettes. Not ideal but we do it anyway ha factorypro basically said throw giant jets in it and work your way down until it worls.... I see not to let the filter boot cover the ovular bent vacuum hole on the carb I'm just curious to see what a REAL MAXIM OWNER THAT DRIVES A DAILY PODDED MAXIM RUNS FOR JETS. everybody says everywhere is different yet I don't see anyone put out any numbers but then the 3 people that did spill their beans said they were running smaller than stock jets to get it to run which doesn't even make sense but hey they said their maxim runs with pods and small jets. I'm just curious is all but people beat around the Bush with this question like it's got AIDS.
Thanks for the insight guys I'll let you know what happens. I'll post a pic of the bike when I put my tires on this weekend.

 

Disclaimer: I do not have pods. I have not made pods work. I DO like the look of pods. Therefore I have done some reading on the subject. Here's a link that may be helpful:
http://www.xjbikes.com/forums/threa...-pods-and-4-into-1-exhaust.29381/#post-251972

 

I'm sorry that you don't like my answers. They are honest and truthful. Machines don't care about anyone's ego; they just work how they work.

Pods lean out the fuel mixture. Fuel jets need to go bigger to compensate. Air jets stay the same. Every tuning change will depend on the condition of your engine and the altitude that you ride at. That's why there are no specific jet sizes that will work for you without you doing the work needed to determine what works for you.

BTW sooty black plugs are a sign of incomplete combustion, and that can happen from being too rich OR from being too lean.

 

doesn't even make sense ....... 3 people gave you answers but you do not like the answers
doesn't even make sense .......... factory pro makes carb jet kits for people who mod bikes tell them what you got you get the jets that may work.
doesn't even mak sense............ factory pro tells you how to tune the carbs but you do not want to go through the process to do it
doesn't even make sense .......... you give someone an answer to the question and it is not what they want to hear

what does make sense is with all the people who come to this site with pods , you would think that they would all post how they had sucsessfuly made the conversion.
so what conclusion do you draw from that ?

"Forgive me for my ignorance I build M1 Abrams for a living." we will not hold this against you every one has to work, ..........................

 

I'm sorry but I side with K-Moe 100% My Seca has the stock airbox and filter...but a Mac 4 into 2 exhaust I'm running 124 main 42 pilot jets runs fantastic ...no hesitation no flat spot will burry the needle on the 85 mph speed ohmmeter...carbs are synched about perfect on my 4 vacuum gauge synch tool. Plugs look good . All that is being said pods can be made to work , but it harder to accomplish.... You stated your plugs are black sooted up, what do you have your mixture screws set at? 2.5 turns out is a good starting point .

 

first off these bikes will start and Idle and rev up with out being connected to the air box.
1) have you done a compression test of the motor? what results did you get?
2) have you checked the valve shims clearance? what were your results? AIRHEAD VALVE ADJUSTMENT with Pics
you have to fix the starting and Idle problem before you can consider fixing the pod problem.
have you removed the carbs and cleaned all the passages in the enrichment circuit, and pilot jet circuit?
3) did you do a bench synch of the carbs?
4) have you measured the wet set fuel levels of the carbs? if so what levels are you running?

look at these links
Something New, Something Naked
very important read
TALKIN' TECH: Various thoughts on various issues

THE SECRET LIFE OF CARBURETORS
and how to clean those carbs
IN THE CHURCH OF CLEAN

and of course this
The Information Overload Hour

starting fluid if you are using it you are likely in one of 3 conditions
1 flooding from carbs
2 plugged up enrichment circuit Starter FUEL Jet and wells in bowls
3 plugged up pilot jet circuit

can you tell us in detail what you have done to the carbs besides changed jets

edit 2 conditions to read 3 conditions

 

Why ask for help here, with all that experience you'll probably do it better yourself...

 

Are you sure every inch of the carbs are cleaned? Sounda like the circuit is clogged. You can check it by shinning a light at one end and try your hardest to look for a pinholw sized light. If you dont then its clogged.

Pods arent the issue here.

 

My downfall is that my experience lies in EFI rather than carburetors :/ k-moe I'm definitely not harsh on anyone's input I apologize if it came off that way I'm a friendly guy just curious what others have done is all my main fuel is 125 somehow or another. I will post a picture of it other than that all I've done to the carbs is clean them and change to brand new jets. My pilot fuel is stock at 40 I think main fuel at 124 or 125. They've been cleaned and taken apart 100 times when I had main fuel at 125 and pilot at 43 it started with ether and ran as long as I stayed on the throttle. When I went down to pilot 40 it would only run for a second no matter how much throttle. I made the mistake of leaving prime on when I took the plug out to check it condition until I saw fuel pouring out of the spark plug hole I ordered about 10 different sets of jet sizes and will report back with my findings when the come in the mail

 

The long golden tube the is not interchangeable and is inside the floats bowl, can someone explain what that is and should I fish some guitar string through it to make sure it's not clogged?

 

Emulsion tube perhaps?

 

A clue!!!
You have a fuel delivery issue that is not related to the jets (though you will still have to rejet for pods). The float needles shut fuel flow off when the float bowls are full. This happens even when the petcock is set to Prime.
Either your float needles aren't sealing, the float seat washers are leaky, or the fuel height was not set correctly. Fuel height does effect the fuel mixture.

How to: http://www.xj4ever.com/setting fuel levels.pdf

 

Also what would happen if you were to try to start the bike with no pod on the carb as opposed to pod on would it still fire and idle if the jets were right

 

You guys are optimistic when the first page to that think says "abandon all hope ye who enter here" hahah

 

That is the emulsion tube. It can be removed with the slide out of the carb and the main fuel jet removed. It can then be cleaned without using wire (usually).

The fact that the emulsion tubes were not removed, and the fuel overflows, tells me that you need to go to The church of Clean, and recheck your work.

 

Optimistic about getting it running, not about getting the fuel mixture correct throughout the full RPM range of the engine.

 

It would still start even with stock jetting. It just wouldn't run very well.

 

The float needle and the hex head shaped hollow bolt with a filter on the bottom of it are brand new and the tang height has not been modified in anyway from stock. The long jet that the needle seats into is brand new so what would cause the needle to not stop the fuel from over flowing out of the carb bowl and into my crankcase and out of the spark plug hole? I apologize for so many ridiculous questions. I've seen many of your names on many many other threads so I definitely appreciate all your guys' help

 

You said I have a fuel delivery problem but if I leave it on prime it fills the entire engine with fuel so I'm a bit confused. Also on other bike I've worked on when it is turning over, the slides move up and down as well so why don't the slides move up and down on my bike when it's turning over? Is that particular to CV carbs?

 

The new float needles are of a different overall height than the originals. The reason why fuel is getting into the crankcase is (most likely) because you did not adjust the float height to suit the new needles. Fuel level is critical, and there is only a 3mm window in which the fuel level will allow the bike to run properly (pods or not, correct fuel levels are key).

The slides on CV carbs are controlled entirely by airflow through the carbs (this is as close to fuel injection as you can get without having fuel injectors). The other bikes you have worked on have cable operated slides, which are lifted directly by turning the throttle.

This is a different carb, so the parts are not in exactly the same place, but the principles of operation are the same:



I posted links to two different threads that will help you address the problems you are having. Please take the time to read them thoroughly.

 

I believe after reading the church of clean and all of your guys posts I owe everyone a drink lol
I believe the hole I did not clean is called the carb bowl starter jet which exactly points to my not starting without starter fluid and not idling problem! I'm about to quit my job because of how excited I am to go grab my carburetors when after doing an entire motor swap including harnesses and so on I've been ready to ghost ride it out into the road in front of the first tractor trailer I see for about 2 months now lol you guys should definitely get paid for all this amazing insight I can't tell you guys how much I appreciate it

 

You're welcome. Now slow down and get it all sorted (including setting the fuel heights)

 

the long rod is part of the enrichment circuit (Starter FUEL Jet) make sure you clean the wells
as i said before
starting fluid if you are using it you are likely in one of 2 conditions ( edit: should be 3 conditions)
1 flooding from carbs
2 plugged up enrichment circuit Starter FUEL Jet and wells in bowls
3 plugged up pilot jet circuit

with fuel coming into the cylinder I would say you have all 3 as a problem

 

bike will start without pods or hooked to airbox, it will rev well but under load is where your problems will start.

 

I'm currently at work on post and have now become the proud new renter of a micrometer and tiny tiny torch tip cleaners hah alright so I'll be annoyed if I find out tomorrow that the needles don't fit in the long jet because they came in the same kit from dynojet. Should I be putting a washer on the needle the protrudes from the slider and diaphragm?

 

Most people say something along the lines of moving the cclip up 1 or 2 notches but I've failed to find such a notch

 

Because there are none on the Hitachi jet needles. There are notches on most aftermarket needles though.

 

You need to add washers between the needle "holder" and the slide in order to raise the needle in Hitachi's.

 

So if I leave my bike on prime and fuel pours out of the spark plug socket in the head then my needles are not seating correctly in the jet, so by putting washers under the needle would I not be worsening the case? And how do I know how many washers are necessary or is that a guessing game based on my jets and intake set up? Is there a possibility the needles aren't seating correctly because they are not broken in to fit right into the jet? I understand these parts are perfectly machined but I hear dynojet is a well known and decent jet kit supplier so I'm weary of what the problem might be if it is not the needles seating into the long jet

 

do not confuse needle valve assembly which is attached to floats with the needle which is attached to the slides and diaphram assemblies

from what you have discribed your needle valve assemblies have failed or are not properly set with a wet set fuel height. or are the floats are sticking when you first fill carbs if floats are sticking you tap bowls with screwdriver handle while they fill to unstick floats
this is how to set fuel levels

Setting the fuel levels

this is you carb jets what I listed in red are part of the main jet circuit and are in the carb from under main jet to the diaphram and slides
Years & Models: 1981-3 XJ750 Maxim, Midnight Maxim, and Seca Canadian models
Carb Manufacturer: Hitachi
Carb Series: HSC32
Carb Model ID: 15T00 (Maxim, Midnight Maxim)
Carb Model ID: 5H200 (Seca)
Main FUEL Jet Size: #120
Pilot FUEL Jet Size: #43
Main AIR Jet Size: #80
Pilot AIR Jet Size: #195
AIR COMPENSATOR Jet Size: #36
Starter FUEL Jet Size: #40 (non-replaceable, in float bowl)
Main jet NEEDLE ID: #Y-14
Main needle JET Size: #3.2mm (the main needle JET is also known as the "power valve" or "emulsion tube").
Fuel Level in float bowls: 3mm +/- 1mm (.118" +/- .039")
Idle RPM's: 1,050 rpms

 

Your problem is with the floats, needles and seats not your main jet needle on the bottom of the piston slides.

 

There's too many things going on here that s/b corrected prior to tangling with pods. Imo take the carbs back to church, return to stock configuration and make it idle; then tangle with pods. Are the valves clearance in spec?

Gary H.

 

Look back at the video I posted. The float needles (float valve in the video) are the parts that keeps the fuel (colored pink) from overflowing the float bowls when the float (floater in the video) rises.

 

That video is awesome!

 

Alright I'll test a few things tomorrow. It would be nice if the bowls were see through obviously that would be stupid though but nice for maintenance in my case. I know that if I blow into the fuel line with a lot of pressure, nothing comes out of the jet holes until I gently push up on the float. But I suppose that doesn't matter

 

That matters some. It tells you that the needles do in fact seal. You do need to set the float height so that they seal at the correct time so the fuel height is within spec.

 

Float height can be checked wet. The proper setting can be difference between running right or too high can make it rich or too low and that be lean.

 

I was hoping that by not adjusting the floats tangs from OEM setting upon my first few disassembles of the carburetor that they would not need adjusting and just replacing the jets and needles would suffice. Tomorrow I'm going to clean out the carb bowl jets and I will report back with my findings you guys are magicians something funny too my baby brother Tank just bought an 82 xj750 for 300 bones my other little brother Junior rides a 99 vmax and my wife rides a 2016 R3 (I think I ride it more than she does) lol