Rough Idle and Flat spot

I have an 85 Maxim X. I just purchased it a few weeks ago. It ran a little rough, so I changed the plugs, but it still ran the same. The bike does have pod style filters (bought ths way) and after looking around here I see that not too many people are keen on them. I just want to get the thing running decent so I can enjoy it for the rest of summer. It will barely idle, and when riding it seems like it hits a wall at about 3500 RPM. You can power through it, but I know it shouldn't be this way. Do I need jets, a carb sync, valve adjustment or what? I don't have a ton of money to spend at the dealer and I am pretty mechanically inclined. Is there anyone in the Chicago area that could help, or just anyone on here that could start me heading in the right direction to resolve this issue. Thanks

 

I am not entirely sure but it may be the carbs. I am having a similar problem with my 86 XJ air-cooled and and have been told by an experienced mechanic that mine is in the carbs.

Keep us posted.

 

are the carbs operating room clean?
if so...
it sounds like a mixture issue caused by the pods
you can tune pods but it can be a PITA

the carbs need to be synced no matter what the issue is...
http://www.xjbikes.com/Forums/viewtopic/t=2132.html

also seeing as you have new plugs running some plug chops will tell you what is going on with your mixtures.

 

The carbs look pretty clean and the dealer I got it from said that they cleaned them. BTW the bike has 45000 miles on it if it makes a difference.

 

If you bought the Bike from a Dealer ... I'd take the bike back to the Dealer and tell them it don't run right!
Of course, they knew that when they sold it to you.
They were probably very happy to sell you the bike with those Pods on there and probably gave you a great deal.

Now, you are holding the bag.
The problem is the Pod Filters ... BUT, I think your Bike has Mikuni Carbs on it.
You should go back and explain that you learned that Bikes with Pods rarely run right without extensive re-jetting and have them do it for you.

They KNEW that!
Now you know that they knew and have a strong position from which to demand they make it right --> EVEN if it means they REMOVE the Pod Filters and restore the Bike back to an airbox and Boots feeding those Carbs.

They knew.
You didn't.
Now, ... you know!

Make them go through the process of tuning the bike to a condition that will be mutually acceptable or return the bike to stock and tune it up right!

Get it tuned-up right or get your money back.
Tell them they knew and you want a bike to RIDE ... Not spend forever and a day trying to get it to run right.

You got hosed in my personal opinion.
Unbelievable.

 

I wish it were that easy. It is a 23 year old bike that was sold as is, although they did not alow me to test ride it. On the other hand I got it dirt cheap. I was just hoping to get it running right. Will I need a YICS tool to do the sync? If so, where exactly does it go? And yes, the carbs are Mikunis

 

You own a Maxim-X.
It's a performer.
5-Valve, Liquid-cooled and fast.

Because some lame-brain modified it by losing the airbox and adding Pods so it would LOOK Cool ... it runs funny now.

My very best advice is for you to do an extensive search and find and airbox, boots and clamps.
Get what you need to return the bike to its stock configuration and you'll be able to make THAT 5-Valve Max-X run better than anybody will be able to make it run with those Pods on there.

Simply stated: Your Maxim-X was de-tuned when the Pods went on.
If you feel confident to remove the Carbs and begin a series of experimental re-jetting sessions to attempt to get your bike to run a little better than it does right now ... you can follow the advice of those who insist it's possible to achieve tuning the bike for good performance from Idle right up to the Red Line.

Personally, I'm not convinced that anyone has the Magic Formula to actually get the bike fully balanced "Air~Fuel Ratio" wise to go from Idle right up to the end of the Tach without suffering either a Mid-Range or Wide-Open performance issue that cannot be corrected without addressing the need for a variable Main AIR Jet Supply.

If I were you ...
I'd restore the bike.
Put an airbox and boots back on it.
Stock jets.
Tune it up right and have fun going fast without worrying about welding a hole through the top of a Piston and having Summer come to a screeching halt!

 

I would not mind doing that, but is the airbox for the X different than the regular 700? I have seen airboxs on ebay, but they are from the non X version and I was not sure if they would fit. Also, when doing the carb sync, do I need the YICS tool for this motor? I do not see any place where it would go. Thanks Rick

 

No YICS.
Lots more Valves doing the Induction.
Tuned right: Faster than a 750 and Liquid Cooling too.
Great machine.

I googled the Yamaha Part Number for airbox:
http://www.boats.net/parts/detail/yamah ... 00-00.html

 

All related Airbox and components:

http://www.boats.net/parts/search/Yamah ... parts.html

 

Maybe ease up on the name-calling there, Rick. There are plenty of members here (myself included) who choose to run pods on their bikes, even if it doesn't jibe with someone else's idea of what's right and wrong. It isn't necessarily an indication of cerebral lameness.

Now spending two years Q-Tipping the fins on a field-find? That's another story... :wink:

 

X85.

There's a guy parting out an X on eBay. Pretty good prices, but he seems to be taking his time listing everything. I'll pm you his address and maybe he'll list the airbox for you if you ask.

 

Please accept my sincere apology for typing "Lame-Brain" in the Post concerning the modifications found on a Members Maxim-X.

I am sure that the Community knows that the remark was not intended to label ALL the "Pod Boys" when I used that cliche' to express my opinion of the one and only one person at whom, in my opinion, that remark is befitting!

Actually, "Lame-Brain" wound-up in the Post after I edited myself several times having used other terms that would have violated the sites Terms Of Service, and I quite successfully Moderated myself down to that choice which was the lesser of evils and didn't contain the profane expression originally typed that would have been a genuine cause for complaints about my language in a Post!

To our Membership's "Pod-Boys" ... no offense.
I'm sorry if any of you were upset with me for saying: "Lame Brain".
I didn't mean YOU!

Unless, of course, YOU are THE Guy who yanked the Airbox off that Maxim-X I was talking about, and are singularly responsible for putting-on those Pods on an Engineering Marvel!

I meant YOU, stupid!
I know you ain't a Member in here.
No self-respecting XJ-Biker would have parted with that Bike.

Does that cover it???

 

Since you already have the pods there is a thread on here where a guy made an intake of pvc joined all the carbs and only used one pod filter. the pvc fittings aren't too expensive and it may get you by until you can locate a proper box or it could restrict the flow down to an acceptable amount and it will run fine. I can't remember if it was in the mod section or here if I find it I will put a link up for you.

Found it:http://www.xjbikes.com/Forums/viewtopic/t=10891/highlight=triumph.html

 

Thanks for that link. I built a PVC airbox similar to that one and the bike does seem to pull harder and not hit that flat spot. However, it still idles poorly, if at all, without the choke on a little bit. I pulled the plugs, they are just a little bit tan, maybe still a little lean. I will follow Rick's advice and richen up the pilot screws a miniscule amount. In any case, would the carb's being out of sync cause the idle problems?

 

If they are way out of Sync the Idle won't be steady and it will tend to "Hunt" for a place it would like to be steady.

If you did a decent job Bench Syncing those Carbs; you might be able to get a steady Idle by adjusting the Pilot Mixtures some.
If you have one or two a little bit more Rich or Lean than the others; you get the same results.

The bike won't Idle steadily. But, the situation will be correctable by tweaking the Pilot Mixtures to be more in balance.

Having the Pods on there is going to make getting everything balanced quite difficult. The bike is getting way too much air than its supposed too.
Finding a solution to the Mixture Puzzle presented by having Air Pods on there is difficult; at best.

Having Mikuni Carbs which have a wide variety of aftermarket Jets for Race applications will allow you to change all your jetting around to bring the bike closer to fine-tuning than those of us running Hitachi's.

It takes quite a bit of trial and error and having to remove the Carbs each time to exchange the Fuel Jets each time can get pretty old and wear you down.

 

you have tried to turn the idle screw up a tad and see if it gets better? it hangs down under in the middle of the carbs. if you are barely tan then you are prob a tad lean still tweak the screws out just a hair as rick would say about or maybe less than the width of a dime. THen I would run it Not extremely hard but run it does it feel better?? recheck plugs and continue the process until you are satisfied with the results.

 

The bike does seem to run better with the pvc intake, but as the bike gets warmer the idle gets worse. When its warm, it will not idle without the choke no matter where the idle screw is. When it is like that, everytime I twist the throttle it dies, even if I try doing it gently. Is this still the pilot mixture or something else? Thanks for all of your help

 

Trying to do the carb sync, but even following Rick's old school method, I can't get the guage to stop fluctuating until about 2000 rpm. Plus, like I said before as the bike warms up, it idles worse and dies if you twist the throttle. Doesn't this mean that it is running rich, even though the plugs are only a little bit tan? Thanks

 

The guage won't stop fluctuating. You need to be sure you have a restricter in there to minimize the fluctuation.
When the fluctuation is sufficiently minimized ... the vacuum that's being pulled is where the guage needle is highest.

It does not mean that you are running Rich IF the Plugs are tanned.
It just means you have the rev's a little too high to be doing the sync.

See if you can adjust the Idle Rod out a bit to get the engine to Idle around 12 or 13-hundred while you are doing the readings.

 

I guess I need to clarify. I built the restrictor and used the filter just as you described, but the guage fluctuates "wildly" until about 2000 rpm. Also, I understand that plugs being tan does not mean that it is rich, but I thought I read on here that if you twist the throttle and it dies then it is rich(which is what is happening on my X after it warms up). Did I misread this somewhere? Thanks for all your help, hopefully I will have this worked out in the next day or two and be back on the road.

 

This is what to expect for awhile until you get rejetted for the Pods.

The Bike will Idle on the Pilot Jets until the Cows come home.
The instant you open the Throttles your Intake Mixture is almost all Fresh Air without enough Fuel to keep the engine running.

You are going to have to compensate for having too much Air and not enough Fuel.

There is a fifth dimension beyond that which is known to man. It is a dimension as vast as space and as timeless as infinity. It is the middle ground between light and shadow, between science and superstition, and it lies between the pit of man's fears and the summit of his knowledge. This is the dimension of imagination. You arrive here by removing the airbox and installing individual Pod Air Filters.

It is an area which we call the Twilight Zone.

http://faultgame.com/images/twilzone.wav

 

Well I found a stock airbox today, so I will try this out. Will keep everyone posted