Problem or not?

Ever since I got my 82 Maxim 650 10 months ago I have been trying to locate the source of an annoying hesitation. Until the bike is very warm it has big hesitation when opening the throttle quickly and does not idle very well. Eventually (10min. later) the idle creeps up to where it should be and all is fine. My dad and I have been through the carbs twice and couldn't find a problem. I did, however, notice that the pilot screw plugs had pilot holes in them like they have been off before.

I have a lot of experience riding dirt bikes and the thing I don't understand is even when they were not at "full" operating temp yet they still reacted nicely to the throttle. My bike doesn't hesitate at all when the choke is on. Any ideas??

 

When was the last valve adjustment? That's a common symptom on the kawi board - I've never let mine get far enough out to get that though.

 

It sounds like you need to richen the idle mixture a little.
Screw the pilot needles in all the way to seat GENTLY and count the # of turns.
Add a 1/2 turn when you reset them.
If that does the trick, you should be fine.
You can fool around with the mixture until you are happy.
Make additional adjustments in 1/8 turn incriments.
Basically you want to start rich and work your way lean.

Nachoman

 

Does anybody about how many turns "out" the pilot screws typically are from seat? I only had two that were the same.

 

Stock bike should be around 2 1/2 turns out.
What were your settings?
If yours were all over the place, you'll probably need a carb synch as well.
There is no way to get them synchronized with the pilots all screwy.
If you need to take it to a shop for this, make sure they know what a YICS tool is if your bike is so equipped.

Nachoman

 

I agree with checking the valve clearances. But I can tell the main thing you need is a colortune and sync. I know from experience that a colortune is the only way to know that the idle mixture is set. I see you are in Washington, how far to San Francisco for you? There is a carb clinic there Sunday.

 

Two of the carbs were 4 turns out, one was 4.5 and the other 3.5. Would it help to even them out to about 3 each and then in turn bump up the idle? I'm just learning about carbs, but it seems like a lack of fuel problem and not to much? I appreciate everyones imput very much. Also, any idea what a valve adjust runs ($$) these days?

 

I agree that mixture and carb synch should be checked - you say it is a pig when cold. Why not pull the spark plugs after starting it and see what they look like. Remember that and after you finish a normal ride (enough to full warm the bike up and have some fun) check the plugs again.

How long have you had the bike? How many miles are on the bike?

 

Wow, thats wierd.
What is the bikes state of tune?
Intake modifications?
Exhaust modifications?

If you were still getting a lean hesitation at those settings, I would pull the carbs and clean them to be sure.
The float heights may need setting.
Also check the carb boots for cracks, you may be getting a pretty significant air leak somewhere.
You could possibly get away with removing the idle mixture screws and spraying carb cleaner down there and then blowing through them with compressed air.
Be careful though as there are very small washers and o-rings that seal the needle which can get lost easily.

If your airbox is stock as well as your exhaust, I would set the pilots at 2 1/2 turns out (that is full 360 degree turns, not 180's), and see whats what.
If the hesitation is still there or worse, pull the carbs and clean them out.
Good time to inspect the boots as well.

Nachoman

 

I'm more curious about the tempature of the engine effecting it's performance. With Kawasaki's I've had more experience with this cold blooded temperment was almost always linked back to valves...

I realize tempature will also effect it's firing behaviour... and that it could quite likely have carbs that aren't synced and all kinds of other little parts of the puzzle.

A month ago someone was talking about how a cold engine differs from a warm engine with regards to poor mixtures and carb balance... if they could step in and repeat it for the original poster's (and mine - I forget!) benefit...

 

Basically, I am suggesting a return to baseline settings and diagnosis from there.
Carbs are arguably the easiest tuning option there, with the most possibilities for problems.

Nachoman

 

oh - I'm not disagreeing - I think that is a good place to start. More background on the bike would also help...

 

Here's what I know about my bike...

1982 Yamaha Maxim 650

Only 14,000 mi.
The guy I bought it from had it 8 years and rode it less than 1000 mi "total"
It is completely stock from what I can tell
The exhaust does leak pretty good right before the megaphones
The carbs have been cleaned twice and the diaphragms checked with
compressed air
It does have a typewriter like ticking sound at times on the right side of the
engine.
The bike handles and runs beautifully on long rides
After the long rides the plugs come out looking light white on the top


I hope this helps you undersand my problem. Thanks for all the feedback.
I planned on tinkering with it today so any more ideas would be GREAT.

 

A bike that runs better after it warms up is indicative of a lean condition and a bike that runs better cold is indicative of a rich condition. This is the base line for carb tuning and trouble shooting.

 

So my question is..if someone had made the mixture screws overly rich and adjusted the idle down to compensate could this actually make it run lean??

The only thing i could think to do would be put the screws back to stock setting and bump up the idle till it runs at 1050 like the book says. Any ideas?
I'm sure the valves need inspecting to, but it sure doesn't have many miles on it.

 

A valve adjustment on an XJ is not too expensive (around $120 but that is a best guess based on the going shop rate I'm familiar with which may be more or less than where you live). But I would encourage you to try it yourself first, you've nothing to lose in trying, only the opportunity to get to know your bike better, learn the process (i.e. experience) and, if you can't get it right, you were going to spend the dough anyway. My carb baseline is at 2 1/2 turns out according to the Yamaha service suppliment microfisce. I've only had to futz with one of my bikes (the Seca) never monkeyed with the others.

 

Well, I changed all four carbs to 2.5 turns out and now it runs very badly and dies ever time the choke is removed even when I up the idle. Any chance the
the factory setting on my carbs are different? Please help!

 

Every engine is different, remember the 2 1/2 turns is a baseline.
Try 3 turns.
Mine are set at 2 3/4 turns.

Problems can be from many sources of wear & tear, compression of each cylinder, valve adjustment, dirty carb passageways, worn out throttle valve seals, or even a very dirty air filter. Just a matter of elimination and working with what you have.

 

Sounds like you need to richen up the mixture. Head to the 2 3/4, and then 3 turns like Nick suggested untill you can get a sustainable idle then start checking the plugs for mixture signature. There is a long discussion about how to do this (search for it if you have the time) but it is a long process and you had better be familiar with your sparkplug wrench (if your not now, you will be).

 

In order to get a decent idle i had to go to 4.5 turns. I must have a big problem somewhere else i guess. Even at 4.5 turns the hesitation is still there big as life.

 

The 2.5 turns is a starting point. It is meant for starting the bike and then using a dyno or in our case a colortune plug to fine tune. You can always go back to your original settings so don't fret. Mine were way too lean at 2.5 and I wound up at about 3.5 for a final. It is quiting because the pilot screw is not allowing enough fuel in. The choke circuit bypasses the mixture screw with extra fuel. As far as I know you don't have a YICS tool or a colortune. So you will have to piss in the wind a bit here. But you can start the bike and set the choke to keep it idling. Check your header pipes and see which ones are cooler or cold. Enrich the mixture on those until you hear the idle come up. This means they have enough fuel to run now. The only real way to set these carbs is with a dyno or colortune. I wish I lived closer to you and I could show you how simple it is to set them. This is the frustrating part of the net.
Once it will run let the bike warm up to operating temp and then check the plugs with the choke off for a while and adjust your settings accordingly. Black and sooty is rich and white is lean. Tan/white is just right. At last years NTCC a guy rode his pristine '82 Maxim in after adjusting his this way. He was pleased with the bikes running. After I colortuned and synced his carbs and installed the right plugs he couldn't get over the difference. He insisted I ride his bike and see how it ran. So i did! He had 2 cylinders intermitently firing and one very rich. Once these were hitting right, were synced and the resistor plugs replaced with non-resistor the difference was amazing. I actually thought I wouldn't have to do much tuning to the bike at first glance. Sounded fairly good. All this is to say that the right tool for the job is irreplaceable. I know it costs to buy a colortune and a YICS but what is a $100 to get the job done right and not have to pay a shop even more?

 

As far as a colortune is concerned...if there is a problem in the engine or in the carbs causing me to have to make it richer for better idle, how would colortune help without knowing the cause of the lean first. Isn't that more of a fine tuning test after you've done everything else? Also, if you wanted to do a valve adjust, carb synch, and colortune what order would you do those in? I know these must be stupid questions but I'm a beginner.

 

It definitely sounds like you have an air leak somewhere or really blocked carbs.
The pilot circuits are full of very small passages that can be hard to get clean.
I still advocate a carb teardown, and full cleaning.
Remove all the brass jets from the bottom of the carbs.
Spray in your carb clean, and let it sit.
Then spray in some more carb clean and let it sit.
Then spray it out thoroughly with carb clean and blow out the passages with air.
Also inspect the carb boots for cracks (common problem).
A good way to test this is spraying a mild soap/water solution on them while the bike is running.
If you see bubbles forming, you have cracks.
Is your bike a YICS bike?
If so check the blockoff plugs on the passage in the head directly below the carb boot mating surfaces.
They are 12mm head bolts and should have copper washers to seal them from outside air.
4.5 turns on a stock bike just sounds wrong.
A small air leak will affect the idle greatly but not be so noticeable at speed.

Nachoman

 

At 4.5 turns is it still possible that it's the valves (at 14,000 mi.) or most likely and air leak or dirty carbs?

 

What a colortune does is show an intermittent fireing on the lean cylinder. As you enrich the mixture you will see a white flash every now and then go to a steady whiteish to light blue flame. This tells you which carb is dirty. IF you can get a bright blue flame then you know that carb is working even if it has opened the mixture screw a lot. If you can't then you know that carb needs cleaning.
At 14000 miles I wouldn't think a tight valve is the culprit. But a valve check would need to be first if you do one. Then I would colortune because the carbs have been apart and cleaned. If the bike was running fairly well then either the sync or colortune could be first. Remember that the colortune will affect the sync setting and vise versa. Doing the colortune first makes certain that all cylinders are firing and once you have that the sync is easy. Remember the bike I talked about in my earlier post? A sync doesn't help much with an intermittent firing. The colortune showed that problem and cured it right away so we didn't have to do the sync twice.

 

One more attempt at explaining what I am getting at. I don't think I have done a good job yet. I reviewed your posts and found one missed point. If you did not remove the pilot mixture screws along with their washers and orings when you cleaned the carbs then your carb's pilot circuit is not clean. Period!
When you colortune you also isolate the carbs. Say you enrich the mixture on #2 carb and the idle is better. If you actually made #2 rich then when # 3 starts sucking fuel and air it may be lean, but with an abundance of fuel available from an open pilot screw on #2 it sucks fuel from it and now #3 fires better. When you isolate the carbs they can't cheat. What they have is what you see in the colortune window. This sounds like your problem. IF you didn't remove those screws then a good cleaning is still needed. However as I said, a colortune will tell you for sure. No more quessing!

 

Thanks BlueMaxim,
Let me see if I can get this right in my head. Because mine is a YICS model it is very difficult to adjust the carbs without the special tool. You need to isolate the carbs for both sync and colortune. Without the tool they will feed off each other and it's hard to determine the faulty/dirty carb. Do I have this right?

The only reason that I didn't remove the screws to clean the carbs was the fact that both books I have tell me not to touch them at all. I guess I need to purchase a colortune and YICS tool before I try to clean them again huh? With the YICS tool is it a matter of just unscrewing the plug and sliding it in??

I'm very thankful to everyone that has been helping me. The reason I want to try to fix things myself is because my dad who was a longtime auto technician and now an automotive instructor has trained me to not trust shops of any kind. Anyway, let me know if there is anything I have not seemed to grasp. Thanks again.

 

Well done BlueMaxim, I think he has it!

hzbshns, the books tell you not to touch them because of emission control regulations. The EPA wanted tighter control of unburned hydrocarbons, and carbon monoxide levels which increase with too rich of a mixture. The dealerships were able to be fined if caught playing with the air mixture settings that were to be preset at the factory.

 

Don't be afraid to remove the pilot screws.
Just be careful as there is a spring holding down a very small washer keeping theoring in place.
You don't need a YICS tool to get "on the paper" with the pilot circuit.
Just keep all the pilots the same until you can get it properly tuned.
I gaurentee you have gunk in the pilot circuit if you didn't pull the needles when you cleaned the carbs.
The needle closes the passage down so small, It would be nearly impossible to get it cleaned out.
Make sure you blow the pilot passage out backwards as well (carb clean, and compressed air in from the small holes in the throttle bore).

Nachoman

 

Right on all counts! The YICS passage in the head may need cleaning to get he YICS tool in. This can be done with a rifle cleaning rod. A.45 caliber bore snake works quite well but a cleaning pad will also work. I agree with your Dad. All of us could tell you stories about getting ripped off by a shop.
Nick, Nachoman, Robert, thanks for the input. I was trying to lead when I should have been giving one of D.V.'s 10,000 word answers!

 

Thanks for the help, sorry to be such a problem.

 

Just to clarify, you NEED to remove the pilot screws? I've never pulled mine ever on my Max and have never had problems. As the manual pointed out, it is not to be disturbed so I, being the ridgid thinking individual that I am, never thought twice about pulling the lead seals to remove them. I do, however, regularly use the Berrymann's fuel treatment which may be my saving grace. Hzbshns, your best off getting the right tools for the job to begin with. Cost about the same as paying some monkeywrench to do the job for you once so concider it an investment in your continued happiness. You will use them more than once and you'll save a bunch of money in the long run. Besides, it's great to know you have done the task yourself and if it runs tops, YOU did it! Of course the flip side is if it runs poorly, who else is to blame? Outstanding thread all of you!!

 

Here's a really weird question...at one time I had acquired a used set of carbs and I just noticed something strange the jet sizes are in the opposite location as the carbs on my bike. In the used set the bigger holed jet is in the pilot circuit and the smaller holed jet is screwed in the main circuit. I'm totally guessing that this is wrong but just thought I ask.

 

Your gut feeling is correct.
The pilot jets should be smaller than the mains.
I didn't even know they would thread in.

Robert,

As long as you keep your carbs clean and running constantly, you shouldn't have to remove/adjust the pilots.
On the other hand all things wear, so adjustment would probably be inevitable.
HZBSHNS said someone already drilled the plugs, so someone has already popped that cherry, and screwed up who knows what.
On stood or gummed up carbs with obvious problems, I always fully disassemble the carbs when cleaning.
It is the only way to be sure, plus how many times do I want to pull the carbs.
Might as well do the whole hog the first time.

Nachoman

 

You were never ever a problem. I was a little slow in realizing you needed an understanding of the problem rather than the next direction to go in. I knew once you set one carb with a colortune you would get that light bulb to go off in your head just like mine went off. You just didnt want to waste time on something you didn't understand the reason for. Totally acceptable. Glad we could help.