fighting a bogging problem

I have had my 82 maxim 550 for about a month now. The main problem i have is getting it to idle right and stay running at idle and an acceleration bog down at 2100 rpm. i have checked the plugs and all are a nice light brown like a lightly roasted marshmallow except #3 which is a little black so need to lean it out a bit. After the bike is started you cannot get it to rev up past 2200 rpm no matter what you do. I have tried adjusting the cold start lever to enrich or lean out the fuel to no avail. It does this in neutral or in gear on the road. Once warmed up it only has a second or 2 hesitation at at 2100 rpm then runs fine.. However if you shut the bike off for say 10-15 min and restart it it then again doesn't want to go past 2100-2200 rpm..I was doing some reading on the bike on this site, the YICS system in particular..The guy I bought the bike from had removed the YICS tube from the block for tuning and left it out because he had read on a forum that it runs better that way. I dont have the tube and am pretty sure he doesnt either. Could this be my idle and bog problem at 2100rpm. A little more added info here as far as amount of throttle im using it doesnt matter what you do with the throttle. Once it hits that bog spot an increase in throttle only makes it sound worse..If its not the missing YICS tube then where the heck do i go..Starting to get really frustrated. It sucks when you pull on the street and are only able to go 10 miles an hour or after its warmed up and your going around a corner and momentarily hits that bog and them accelerates you have to really watch it. A little more info on what all I have done. Replaced plug ends as one was completely open and 2 of the rest were way over 5k resistance. New plugs. cleaned carbs, performed klunk test, new air filter, cleaned all electrical connections, installed a fuel filter. I am at a loss as to what to do from here. UPDATE pardon my ignorance but this bike is all new to me.. What is in the YICS passage way is the YICS cut off tool thats used for carb sync . I think anyway. The guy I bought it from left it in there because he was told it would run better with the cut off tool in place rather than using the YICS system..Other thing I noticed is that when it hits that 2100-2200 rpm bog the exhaust gets thick and visible when you apply more throttle due to excessive fuel. Will removing the tool possibly help? The guy said its a bugger to get in and out..

 

I think you have more than one issue going on here. I don't have the expertise to actually help you, but since no one else is replying, I will. I'm assuming that what you said you did is all you did.

First, your new plugs and carb clean is not going to show much result if you haven't done a valve clearance adjustment. Bigfitz on this site has a superb pictorial seminar on this subject. You will need that special bucket hold-down tool. (I can't get the link to load but you'll find it easily.) Your one black plug could be from out of spec valve clearances not your fuel/air mix. Out of spec valve clearances prevent your piston cylinders from properly sequenced intake/compression/power/exhaust. That's very bad for performance and possibly damaging to the engine.

Second, cleaned carbs still need to be checked for float level and then bench synched, then vacuum synched. Then colortuned. It's all on this site. Except for getting your hands on a manometer or carbtune and colortune, this part is easier than the removal/cleaning of carbs.

Third, vacuum leaks at the connector boots of your carbs, can cause bogging and idling problems. Your boots could be old and cracked, but even if you have fairly new ones like I do, I found out that even slight misfits can cause problems that disappear when the boots are properly fitted. How to check for leaks also covered on XJBikes.

Last, the YICS system is an integral part of your engine casting, and can't be removed. On my XJ750 it's right below where the carb boots connect to the engine. You should see a bolt (12mm, I think). Directly on the other side of your engine is an identical bolt. If you take those out you'll find what looks like a smooth. empty passage from one end to the other. That is the YICS passage. You can discover its purpose on the internet. The tube that you mention is a special YICS tool you buy (or make yourself) that is inserted into the YICS passage to facilitate vacuum synching of the carbs. It's removed after synching. Lots on that subject here, also.

 

Thanks for replying back. I know I have a lot to learn about this bike. Thank the good Lord this site exists with all its info..

 

GADFREY! No, a 550 will NOT "run better" with the YICS block-off tool left in there.

YICS:




That dark, horizontal band across the top of the head in the diagram is the passage in question. You don't want to leave it blocked.

Now then. Since you got the bike, have you checked the rear brake shoes for signs of delamination?

If not, do that BEFORE you ride it another mile. Serious biz: http://xjbikes.com/Forums/viewtopic/t=15874.html

 

I would check the spark and see if you have a bad coil.

 

I will be removing the tics cut off tool today. Thanks for the advice everyone. Also is using an inductive timing light suitable for checking spark?

 

I guess; you don't need to check the timing though; it's controlled by the TCI and either right or broken; there's no adjustment like on a car.

 

Back to your original post for a second;

Once your VALVES ARE IN SPEC you will need to block off the YICS to vacuum sync the carbs; but once sync'ed the tool needs to come back out. The "leave it in there" tool is incorrect for doing a vacuum sync anyway, and is likely burnt to a crisp by now.

In order:
Valves in spec. First. Can't sync if they aren't.
Carbs clean.
FLOAT LEVELS verified usiing fuel and the "clear tube method."
Bench sync.
--carbs back on bike--
Running vacuum sync.
ColorTune or tweak mixtures based on plug reading/"plug chops."

IN ORDER. Skip any or try to do them out of order and you'll be chasing your tail until you break down and do it right.

You never answered my question about your rear brake. That has to be first.