82 Maxim 650 power

Hey all,

Great site! I've gotten a lot of useful information from this site just by lurking. But now I have a question of my own. This is going to be long, but I want to let you know what I've done so far.
I have an 82 Maxim 650 with about 11,000 miles on it. I got it last summer from a previous owner who hadn't ridden it in about 15 years(yeah I know big risk on the bike!) Well after putting in a new(cheap) battery, new NGK BP7ES spark plugs, new tires, changing the oil, changing the final gear oil, bleeding and replacing the front brake fluid, and cleaning and rebuilding the carbs I was able to get it running. Surprisingly the carbs where not as gunked up as it sounds like they should have been(from reading others posts here.) There was a stuck float on just one of them, but I replaced 2 of the floats as well as all of the gaskets. All the jets cleaned up nicely, and the rubber diaphrams looked good. The bike had some problems with starting in the cold weather last fall, but this year the bike was firing right up with full choke. It would then need several minutes to warm up before I could turn down the choke and take off. It would be idling around 1100 or so. Then, after riding it for a while, the warm idle would be around 1500. But for the most part, the bike was running smooth. I was under the impression that the bike was running lean. Well after getting a colortune and some carb sticks, I decided to try to enrich the mixtures and sync the carbs. I have not been able to remove completely the mixture screws, so I'm not sure if they need to be cleaned. But I was able to adjust them. At first, I set all the carbs to about 3.5 - turns outs, and then synced them up. After doing this, the next time I started the bike it started right up without any choke at all and I could take off almost right away. I was very happy about that! But then as I was riding I noticed a change in the bikes performance. It seemed that when I was riding along at a constant speed, if I let off the throttle just the tiniest bit there was a sudden deceleration, not the smooth drop in power that I was used to. Then, if I got back on the throttle just a little, their was a sudden surge of power instead of a smooth acceleration. This seemed to happen in 2nd and 3rd gears between 2-4k rpms. Well I decided to play with the mixtures again, so this time I set them all to 3 turns out, and then did a sync. Now, the surge problem has lessened but is still there and the bike needs full choke again to start and a couple minutes to warm up. Also, after turning off the choke the bike will idle at about 1000-1100 cold and then warm up to about 1400-1500 again.
I've tried running seafoam thru the tank and that made no difference. The spark plugs and oil were both changed this spring before I messed with the mixtures.
Basically what I'm looking for is the reason why the throttle response is not as smooth after I enriched the mixture. I could go back down to 2.5 turns out, but then the bike has a heck of a time warming up. Is there something in the carbs that I should take a look at again? Needles, floats, etc. I did try to check the float levels and they looked ok, but I did not get exact measurments. Any ideas would be greatly appreciated. Thanks,

John
1982 Maxim 650

 

Is it a yics engine? If so you need a yics tool to properly sync the carbs.
Did you check the throttle shaft seals condition. If you dipped the carbs in cleaner it may have eaten the shaft seals and the orings in the mixture screw bores. You can check the condition of the 2 outer(1 on each side)
throttle shaft seals by removing the retaining clips and plastic washers.
That will give you an indication of there condition.

You might also try spraying penatrating oil around the carb to cyl. head rubber manifolds. A change in RPM's would indicate an intake leak.

There are ways to repair the manifold boots posted here some where.
I would try to get the mixture screws out also to check those orings as well.

When you remove the screws, there will be a spring, a small flat washer and then the oring.

Just my 2 cents
Good luck

 

First I want to commend you on your post. All the background info we need and an very articulate explaination of the bikes problem and symptoms. Your carbs are rich. The surge of power just as you open the throttle slightly is from air rushing in and allowing the extra fuel present in the mixture to burn. Then the mixture turns rich again once the air sucks extra fuel up into the intake. You need to use the colortune to set the flame color to blue. You don't use the colortune to correct what you have decided is a lean carb. The colortune is there to tell you what is going on where you can't see what is going on.
So set the mixture to blue and check the fuel level set by the floats. Also check to see if the choke is stuck on or the petcock is leaking fuel in to the intake via the #3 vacuum line. Too much fuel is getting in somehow and the most likely sources are the float level, idle mixture, choke, (enrichener circuit) or petcock.
Let us know if you need any help checking any of these things. If you have the XJCD go over the carb stuff DV wrote and use his ethod of checking and setting the float/fuel levels.