low end hesitation

I have a 1981 Maxim 650 that belonged to my Dad. It has a Mac style(not a Mac) 4 inti 1 pipe. It has some hesitation below 3000 RPM. It runs find once you get past that. Main & Pilot jets are stock. I have the pilot screws out 3 turns so far and it is much better than before but not sure about how far I should go. Maybe needs to be rejetted? Any help would be great. Thanks

 

when was the last time the carbs were cleaned and valves put in spec? as far as how many turns out on the pilot screws? that's best determined by a colortune plug and if you don't have access to that then do some plug chops. are you still running the stock airbox?

 

Carbs were off and cleaned last winter. have never heard of a colrtune plug . I need to get some new plugs before trying plug chops. The plugs in it are almost a year old. I bought a 1981 Seca 750 new back in the day. I installed a Kerker 4 into1 and it was the biggest mistake ever. we never could get it jetted to run right. Always had a studder. Can find a good stock exhaust without speding a mint or I would get one.

 

is it hesitation or just lack of beans? they don't make much steam under 3k but should pull smoothly from there

 

Not smooth at all below 3K. It sputters, hesitates, just flat out hard to be smooth with out jerking around or all of a sudden lunging away. Just not right.

 

Valves first, put your new plugs in (make sure they are the correct size for your bike), Sync with YICS Tool, Colortune, then repeat the Sync again and the colortune one last time. If this doesn't clear it up then you will probably be needing to clean those carbs.
This is how I would approach it, at least to begin with.
P.S. You can get the Colortune Plug you need from Len at XJ4Ever.

 

There are several things you need to check and do:

Your situation sounds like a Lean condition in the lower-end of the power band.

Check Diaphragm Pistons for sticking. Search: Clunk Test
Insure that Center Nozzles are Cleaned and Air Ports clear.
Float Heights correct.
Pilot Jets / Passages; clean and clear.

 

GET THE VALVES IN SPEC;

verify your float levels using fuel and clear tubing;

then get a good running vacuum sync done;

all before you start any more mixture tweaking. You're attacking backwards.

 

This model doen't have YICS like my Seca 750 did. Will ck valves. Float levels were set using clear hose. Will ck into getting Coolrtune. I'm glad everyone's willing to help. Been away from bkies for awhile. Didn't realize how much I missed it.

 

I just overcame the same exact issue over the past few days. But in fact the other members suggestions could be right on. This is just one of many possibilities. Some carbs came with fine thread on the mixture screws and others came with course thread.

I just did my whole top end so I know it's sealed well, I started the motor for the first time at 1.5 out accross the rack. After colortuning I ended up coming out About 3 more turns, don't know for sure/exactly cause I was looking at the colortune. but until I did this I had identical symptoms to what you've described

But I did hear a change in idle at the point I need to be at. The idle actually came down a little when the mixture turned orange, slightly in again and it comes up slightly when you get a cleaner burn, at the very last point the combustion turns from orange to blue. but it was stay higher when it's blue, but you need to be at the very threshold where it changes

a very quick test (if in fact you have the fine thread mixture screws, which I think Most do) before you remove the valve cover, need a new gasket, get oil everywhere, deal w/ a thousand screws, come out 1 or more turns on the screw, see if the hesitation goes away. Its just one more turn. Going richer will never hurt you anyway. I been through hell and back tuning my 650, amuse me. No doubt you need to check the valves

 

The inherent problem to overcome with the ColorTune Plug is understanding that the ... "Bunsen Burner Blue" -- you can observe in its clear window is the Ideal Air~Fuel Mixture for IDLE.

When you have set the Mixtures to achieve the Air~Fuel Mixtures to generate a
BLUE Flame, ... you have arrived at the point where Fine Tuning commences.
Fine Tuning BEGINS with IDLE.

The ColorTune get you there quickly.

Adding additional Richness to sustain combustion during the transition from IDLE to OFF-IDLE means that BLUE might be too LEAN for a Bike that had Pilot Mixtures set to enable getting-away from a light without hesitations.