82 maxim carb question

ive begun getting a hesitation at about 5k rpms. kinda like a bogging. its a recent developement. when i get past that point it accelerates and cruises normally. any ideas to the cause?

 

Yea your post is titled correctly. More than likely it's a dirty carb issue. Do you have an inline filter installed? If not you need one. Because it just showed up is your first and most important clue and second clue is that its happening in that harmonic rpm point. Good bet that something is getting clogged, varnished or is otherwise wrong in your mixture. Search through here and do all the diagnostics you can. Rick is the resident carb wizard around here and he will find your post and I know he has seen something similar before so heed his advice. You are probably due for a carb cleaning at the least.

More information is needed though. How is your idle? Do you have any backfiring, sputtering, etc. Have you checked inside your tank for rust or debris? How many miles? What maintenance has been done to the bike? Are your valves in spec?

 

it backfires when i first start it in the morning. after it warms up its fine. it has an inline filter. about a month or so ago some "person" messed with my bike and i hadnt noticed but they put my petcock from on to reserve. maybe a good cleaning is all that is needed. it has a little over 34k miles. its idle has been a little strange at night when the temp drops to about 60. it will idle at around 2k till i come to a dead stop, then it returns to normal. it only does that when its cold out. if it needs a rebuild, wheres a good pace to get the rebuil kits from?

 

Once it gets cool outside, the XJ Bike Engine starts to act-up.
They are hard to get stated and need to be tuned well to get top performance when it gets cold.

Your symptom, might not be totally cold weather related.

When the Engine is at 5000 rpm's and climbing, ...
You NEED:
A constant supply of FUEL. (Float Heights. Check)
CLEAN Emulsion Tubes. (Nozzles. ALL Drilled Ports clean.)
Diaphragm Pistons able to Rise and Fall within their Bores without hesitation and sticking. ( Cleaned and refinished (or Polished) Diaphragm Piston Bores.

There are three things to consider.
There's also all the elements of a good Tuning:
Valves
Floats Heights
Sync
Plugs

And the Seasonal change in Blending of Fuels for Cold Weather regions.

 

so i should give them a good cleaning to make sure nothing is sticking.

 

Had similar problems as yours and my bike was also running dangerously lean-so far this is done:

Created workspace just for carbs with muffin tin for organizing parts.
Pulled carbs off and took #1 apart while taking many pics and notes, then the rest
soaked all metal in carb cleaner & checked all wear items
got new o-rings for pilot screw from Chacal(XJ4Ever)-they looked ok but to be sure new
used pipe cleaners, stiff plastic bristles, scotch brite, 800&1000 grit, and finally carb cleaner and compressed air to clean and verify clean.
Checked manifold boots for leaks-used bright light inside in dark garage and examined carefully.
Checked operation of floats, needle valve-be careful w/float assembly pins
Bench synched, checked/adjusted float levels, put it all back together

Waiting on YICS tool and borrowing a friends Carbtune to finalize tune, and new choke cable as mine broke (30 years old).
Before all of this I put my valves in check and did many other saftey related repairs/replace (tires, brakes, etc.)

Hope this helps you - I know it sounds like a lot but it's not as bad as it seems. It did/has taken me a while but that is mostly because I go slow to make sure I don't screw up and I don't have immense amounts of free time. On the plus side I have learned a lot about my moto and more than I want to know about Mikuni carbs 8-]

If any of this is confusing look up the faq in here about carb cleaning etc. You can also find videos and how-to's on the internet that will give you pointers. Mostly you need no obstructions/varnish in your tiny passages, your carbs should pass the "clunk" test so no sticking, and your float level & fuel/air mixture needs to be right (so no leaks). Good plugs, valves in spec and you'll be pulling from idle to red-line with no problems.

 

That's the bottom line, and in that order. (Assuming carbs are thoroughly clean.)

You really need to check your valve clearances unless you know for a fact that they've been adjusted within the last 5000 miles.

Then it's carburetor time. Clean clean clean, slides go "clunk," float levels set and verified using fuel and clear tubing, and a good bench sync. Once back on the bike, running vacuum sync with YICS blocked, a little mixture tweaking and you're good to go.

But the valves have to be in spec to sync the carbs. And the carbs need to be clean to properly tune anything.