Very high compression, and lean

[DELL82]

well I got about 1000 miles on the resurrection of the XJ1100 '82 Maxim. Still having trouble getting straw color on the plugs. Turned the pilot screws out 4-1/2 turns, it helped but no banana's. Checked compression after 14 mile run.
#1=180 PSI
#2=185 PSI
#3= 180 PSI
#4= 185 PSI
Thought the gage was off so got another and run them in parallel. Same result. All plugs out, full throttle, cranked until needles came to a stop. What do I do now! Buddy told me to disregard the specifications that say 152 PSI MAX on the 1100. As far as I know PO did not go into the engine. She runs like, very good.
ANY help and comments very welcome

[audijunky]

I am not sure if the head gasket thickness affects compession per cylinder or not, I have been told that you can increase your compression ratio by switching to a thinner gasket. My compression tests were over specs as well. 160, 165, 175, 170 and I haven't had any problems yet. I am no guru but I think your fine. Done some searching a low comp. is really what you need to worry about. So what color were your plugs?

[DELL82]

Steve the plugs are just off white but not as dark as straw color. The outer diameter of the threaded part is jet black, light carbon and the short bar is light gray at the thread and near black across from the plug anode. The muffler is non standard megaphone type but looks like the stock type and has baffles in it. Jet sizes are standard.
Any helps greatly needed

[Snow]

I got 180+ on my bike...1196 if that matters

[DELL82]

Thx it enforces the readings I got, and that helps.

[TopCatGr58]

Hey Dell,

I, too, had comps in the 180's, after only an 1179cc 'little' big bore! As for the plug color on the insulator, regrettably according to some very knowledgable folks, that's now unreliable due to the cleaner fuels and unleaded gas!

Your note of black around the threaded base could actually indicate a bit too rich? If you're running the stock box, and your pipes are very close to stock, then you may not need to have the pilots turned out so many turns. Main thing is how does it respong to throttle? Can you take it up to redline in the lower gears, any hesitation at low rpms??
T.C.

[DELL82]

I haven't tried going to RED LINE yet, but will try tonight or tomorrow and let you know the out come. When I unscrewed the pilot screws the engine started better and run better in lower RPM's. I initially started at 1.5 turns and worked my way up to 4.5 in increments of 0.5 turn steps. It seemed that the farther out I got the better the engine started and run.
Guess I need a carb tune clinic to resolve this dilemma for good though. Or a color tune plug , expensive

[mro]

I initially started at 1.5 turns and worked my way up to 4.5 in increments of 0.5 tur

Generally a sign that something else is wrong.
Floats set and all same?
Have you Sync'ed the carbs?


mro

[DELL82]

Read a thread on this site about setting bowl levels proper height and did so. Using hose in drain plug hole and lowering it to see the level. All set the same and at specification.
I mechanically synced the carbs using a 0.001 feeler gage to set levels and center the butterfly's. Do not have sync tools. I do have vacuum gages(bank) and all seemed to be at same level when engine at 3000 RPM. However the needles were really dancing. I read that I can put the inner core of coax cable in the lines(wire removed) to act as a re stricter to the pulsing but have not tried that yet, recommend it! I know you guys do not recommend the gages, but that is all I have.

[DiverRay]

DELL82,
We usually use the mercury stick because of cost. They also need the restrictor in the lines. Your vacume gauges should work fine, but you need to adjust them at idle, not 3K RPM.
Put a restrictor of some kind in the line, and try again. If the needles still dance, look at the middle of the movement, and adjust them all as close as you can. Until the carbs are synced, you CANNOT try to find your running problem.
Ray

[mro]

I use but a single gauge.
PITA,.... but works.
Quick and easy fix for needle jumping is to put a hose clamp over hose, insert small bolt and tighten until needle smooths out. Bolt pinches the hose making the restriction.


mro

[Incubus]

As for plug color, perhaps this might help:

http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html

Patrick

[MAXIMAN]

I wouldn't be too concerned with 180+ pumping compression

Poprock's '80 SG is bone stock with 56,000 miles and it rang up 180 to 185 psi a few weeks ago.

Even though my 1196 big bore is rated at much higher static compression ratio the pumping psi around 150 to 155. Alot of pumping compression has to do with valve timimg and overlap. Sensei (Dan) is good at explaining this.

If you could post photos of your plugs it might help.

[TopCatGr58]

Originally posted by Succubus
As for plug color, perhaps this might help:

http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html

Patrick

Hey Patrick,

Thanks for that link from Dan'sMC site, I addd it to the other spark plug examples tech tip in the Maintainance, Electrical section!
T.C.

[Incubus]

I like to share when I can, T.C. My own technical knowledge is limited, but I'm pretty good at finding stuff.

Patrick