Thanks for all the great help on the engine noiise. Ran a compression check and got consistent 85-90 psi across the cylinders. Noticed in the manual that the reading should be much higher but I am in Denver and was wondering if this is ok. Anybody know the correct reading for the mile high city?
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Okay Jeff,
NOW...OPEN the throttle ALL THE WAY, have all 4 plugs out, and possibly use a car booster battery, and then repeat the test, and you'll probably find that they jump up to 130 or so...stock is 142 but that's at sea level, so a bit less would be expected, but not that much less!
T.C.T. C. Gresham
81SH "Godzilla" . . .1179cc super-rat.
79SF "The Teacher" . . .basket case!
History shows again and again,
How nature points out the folly of men!
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With the throttle closed, you can't move any air into the engine! You need WOT so there is no restriction. The readings should then all be about the same.Ray Matteis
KE6NHG
XS1100 E '78 (winter project)
XS1100 SF Bob Jones worked on it!
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90psi is low, but you have to realize that in the mile high city, air density is about 80% of seal level. You would get zero compression in outerspace. So I am thinking that .8 x 140 is about 112psi. Aslo, there are a lot if differences between gages. Even compression is a good sign. If she doesn't go through a lot of oil or foul plugs, I say run the thing!Skids (Sid Hansen)
Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.
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Run the bike to normal temp, then let her cool off a bit, then do the readings. Crank it until the gage stops increasing.
Originally posted by jeffnew29 View Postok, about how many cranks to reach the highest reafing would you guess/Skids (Sid Hansen)
Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.
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Usually three or four POWER strokes should do it. If it will go up, but takes a little time, you may have problems. I try to watch for he first, just to see what it is. After that, I look at the end results.Ray Matteis
KE6NHG
XS1100 E '78 (winter project)
XS1100 SF Bob Jones worked on it!
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Wot
Wouldn't it be better to remove the carbs before making a compression check?It seems to me even at WOT while cranking The slides are still in the down position,right?
Terry1980 special (Phyllis)
1196 10.5 to 1 kit,megacycle cams,shaved head,dynojet carb kit,ported intake and exhaust,mac 4 into 1 exhaust,drilled rotors,ss brake lines,pods,mikes xs green coils,iridium plugs,led lights,throttle lock,progressive shocks,oil cooler,ajustable cam gears,HD valve springs,Vmax tensioner mod
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Originally posted by tw1980 View PostWouldn't it be better to remove the carbs before making a compression check?It seems to me even at WOT while cranking The slides are still in the down position,right?
Terry
When the throttle is closed, so are the butterflies, and this is where the air gets choked off:
Ken Talbot
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Do the test at WOT, but don't get all freaked out if you don't match the readings from the manual. If they all are about the same you are probably good. I got all unhappy when I couldn't match the compression readings the manual called for on one of my other bikes, even after a fresh top end rebuild and break in. I built it as a high-compression high-performance engine and while I was getting equal compression across all four cylinders I wasn't even getting the stock readings. Turns out the stock Honda compression tester the manual expected attaches directly to the plug hole and the one I was using had about a 12 inch hose. The amount of air trapped in the hose lowered the reading considerably. I tested it again with a gauge with a much shorter hose and the readings shot up way past stock.
Look for equal, not necessarily a target number.
PatrickThe glorious rays of the rising sun exist only to create shadows in which doom may hide.
XS11F (Incubus, daily rider)
1969 Yamaha DT1B
Five other bikes whose names do not begin with "Y"
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Hi Jeff,
how long had the bike sat around not running before you got it?
A bike that's been parked for a year or so will typically have low compression numbers because the rings may be partially stuck in their grooves.
So long as it runs nice, don't worry. Most likely the rings will free up as the miles add up.Fred Hill, S'toon
XS11SG with Spirit of America sidecar
"The Flying Pumpkin"
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