Draw down test
- Thread starter nobbyjohn
- Start date
Jersey Big Mike
100K mile club
If you're asking this about the battery, maybe you need to have it load tested at a good shop.
Also remember, crank the bike for < 3 seconds at a time, more than that and you are likely to start melting things.
Here at cheap bastard biker shop, we take your seat off, set that cheapass harbor freight meter to 20v, alligator clip that meter to the battery posts, see 12.8v... where we charged your battery overnight [storage charge] was to start the bike and watch the motor load that battery on startup. We shot that load... that's what she said... ran a copy to your work order, and watched the battery come back to 12.6... no 12.7... no wait a minute... 12.8... yeah, 12.8v came back up. See the cashier on your way out.
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nobbyjohn
Active Member
I’m sorry I worded that wrong, I ment what is the compression supposed to be on a 117 motor
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SKOGDOG
One of the old ones.
Leak down tests are great! Blacktopper and I did one on my first K9, and as I recall a stock S&S 117 will push around 150 psi—but that’s influenced by engine wear of course, so if you have 20 or 30K miles on the engine it may be a little lower. I think mine was like 138.
The article said that anything over a 10% difference between the two cylinder readings is cause for concern. It can point to a blown head gasket, but often you can see those between your cooling fins. Mine was due to a severely worn exhaust valve guide—it also was ticking like crazy.
If the PSI reading is low, it may be due to ring wear or leaky valve guide(s). You can squirt enough oil into the spark plug hole to seal the rings and try it again. If the reading goes up, it’s ring wear—if it stays low, look at the valve guides.
reference: http://www.healey6.com/Technical/Nominal compression pressure.pdf
The article said that anything over a 10% difference between the two cylinder readings is cause for concern. It can point to a blown head gasket, but often you can see those between your cooling fins. Mine was due to a severely worn exhaust valve guide—it also was ticking like crazy.
If the PSI reading is low, it may be due to ring wear or leaky valve guide(s). You can squirt enough oil into the spark plug hole to seal the rings and try it again. If the reading goes up, it’s ring wear—if it stays low, look at the valve guides.
reference: http://www.healey6.com/Technical/Nominal compression pressure.pdf
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Random field numbers, meaning; roll bike on the rack-check compression first - call customer, and prepping for racing still. Out of cranium, not wiki:
Leak:
1-2% = Race ready.
3-5% = Say production on the very low side being fresh out the crate.
6-7% = Racing rebuild on the low side - Production engine getting tired.
8-10% = Production rebuild.
12-14% = Hard starting but runs - Done.
15%-Up = My bike does not run. I rebuilt the carb/changed every ignition part and WOT did you say, did you check compression first before the wallet opened wide throttle my ass like that?
Comp Gauge on a cold engine. Why? It comes a day you go out for a putt and it does not start:
240+ psi = on today's hi-po inline engines.
180+/- psi = on say a production twin out of the crate [a guess].
-150 psi = on that number we begin to fatten the wallet... little baby needs a ring and valve job if not> bore/new valve seats.
-100 psi = My bike does not run. I rebuilt the carb/changed every ignition part and WOT did you say, did you check compression first?
Battery Draw using meter set at 20v and the starter motor is the load:
12.8v down to 10v then battery returns to 12.7 -12.8v = New.
12.6v down to 9v then returns to 12.4v but returns to 12.6v while riding = Still serviceable.
12.8 -12.6 v in voltage surface, but when amps meet compression and 8v says, Click-Click - Then Nothing = Replace battery.
Leak:
1-2% = Race ready.
3-5% = Say production on the very low side being fresh out the crate.
6-7% = Racing rebuild on the low side - Production engine getting tired.
8-10% = Production rebuild.
12-14% = Hard starting but runs - Done.
15%-Up = My bike does not run. I rebuilt the carb/changed every ignition part and WOT did you say, did you check compression first before the wallet opened wide throttle my ass like that?
Comp Gauge on a cold engine. Why? It comes a day you go out for a putt and it does not start:
240+ psi = on today's hi-po inline engines.
180+/- psi = on say a production twin out of the crate [a guess].
-150 psi = on that number we begin to fatten the wallet... little baby needs a ring and valve job if not> bore/new valve seats.
-100 psi = My bike does not run. I rebuilt the carb/changed every ignition part and WOT did you say, did you check compression first?
Battery Draw using meter set at 20v and the starter motor is the load:
12.8v down to 10v then battery returns to 12.7 -12.8v = New.
12.6v down to 9v then returns to 12.4v but returns to 12.6v while riding = Still serviceable.
12.8 -12.6 v in voltage surface, but when amps meet compression and 8v says, Click-Click - Then Nothing = Replace battery.
Robert Arviso
New Member
Check all your connections. Battery, starter. Ground on the starter.....
Take them apart, Clean, then tighten back up. Remember starter motor is for short runs around 3 second at a time.
Maybe two scenarios for the cable to get hot? Probably missing a third one.
1. What Rott said. Sure, I can see push from the battery as it pushes current thru the cable and if the starter is in a sustained, meaning, to the point of one being out of gas and you just keep cranking as it sucks up what little is left in the carb bowl, fires off and you get all excited and keep going not knowing.
2. Or, something like I'm thinking flow vs dam equals resistance. And the analogy would be something like a rusted ground cable. There is a backup in flow to ground if say rust touches rust, rather than bare metal meets the clean transfer of flow and the electrons are batting each other, and heating up kind of hanging in the cable and not out to the frame to complete an electrical loop.
3. The third thought is that it is normal? Meaning, sure I can see the motor demands more turning and [the cable] heats up normally. Apart from the normal, then it instantly heats up? I agree, that's not normal.
I have to think; can't separate heat from a chemical reaction once you bring up E or magnetism. Like, never had my bike in the rain. Never washed my bike with water. Never parked outside. You or the old lady have a washer and drier out with the bike in the garage? Well yeah. You have wet cloths pushing water out the drier and you cannot create or destroy condensation or that cloud you can't see for 14-16yrs of owning that bike?
Not saying that condi is the problem. Not saying rust is the problem. Not knowing how many times that cable has been off the bike. All I can do is add a variable. I work with a starter motor, I want to check-etch-first, if not score the touch points and tighten the main ground back on the frame. Then a steel braded strap from engine to frame. Ass is covered from battery to frame. Motor is covered from engine to frame with the steel braid. Now that I have compression out of the way, I hear starter motor. And now on with the other variables. Because file addressed the Big G out of the way- for Mr. PUSH [battery] so he and motor turn, not click, overheat the cable, where is ground in all this? Where is compression in all this? First thing first. Get it?
Chase your tail. I comp test and I grind to bare metal, if not dip the battery end of the ground cable in vinny and watch the bubbles stop. Now I start looking after I know the contact points are clean, one after the other is the flow chart.
Flow chart:
Battery +/- lead posts are clean of the chemical reaction. Remove the white acid with vinegar. Dabs not drip the vinny on the battery, then the acid flows down the side of the battery, no. One Q-tip at a time.
Battery cable eye is one side is bare metal to razor scraped lead battery post.
Battery cable down to frame. Clean touch points to fresh bare metal.
Frame to engine steel braded strap. No scraping needed from steel to steel, but scrape paint away is the new bare frame ground to braided strap, and I think you have a complete ground loop from battery (-) to Big G.
1. What Rott said. Sure, I can see push from the battery as it pushes current thru the cable and if the starter is in a sustained, meaning, to the point of one being out of gas and you just keep cranking as it sucks up what little is left in the carb bowl, fires off and you get all excited and keep going not knowing.
2. Or, something like I'm thinking flow vs dam equals resistance. And the analogy would be something like a rusted ground cable. There is a backup in flow to ground if say rust touches rust, rather than bare metal meets the clean transfer of flow and the electrons are batting each other, and heating up kind of hanging in the cable and not out to the frame to complete an electrical loop.
3. The third thought is that it is normal? Meaning, sure I can see the motor demands more turning and [the cable] heats up normally. Apart from the normal, then it instantly heats up? I agree, that's not normal.
I have to think; can't separate heat from a chemical reaction once you bring up E or magnetism. Like, never had my bike in the rain. Never washed my bike with water. Never parked outside. You or the old lady have a washer and drier out with the bike in the garage? Well yeah. You have wet cloths pushing water out the drier and you cannot create or destroy condensation or that cloud you can't see for 14-16yrs of owning that bike?
Not saying that condi is the problem. Not saying rust is the problem. Not knowing how many times that cable has been off the bike. All I can do is add a variable. I work with a starter motor, I want to check-etch-first, if not score the touch points and tighten the main ground back on the frame. Then a steel braded strap from engine to frame. Ass is covered from battery to frame. Motor is covered from engine to frame with the steel braid. Now that I have compression out of the way, I hear starter motor. And now on with the other variables. Because file addressed the Big G out of the way- for Mr. PUSH [battery] so he and motor turn, not click, overheat the cable, where is ground in all this? Where is compression in all this? First thing first. Get it?
Chase your tail. I comp test and I grind to bare metal, if not dip the battery end of the ground cable in vinny and watch the bubbles stop. Now I start looking after I know the contact points are clean, one after the other is the flow chart.
Flow chart:
Battery +/- lead posts are clean of the chemical reaction. Remove the white acid with vinegar. Dabs not drip the vinny on the battery, then the acid flows down the side of the battery, no. One Q-tip at a time.
Battery cable eye is one side is bare metal to razor scraped lead battery post.
Battery cable down to frame. Clean touch points to fresh bare metal.
Frame to engine steel braded strap. No scraping needed from steel to steel, but scrape paint away is the new bare frame ground to braided strap, and I think you have a complete ground loop from battery (-) to Big G.