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Compression test on non-running elite

Posted: Fri Jun 25, 2010 4:31 pm
by kentdog007
The service manual gives compression test instructions for a bike that is assumes starts"...open throttle and engage starter for a few seconds..."

My 87 elite SA50P has spark and I cleaned the carb but I cannot get the starter or any other electrical to work.

Can I kick start for a compression test? how many kicks before you take the reading?

Also what needs to be on the motor for the compression test? Carb, exhaust, etc? I have another motor and rear wheel setup, can I test that as it sits on the floor? Thank you for your patience.

Re: Compression test on non-running elite

Posted: Fri Jun 25, 2010 9:57 pm
by Wheelman-111
Greetings:

The carb can be off, but accurate readings require functional reed block and pipe. It may require a dozen firm kicks but theoretically you shoud end up with the same value as a starter. Alternatively, remove or use a spare battery to hotwire the starter. I made a connector for that purpose attached between the positive pole and the starter motor connection. Push the negative pole against any metal part on the block to activate the starter.

Re: Compression test on non-running elite

Posted: Fri Jul 09, 2010 12:27 pm
by kentdog007
So I got a compression tester...three kicks with the throttle open and I got a 125-130 reading. Put a few drops of fuel in before replacing the plug...forgot to put the plug wire back on and kicked it over a few times and then once I realized the plug wire was off and put it on...it ran for a second or two...a real quiet purr, nothing like the chainsaw sound my spree has. The odometer read 6000+ could this thing really log those kinda miles and still run?

Tried it again and nothing, even repeated my plug wire mistake and nothing. gonna keep trying in hopes that if it start running I can break free whatever it is in the carb that might be clogged. I tried to clean the carb, lots of varnish in there but the one very fine hole opening looked clear. Any help is appreciated.

Re: Compression test on non-running elite

Posted: Fri Jul 09, 2010 5:02 pm
by kingearwig
kentdog007 wrote:So I got a compression tester...three kicks with the throttle open and I got a 125-130 reading. Put a few drops of fuel in before replacing the plug...forgot to put the plug wire back on and kicked it over a few times and then once I realized the plug wire was off and put it on...it ran for a second or two...a real quiet purr, nothing like the chainsaw sound my spree has. The odometer read 6000+ could this thing really log those kinda miles and still run?

Tried it again and nothing, even repeated my plug wire mistake and nothing. gonna keep trying in hopes that if it start running I can break free whatever it is in the carb that might be clogged. I tried to clean the carb, lots of varnish in there but the one very fine hole opening looked clear. Any help is appreciated.
The answer is going to be clean the carb.... maybe change the gas... test the petcock... but my money is on clean the carb.

Re: Compression test on non-running elite

Posted: Fri Jul 09, 2010 8:58 pm
by mr pibbs
2 stokes have three main issues.
spark - compression - fuel

if you have two of three, it's probably the other one.

Clean the carb, like crazy.

Re: Compression test on non-running elite

Posted: Sat Jul 10, 2010 12:19 am
by kentdog007
The manual I have says that the mix screw should be 1 3/8ths turns out...where should I start for the idle screw? I will try to clean the carb again. Thank you.

Re: Compression test on non-running elite

Posted: Mon Jul 26, 2010 11:25 am
by kentdog007
Cleaned the carb again, still no luck.

So could this be a bad bystarter or a greater electrical issue?

The bike horn, lights, starter won't work even with a 12V charge applied. I hotwired the starter and it worked fine, but clearly no power getting to the switches - is there another fuse other than the Positive battery inline fuse? I get spark; could it be that the bystarter (like every other electrical device) isn't getting a charge and keeping it from starting?

I have good compression.
The plug is wet when I pull it; unscrew the carb drain and it pours clean gas...

I have the airscrew to the spec; no info on the idle adjustment screw when first starting the bike.

I have tried with the airfilter box on and off; the exhaust on/off. No luck. :*:



I heard the bike run for a second or two, several carb cleanings ago when I put a little gas right into the cylinder and replaced the plug...fired up, ran quietly and then quit.

God I would love to have to buy some tires for this thing...

Re: Compression test on non-running elite

Posted: Mon Jul 26, 2010 11:38 am
by Bear45-70
Do you actually have fuel in the carb? Open the float bowl drain and see if fuel runs out of the drain hose. No fuel in the carb means no start and run. No fuel in the carb means either the needle is stuck closed, the petcock is stuck closed or the filter in the tank is plugged.

Re: Compression test on non-running elite

Posted: Mon Jul 26, 2010 12:03 pm
by kentdog007
After 4-5 kick start attempts I open up the drain screw and it pours clean gas. Plug is wet.

Re: Compression test on non-running elite

Posted: Mon Jul 26, 2010 10:50 pm
by kingearwig
test for compression by removing the spark plug and putting your finger or thumb over the spark plug hole. With the ignition off turn the motor over and attempt to hold the pressure in the piston with your thumb or finger. If the turning over of the motor does not push your finger out .... ie you can hold the pressure in with your thumb... then you probably have an issue with compression. You don't need to know what the compression pressure is you just need to know if you have some.

If this checks out you need to test for spark.

Re: Compression test on non-running elite

Posted: Tue Jul 27, 2010 12:35 am
by kentdog007
A previous post dealt with the compression and spark tests that I had performed; you had replied with a suggestion to clean the carb...my questions are:

1) does the bystarter not being (hooked up) electrically cause the bike not too start? Too much gas?
2) Where should the idle stop screw be set on the carb? The book only deals with the air mix screw

I get spark and the plug is wet...The compression test read 130+...is there too much fuel? :crazy:

Re: Compression test on non-running elite

Posted: Tue Jul 27, 2010 3:41 am
by Bear45-70
kingearwig wrote:test for compression by removing the spark plug and putting your finger or thumb over the spark plug hole. With the ignition off turn the motor over and attempt to hold the pressure in the piston with your thumb or finger. If the turning over of the motor does not push your finger out .... ie you can hold the pressure in with your thumb... then you probably have an issue with compression. You don't need to know what the compression pressure is you just need to know if you have some.

If this checks out you need to test for spark.
Your test is worthless for any valid troubleshoot and tell the tester nothing worth while in trying to fix an engine. 50 PSI will pop your finger off the plug hole but most engines will not run or run very poorly at 50 PSI and Honda say 114 PSI minimum. Also you need to read all the thred before you post.

Kentdog, It sound like you are flooding the engine, which means carb, probably the float not floating or the needle not seating.

Re: Compression test on non-running elite

Posted: Tue Jul 27, 2010 9:52 am
by kentdog007
Bear: You are the only one listening....

So the carb float is held on with that little "axle" via the screw. I have that screw tightened right down, and there is movement of the float up/down.

There is that small pivot point piece that sits under the float; I have the point end down and the top part is slid into the float mechanism to hold it in place. THought this was how my spree was set up.

Lastly, the main jet can only go in one way, right? It fit in just fine so I think it is in there right, any help with that one? THank you.

Re: Compression test on non-running elite

Posted: Tue Jul 27, 2010 10:20 am
by Wheelman-111
Greetings:

The float needs to engage the little flange at the base of the needle correctly. There are better examples, but scroll down to the 5th picture here to see how it's supposed to look. Here's one of Mousewheels' legendary pics.

Re: Compression test on non-running elite

Posted: Tue Jul 27, 2010 1:52 pm
by Clivester
kentdog007 wrote:A previous post dealt with the compression and spark tests that I had performed; you had replied with a suggestion to clean the carb...my questions are:1) does the bystarter not being (hooked up) electrically cause the bike not too start? Too much gas?
It should not prevent the bike from starting if it has no power. It will only start to impact performance once the bike is warmed up. Just make sure it is sealed properly in its seat with the o-ring.

During your several cleanings of the carb did you visually check that the pilot jet is clear?. Read this thread from about this post on in:
http://www.hondaspree.net/phpBB3/viewto ... do#p105054