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miket007
03-04-2016, 06:49 PM
Hey guys...

So as the title says....bought an 83 that ran but with low compression. Pulled the top end apart, had the cylinder done, new piston kit...etc. I have everything back together and am going through a mental checklist of whats next.

Since this will essentially be a new break-in, I plan on emptying the existing tank (have no idea whats in it) and using 91 with non-synth oil. Question, what ratio should it be?

Second, I pulled the carb, cleaned it out (it wasn't dirty) made sure everything was as it should be. What should a baseline mixture be at to break in the motor? I am sure it was adjusted to run on it's low compression condition and at a slightly higher/cooler altitude than where I am now.

Third...I did some searching and found many different views on "how to break in" a new motor. What seemed to be consistent is, "no full throttle romp", "let it warm up gently before riding and only do so for a brief period of time"...rinse and repeat. Anything I missed here?

atc300r
03-04-2016, 07:00 PM
Did you check or replace the crank bearings and seals.32:1 is what most of us run.

miket007
03-04-2016, 07:40 PM
Yup. Will start with 32:1.

miket007
03-05-2016, 05:42 PM
Well got 'er up and running today. Trying to track down some mysterious engine behavior. Something I noticed recently.... one of the previous owners converted it to twist throttle but used a cable that has threads at the carb end which obviously isn't threaded into the carb and is just hanging lose...therefore it's just open. I am thinking they may have just swapped the slide and needle from another bike. I have idling pretty well. The needle in the slide was set with the clip all the way to the top. With the new top end I put the clip at the middle. The one thing I can't quite pin down and its hard to describe...I have ran it twice roughly no more than 30 minutes...about 10-15 minutes tuning and 10 with light (no more than 1/4 throttle) riding. Twice towards the end of each session it started not responding to throttle and then slowly died. Now the first time this happened, I thought I messed up the top end and it seized. But as soon as it died I kicked it over and it fired up again. I let it site for about an hour and a half..fired it back up, did some additional tuning on the carb....went back out drove it for about 10 minutes again light throttle...and just as pulled in the garage...same behavior...it died. Kicked it over and it fired right up. Could this be a fuel starvation issue?

BigRedGrizzly
03-07-2016, 09:33 PM
Sounds like. Check the quality of fuel flow from the tank to the carb. Towards the end of riding when it didn't have much throttle response.. Did the RPMs start to pick up? This is usually a sign of running lean which can happen if there is fuel starvation. It's sounds like to me that the
Needle jet may be hanging up in the seat. This is not allowing the bowl to fill. Basically you may be burning fuel at a quicker rate that which it is being replenished in the bowl. When it seems like it wants to die put the choke on. See if it runs a little better. This will richen it up a bit and help you confirm your symptom.

miket007
03-07-2016, 10:05 PM
Thanks BigRed...I played with it alot more yesterday. The symptom got worse to the point if I touched the throttle it would die...just bog and die. As soon as that I happened I checked the inline fuel filter between the tank and carb...it was full..I also pulled the plug and it was really wet. I actually think its a failing coil and or plug...those are on order. I pulled the plug and just let it touch the cylinder and cranked it over...never saw one spark but it was in daylight. I have watched the from the intake side of the carb when this happens and don't see anything unusual....slide and needle seem to work fine. I put an ohm meter on the coil and one side was just out of spec...who knows how long that coil has been other. I am going to replace the coil and plug...cross my fingers.

yaegerb
03-07-2016, 11:18 PM
Did you perform a pressure test after reassembling to ensure good seals and no air leaks?

miket007
03-08-2016, 04:23 AM
Did you perform a pressure test after reassembling to ensure good seals and no air leaks?

No I did not do that. What is the best way to a coming that?

yaegerb
03-08-2016, 10:09 AM
Here is the procedure....read the article below.

http://www.klemmvintage.com/airleaks.htm

Below are some pictures of me pressure testing my banshee.

228711
228712
228713

Essentially you plug up the exhaust with an expandable plug (can be bought at autozone for 2.50). Then you either make the spigot that attaches to your intake manifold with a pressure gauge or you can buy one. Harry Klemm sells them for 20 bucks or so.

Rule of thumb is the engine should hold 6PSI for 6 minutes. Any loss of pressure over that time indicates an air leak. To find an air leak spray a soapy solution or WD-40 over all gaskets/seals. If you can't find the leak externally then likely your leak is internal (I.E. crank seal) and you must remove the outer covers and inspect those as well.

I can tell you the pressure test is one of the more important procedures to understand and execute for two stroke motors. Its a good practice to pressure test before disassembly and after reassembly to ensure a healthy, long living motor.

Hope this helps.

miket007
03-08-2016, 06:33 PM
Here is the procedure....read the article below.

http://www.klemmvintage.com/airleaks.htm

Below are some pictures of me pressure testing my banshee.

228711
228712
228713

Essentially you plug up the exhaust with an expandable plug (can be bought at autozone for 2.50). Then you either make the spigot that attaches to your intake manifold with a pressure gauge or you can buy one. Harry Klemm sells them for 20 bucks or so.

Rule of thumb is the engine should hold 6PSI for 6 minutes. Any loss of pressure over that time indicates an air leak. To find an air leak spray a soapy solution or WD-40 over all gaskets/seals. If you can't find the leak externally then likely your leak is internal (I.E. crank seal) and you must remove the outer covers and inspect those as well.

I can tell you the pressure test is one of the more important procedures to understand and execute for two stroke motors. Its a good practice to pressure test before disassembly and after reassembly to ensure a healthy, long living motor.

Hope this helps.

It does...thanks a bunch.

John Tice
03-09-2016, 10:18 PM
Break in time; Is your cylinder finish honed with a fine enough hone stone? Sunnen’s fine grit stones start at around a 280 grit. The finer the stones get the longer it takes to remove bore material. We start with a rather coarse stone set if much stock is needed to be removed. It’s always desirable to be as close to finish bore size when using a boring bar. The problem is; the closer we get to finish bore the easier it is to make a mistake & spoil the job. The other question is; is your cylinder bore round & straight.
Does your dealer use a Sunnen Hone? Sunnen’s the Best, don’t kid yourself.

Basic Sunnen hand held hone
http://i1152.photobucket.com/albums/p497/johntice1/P5230142.jpg (http://s1152.photobucket.com/user/johntice1/media/P5230142.jpg.html)

AN Sunnen head mounted on a horizontal Con Rod machine
http://i1152.photobucket.com/albums/p497/johntice1/P5210128.jpg (http://s1152.photobucket.com/user/johntice1/media/P5210128.jpg.html)

Best Choice; Stone set especially made to hone splines. Best all around for 2-stroke cylinders
http://i1152.photobucket.com/albums/p497/johntice1/P5200120.jpg (http://s1152.photobucket.com/user/johntice1/media/P5200120.jpg.html)

Small bore 3 point Sunnen mandrels gurentees your bore is Round & Straight
http://i1152.photobucket.com/albums/p497/johntice1/P1210342-Copy-1.jpg (http://s1152.photobucket.com/user/johntice1/media/P1210342-Copy-1.jpg.html)

Other types of hones; L, Ball hone aka dingle berry, C, Amco the only head in photo capable of any size control. R, brake cylinder hone. Aka Egg Beater.
http://i1152.photobucket.com/albums/p497/johntice1/082f2646-cb74-4be1-ad51-ed58b2089854.jpg (http://s1152.photobucket.com/user/johntice1/media/082f2646-cb74-4be1-ad51-ed58b2089854.jpg.html)


Does your dealer use a good dial bore Gauge?
http://i1152.photobucket.com/albums/p497/johntice1/P5200117.jpg (http://s1152.photobucket.com/user/johntice1/media/P5200117.jpg.html)

http://i1152.photobucket.com/albums/p497/johntice1/P5200119.jpg (http://s1152.photobucket.com/user/johntice1/media/P5200119.jpg.html)


I have found after a lifetime in the business that a proper break in is rather simple. ( Do a Leak Down Test FIRST ) Easy running on a couple tanks of fuel; finally, retorque the head bolts & your ready to go. If the bore is smooth; 300 grit or finer, round & straight your break in is a simple procedure.

John Tice
www.smallenginemachineworks.com & www.nwsleeve.com
Turning Custom Cylinder Sleeves Since 1971

I just took a look at the fine page on pressure testing. Kudos to the author who really has knowledge in his Bean.

I’m not attempting to hijack the thread; Basic knowledge of your cylinder sizing is the Heart of your engine.

:beer

miket007
03-09-2016, 11:11 PM
Break in time; Is your cylinder finish honed with a fine enough hone stone? Sunnen’s fine grit stones start at around a 280 grit. The finer the stones get the longer it takes to remove bore material. We start with a rather coarse stone set if much stock is needed to be removed. It’s always desirable to be as close to finish bore size when using a boring bar. The problem is; the closer we get to finish bore the easier it is to make a mistake & spoil the job. The other question is; is your cylinder bore round & straight.
Does your dealer use a Sunnen Hone? Sunnen’s the Best, don’t kid yourself.

Basic Sunnen hand held hone
http://i1152.photobucket.com/albums/p497/johntice1/P5230142.jpg (http://s1152.photobucket.com/user/johntice1/media/P5230142.jpg.html)

AN Sunnen head mounted on a horizontal Con Rod machine
http://i1152.photobucket.com/albums/p497/johntice1/P5210128.jpg (http://s1152.photobucket.com/user/johntice1/media/P5210128.jpg.html)

Best Choice; Stone set especially made to hone splines. Best all around for 2-stroke cylinders
http://i1152.photobucket.com/albums/p497/johntice1/P5200120.jpg (http://s1152.photobucket.com/user/johntice1/media/P5200120.jpg.html)

Small bore 3 point Sunnen mandrels gurentees your bore is Round & Straight
http://i1152.photobucket.com/albums/p497/johntice1/P1210342-Copy-1.jpg (http://s1152.photobucket.com/user/johntice1/media/P1210342-Copy-1.jpg.html)

Other types of hones; L, Ball hone aka dingle berry, C, Amco the only head in photo capable of any size control. R, brake cylinder hone. Aka Egg Beater.
http://i1152.photobucket.com/albums/p497/johntice1/082f2646-cb74-4be1-ad51-ed58b2089854.jpg (http://s1152.photobucket.com/user/johntice1/media/082f2646-cb74-4be1-ad51-ed58b2089854.jpg.html)


Does your dealer use a good dial bore Gauge?
http://i1152.photobucket.com/albums/p497/johntice1/P5200117.jpg (http://s1152.photobucket.com/user/johntice1/media/P5200117.jpg.html)

http://i1152.photobucket.com/albums/p497/johntice1/P5200119.jpg (http://s1152.photobucket.com/user/johntice1/media/P5200119.jpg.html)


I have found after a lifetime in the business that a proper break in is rather simple. ( Do a Leak Down Test FIRST ) Easy running on a couple tanks of fuel; finally, retorque the head bolts & your ready to go. If the bore is smooth; 300 grit or finer, round & straight your break in is a simple procedure.

John Tice
www.smallenginemachineworks.com & www.nwsleeve.com
Turning Custom Cylinder Sleeves Since 1971

I just took a look at the fine page on pressure testing. Kudos to the author who really has knowledge in his Bean.

I’m not attempting to hijack the thread; Basic knowledge of your cylinder sizing is the Heart of your engine.

:beer

Good stuff. Can't say for sure. I had Jerry do the work at Halls Precision Racing here in Peoria.

miket007
03-11-2016, 02:39 PM
Good stuff. Can't say for sure. I had Jerry do the work at Halls Precision Racing here in Peoria.

It was the coil....it was failing....replaced it and it's up and running. Still need to do the leak test and fine tune...but it's out of the intensive care unit. :lol:

yaegerb
03-11-2016, 02:42 PM
Good work and yes, do yourself a favor and pressure test it. Its a good habit :)