Rebuilding a 2 stroke? | Page 13 | GTAMotorcycle.com

Rebuilding a 2 stroke?

Seems like a good idea.
 
Looks easy enough to take the carb out so I'm gonna do that on a less rainy day.

Left my siphon on my balcony to let the little fuel stuck in it evaporate. That wasn't a good idea as the wind took it away somewhere, lol.
 
Dealt with the carb today. To get it out required removing the airbox which requires removing the oil tank. Also took the fuel tank off. Got everything off except the oil line as I wasn't sure how to remove the crimped metal clamp or if I'd need to bleed the line somehow (I saw something about that in the service manual but didn't have it with me). Took the bowl off and it actually still had a bit of fuel in it, which went everywhere as I was expecting it to be empty. I wiped it out anyway.

Got everything back together. Put the battery on a tender for about 30 minutes. Only read 10V after but the bike started right up after adding some gas.

Anyway, got my appointment with Pro6 Thursday/Friday. Hopefully they can correct the compression issue.
 
Oh, also put in the fuel filter the previous owner gave me.

Probably going to put in a quick response EGT gauge as well for extra insurance. I'm tired of melting pistons, lol.
 
unL33T said:
Oh, also put in the fuel filter the previous owner gave me.

Probably going to put in a quick response EGT gauge as well for extra insurance. I'm tired of melting pistons, lol.
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You can get a EGT at Spruce Aircraft in Brantford. (Most of the probes come from asia, so you can get one on Alibaba or Banggood for less than $10... if you want).
http://www.aircraftspruce.ca/catego...ents/av/menus/in/probesandsenders_egtcht.html
Get a "K" probe and the gauge that looks best.
I prefer to weld in a bung instead of using a clamp to mount the probe. Figure out where you want the probe and bring me the pipe and I will weld it in for you. If you use a bung you can tune using a multi-meter, then remove the probe and cap the bung.

The "under the plug" EGTs are not as fast as a "K" probe in the exhaust stream.
 
I thought it came with a weld in bung but I see now it's only clamp. Can the clamp style be welded on or should I get a different one?

After welding it in I was going to paint the exhaust as well. I recall it was getting a little rough when you had it off last.
 
Nothing wrong with that Koso kit.
The Koso mount is universal. you can clamp it on, screw it on or weld it on.
If you clamp it, the clamp always loosens and rattles.
Threading it on either involves a pre-welded in bulkhead that is drilled and threaded (Too late for that) or a nut inside the pipe. If that nut falls off....

Here is an under plug CHT sensor
View attachment 38684
 
bitzz said:
Threading it on either involves a pre-welded in bulkhead that is drilled and threaded (Too late for that) or a nut inside the pipe. If that nut falls off....
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Why too late for that? I needed a bung welded on and took the pipe into a muffler shop with the bung and pipe with predrilled hole and they welded it in for not much money.
 
Well Pro6 says their techs read 125 PSI so I guess I have a bad gauge. But I borrowed a gauge from PartSource back when it read low after the first rebuild and it read within a couple PSI of my gauge. Guess they are both bad?
 
unL33T said:
Well Pro6 says their techs read 125 PSI so I guess I have a bad gauge. But I borrowed a gauge from PartSource back when it read low after the first rebuild and it read within a couple PSI of my gauge. Guess they are both bad?
Click to expand...

It's easy to check your gauge at ~120, just make a seal somehow and use an air compressor to see what it says (easiest is a rubber tipped blow gun). The air compressor has two more gauges that can be compared.

Second test is take it for a spin, if compression is off by 25%, you will notice the lack of power.

EDIT:
Even 125 seems really low for a fresh engine? Did you decide to drop the compression ratio on this rebuild?
 
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GreyGhost said:
It's easy to check your gauge at ~120, just make a seal somehow and use an air compressor to see what it says (easiest is a rubber tipped blow gun). The air compressor has two more gauges that can be compared.

Second test is take it for a spin, if compression is off by 25%, you will notice the lack of power.

EDIT:
Even 125 seems really low for a fresh engine? Did you decide to drop the compression ratio on this rebuild?
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Now that you mention it I think I also did that previously. I'll check it that way again.

Power seems alright but I'm also not revving it into the power band as per manufacturer's break in procedure.

AF1 Racing out of the US says 120 PSI is their minimum for a fresh rebuild but most are at 125. It should go up over time. Although I'm not sure how many km that takes as I've put about 200 km on it since the rebuild.
 
They said compression is good at exactly 125 and they looked into the exhaust hole and said the piston looks fine. 4 hours of my time and $160 for nothing lol. Would've thought they'd do a compression test as part of the rebuild but apparently not. Told me they were going to clean it but it looks the same as when I dropped it off. Oh well. Noticed a new scratch on the steering stem nut but it was probably already there. Gonna bug me now.
 
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the best way to check condition of a 2-stroke is a cylinder lead down tester, it measure the percentage of
air past the rings, you want to see 2-3 %
2rfvbpz.jpg
 
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Seems the zip tie holding the fuel line on isn't enough anymore. Even with the vacuum line removed from the vacuum operated fuel valve it's spitting fuel. Replaced the zip tie with a cheapo hose clamp and really tightened it down and it seems to have stopped the leak. Hopefully the cheap clamp doesn't cut the hose though (had that happen to a coolant line on a car once, wasn't fun).
 
Got the EGT gauge installed finally. I put in the display. Mechanic put on the sensor. Sensor looks way to far from the piston to me. Guess he didn’t look at the instructions. Now I gotta fix this. Instructions say 4” but this looks like 12” or so to me.

I12FG78.jpg


QSp2z2g.jpg


Been riding daily though which has been nice.
 
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bitzz said:
What temps are you seeing on the EGT?
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Anywhere from no reading (under 100C) to high 300s usually. Think I saw 446C once. I’d have to check the max reading on the gauge.
 
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