Bikeguy Joe
Godfather of Motorized Bicycles
Only if improperly used.
RAW 80cc 2 stroke performance upgrades
- Thread starter moosinatrix
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Outrunner
New Member
If you're gonna make your bike go fast; you'd better make it stop fast too!
I would HIGHLY recommend an update of your INSURANCE policy before you attempt
over 35-40 mph. At least start with good brakes before you modify your engine. I'm
not sure but I bet it would be very painful to blow through a stop sign or red light because of low quality bicycle brakes and then get pancaked by a bus!
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Please install your slant head the correct way. LoL. Also take a picture of the combustion chamber to post up.
Look at the first pic, the slant head is od correctly. I don't seem to have any problems with it the way it is. Later I may reduce the gasket material and then I'll take pix of the gaskets and the chamber. I am now at this time working on my new chambered exhaust upgrade from sick bike parts. I just got done porting the welded areas of the flange and tubing. I think it will make a big difference. I also have been reading about homade reed valves. This is something worth looking in to. I am still waiting for my the mounting hardware for the 36 tooth sproket.
I'm also curious about this slant head orientation issue. Is it only for running a little cooler or is there any noticeable performance benefit?
Creative Engineering
New Member
Look at the first pic, the slant head is od correctly. I don't seem to have any problems with it the way it is. Later I may reduce the gasket material and then I'll take pix of the gaskets and the chamber. I am now at this time working on my new chambered exhaust upgrade from sick bike parts. I just got done porting the welded areas of the flange and tubing. I think it will make a big difference. I also have been reading about homade reed valves. This is something worth looking in to. I am still waiting for my the mounting hardware for the 36 tooth sproket.
jflyer,
What kind of hardware are you looking for? I have a ton of stuff here at the shop!
Jim
From a center fire head it makes a pretty noticable drop in cylinder temperature. However from being installed backwards, it should make a very noticable drop in cylinder temperature after sustained riding. Also cylinder dynamics promote better filling and combustion on the intake side.
Flip your head. You may not notice it, but your engine will.
In 10 Months ive only ever seen 1 slant head on the wrong way, they are ment to face foward as in the plug wire end is out the front and was designed this way for those with tight triangles in there frame not as a performance or compression booster.
Lmao ok then i dont know any better bro.
I finally got my chambered exhaust installed. I took a short test ride and you can definately notice a difference. The bike pulls better and runs a bit smoother. Next is the 36 sproket. I'll keep you posted. About the slant head. If it is soposed to go over the intake port, then, it would need to be installed 90 degrees to the right. That is where the intake port is. Otherwise, if it is better to have the plug opposite the exhaust port, then it needs to be installed 180 degrees facing to the rear of the bike. What is your take on this? Also, you can see on on of the pic that I have an extra thick amount of gasket material. I believe I have more than needed. I did this to fix the piston slap problem I got when I first installed the slant head. I will probably reduce the thickness as much as allowable to increase compression.
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I finally got my chambered exhaust installed. I took a short test ride and you can definately notice a difference. The bike pulls better and runs a bit smoother. Next is the 36 sproket. I'll keep you posted. About the slant head. If it is soposed to go over the intake port, then, it would need to be installed 90 degrees to the right. That is where the intake port is. Otherwise, if it is better to have the plug opposite the exhaust port, then it needs to be installed 180 degrees facing to the rear of the bike. What is your take on this? Also, you can see on on of the pic that I have an extra thick amount of gasket material. I believe I have more than needed. I did this to fix the piston slap problem I got when I first installed the slant head. I will probably reduce the thickness as much as allowable to increase compression.
You are confusing the intake port with the transfer ports. Transfer ports are 90* and 270* in the cylinder.
Also since the transfers are pointed torward the intake side, air collides upward with the fresh charge and spirals into the intake offset chamber. When this fires it wants to expand outward towards the exhaust port. So you are actually promoting faster loop scavenging.
After riding the bike around today, I found that it now has an extreme amount of viabration at higher rpms and that it cuts out at high rpms due to lack of fuel. The high rpm harmonic viabration is so bad, that it not only makes it extremely uncomfortable to ride, but it shakes loose all the bolts on the bike causing a major ongoing maintenance issue around tightening bolts and nuts all over the bike. I tried to make it richer with no success. I adjusted the float as much as possible with out it flooding, and again no luck. It still acts like it is starving for fuel and cutting out at the upper end of the rpm band. Remember, this bike is ported as well. With these problems persisting, I will have to go back to the stock exhaust. Anybody have any suggections?
After riding the bike around today, I found that it now has an extreme amount of viabration at higher rpms and that it cuts out at high rpms due to lack of fuel. The high rpm harmonic viabration is so bad, that it not only makes it extremely uncomfortable to ride, but it shakes loose all the bolts on the bike causing a major ongoing maintenance issue around tightening bolts and nuts all over the bike. I tried to make it richer with no success. I adjusted the float as much as possible with out it flooding, and again no luck. It still acts like it is starving for fuel and cutting out at the upper end of the rpm band. Remember, this bike is ported as well. With these problems persisting, I will have to go back to the stock exhaust. Anybody have any suggections?
This extreme harmonic vibration could be causing the fuel in the bowl to foam, making it seem like its running outta fuel when the vibration gets really bad. very common with bad vibration.
Outrunner
New Member
Your problem with vibrations has absolutely nothing to do with the exp-chamber.After riding the bike around today, I found that it now has an extreme amount of viabration at higher rpms and that it cuts out at high rpms due to lack of fuel. The high rpm harmonic viabration is so bad, that it not only makes it extremely uncomfortable to ride, but it shakes loose all the bolts on the bike causing a major ongoing maintenance issue around tightening bolts and nuts all over the bike. I tried to make it richer with no success. I adjusted the float as much as possible with out it flooding, and again no luck. It still acts like it is starving for fuel and cutting out at the upper end of the rpm band. Remember, this bike is ported as well. With these problems persisting, I will have to go back to the stock exhaust. Anybody have any suggections?
As far as running too lean, do not adjust your float bowl level! Instead go to a larger main jet, keeping in mind that excessive vibrations of the carb can easily cause temporary foaming to cause some lean run conditions. Although, that is one reason that the fuel is drawn from the bottom of the float bowl, so make sure your engine is tightened down securely and definitely use lock tite on ALL
of your threads. These China motors are known for high rpm vibrations.
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