Intake port issue and head stud question..

Piston_Pedals

New Member
Joined
Jun 29, 2020
Messages
2
I am building my first motorized bike and my motor kit just showed up today. I am super excited about it. I have a fair bit of experience with cars/trucks and other mechanical + electronic stuff... But this is a whole new avenue for me. It's something I've wanted to do for many years. I've been doing a lot of research on the basics of these motors to try and get a head start knowledge wise before it showed up on the door step.. I can build a car engine, but I am a noob to these little 2 stroke engines through and through. I haven't had time to really dig into it today... But I did open the box and took a brief look at the engine and immediately have a question..

Seeing reports of people with backwards pistons and whatnot from the factory, I pre-made the decision to at least tear down the top end of this thing and go through it before I fire it up. Upon opening the box and removing the motor (It's supposed to be a Zeda 80, it has all the upgraded allen bolts and a large round exhaust port)..... I looked in the exhaust port, and in the center it (kind of) has the vertical piece you can see in this person's photo below. It's the part that everyone says is there to keep the rings from catching on the port... Only issue is.. The center of that vertical piece is missing in my port... So it looks like it has a little spike on the top and bottom... otherwise, the port is cast better than a lot of photos I have seen of other new motors... At least judging from a quick look from the outside. I can take a photo of the port tomorrow when I have good light.

*example of the piece that is partially missing in my jug*


Has anyone heard of such a thing? If so, is it a problem? I would think being it's not continuous that the rings might want to hang up due to it being spike like (I haven't attempted to rotate the motor yet).. If it's a problem, should I just grind it out? I assume that the race guys are opening these ports up bigger than the stock one without ring problems, so maybe grinding it out could be fine? Or should I ask the vendor to send me a new jug? I also wonder if the missing chunk is down in the crankcase...... or if it happened when it was cast and isn't inside the motor........

Also, do the head studs in these stretch a lot? Should I replace them with better ones while I have it apart? If so, any recommendation on what to buy and what length?
 


Street Ryderz

Well-Known Member
Joined
Oct 14, 2016
Messages
3,560
I am building my first motorized bike and my motor kit just showed up today. I am super excited about it. I have a fair bit of experience with cars/trucks and other mechanical + electronic stuff... But this is a whole new avenue for me. It's something I've wanted to do for many years. I've been doing a lot of research on the basics of these motors to try and get a head start knowledge wise before it showed up on the door step.. I can build a car engine, but I am a noob to these little 2 stroke engines through and through. I haven't had time to really dig into it today... But I did open the box and took a brief look at the engine and immediately have a question..

Seeing reports of people with backwards pistons and whatnot from the factory, I pre-made the decision to at least tear down the top end of this thing and go through it before I fire it up. Upon opening the box and removing the motor (It's supposed to be a Zeda 80, it has all the upgraded allen bolts and a large round exhaust port)..... I looked in the exhaust port, and in the center it (kind of) has the vertical piece you can see in this person's photo below. It's the part that everyone says is there to keep the rings from catching on the port... Only issue is.. The center of that vertical piece is missing in my port... So it looks like it has a little spike on the top and bottom... otherwise, the port is cast better than a lot of photos I have seen of other new motors... At least judging from a quick look from the outside. I can take a photo of the port tomorrow when I have good light.

*example of the piece that is partially missing in my jug*


Has anyone heard of such a thing? If so, is it a problem? I would think being it's not continuous that the rings might want to hang up due to it being spike like (I haven't attempted to rotate the motor yet).. If it's a problem, should I just grind it out? I assume that the race guys are opening these ports up bigger than the stock one without ring problems, so maybe grinding it out could be fine? Or should I ask the vendor to send me a new jug? I also wonder if the missing chunk is down in the crankcase...... or if it happened when it was cast and isn't inside the motor........

Also, do the head studs in these stretch a lot? Should I replace them with better ones while I have it apart? If so, any recommendation on what to buy and what length?
I am building my first motorized bike and my motor kit just showed up today. I am super excited about it. I have a fair bit of experience with cars/trucks and other mechanical + electronic stuff... But this is a whole new avenue for me. It's something I've wanted to do for many years. I've been doing a lot of research on the basics of these motors to try and get a head start knowledge wise before it showed up on the door step.. I can build a car engine, but I am a noob to these little 2 stroke engines through and through. I haven't had time to really dig into it today... But I did open the box and took a brief look at the engine and immediately have a question..

Seeing reports of people with backwards pistons and whatnot from the factory, I pre-made the decision to at least tear down the top end of this thing and go through it before I fire it up. Upon opening the box and removing the motor (It's supposed to be a Zeda 80, it has all the upgraded allen bolts and a large round exhaust port)..... I looked in the exhaust port, and in the center it (kind of) has the vertical piece you can see in this person's photo below. It's the part that everyone says is there to keep the rings from catching on the port... Only issue is.. The center of that vertical piece is missing in my port... So it looks like it has a little spike on the top and bottom... otherwise, the port is cast better than a lot of photos I have seen of other new motors... At least judging from a quick look from the outside. I can take a photo of the port tomorrow when I have good light.

*example of the piece that is partially missing in my jug*


Has anyone heard of such a thing? If so, is it a problem? I would think being it's not continuous that the rings might want to hang up due to it being spike like (I haven't attempted to rotate the motor yet).. If it's a problem, should I just grind it out? I assume that the race guys are opening these ports up bigger than the stock one without ring problems, so maybe grinding it out could be fine? Or should I ask the vendor to send me a new jug? I also wonder if the missing chunk is down in the crankcase...... or if it happened when it was cast and isn't inside the motor........

Also, do the head studs in these stretch a lot? Should I replace them with better ones while I have it apart? If so, any recommendation on what to buy and what length?
Yes you can grind them out and should as i would also double check that the piece isn't in the case.If you intend on hogging out the port then I would see if the vendor will replace it! The bridge is very handy when going to extreme's of port width so as not to snag the rings and yes we hog out port's with no bridge and port shape is then very important to prevent snagging the rings.The studs will require re torqued regularly with the stock once or twice with a big cnc head.
 

Piston_Pedals

New Member
Joined
Jun 29, 2020
Messages
2
Awesome, thanks. I'm not planning on building it up fast or anything right off the bat.. I just wanted to experience it stock for the most part and get a baseline understanding of what fails and doesn't on these things before attempting to make any significant increases in output.

Since I'm not planning to really open up the ports yet, I'll probably just pull the remnants of the bridge out of the port and make sure nothing foreign is hanging around down in the case. I figure by the time I am ready to start building a more serious motor, it'll be time to replace the cylinder at that point anyway. Right now I just wanna cruise with the family and maybe attempt a 50-100 mile ride after I get it rolling well. :)
 
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