Some of you might have seen my introduction and the start of my 20” dual suspension BMX build. That bike is a more in depth build, with full light system, moped seat, battery, on board charging, headlight fairing, shift kit, vapor speedo, custom paint and many more details/parts. I have the majority of everything I need for that build besides the last few critical pieces. I plan to gather parts and finish that build before summer starts. In the mean time I wanted to build a less complex bike to cruise around on while I slowly build the BMX.
The Micargi Jetta was a really fun and pretty simple build. In my intro and info about the BMX I mentioned that the wheels on the BMX are from a donor bike. The triple tree and kick stand I used on the Jetta are also from that same donor bike. I ended up using the original wheels from the BMX on this Jetta build. At this point the only thing left from the stock Jetta is the handlebars, cranks, pedals and sprocket (which will change soon). I ride the Jetta now and it looks done but I still have a few details yet to do.
I’m building this bike as a mild cruiser. Its main use will be to let friends ride when I’m on the BMX. The motor is a 66cc china girl. I cleaned up/slightly opened (~1-2 mm wider) the intake and exhaust ports and polished the exhaust port. I also cleaned up the transfer ports where they meet the crank case. I then chamfered the insides of the intake and exhaust ports. The piston dome got ramped at the exhaust and transfer port sides. The piston skirt also had a little over 1 mm blocking the intake at TDC. So I notched the piston skirt where it was blocking the intake to take care of that.
Something I noticed on the last two new motors I've got is both had the top of the cylinder and head milled flat and the heads have nice combustion chamber shape and a machined in squish band! Even though the head and cylinder top was flat, I still sanded them down a bit on glass and installed a thinner head gasket to increase compression a bit. I replaced all the bolts with black high grade hex head bolts as well as HD head studs from SBP. The intake is a MM style billet short intake. An R/T carb is what I went with on this bike. There wasn't enough space to install the nice aftermarket air filter but I will get something to work eventually.
The motor on the Jetta is almost exactly how I built the one on my BMX besides one critical part, the exhaust. On the BMX with the shift kit I went with the SBP expansion chamber exhaust and it is scary fast when it gets into the power band (mid rpm’s). However on the Jetta I wanted more of a cruiser look and not really building for performance, I went with the “Motocross flexible poo poo pipe muffler” from Kings motor bikes. In stock form that pipe is an ugly beast. The paint is horrible. The muffler is cheap looking(tons of scratches) polished steel
and had a lot of over spray or lack of taping where the muffler meets the rest of the exhaust. As you can see I used black exhaust wrap to take care of the ugliness. I also painted the header part of the pipe which btw was far from flat and would not have worked without a lot of hammering, filing and sanding. The header part that bolts to the cylinder has a tiny exhaust hole and needed lots of work with minimal results.
On my BMX with the SBP pipe and the r/t carb it ran great right off the bat with the stock size 70 jet. The Jetta on the other hand, with the very restrictive exhaust and 70 jet ran like poo poo (maybe that’s why they call it that)! I went down to a 66(smallest I had on hand) and it help a lot but still runs pretty fat in the mid to upper rpm’s. I’m gonna keep it like that for a few tanks to break it in a little rich. I figure it probably needs a 58-62 jet to run the way it’s supposed to without four stroking.
I originally ordered a 26 tooth sprocket from the other “Kings” website. I figured it would take a while but I had plenty of work to do on the bike to keep me busy until it got here. Two weeks after nothing from kings, I sent an email to check on my order. I immediately got a message back saying the email was no longer in use. So, I waited until Monday and called. As soon as they answer all I hear is a loud rustling sound of someone crinkling paper close to the phones microphone. I could barely hear him and barely speak it was so loud. Don’t ask me why but that’s all I could hear until finally I told him what I needed and once he realized who I was the paper sound stopped. Then he proceeded to tell me that he had forgot about my order on accident and very scatter brained sounding stated he was very busy but he knows my order and to call back tomorrow to remind him!
The next day I got an answer and was told because my sprocket was a 26 tooth, I needed another part called the "sombrero" (an adapter for your adapter at an additional $50). It would have been nice to know this when I originally placed my order so I could have gotten it then. Seemed kinda shady the way it’s not mentioned on the sprocket order page. By this time I was low on funds and had to wait until next payday to order the sombrero. I finally got it ordered and again after two weeks without a peep I call again, with no answer. I found a contact page on his site and I filled out the form with no reply.
At this point since it’s been very drug out, I was past the 45 day PayPal claim limit on the sprocket. I tried calling again the next day with still no answer and no other way to make contact, the only thing I could do was to make a claim with PayPal to get my money back. I was able to get the money back for the stupid sombrero but like I said was too late to do anything on the sprocket. I was told by PayPal to talk to my bank about it, so I did and ended up getting my money back. With everything pretty much done on the Jetta for a while besides the rear sprocket, I got tired of waiting.
When I was working on my BMX, I ordered a 30t sprocket from SBP to maybe use on the BMX shift kit. Turns out I didn't need it on the BMX, so it was in my parts bin. After doing some calculations on the gear ratio tool, I found that the difference between similar ratios on a 26” wheel compared to a 20” wheel is about 10 teeth. In other word to get a close ratio to the stock 44t on a 26” bike you would need a 34t on a 20” bike. So the 30t on this 20” bike is gonna be similar to a 40t on a 26” bike. That’s a good all around ratio that can handle hills but still cruise at a slightly lower rpm.
Luckily the sprocket has 30 teeth and I’m using a 3 prong hub adapter. So, all I did was put a layer of painters tape on the sprocket so I could make marks and measurements. Since I needed 3 holes on a 30 tooth all I had to do was count 10 teeth and make a mark. The sprocket diameter is also perfect to fit the adapter with the holes being close to the outside of the sprocket but not too close to the teeth/chain.
Once I had my marks, I made sure the distances where right and all equal with my calipers. Then I used a hand power drill starting with small bits working up to the proper size needed. Once the holes where made I used a bigger bit to put a small bevel on the edge of the new holes to match the beveled bolts on the adapter. Besides being a little thinner and flat making my chain close to my tire, it works perfectly. I got really lucky and made all my holes perfect and my sprocket was nice and centered. Eventually I will upgrade to a heavier/thicker 30t sprocket but not a top priority. I’m really happy with the 30t ratio on this bike.
The handlebars are the stock Jetta bars. They fit the look I wanted and put my arms in the perfect upright cruising position. The stem is an aftermarket BMX unit. I used the same foam grips that I have used on every other build with great results. The throttle, dual brake lever, petcock, and kill switch are all from SBP. The lay back seat post was made by my dad and the seat is a thick gel cruiser saddle with nice big springs. In order to use the nice suspension triple trees I got from the donor bike I had to cut quite a bit off the Jetta’s stock head tube. If it needed to be any shorter they would not have worked on this frame. As you can see just like most things on this bike it’s a tight fit.
The head light is an automotive fog lamp with an H3 led (soon to change) bulb. The head light is powered by a 12v mini-gen straight to the light. The taillight/blinker kit is an elcheapo from Amazon, but it gets the job done and doesn't look too bad.
Since this build is a bobber, I yanked the front fender off and used it in combination with one of the rear fender brackets to use as a “bobbed” rear fender. I think it did the trick just right. The tires on the Jetta are Odyssey Chase Hawk 2.2" black with red reflective stripe (looks white/pink in the pics because of the flash). They roll easy and are super sticky.
Only a few things left to do. I plan to install a smaller pedal sprocket for easier pedaling at starts. I also wanna use the moped pedals from my BMX (since I found some different ones for it). Other than that it’s just small stuff like dong the final tune on the carb, which I will do once the weather gets a little better. She should be finished before summer but as you all know they are never really done!
TL;DR
Here is my Micargi Jetta bobber build. What do you think?
The Micargi Jetta was a really fun and pretty simple build. In my intro and info about the BMX I mentioned that the wheels on the BMX are from a donor bike. The triple tree and kick stand I used on the Jetta are also from that same donor bike. I ended up using the original wheels from the BMX on this Jetta build. At this point the only thing left from the stock Jetta is the handlebars, cranks, pedals and sprocket (which will change soon). I ride the Jetta now and it looks done but I still have a few details yet to do.
I’m building this bike as a mild cruiser. Its main use will be to let friends ride when I’m on the BMX. The motor is a 66cc china girl. I cleaned up/slightly opened (~1-2 mm wider) the intake and exhaust ports and polished the exhaust port. I also cleaned up the transfer ports where they meet the crank case. I then chamfered the insides of the intake and exhaust ports. The piston dome got ramped at the exhaust and transfer port sides. The piston skirt also had a little over 1 mm blocking the intake at TDC. So I notched the piston skirt where it was blocking the intake to take care of that.
Something I noticed on the last two new motors I've got is both had the top of the cylinder and head milled flat and the heads have nice combustion chamber shape and a machined in squish band! Even though the head and cylinder top was flat, I still sanded them down a bit on glass and installed a thinner head gasket to increase compression a bit. I replaced all the bolts with black high grade hex head bolts as well as HD head studs from SBP. The intake is a MM style billet short intake. An R/T carb is what I went with on this bike. There wasn't enough space to install the nice aftermarket air filter but I will get something to work eventually.
The motor on the Jetta is almost exactly how I built the one on my BMX besides one critical part, the exhaust. On the BMX with the shift kit I went with the SBP expansion chamber exhaust and it is scary fast when it gets into the power band (mid rpm’s). However on the Jetta I wanted more of a cruiser look and not really building for performance, I went with the “Motocross flexible poo poo pipe muffler” from Kings motor bikes. In stock form that pipe is an ugly beast. The paint is horrible. The muffler is cheap looking(tons of scratches) polished steel
and had a lot of over spray or lack of taping where the muffler meets the rest of the exhaust. As you can see I used black exhaust wrap to take care of the ugliness. I also painted the header part of the pipe which btw was far from flat and would not have worked without a lot of hammering, filing and sanding. The header part that bolts to the cylinder has a tiny exhaust hole and needed lots of work with minimal results.On my BMX with the SBP pipe and the r/t carb it ran great right off the bat with the stock size 70 jet. The Jetta on the other hand, with the very restrictive exhaust and 70 jet ran like poo poo (maybe that’s why they call it that)! I went down to a 66(smallest I had on hand) and it help a lot but still runs pretty fat in the mid to upper rpm’s. I’m gonna keep it like that for a few tanks to break it in a little rich. I figure it probably needs a 58-62 jet to run the way it’s supposed to without four stroking.
I originally ordered a 26 tooth sprocket from the other “Kings” website. I figured it would take a while but I had plenty of work to do on the bike to keep me busy until it got here. Two weeks after nothing from kings, I sent an email to check on my order. I immediately got a message back saying the email was no longer in use. So, I waited until Monday and called. As soon as they answer all I hear is a loud rustling sound of someone crinkling paper close to the phones microphone. I could barely hear him and barely speak it was so loud. Don’t ask me why but that’s all I could hear until finally I told him what I needed and once he realized who I was the paper sound stopped. Then he proceeded to tell me that he had forgot about my order on accident and very scatter brained sounding stated he was very busy but he knows my order and to call back tomorrow to remind him!
The next day I got an answer and was told because my sprocket was a 26 tooth, I needed another part called the "sombrero" (an adapter for your adapter at an additional $50). It would have been nice to know this when I originally placed my order so I could have gotten it then. Seemed kinda shady the way it’s not mentioned on the sprocket order page. By this time I was low on funds and had to wait until next payday to order the sombrero. I finally got it ordered and again after two weeks without a peep I call again, with no answer. I found a contact page on his site and I filled out the form with no reply.
At this point since it’s been very drug out, I was past the 45 day PayPal claim limit on the sprocket. I tried calling again the next day with still no answer and no other way to make contact, the only thing I could do was to make a claim with PayPal to get my money back. I was able to get the money back for the stupid sombrero but like I said was too late to do anything on the sprocket. I was told by PayPal to talk to my bank about it, so I did and ended up getting my money back. With everything pretty much done on the Jetta for a while besides the rear sprocket, I got tired of waiting.
When I was working on my BMX, I ordered a 30t sprocket from SBP to maybe use on the BMX shift kit. Turns out I didn't need it on the BMX, so it was in my parts bin. After doing some calculations on the gear ratio tool, I found that the difference between similar ratios on a 26” wheel compared to a 20” wheel is about 10 teeth. In other word to get a close ratio to the stock 44t on a 26” bike you would need a 34t on a 20” bike. So the 30t on this 20” bike is gonna be similar to a 40t on a 26” bike. That’s a good all around ratio that can handle hills but still cruise at a slightly lower rpm.
Luckily the sprocket has 30 teeth and I’m using a 3 prong hub adapter. So, all I did was put a layer of painters tape on the sprocket so I could make marks and measurements. Since I needed 3 holes on a 30 tooth all I had to do was count 10 teeth and make a mark. The sprocket diameter is also perfect to fit the adapter with the holes being close to the outside of the sprocket but not too close to the teeth/chain.
Once I had my marks, I made sure the distances where right and all equal with my calipers. Then I used a hand power drill starting with small bits working up to the proper size needed. Once the holes where made I used a bigger bit to put a small bevel on the edge of the new holes to match the beveled bolts on the adapter. Besides being a little thinner and flat making my chain close to my tire, it works perfectly. I got really lucky and made all my holes perfect and my sprocket was nice and centered. Eventually I will upgrade to a heavier/thicker 30t sprocket but not a top priority. I’m really happy with the 30t ratio on this bike.
The handlebars are the stock Jetta bars. They fit the look I wanted and put my arms in the perfect upright cruising position. The stem is an aftermarket BMX unit. I used the same foam grips that I have used on every other build with great results. The throttle, dual brake lever, petcock, and kill switch are all from SBP. The lay back seat post was made by my dad and the seat is a thick gel cruiser saddle with nice big springs. In order to use the nice suspension triple trees I got from the donor bike I had to cut quite a bit off the Jetta’s stock head tube. If it needed to be any shorter they would not have worked on this frame. As you can see just like most things on this bike it’s a tight fit.
The head light is an automotive fog lamp with an H3 led (soon to change) bulb. The head light is powered by a 12v mini-gen straight to the light. The taillight/blinker kit is an elcheapo from Amazon, but it gets the job done and doesn't look too bad.
Since this build is a bobber, I yanked the front fender off and used it in combination with one of the rear fender brackets to use as a “bobbed” rear fender. I think it did the trick just right. The tires on the Jetta are Odyssey Chase Hawk 2.2" black with red reflective stripe (looks white/pink in the pics because of the flash). They roll easy and are super sticky.
Only a few things left to do. I plan to install a smaller pedal sprocket for easier pedaling at starts. I also wanna use the moped pedals from my BMX (since I found some different ones for it). Other than that it’s just small stuff like dong the final tune on the carb, which I will do once the weather gets a little better. She should be finished before summer but as you all know they are never really done!
TL;DR
Here is my Micargi Jetta bobber build. What do you think?
