Customize my D250RTC

Hey guys, I wanted to set up this thread for when I start to modify my 250rtc. I remember reading something from a guy who said not to modify if you ever plan on reselling your bike. I honestly have no interest in selling it. I will keep it till it runs into the ground even if I own another bike. I am posting a pic of the stock bike and then my rough drawing of what it will look like when I am mostly done. I hope to start a movement with custom chinese bikes. Show the world that I really can mod anything you put in front of me. Post your progress and custom work. I look forward to having people with me start this movement.

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Originally Posted by Homebuilt84

Hey guys, I wanted to set up this thread for when I start to modify my 250rtc. I remember reading something from a guy who said not to modify if you ever plan on reselling your bike. I honestly have no interest in selling it. I will keep it till it runs into the ground even if I own another bike. I am posting a pic of the stock bike and then my rough drawing of what it will look like when I am mostly done. I hope to start a movement with custom chinese bikes. Show the world that I really can mod anything you put in front of me. Post your progress and custom work. I look forward to having people with me start this movement.

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I have the same bike. I have considered dropping it some in the front, but would have to find an adjustable mono-shock to fit the rear. Might need to put on a steering damper if the rake angle gets changed too much so it doesn't get squirrely. Let us know how it works out. I'd like to see it. I ordered a 35-tooth sprocket for the rear, and am researching a re-jet for the carburetor.

what is the size of the carb on that

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Originally Posted by anthony.parris4

what is the size of the carb on that

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It is a Deni PZ30 with a 42mm inlet. The stock main jet is a 105 which I measured with a small drill bit to be approx. .038". I drilled it out to .051" after installing a performance air intake. The bottom end and midrange are better, but top end is a little rich. I'm trying to find replacement jets to experiment with a little smaller jet size to see how it works.

ok so you are staying they come jetted stock? would you recomend drilling it out? and how much of an increase in speed did you recieve when you did im looking to try and get 90 mph out of it

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Originally Posted by anthony.parris4

ok so you are staying they come jetted stock? would you recomend drilling it out? and how much of an increase in speed did you recieve when you did im looking to try and get 90 mph out of it

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No, they come with standard jets and a fairly restricted airbox. I got an angled-mount high-performance air filter kit from eBay. The reduction in air restriction causes the air/fuel mixture to become too lean. I drilled out the main jet to make up for this. Unfortunately, since I went a little too big it is too rich at wide open throttle so I actually did not get a top end increase. If you choose to drill it out, do it in small increments so you don't go too far with it. I would try to find a spare main jet too if you can. Supposedly, this carb is a Keihin PZ30 clone, so maybe spare jets for that carb would fit? I will have to try to find some or I will need to buy another carburetor. These bikes are geared low also. If you want to increase the top speed, you will need to get a smaller rear sprocket. You can get them from http://china-moto.com/cm/store/#ecwi...=0&sort=normal Be warned though that their sprockets are made of aluminum and have a shorter lifespan than the steel ones. I am trying to find a steel one, but have had no luck. Let me know if you find one.

ok well i have already bought the sprocket but how much do you think it will increase the speed supposibly it has 42 teeth stock i bought a 37 and a 33 both aluminum from china moto and do you know of any exhaust that will fit on this bike? the rear sprocket will last 3000 to 5000 miles according to the tech rep

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Originally Posted by mototech77

It is a Deni PZ30 with a 42mm inlet. The stock main jet is a 105 which I measured with a small drill bit to be approx. .038". I drilled it out to .051" after installing a performance air intake. The bottom end and midrange are better, but top end is a little rich. I'm trying to find replacement jets to experiment with a little smaller jet size to see how it works.

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what would u recommend the finish drill size

ok customize sprocket found a website http://sidewindersprockets.com/custom.html it looks like it would be worth a try but i would need to have my bike to get the exact specs but if you do get the measurements and everything you need to make it custom please let me know thank you

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Originally Posted by anthony.parris4

ok customize sprocket found a website http://sidewindersprockets.com/custom.html it looks like it would be worth a try but i would need to have my bike to get the exact specs but if you do get the measurements and everything you need to make it custom please let me know thank you

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I am going to probably try a .045" main jet size next and see how it works. Don't do any rejetting until you also open up the air intake and exhaust. Let me know what kind of results you get with the sprockets too. Two things to be aware of with these bikes that are common: 1. put blue loctite on the bolts holding the mirrors, turn signals, etc. to keep them from vibrating loose. 2. Make sure brake systems don't have any air in them. My rears stopped working recently because of air. I had to bleed it out. Works great now. I think that any flange-on aftermarket muffler will probably match up, but I cut mine down 4", and opened up the outlet. The upgrade mufflers are fairly expensive.

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Originally Posted by anthony.parris4

ok customize sprocket found a website http://sidewindersprockets.com/custom.html it looks like it would be worth a try but i would need to have my bike to get the exact specs but if you do get the measurements and everything you need to make it custom please let me know thank you

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Thanks for the link for Sidewinder Sprockets. That is what I have been looking for. This is the kind of info that makes these forums great. Let us know what tooth sprocket works the best for you.