300cc Kit

[2LZ]

No heating problems here. If anything, I think it may be running a bit cooler. I have one long, steep canyon and it usually hit four bars by the top and it's only hitting three now. May have to do with not needing to wind it so high.

[Huck369]

No cooling issues on mine either

[Meloman]

I bought a kit but am hesitant to install it until I see how many total kits have been installed successfully and running. I know there was one that self destructed so it’s important for me to see the percentage. If only 3 are out there, then that’s a 33% defective rate.

Can all you 300 guys out there chime in and let me know:
a: how many miles you have on your kit
b: any problems you’ve experienced installing it
c: pros and cons now that you’ve lived with it

Thanks,
Mel

[rjmorel]

I just put it on last week so about 30 miles, no problems.
Installation was a little time consuming. Remove seat, tank and plastics, take off front crash bars, remove radiators, unbolt all motor mounts except the most rear one going thru swing arm. So you can pivot motor down enough to get head and cylinder off. Only problem I had if you read thru the last few weeks of this post is I lost the carb manifold O Ring someplace and had to order a new one.
I had 16,700 miles on original 250 motor, still ran great. rj

[NzBrakelathes]

Originally Posted by Meloman

I bought a kit but am hesitant to install it until I see how many total kits have been installed successfully and running. I know there was one that self destructed so it’s important for me to see the percentage. If only 3 are out there, then that’s a 33% defective rate.

Can all you 300 guys out there chime in and let me know:
a: how many miles you have on your kit
b: any problems you’ve experienced installing it
c: pros and cons now that you’ve lived with it

Thanks,
Mel

Hi Mel

The person who had issues if he is the same chap also had trouble fitting rings and then assembled it with an oil scrapper wrong/missing, then pulled it apart and then managed to fit the final scraper.

To be fair if this is the failure you mention I am pretty sure it was all operator error and not component error - I also sent the pics to the factory and they said the same (be it to pass the buck or not).

I think only same of the guys I sold kits to are here - Also to other brand bikes like PitsterPro and GPX, AJP PR5 etc.

But yes of course as I sell kits I might be one sided and sure consider that too.

Those are my thoughts and yes I have fitted 2 kits to 2 bikes and all is very very well (maybe I have decent mechanical skills lol)

BUT 100% true there is an MX bike sold here in China and it has 100% the 300 kit fitted new from the factory - yes the very kit I have etc.

Most of the talk in theory etc is just that and no real life experience with this kit or other bikes that in the past had big bores offered and fitted etc.
Some people are affraid the counter balance is different (yes it is) and some think the piston will fly apart on its on (I really doubt that!) and I am not going to preach hard to pressure you or anyone to fit it or not, If you feel you have the skills and knowledge to make a decision then you choose which it will be - many happy riders so far and like you said only 1 "failure" and that wasn't proven to be the parts or operator as only a few photos were supplied.

[Huck369]

I have the 300 kit, and probably have a little over 1,000 miles on it, no issues, great "bang for the buck"

[2LZ]

Originally Posted by Meloman

I bought a kit but am hesitant to install it until I see how many total kits have been installed successfully and running. I know there was one that self destructed so it’s important for me to see the percentage. If only 3 are out there, then that’s a 33% defective rate.

Can all you 300 guys out there chime in and let me know:
a: how many miles you have on your kit
b: any problems you’ve experienced installing it
c: pros and cons now that you’ve lived with it

Thanks,
Mel

a: About 750 miles. No issues other than the same annoying occasional stalling on decel, but it did that before the kit.

b: No real problems but as stated earlier, a bit time consuming. That said, I did it in my spare time plus I had 'friends" dying to help and get their hands involved.
Yes, sitting at the bench with the piston and rings, it's a slight challenge to get the oil rings in. After trying and trying, I ended up fitting them all at once and they slipped right in. You're gonna swear that the ring groove isn't wide enough.

c: Pros...the low end and mid-range are what I always wanted in the bike. With our terrain, it's awesome. i don't have to ring its neck to get up and down the canyons.
Cons... I think I lost a little top end. In the last 1000 r's before redline, it flattens out. For my terrain, it's not a big deal. If I lived in the flats, it may be.

[NzBrakelathes]

Funny you say you feel like you lost top speed? 13 or 14 tooth sprocket?
On my bike 14 tooth I can ride it all the way to red line or real near and get a higher top speed quicker then ever before.
I’d say your decel issue relates to stepper motor and passage, read my posts on cleaning and give that a go if you feel like it

Oil rings slipped in easily but be sure you fit the wave part butted together no over lap
Be sure you fit each ring next to wave ring not on it

[2LZ]

Originally Posted by NzBrakelathes

Funny you say you feel like you lost top speed? 13 or 14 tooth sprocket?
On my bike 14 tooth I can ride it all the way to red line or real near and get a higher top speed quicker then ever before.
I’d say your decel issue relates to stepper motor and passage, read my posts on cleaning and give that a go if you feel like it

Oil rings slipped in easily but be sure you fit the wave part butted together no over lap
Be sure you fit each ring next to wave ring not on it

Not top speed, top end in the power curve. The power arc seems to fall a little flat in the last 1000 r's. It still goes as fast as it used to, no problem. It just doesn't pull quite the same. I figured it's because I'm feeding a bigger hole with the same injection mapping.

[NzBrakelathes]

Ok got you, I get to very near redline on stock gearing and then the engine wont really or doesn't increase.
Stock gearing with 250 set up I wouldn't quite get there before

[Meloman]

“Oil rings slipped in easily but be sure you fit the wave part butted together no over lap
Be sure you fit each ring next to wave ring not on it”

Tako, can you post pictures of the right and wrong way to position the oil rings ?

[NzBrakelathes]

Originally Posted by Meloman

“Oil rings slipped in easily but be sure you fit the wave part butted together no over lap
Be sure you fit each ring next to wave ring not on it”

Tako, can you post pictures of the right and wrong way to position the oil rings ?

Check this thread - he made good photos and details - better then I could do.
http://chinariders.net/showthread.php?t=21779

Or if you’re not confident maybe find an MC mechanic as that would avoid troubles etc.
This job isn’t a beginners to mechanics type job IMO and you don’t want to find out a mistake the hard way

[sqwert]

Originally Posted by NzBrakelathes

Heating up? as in reading the temp or as on the bars on the gauge? they are high standard etc. I missed this comment and I haven't heard anyone report heating issue. Have you check the system is working correctly? I mean adding more cc might tip a weak or faulty system over the edge but that doesn't mean it is the extra cc or kit causing the issue.

Currently my cooling system is TOO cold and only goes to 1-2 bars up the gauge - thermostat issue I assume and I gotta fix 3rd gear........... don't feel like doing that part!

95-100*F (35-38*C), WFO, 75-80+mph (125-130+kph), slowly heats up enough after 12-15 minutes to boil over. Stock system is inadequate for sustained WFO running with 300 kit, engine simply makes too much power to cool in such hot weather. Other bikes, stock, in such conditions boil over in 3-5 minutes, so not a serious problem. So will cars and trucks.

Legal speeds and comfortable temps 2-3 bars on gauge.

[Working_ZS]

Originally Posted by sqwert

95-100*F (35-38*C), WFO, 75-80+mph (125-130+kph), slowly heats up enough after 12-15 minutes to boil over. Stock system is inadequate for sustained WFO running with 300 kit, engine simply makes too much power to cool in such hot weather. Other bikes, stock, in such conditions boil over in 3-5 minutes, so not a serious problem. So will cars and trucks.

Legal speeds and comfortable temps 2-3 bars on gauge.

Interesting. On my stock RX3, I'm running with one of the radiators blocked off up until 80-85 degrees F, sometimes with half of the other one blocked off as well this time of the year, with temps in the 20-40 degree F range. Running at two bars usually, briefly touching three bars, but at part throttle. Not much reason for wide open throttle all the time for the riding that I do.

[2LZ]

Originally Posted by Working_ZS

Not much reason for wide open throttle all the time for the riding that I do.

Same here. I'd end up off a canyon or eating a pine tree. i don't think my bikes been WFO in top gear for any longer than 5 seconds. Could be why I experience no heating issues.