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Working_ZS · 03-18-2021, 06:08 PM

My advice is to replace the head, at the very least, and possibly the cylinder and piston as well. This is due to the fact that everything got so hot when you leaned it out WOT. It takes a lot of heat to burn thru a catalytic converter's ceramic honeycomb, so all of the power generating parts of the engine (piston, rings, cylinder, head and valves) are suspect to me now.

Where you source parts from depends upon a few things; how fast you want to get it back on the road, who has it in stock, and how much they want for the parts. Optimally, getting the parts from CSC is your best bet from a quality standpoint, if they have them in stock, which isn't a sure thing right now, given the pandemic and its effects on manufacturers production and shipping chains. They probably won't be the cheapest though. If they don't have one in stock, then AliExpress or eBay will probably have to do, and you will have to take what you get from them, metallurgy-wise. Personally, I wouldn't have a problem with AliExpress and eBay, apart from being in a hurry and having to wait for it to come from China.

As for the original metallurgy being no good, I have to point out that there are literally several hundred, if not over a thousand of these bikes here in the US now, not to mention tens of thousands worldwide, and yours is the only low mileage exhaust valve failure that I am aware of. My own RX3, which has ever only had one valve adjustment, is at over 17,000 miles without any issues, and others have even more on theirs. I think that the valves were OK, they just got way too hot and are now toast.

I would suggest that when you get it back together that you not hammer the crap out of it until after you put 3000 or 4000 miles it; after that you can go more WOT, but you need to always keep in mind that it is only a 250 cc engine and it's pushing a 400 lb bike, plus rider. It's fine to break in hard a new bike that you purchased from a dealer, with a warranty; not so much for one that is used, even if it was extremely low miles. Used means no warranty, putting you are on the hook for repairs if anything lets go. Luckily, you got the bike for $1200, which was a literal steal, so you don't have a lot in it even after repairs are factored in. Also, I would recommend that you use the Lucas Fuel Injection and Upper Cylinder Lubricant that CSC recommends for it. One gallon of it literally lasts me over 10,000 miles, and that is at over three times the recommended dilution rate. At $25 or so from Walmart or Amazon, it is very cheap insurance against what you are dealing with right now.

03-18-2021, 06:08 PM	#10
Working_ZS Join Date: Aug 2016 Posts: 365	Replace The Head My advice is to replace the head, at the very least, and possibly the cylinder and piston as well. This is due to the fact that everything got so hot when you leaned it out WOT. It takes a lot of heat to burn thru a catalytic converter's ceramic honeycomb, so all of the power generating parts of the engine (piston, rings, cylinder, head and valves) are suspect to me now. Where you source parts from depends upon a few things; how fast you want to get it back on the road, who has it in stock, and how much they want for the parts. Optimally, getting the parts from CSC is your best bet from a quality standpoint, if they have them in stock, which isn't a sure thing right now, given the pandemic and its effects on manufacturers production and shipping chains. They probably won't be the cheapest though. If they don't have one in stock, then AliExpress or eBay will probably have to do, and you will have to take what you get from them, metallurgy-wise. Personally, I wouldn't have a problem with AliExpress and eBay, apart from being in a hurry and having to wait for it to come from China. As for the original metallurgy being no good, I have to point out that there are literally several hundred, if not over a thousand of these bikes here in the US now, not to mention tens of thousands worldwide, and yours is the only low mileage exhaust valve failure that I am aware of. My own RX3, which has ever only had one valve adjustment, is at over 17,000 miles without any issues, and others have even more on theirs. I think that the valves were OK, they just got way too hot and are now toast. I would suggest that when you get it back together that you not hammer the crap out of it until after you put 3000 or 4000 miles it; after that you can go more WOT, but you need to always keep in mind that it is only a 250 cc engine and it's pushing a 400 lb bike, plus rider. It's fine to break in hard a new bike that you purchased from a dealer, with a warranty; not so much for one that is used, even if it was extremely low miles. Used means no warranty, putting you are on the hook for repairs if anything lets go. Luckily, you got the bike for $1200, which was a literal steal, so you don't have a lot in it even after repairs are factored in. Also, I would recommend that you use the Lucas Fuel Injection and Upper Cylinder Lubricant that CSC recommends for it. One gallon of it literally lasts me over 10,000 miles, and that is at over three times the recommended dilution rate. At $25 or so from Walmart or Amazon, it is very cheap insurance against what you are dealing with right now.
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