• New Owner - Cylinder Questions

November 2019 Forum Retirement
Due to lack of extra personal time (and too much spam), I'm retiring the forum and setting it to a read-only state. No new registrations or posts will be accepted as of 11/09/19. However, all information will stay up and searchable. If you spend a few minutes searching, you'll find the answers you're looking for. We may re-open the forum next spring.
 #10478  by Aaron407
 Wed Jun 29, 2016 12:23 pm
Hello everyone,

I'm a new forum member and Kandi Spyder 150cc owner as of last weekend when I picked up a used one from a couple who said that it wouldn't run, and their mechanic said it needed a new carburetor. I picked it up and, after a few hours of troubleshooting, traced the main issue down to a lack of spark caused by a bad ignition coil. I swapped it out and it fired up, but it's pumping out a lot of white smoke, suggesting that either the valve seals or piston rings need to be replaced. I'll be doing a compression test tonight, then will fire in some oil and seeing if the test result changes to determine whether it's the rings or the seals. Since startup is quite rough, I'm leaning towards the rings being the issue after I confirm that there is no vacuum leak at the intake manifold.


If I'm going to be pulling the cylinder to replace the piston rings, I feel that I might as well do a slightly larger GY6 bore kit. Unfortunately, there seems to be a massive amount of contradictory information online in terms of the largest bore kit that can be accommodated without machining the case, with some (e.g., gokartusa) claiming even a 200cc kit not needing machining.

So, to set the record straight in my mind for what I will need, I'm hoping to ask the forum community a few questions.

1) I have read a number of posts stating that a 58.5mm bore is the largest without machining. However, a number of posters (possibly not on this forum) have also noted that the Taida 61 mm kit also doesn't require boring. Can anyone confirm this with any level of certainty?

2) How would I determine if I need an emissions head design, and what would happen if I needed one but installed one without the emissions port? I have been searching for a stamped engine code to no avail.

3) At what bore size is the stock head design size no longer considered appropriate and would be in need of a matching size to the bore?

4) At what point of bore size would the carb need to be rejetted if there are no other modifications (i.e., no changes to intake/exhaust)?

I sincerely apologize if this information is buried in numerous posts. I searched, but couldn't find clear answers. I would greatly appreciate anyone's thoughts. Thanks.
 #10488  by Aaron407
 Mon Jul 11, 2016 1:44 pm
Through trial and error, and more research, I have answered my questions. I went with and installed a 58.5 mm bore kit from Naraku as I couldn't confidently find information on anything larger not requiring boring. I found that it wasn't an emissions type as it didn't have the U piping at the valve cover. There is now no smoke and it runs strong now. It's a bit lean judging by the plug, so I'll be rejetting the carburetor while also installing a UNI filter. I found the stock intake piping had broken away at one of the connections, likely letting in dirt and causing the original ring damage. The piston was rattling away in the original cylinder, and the oil rings were almost non-existent.

Interestingly, my carburetor was sealed for all intents and purposes. The screws for the bowl were cut off and the holes filled at the face to make it so you couldn't easily remove the bowl screws to clean things or rejet. I drilled out the old screws and tapped new holes, and things seem to be working. If only I hadn't cracked the intake manifold spacer...
Last edited by Aaron407 on Sat Aug 20, 2016 11:55 pm, edited 2 times in total.
 #10530  by NCFRC
 Sat Aug 20, 2016 7:57 pm
Where did you get this kit ??