03-09-2010, 09:37 PM
|
#1 |
| PWCToday.com Is My Home Away From Home
Join Date: Jan 2009 Location: Olympia, WA
Posts: 3,150
| JS 300 question
I pulled the engine on my JS 300 apart today to locate why it has low compression, and found a chip in the piston on the exhaust side. It's been down for a while (note the rust on the cylinder). I read the JS 300 has the same pistons as a 650, and should be 76mm, so I measured the bore with my digital calipers - 75.52, checked it twice. Is that right or are my calipers not calibrated? I reset them to zero on both checks. It also looks like it was ported - at least on the exhaust port - nice looking work from what I can see so far... so, is the 650 the same piston as the 300? What else can I do (other than a swap)?- I've already got a decent 550 and 750, just want something more out of this old 1 lunger!!! It's got a milled head, port work, Kerker pipe, port work. I've got an SBN 38 lying around, I might try that out too. What jetting should I run on it? I figure it would be close to the same as a dual 38 setup on a 650?
__________________
1991 550sx, 1993 750sx, 1993 750sx (Wife's ski), 1998STX, 1994 Waveblaster, 1983 550
Big thanks to Newmiller Machine in Oregon for the great work! (Mcn6 on PWCtoday)
"The number of ways of playing footsie with detonation is endless, but nothing works every time. This guarantees that we will never be bored, and will never run out of seized pistons. " - Kevin Cameron |
|  |
)
Linear Mode
