n33r54 wrote:
I have the curved fin head 78.50mm but it has a blown piston so I picked up a new OE honda piston off of evilbay. It was supposed to be .50 over stock. When I asked the seller was it 79mm or 80.50 they replied with, its .50 over stock. I assumed it was 79mm but ended up being 80.50 so technically they didn't lie it was .50 over the 80mm stock bore. I had the rings for the 79mm so I would have been good to go. It's my fault, I should of had them them measure it, or just not bought it. So now I'm trying to find rings to match it.
Ok now I got it.
There is always more to a story than what's being told -- Baahahahahaha.
Here is my opinion:
You have a stock, post recall, curved fin head, ART piston 78.5mm bore Engine.
You wanted to go up one size to 79mm.
You got the wrong piston because it's 80.5mm.
At this point I bet you don't know if it's an ART 80.5mm or a Wiseco 80.5mm piston.
So now we are left guessing.
At this point I would just eat the cost of that 80.5mm for two reasons:
1) First we have to know what you actually got there
2) and this is the most important point -- your current bore is 78.5mm so if you go straight to 80.5 mm you miss out on several re-bores if you can even get those other smaller pistons and rings.
The smallest piston you can get from Wiseco is an 80mm.
Wiseco is the ONLY manufacturer (that I'm aware of) for pistons for this Engine.
If Derek has the original ART piston and rings then you can get many more bores out of your Engine.
Many of us have been in this position before we found out Derek had parts for these machines. We had to go from 78mm or 79mm straight to a Wiseco 80mm. At the end of the day I would drop a dime and call Derek. I have ordered transmission parts from him and he's a great guy to deal with. Then you will know for sure what bore you will have to go to.
Anyway you look at it, it's gona cost peso's.
A machine shop will have to bore that cylinder for you. I'm not sure what the costs of that are in your area and it's been many years since I've had to do mine. Do NOT send that cylinder to a machine shop and say bore this cylinder. You MUST send the piston with it. They will ask you what clearance you want. There is some controversy here as to what clearance you should run. Many an argument has been posted here on that. In my opinion I would run at least .005" or even .006" clearance because you are still running an air cooled Engine. Just my opinion.
My next questions are:
1) What happened to your
Engine ? Why do you need a new piston ?
2) What fuel are you running ?
3) Are you running the stock fuel pump ?
4) MOST IMPORTANT -- what is the fuel flow rate of your fuel pump ?
I'm not trying to be an azz hole, I'm actually asking valid questions because many of us have been down this sorry road and I'm trying to figure out your mechanical abilities and who you are. No offense.
CO