athena big bore jetting help

[JoeHazzard]

Hello Everyone,

 

I recently bought a 93 Banshee and decided to tear it down, paint the frame, and put a big bore kit on. I bought the athena 392cc kit even tho there was'nt a whole lot of reviews on here about it I figured I would try it out and see what its all about. I got the kit in yesterday paid $765 shipped and got it about three days. Which I thought was a pretty good deal I guess. The cylinders definitly have bigger ports than stock and have 2 extra holes on the exhaust side not sure what there called (power ports maybe?). I don't know much about port timing or how to check it. The pistons looked kinda cheap, their cast aluminum but will probaly work fine. It also came with what looks like a cool head w/ domes, studs and gaskets. It did'nt come with wrist pin bearings so I am ordering some before I install the kit.

 

I was planning on running my stock carbs for now and just jetting them accordingly. I'm not sure what size later to go up to later, any input would be great. I'm running the stock airbox modded w/ those foam holes w/ lid no snorkle w/ a Toomy foam filter. FMF Fattys, power core 2s, timing advanced +4. Compression is 11.9:1, 68mm pistons, and it says I have to run at least 96 octane fuel w/ synthetic oil.

 

Will the stock carbs be big enough?

 

My elevation is 120 ft above sea level

I was thinking on mains.

-snorkel removed 1-2+

-Toomy foam filter 0-2+

-FMF Fattys 8+ (2+ on pilots)

-Timing advance 0-1+

-look like prostock reeds 0-1+

Equals 9 to 14 sizes bigger on mains so between 310 to 360 and 27.5 to 30 on pilots.

Not sure though what the different porting is going to do and what needle to run.

I guess I'll run 110 octane race fuel and a 32:1 mix.

 

Any input or suggestions? I plan on using this machine for wooded trails, MX tracks, and PA hill climbs.

[JoeHazzard]

I took some pictures of the new cylinders just for comparison.

Here's the old one's. I bought this kit because I was going to just have the cylinders bored and fitted with new pistons but the one cylinder had a hairline crack underneath the exhaust port, it had a crapy port job, and they had two different pistons in it. Same size different brands which had caused a compression difference of 8lbs. 120psi on one 128psi on the other.

On a different note. My gas station down the street is now carrying Sunoco race fuel. I was wondering which would be best for this application.

"The Standard" which is 110 octane leaded fuel non-oxgenated. Or The 260 GT which is 100 octane unleaded gasoline thats oxygenated 3.3%.

Both cost $7.29 a gallon right now.

[rdzbangshee]

I took some pictures of the new cylinders just for comparison.

Here's the old one's. I bought this kit because I was going to just have the cylinders bored and fitted with new pistons but the one cylinder had a hairline crack underneath the exhaust port, it had a crapy port job, and they had two different pistons in it. Same size different brands which had caused a compression difference of 8lbs. 120psi on one 128psi on the other.

On a different note. My gas station down the street is now carrying Sunoco race fuel. I was wondering which would be best for this application.

"The Standard" which is 110 octane leaded fuel non-oxgenated. Or The 260 GT which is 100 octane unleaded gasoline thats oxygenated 3.3%.

Both cost $7.29 a gallon right now.

i would have some pro shop do a miner port job your compression shoud be around 150 psi . athena pistons only make like 55 hp they say . i use pump gas on my vitos 421 . i just need some big bore pipes my t5s choke my top end

[rdzbangshee]

get them reported right buy a pro .

[EvilBanshee]

Run the Leaded fuel, its better for the engine. Keeps stuff lubed up.