How to tell a big bore kit from stock?

[darnizzle8805]

As the title states, How do you tell a big bore jug from stock? I am replacing my carb with a 34mm PJ. I am trying to get a ballpark to set my jetting to. As we all know when replacing a small carb with that of an oversized unit, you have to modify your reeds. I have bored my VF3 that fits into the intake. While I had it off I noticed that intake ports looked really big. I will also take a closer look at my piston to see if it is forged. So back to my main question... How can I be 100% positive that my jug is a big bore jug without tearing the top end apart? Also jetting advice for an 03 Blaster with CFM airbox w/foam UNI, Keihin PJ34, FMF pipe and silencer, 30-50ft elevation. Has: 150m, 48p, 3slot.

 

[Awk08]

here ya go................

http://www.blasterforum.com/engine-13/240-big-bore-vitos-la-sleeve-stock-36386/

 

[darnizzle8805]

Thanks Awk. That helps a lot

 

[Awk08]

figure out what you have and we'll go from there on jetting

 

[sicivicdude]

if it's a LA sleeve top end, that's easy. If it's a "sleeved" stock cylinder or a vito's, it's difficult to look at from the outside and tell. Once a vito's has been ported you can't even really tell from the look down into the ports...

The surest way is to measure the bore size, anything above 68.25 being a "big bore" kit.

 

[darnizzle8805]

I know that it's not an LA Sleeve jug. I know it has the 195cm.cu. markings but I cant remember if it has the Y-1 marking. The whole topend is black so I didn't know what it could be. Now I know what to look for, as soon as I get to the house i'll double check for the markings.

 

[sicivicdude]

I know that it's not an LA Sleeve jug. I know it has the 195cm.cu. markings but I cant remember if it has the Y-1 marking. The whole topend is black so I didn't know what it could be. Now I know what to look for, as soon as I get to the house i'll double check for the markings.

Vito's cylinders start off life "raw" aluminum. Someone could have painted it I guess....

Most likely it's a stock bore cylinder but it's possible that it's a sleeved stock cylinder too.

 

[darnizzle8805]

Alas I have a stock cylinder. It has a cast piston in it also, so i highly doubt that it's a BBK sleeved stock cylinder. I checked the jetting in the stock carb: 220m, 32.5p, 2nd from top slot. I guess I shouldnt have put so much faith in the man who has been a motorcycle and car mechanic for the majority of his 40 years of his life. I have an 03 so shouldnt i have a 230m stock? also I have VF3's and the FMF pipe so I would think both main and pilot jets would have been much higher. I bought the PJ34 and the CFM airbox because I was almost certain I had a 240 kit. The motor never missed a beat with the jetting I had with stock carb. I really dont want to pull the motor apart to see what size the bore is, cuz it runs so well.

 

[sicivicdude]

Alas I have a stock cylinder. It has a cast piston in it also, so i highly doubt that it's a BBK sleeved stock cylinder. I checked the jetting in the stock carb: 220m, 32.5p, 2nd from top slot. I guess I shouldnt have put so much faith in the man who has been a motorcycle and car mechanic for the majority of his 40 years of his life. I have an 03 so shouldnt i have a 230m stock? also I have VF3's and the FMF pipe so I would think both main and pilot jets would have been much higher. I bought the PJ34 and the CFM airbox because I was almost certain I had a 240 kit. The motor never missed a beat with the jetting I had with stock carb. I really dont want to pull the motor apart to see what size the bore is, cuz it runs so well.

Your jetting SHOULD be about a 300 main, stock pilot, needle on the third clip position with the stock carburetor. If he's been a MC mechanic for 40 years, he should have known better than that jetting....

You can still run the PJ34 and airbox even with the stock bore cylinder as long as it's setup pretty hot. Is that cylinder ported? Is the head rechambered?

 

[slickerthanyou]

Alas I have a stock cylinder. It has a cast piston in it also, so i highly doubt that it's a BBK sleeved stock cylinder. I checked the jetting in the stock carb: 220m, 32.5p, 2nd from top slot. I guess I shouldnt have put so much faith in the man who has been a motorcycle and car mechanic for the majority of his 40 years of his life. I have an 03 so shouldnt i have a 230m stock? also I have VF3's and the FMF pipe so I would think both main and pilot jets would have been much higher. I bought the PJ34 and the CFM airbox because I was almost certain I had a 240 kit. The motor never missed a beat with the jetting I had with stock carb. I really dont want to pull the motor apart to see what size the bore is, cuz it runs so well.

With vf3's, fmf, cfm air box, I can gaurentee that is one lean mother! Sure it rips but isn't gonna last long!

The 34pj u have I would start maybe 158, 45 pilot, middle clip (try a CEL or DGH needle)

The stock carb, I'd start at 300 , stock pilot, stock needle position.

My PWK33 150main- 45pilot , cel needle 2nd clip from top, The 35mm likes a richer pilot and main but only one size bigger on each , I am running ported VF3's, CFM box stock cylinder +3 crank, toomey pipe.

 

[darnizzle8805]

with the stock carb I was running the stock airbox, with the pj34 i want to run my cfm box. The jug isn't ported, so I doubt the head has been rechambered. i'll pick up some jets. do you guys think the 48p is too big?