Does anyone know how much you need to bore a 1200 to get to 1250? Is there enough cylinder wall there or should I buy a 1250 kit? Not sure I want to buy new jugs if I don't have to.

Thanks.

I think it is a .040 over bore but I am not 100%. Thats what mine is bored to.

A .030" over bore will yield 1221cc

Not sure about a .040" over bore

I can't see that there is enough material in the sleeves to get you to 1250cc

looks like 7cc per .010. so that would be 1228.

If you want to go that big, I'd opt for the 1250 kit!!! It will last you a lot longer!!! :D

Why will the 1250 kit last longer than boring cylinders out to 1250?

Yes, it will!! give Nallin's a shout!! :D 303-833-5616

A 1250 bore is about 3.568 inches or almost .070 over.

Bore x Bore x stroke x .7854 x 2cyl / .061 = CC's
3.568 x 3.568 x 3.812 x .7854 x 2cyl divided by .061 = 1250.36cc's

Nallins uses a 3.563in piston which actually yields about 1246cc's.

Why will the kit last longer?

Why will the kit last longer?
I am not sure, but if Nallin has them made to that spec then the walls would not be as thin on the cylinders as if you had the already bored out 1200 jugs bored even moreso..

Does anyone know the HP increase, all things equal (stock) for 1250 vs 1200?

I would get the Nallin 1250cc kit if you have a choice. Not just for the fact that the motor will yeild 50 more cc's and be closer to a square design, but because the cylinder jugs are far superior with a 1 piece designed Nikasil liner which will also lower your engine temp significantly. Lower temps and less fricition with Nikasil liners on an oil cooled motor is a good thing.

Don't get all excited over a lousy 50cc of displacement.50cc is chump change. And $1200 while you do the work? What Bullsh*t.

Get a Wiseco 1200 Conv. w/ labor- $650/$700
Street Port heads and 1200 Valves- $500

This will eat the Nallins Conv. alive for about the same money or less.

What maddig said. 50cc's is nothing. You currently have a pretty indestructable cast iron sleeve that can be bored many times. The other cylinders are Nikasil which is what dirt bikes use on their motors. How long do you get from a new dirt bike motor?
I'll take the cast iron and bore it 10 then to 20 and then 30 before it needs to be replaced. I don't think Nikasil would last that long. Just my .02.

I dont know where you get the $1200 for the kit. I paid $800 for mine, and remember this comes with a quality FORGED piston and gasket/ring set. 50cc's isnt alot(but its still something), but the sleeves themselves are of a stronger superior 1 piece design which is more resistant to flexing and distorting over time with superior cooling properties, rings will also last longer with less friction too. These are reasons why the jugs have a LIFETIME warrenty on them. The old style iron sleeved jugs are a 2 piece design and are suseptible to flexing and retain alot more heat due to higher friction. There is a reason why snowmobiles and dirtbikes use Nikasil liners.But please dont use snowmobiles or dirbikes as a comparison on longevity, remember these engines have to endure a much harsher offrroad environment that a street ridden engine. Not a proper comparison at all. BMW's,Ferrari's and other high end/exotic auto's themselves have Nikasil lined blocks for many a reason. DUrability is one of them.

Nightboy

Where did you get your 1250 Kit!!

I got my kit from Revolution Performance.

http://www.revperf.com Just tell them that your a member of "vtwin" forum and that you heard about the $800 deal from other members on the board who picked the kit up and they will honor the price. You get Nikasil jugs with a lifetime warrenty, CP forged pistons and wrist pins,Total seal rings and cometic gaskets. Killer setup and a great price.

Thanks Nightboy, I'll check them out!!! :D

I'm working on my '04 1200 and am fitting 10.5:1 pistons (and head work, cams, etc.) and decided that boring the cylinders out as much as I could would give me around 1,250 cc. This didn't seem like enough to make it worth boring so I decided not to. Am I missing something?

I would bother boring out the cylinder to gain the extra 50cc or whatever it is. The big reason why I got the 1250cc kit for my SO was the fact that the jugs are Nikasil lined. They will drop engine temps around 20-30 degrees or so due to the one piece design with less friction and lack of an iron lining which is significant in an oil cooled motor. Couple this with a quality oil cooler and the operating temps will be very favorable when romping on the engine hard, especially in warmer weather. The extra 50cc's will probably also add a few extra hp/tq to the powerband too, but nothing major.

I don't see how anyone is going to get 1250cc from the stock 1200 cylinders. The liners are just too thin and loose integrity if bored much over .030"

BTW, boring a stock cylinder .030" will get you 1221cc

Also, if you bore it .030", that will be your last boring job. Hope you never need a re-bore, cause you won't get it on your jugs. If you want to install high CR pistons in a stock 04-05 H-D 1200 cylinder, go .015" overbore. That will leave you with another .015" later if ever needed.

If you really want that 1250cc, you are going to have to look at aftermarket jugs.

Nallin can even set you up with 1430cc, but it will require you to remove the engine and have the cases clearanced (machined).

Wiesco makes a 040 kit 1228cc when using Buell heads...why not bore it out max cylinders are cheap and can be replaced. There is no replacement for Displacement!

You may have talked me into telling Nallin to bore mine .030" --- I'm easy :)

I want to use the Hurricane dome 10.5 to 1 CR 'Bathtub' pistons, so I can only get them in .015" and .030" overbore for my stock jugs.