Head gasket internal diameters

I recently got hold of one of these kits:
1200 SILVER BIG BORE CONVERSION from a bloke who bought it then sold the bike.

I have contacted the company he purchased it from and they have been very helpful, but they have been unable to get the info (as yet) from the manufacturer.

The question or problem I have is this. The head gaskets that came with the kit are marked 1340 cc and not 1200cc.



Now I have measured the internal diameter of the gaskets and they have an internal diameter of 3.5840 inches, (or approx 3 and 19/32 inch).

To me these are the wrong gaskets, can anyone give me advice here. What is the relationship between cylinder diameter and gasket diameter. I would assume the head gasket diameter is going to be larger than cylinder diameter, but by how much. Do you reckon these gaskets would be OK?



Cheers

Neil

No - they obviously sent you the wrong ones. The cylinder diameter should be 3.498" & you have to allow a little bit for the O-ring to "crush" as the heads are torqued down, so the inside diameter should be 3.5".

Thought as much, I am still waiting on the company to sort it out

Just heard back from them, and also found a part number on the V-Twin Manufacturing Web site and pdf catalogue, and it appears that they ARE the correct parts, so it would seem no need to worry. Thankfully

Cheers for the input

I dug out the V-Twin catalog I've got & the part #15-0366 shown on the photo you included is for 1984-1999 80-inch (1340cc) Evo Big Twin engines, not Sportsters.

For 1200 Sportsters 1986-up, the V-Twin number is 15-0313.

Strange

Th online catalogue http://www.vtwinmfg.com/catalogs/cyr/pdf/804.pdf
shows that part number 15-0366 as for 1200cc 88 - 2000. But my bike is 2004

15-0313 does show on the same page as for 1988 up 1200cc also.

And the e-mail from them does say that it is the one for the 883-1200cc kit that they supply.

So don't know now. They say it is the right one, so will just have to try it and see.

It also shows a crossover to original equipment PN 16773-86B, which doesn't come up online. Notice the PN they're showing for a 2004-up 1200 Sportster is 15-0055, crossing over to OEM #17049-04. The last 2 numbers in a factory part number tell you the 1st year that part was used.

Just the 3.584" diameter measurement tells you it's wrong. The stock gasket's ID is 3.512".

Well if that is the case and these jokers at V-Twin Manufacturing do not even know and can't send the correct head gasket, then chances are the pistons/barrels/rings could be wrong.
I think I will just dump (put back on e-bay?) the kit and forget it.
These V Twin Manufacturing people sound like a bunch of cowboys who don't know what they are doing.

The labels say Made In Taiwan, the bloke who originally bought it got it from E-Bay...and he did not fit it either...says it all really doesn't it.

Art_NJr has made me see the light.

I was stupid enough to believe the kit is what it says it is.
Think I will forget it

Well it is all forgotten for a few weeks.
I am on 'vacation' for a while, left the snow and cold of the UK last night and am now in 'the sandbox' for a few weeks.