1170cc question

Hi, my bike is an 82 1000LTD, I found a guy who has some nice 1170 pistons and rings...could I use these with my regular J head? or would it be counterproductive to not use the GPz head? I think he has a complete 84 GPz motor too.

The 1170 kit leaves the leaves very thin. With out resleving, the liner will be less than .040 thick, also the GPZ pistons have a different size wrist pin than your J motor. You will also loose quite a bit of compression with a stock J head.

cool, gotcha. Thanks

AMENDMENT You will not loose compression but GAIN compression. The piston crown might even hit the top of the combustion chamber. I got a little turned around since many people ask about using the old stile pistons in the J series and GPz motors. But, you want to go the other way around. And the last thing I forgot was that the 83+ GPz valves had a slightly different angle inside the head from previous engines and the corresponding recess in the piston has to match. So in your case, if you wanted to use GPz pistons you would have to change the, Head and Crank shaft also to be able to use them.

However, What you CAN use are the earlies series pistons in your engine. You would want to find a set of 1135 pistons with 12:1 compression in the old stile pistons to wind up with about 10:1 because of the larger chamber in the head you have. Otherwise the old stile pistons would work fine in a J series head. Also you would have to use a 80/81 1100 cylinder for boring. The cylinder you have will only safely bore to a 1075. You can follow my project at this link. kzrider.com/index.php?option=com_kunena&...w&catid=11&id=169462

cool, thanks a lot! He has 84 gpz11 cams for 200$ (canadian) I am wondering about getting them...

No eBay APP ID and/or Cert ID defined in Kunena configurationThose WILL work but why pay $200 if you can get them here fore less. Also, ALL GPz's had electronic tacs, so unless you have a electronic tach on your bike expect to loose that function because the exhaust cam will not come with the tach drive gear cut into it.

cause those are 82, same lift as my J cams...I guess the 83-84 are higher lift. Also, the 82 1000M2 had the mechanical tach, but the K2 and J had electronic, so I am OK. thx

otakar wrote:

However, What you CAN use are the earlies series pistons in your engine. You would want to find a set of 1135 pistons with 12:1 compression in the old stile pistons to wind up with about 10:1 because of the larger chamber in the head you have. Otherwise the old stile pistons would work fine in a J series head. Also you would have to use a 80/81 1100 cylinder for boring. The cylinder you have will only safely bore to a 1075. You can follow my project at this link. kzrider.com/index.php?option=com_kunena&...w&catid=11&id=169462

So if I were to use my stock J head and the 1075 pistons, what would my compression ratio be? around 10.5:1? then if I were to throw on a GPz head would it drop back down? I would eventually like to put a turbocharger on so I think I need to have lower comp right?

thx for addressing my quandaries

Wrong, not all 82 cams were the same. LTD/CSR/Specter had one set of cams, J had a different set of cams and the GPz had a different set yet. And I did look it up, you do have an electronic tach so the cams will work. The 82 and on GPz cams were the same. If you want to spend $200 than just spend $300 and get a real set of cams that have at least .400 lift on them. You should be able to go as high as .410 lift with little to no head modifications.

The LTD/CSR/Specter came with cams that were cut for fuel efficiency and cruising. The J cams were cut for mid range and low end take off. The GPz cams were cut for top end. In fact the cams wer the only performance difference between the motors.