Engine Parts

[graduc]

looking for hi comp pistons and may be heads for 99 750ss also do 800 barrels and pistons fit the 750

Graduc

[funonone]

I have an 800 I am parting out, these should fit the 750 since they fit the 620.
I have the cylinders, pistons and heads , larger valves, 150 lbs of compression. The 750 and 800 are both 88mm pistonsm 800 is longer stroke. I want $159 each complete head, each cylinder w/ pistons and ring set.

Originally Posted by graduc

looking for hi comp pistons and may be heads for 99 750ss also do 800 barrels and pistons fit the 750

Graduc

[996f1]

I keep seeing this question. I am not sure, but I think if you put 800 pistons on a 750 rod/crank you will in up with compression like a diesel.

Since the 800 crank in a longer stroke (66mm) the piston pin is set higher, to keep to dome lower and stop it from crashing into the combustion chamber. Put that piston on a 750 crank (61.5MM) and it will be about 2.25mm lower than before.

I see someone on eBay suggesting they will drop in too. Just depends on what you want.

[brad black]

the only 750 high comp pistons i've found are from ferracci. i have some of them that i got s/h in my 750.

the 800 chamber will be bigger, as it has 900 sized valves. the std 800 pistons have quite a big dome on them, like a high comp 750, to compensate for the larger chamber.

the 800 cylinders are the same bore and height, but the locating dowel location is different and the style of the oil supply passage at the rh rear is slightly different.

i've been thinking of putting my 750 back to std stuff and selling the hot bits - the 42.5/37mm big valve heads with 900 cams and the ferracci high comps. it has 76hp, up from 65 with std heads and pistons.

[graduc]

Thanks for your help and advice this would my winter project. i use my bike for track days and need a bit more HP. I do not want to a Jap bike

Graham

[brad black]

the 750 engines are dogs in std form, due to the heads - valves and cams - mostly. the ss has smaller headers that you need to replace too - 620 and 800ss headers fit but are probably hard to come by. you can shorten 900 headers slightly to suit or just force them on too.

[996f1]

Bruce Meyers (not BCM) has some 88 and 90mm H/C piston sets for sale. But, I went to the web site for the new business location and it was gone, so I have no way to offer a direct contact. Ed Milich of Guzzitech & Bimota.com sells them too; $350/set.

The 88s are definitely made for the early 750 heads, and are certainly H/C. I am not willing to try the 90s because of the thin cylinder wall that would be left.

Brad: Am I correct that to use the 800cc pistons the 66mm crank must go with it---or special-length (2.25mm longer) rods?

[brad black]

Originally Posted by 996f1

Brad: Am I correct that to use the 800cc pistons the 66mm crank must go with it---or special-length (2.25mm longer) rods?

the rods are the same, as is the cylinder length, so it can only be the pistons that are different, as you say by 2.25mm.

[graduc]

I have been studying the headers, I have a friend that custome makes pipes etc. Why does the exhaust pipes go in to the four way at the back is it purely for back pressure can you do away with that section

Thanks Graham (Graduc)