GS 550 rebuild with wiseco pistons

[Cipher]

The motor is heavy surprisingly, even with its top end removed.
A couple years or 5 or ten ago I got a wiscoe big bore kit for like less than 100 usd on ebay.

So today I finally moved the lump into the basement for a winter festival of excess expense and frustration.

My original bores still have the crosshatch in them though a few valves appear burnt and have lost edge material.
In spite of this it ran really well. Crazy but true. One might assume from this that any internal impacts to the pistons were minimal. Esp since I can see no witness marks.

I also removed my front brake apparatus in order to check the caliper and master and to measure the brake line for a replacement. After 37 years I feel it may be time.
The brake worked but was firm and not very effective. Master whn disconnected had full range and pumped hard and cleanly. So recalcitrant caliper pistons or maybe a collapsing line. We shall see.

Anyway Ill soon have a 200 hp 550. May forgo carbs and just pour gas directly into intake from a orange crush bottle.

 

[Cipher]

A 58 cc increase anyone have an online calc to gauge the hp increase.

 

[Buffalo Bill]

We also need the compression ratio before and after the Wiseco pistons, to do an accurate estimate.

 

[Nessism]

My guess is 3 hp extra. Torque may take a bigger jump though.

 

[Cipher]

We also need the compression ratio before and after the Wiseco pistons, to do an accurate estimate.

nothing in the box except some generic fitting information
Wiseco has long ceased to care about specs on these in this application.

Stock is 9.8 to 1 60 mm bore 50.6 mm stroke

These are 63 mm bore but I assume the crowns would fudge the comp ratio up or down.

 

[Buffalo Bill]

Ok, same in my garage. I haven't got time to measure something I can't change anyway.
I can remember reading in some engine builder books, an important measure was to CC the combustion chamber. Really getting into the engineering craft.

 

[GregT]

nothing in the box except some generic fitting information
Wiseco has long ceased to care about specs on these in this application.

Stock is 9.8 to 1 60 mm bore 50.6 mm stroke

These are 63 mm bore but I assume the crowns would fudge the comp ratio up or down.

If the kit is #K-631 they're 10.25 : 1 compression.

Nearly all Wiseco big bore kits of that period are 10.25 with higher compressions available to order. Enough of a boost to make a difference without needing race gas.

 

[Cipher]

If the kit is #K-631 they're 10.25 : 1 compression.

Nearly all Wiseco big bore kits of that period are 10.25 with higher compressions available to order. Enough of a boost to make a difference without needing race gas.

Yes its k 631