Compression ratio etc, slabby 1100

[crow]

Morning all

I've just installed a Wiseco 1109 kit, and my CR measurements/calcs are yielding some unexpected results.

Overall compression ratio is coming out at 11:1, according to Wiseco it should be 12:1.

Squish clearance (measured directly using a blob of solder) is 1.56mm.

Is it usual run without the base gasket to achieve the CR quoted for the pistons? Assuming the base gasket to be ~0.5mm, removing this gets me pretty close to 12:1 and 1mm squish, which I believe is about the right place to be. Must be more on a standard engine though?

If anyone has some numbers from a similar build or a standard 1052 I can compare against it would be much appreciated!

Cheers

[Blubber]

If the response are slow or even lacking....

 

We have a search in the upper right section,  that way, you can distill and digest the info in your own pace. 

[Duckndive]

Have you took into account the compressed head gasket thickness as opposed to a new one...? 

Not a massive difference but it all matters 

 

[crow]

2 hours ago, Duckndive said:

Have you took into account the compressed head gasket thickness as opposed to a new one...? 

Not a massive difference but it all matters 

 

I measured squish clearance with the head gasket in & torqued down to spec.

It was difficult to measure deck height accurately, so found it by subtracting nominal gasket thickness (0.03") from measured squish clearance. Gasket diameter is only 0.2mm oversized to the bore, so the split between gasket height and deck height makes naff all difference to the CR result.

[Duckndive]

40 minutes ago, crow said:

I measured squish clearance with the head gasket in & torqued down to spec.

It was difficult to measure deck height accurately, so found it by subtracting nominal gasket thickness (0.03") from measured squish clearance. Gasket diameter is only 0.2mm oversized to the bore, so the split between gasket height and deck height makes naff all difference to the CR result.

Its is what it is then  

TBH I think manufactures quoted C/Rs can be on the optimistic side at times  

[clivegto]

I would be tempted to leave the base gasket out if you want to increase the cr a bit more. 

[Gixer1460]

1 hour ago, clivegto said:

I would be tempted to leave the base gasket out if you want to increase the cr a bit more. 

Ok if you go dry block with external oil lines but would be risky (IMO) with pressurised oil up studs! I certainly wouldn't trust some Hylomar or ATV sealant in lieu of a shim steel / copper / paper gasket.

[clivegto]

59 minutes ago, Gixer1460 said:

Ok if you go dry block with external oil lines but would be risky (IMO) with pressurised oil up studs! I certainly wouldn't trust some Hylomar or ATV sealant in lieu of a shim steel / copper / paper gasket.

Some of the America lads were doing it on the cheap (on this site) a few years ago by lapping in as they described it. I reckon a small amount of sealant would do the job, but have not done this my self with the base gasket. 

Edited January 27, 2020 by clivegto

[manden]

i bought an copper gasket that was 0.254mm thick uncompressed on fleabay. not that they compress much but it will help you. i have 11,7 comp on the 1108

[manden]

just checked and found this:

 

https://www.Eblag.co.uk/itm/Cometic-Base-Gasket-005-Copper-C8246-Suzuki-GSX1100F-Katana-1100-GSX-R1100/383268686042?epid=214738069&hash=item593c9808da:g:6CAAAOSw0fZdzwhc