Problem setting squish - only getting 0.5mm

[Donnie]

Hi all, got some more free time to build the gt186 and am having a problem setting the squish.

Standard base gasket plus no head gasket - piston hit's head!
Standard base gasket and 1.0mm head gasket and Im getting 0.5mm squish which is obviously too little.

Now I've never been a tuner etc so wondering what my next best step is, my options as I see it are

a) get a 1.5mm headgasket and add another base gasket which would leave me with a squish of about 1.4-1.5mm
b) source a 2mm headgasket (can't find any via google though) to leave me with about the same squish
c) put 2 0.7mm headgaskets on but that feels like a bodge

Anyone got any preferences or another solution?

[dickie]

Donnie,

Mb do 2.0mm ones. Part no. MBP0299

Just be aware that by adding head gaskets instead of base packers will reduce exhaust and transfer timing. Have you checked your timings with just a single base gasket?

For a rough guide, 1mm on the base adds about 5degrees to exhaust and transfer timing.

Mb also do a good variety of base packers from about 0.5mm to 4mm, or something like that.

Hope this helps.

Dickie

[Captain Pugwash]

Have you got a 60mm stroke crank fitted ?

[Donnie]

Standard size crank Captain but as for port timings ive never done them, never bothered as I don't do any tuning nor learnt to. So Dickie I have no clue about the port timings at all or how to check them.

[dickie]

Standard size crank Captain but as for port timings ive never done them, never bothered as I don't do any tuning nor learnt to. So Dickie I have no clue about the port timings at all or how to check them.

Ok, in that case, as Rich Taylor's got good quality control, it's pretty safe to assume that the variation is in your crankcase.

In that case, I'd buy 0.3mm head gasket (MBP0398) and 2.0mm base packer (MRB0600M20). On the assumption that your base gasket is 0.5mm plus your head gasket at 1.0mm and this is giving you 0.5mm, then this combination should give you a squish of 1.3mm and keep the port timings pretty much where they are designed to be.

[CHRIS in MARGATE]

I personally would leave the base gasket alone as changing that will have an effect on port timings. Fit a thicker head gasket and remeasure.

[dickie]

You're right Chris but so will putting gaskets on top.

It's impossible to say without measuring but the likelihood is that the crankcase is more variable than the barrel and head, which is why I feel it's better to pack the case up to where it's supposed to be than push the barrel down to a crankcase that's badly machined.

See what I mean?

[stonerosesmod]

You're right Chris but so will putting gaskets on top.

It's impossible to say without measuring but the likelihood is that the crankcase is more variable than the barrel and head, which is why I feel it's better to pack the case up to where it's supposed to be than push the barrel down to a crankcase that's badly machined.

See what I mean?

I do now

You given up on the Mugello then Donnie,or fancied a change?

[Donnie]

never had a reed valve and fancied the gt and got it at a good price

Plus I doubt id bother with another mugello ever again to be honest with the issues ive had with the stupid exhaust port position