Standard series 3 TV175 squish......

FAQ tech questions, please check if the answer to your question is in here before posting elsewhere.
fluff34567
registered user
Posts: 363
Joined: Tue Dec 20, 2016 2:27 pm
Location: Switzerland
Contact:

Wed Aug 29, 2018 6:38 pm

Hi all,

I have the same Q on FB but maybe targeting a different audience here.

I looked in stickys but didn't see anything.

Anyone know the standard squish on a TV175?

I had the case machined to remove some damage on the base gasket face and supposedly 1mm was removed.

If I use a 1.5 base packer or a 1mm packer and standard gasket plus standard head gasket I get a squish of +-2.2mm. if I just use the standard base gasket and head gasket it's +- 1.2mm... but then the port timing would be out.

2.2mm seems large -. Was the tv175 different to the others?

Sent from my BND-L21 using Tapatalk


holty
registered user
Posts: 808
Joined: Wed Jul 15, 2015 11:52 pm
ebay user ID: amholt123
Main scooter: lambretta gp
Location: east yorkshire
Contact:

Wed Aug 29, 2018 9:52 pm

i would aim for 1.2 squish, but your port timing needs to be correct as well, 2.2 is massive and would cause power loss for sure.

User avatar
rosscla
registered user
Posts: 5587
Joined: Tue Oct 25, 2011 9:50 pm
Main scooter: Lambretta
Location: Lanarkshire
Contact:

Wed Aug 29, 2018 10:34 pm

1.2 is the target though I suspect this matters less in standard engines than in tuned ones.

How thick are your head and base gaskets?

How much below the top gasket face is the piston at TDC?

The only way you'll improve what you have, without engineering is to leave the gaskets out.

You could skim the top or bottom of your barrel depending on the position of the piston at TDC and BDC but this might slightly alter the port timing so you need to understand the impact of that.
"Our dilemma is that we hate change and love it at the same time; what we really want is for things to remain the same but get better."

Muppet
registered user
Posts: 1374
Joined: Thu Sep 16, 2010 9:54 pm
Main scooter: SX 150 running in

Thu Aug 30, 2018 10:34 am

how much clearance gives maximum cooling on an off set squished head?
im not a complete idiot
.
.
s me of the piec s are mis i g

johnny650
registered user
Posts: 341
Joined: Wed Oct 12, 2016 10:18 pm
Main scooter: lambretta 64 li 150 Special
Contact:

Thu Aug 30, 2018 3:07 pm

Muppet wrote:
Thu Aug 30, 2018 10:34 am
how much clearance gives maximum cooling on an off set squished head?

3x metres ;) :lol:
Its not just squish ...there are so many factors involved in determining engine temperature that I doubt you'd get a meaningful answer to that question .

User avatar
HxPaul
registered user
Posts: 1040
Joined: Fri Dec 06, 2013 1:58 pm
ebay user ID: panhead_5
Main scooter: lambretta Li 150
Location: Halifax,Yorkshire
Contact:

Tue Sep 04, 2018 9:41 am

"but then the port timing would be out"


Have you checked the port timing?

fluff34567
registered user
Posts: 363
Joined: Tue Dec 20, 2016 2:27 pm
Location: Switzerland
Contact:

Sat Sep 08, 2018 3:32 pm

Closure... Port timing was good and after speaking with few tuners appears head is bit of a known issue. Got it down to 1.7mm after a quick skim

Sent from my BND-L21 using Tapatalk


holty
registered user
Posts: 808
Joined: Wed Jul 15, 2015 11:52 pm
ebay user ID: amholt123
Main scooter: lambretta gp
Location: east yorkshire
Contact:

Sat Sep 08, 2018 4:59 pm

what gaskets and packers are you using to get 1.7 , my understanding is 1.2 is the best squish for power and also runs the coolest

fluff34567
registered user
Posts: 363
Joined: Tue Dec 20, 2016 2:27 pm
Location: Switzerland
Contact:

Sun Sep 09, 2018 8:43 am

1.5 packer but 1.0 has been removed from the casing so it's the same as having a standard gasket on a standard case. Port timing comes into play here if adjusting the base thickness. No head gasket used.

Depends who you speak to, stickys says 1.2 - 1.5 that's from MB I believe, others say max 1.75. all depends who you talk to.



Sent from my BND-L21 using Tapatalk


Post Reply Previous topicNext topic
  • Information
  • Who is online

    Users browsing this forum: No registered users and 2 guests