170cc Autisa - What supporting mods?

[simon998]

I've a 67.5mm (180cc-ish) Autisa barrel here that I'm about to fit to a standard 10w bottom end. It's been o-ringed so won't be running a headgasket. 67.5 (1.5mm o/s) Blaster piston. the head is currently away being machined to accept the larger piston and the barrel is having larged headstuds fitted (old threads were scrap). It will be running a late Micron with the removable alloy can.

I've read about them having over heating and oiling issues with the increased CC.

Are there any supporting mod's anyone has tried that you would recommend I do whilst the engine/bike is being rebuilt?

[arrow]

Hi Simon, the oil pump can be modified for the new 180cc capacity.
Its a completely different set of mods. compared to the uprated pumps for the 421cc big bore kits.

[simon998]

My plan for that was to premix, I've already spent way more than I wanted to on this build. I think my pumps a bit knackard anyway!

[arrow]

A bit knackered, heck!!
You know where I am if you change your mind.
No worries.

[raven13]

Jan 31, 2021 10:54:12 GMT 1 simon998 said:

My plan for that was to premix, I've already spent way more than I wanted to on this build. I think my pumps a bit knackard anyway!

I have a big bore 125 that used to fitted to one of my rd's and unless you like rebuilding the top end I wouldnt recommend premix, these bikes spend far to long at zero throttle coast ( hi revs but zero throttle = zero fuel/oil mix)to make premix worth the risk.
Spend a bit of dosh and get a pump from Arrow that will give enough oil and get to enjoy riding it.

[rdv]

Hi,interesting reading all the bigbore upgrades,would like to know about converting back
to an aircooled bigbore version.
Has the dt175 barrel ever been used or the YFS200 blaster barrel and cylinder head?
What about using the standard crank but using a different stroke conrod?

[cinder]

I've been running one for a whilst now and found heat is the biggest issue.
You cant just junk the head gasket as its needed to ensure flow round the top end .
I run an o ringed head and cylinder with a copper gasket sandwiched between.
Also head volume is critical.

[simon998]

The heads getting cut to 28 degrees and opened up to 67.5mm (bore size), do you have a volume (cc) that you would recommend?

Has anyone ever modded a waterpump for these to get more flow? I'm thinking of adding an alloy radiator.

[cinder]

I did the same to my head.i ended up going back to mick abbey who recut again with a bigger volume.i run 1&1/2 alloy rads behind a stock cowl and have fitted another expansion tank under fuel tank which brought temp down 8 degrees.

[museumman]

Feb 15, 2021 0:47:55 GMT 1 rdv said:

Hi,interesting reading all the bigbore upgrades,would like to know about converting back
to an aircooled bigbore version.
Has the dt175 barrel ever been used or the YFS200 blaster barrel and cylinder head?
What about using the standard crank but using a different stroke conrod?

These bikes were always water cooled. 
The DT and Blaster top ends give the characteristics of a dirt bike. Good for around the city they make their power lower down. The Blaster only has 17HP.

A tuned Autisa can be high 20s. Ideally you want to shoe horn in a TZR, TZM or SDR complete motor for power and reliability. 

[museumman]

Feb 23, 2021 12:58:54 GMT 1 simon998 said:

The heads getting cut to 28 degrees and opened up to 67.5mm (bore size), do you have a volume (cc) that you would recommend?

Has anyone ever modded a waterpump for these to get more flow? I'm thinking of adding an alloy radiator.

You could look at the electric water pumps. Usually found on scooter and moped sites but available for bigger bikes. Look easy to fit. 

[brigitte]

When I look at the tiny fork and the little front brake. I think, about 20HP is enough. For more power, better get a bigger bike. But what do I know?