big bore update 2

[sno335]

Hi, thanks for the wake up call,Dave. Lost 2 passwords and hibernated.
Attemping to put bored out XRV 750 in Bros. After drawing blank with African Queens ,found out U.S. Hawk GT bigbore (82mm) kit fits.
C.R. is about 11;1. Downside is only small capacity increase 760cc
Also spigot and pistons need to be machined to miss longer stroke crank.
Problems of detonation and the need for high octanes also experienced.
So started to put top end together with std pistons/bores. However got heads flowed and 2mm larger inlets by Hordpower in Ohio.As the leading expert in the U.S. tuning Hawks J.D Hord reckons this makes the 3 valve engines go.As well as being a seriously successful racer he's a really nice guy to deal with.(Check out the Hordpower website-loads of goodies)

[DaveS]

Hi, thanks for the wake up call,Dave. Lost 2 passwords and hibernated.

See there's no getting away now!!

Pics and more detail required on the project. Keep us up to date I'm sure there's loads of people interested.

[anton88]

Yep, as Dave S says - get some pics up and more info if you can pleeeeeese - very intersted to know how you get on

[atgreg]

Hi, thanks for the wake up call,Dave. Lost 2 passwords and hibernated.
Attemping to put bored out XRV 750 in Bros. After drawing blank with African Queens ,found out U.S. Hawk GT bigbore (82mm) kit fits.
C.R. is about 11;1. Downside is only small capacity increase 760cc
Also spigot and pistons need to be machined to miss longer stroke crank.
Problems of detonation and the need for high octanes also experienced.
So started to put top end together with std pistons/bores. However got heads flowed and 2mm larger inlets by Hordpower in Ohio.As the leading expert in the U.S. tuning Hawks J.D Hord reckons this makes the 3 valve engines go.As well as being a seriously successful racer he's a really nice guy to deal with.(Check out the Hordpower website-loads of goodies)

I fitted a set of wiseco 82mm hawk pistons to my AT, great power increase, a real big boost to the midrange but did have some detonation problems. Biggest drama was the ****ty wiseco pistons, the recomended bore clearances were 2.5 times the standard honda clearances so after 50,000km it was using so much oil i went back to my standard spare engine. there is a place in germany that sells 2mm OS high comp pistons for the AT, also cams and various other bits. It's tuning by Mende.

http://www.powered-by-mende.de/

Ive also got a 2 brothers set of OS inlet valves for the hawk but they are the same size as the standard 750 valves, they'd probably be good for a 650 AT or TA.

did you look into fitting any of the hot hawk cams to the AT ???

[atgreg]

Another AT - big bore tuning shop

http://www.stf.at/

[atgreg]

Hi,

I was wondering how your big valve heads are going ??. Im considering getting the same thing done.

[atgreg]

Hordpower http://hordpower.com/index.php?main_page=index is the top hawk 650 tuner in the states, many of the hawk hot up bits will fit the At eg, cams, big valves etc, send him an email he is very helpfull, ive been discussing this with him a bit lately. he thinks 10hp extra (15% extra approx) would not be hard to get reliabily with a good power spread, they are getting almost 90hp out of a full race hawk, however not cheap aprrox $US1200 for ported heads with 2mm OS inlet valves, mild cams, pod filters, mildly raised compression from skimmed heads and a jet kit, thats not including post to send him your heads and return post

http://www.stf.at/ , do big bore kits and cams for the At, this is the stuff Africa Queens sells

http://www.powered-by-mende.de/ also does tuning for AT's including bigbore and cams

http://www.thiel-motoren.de/ also does AT hot up gear

[atgreg]

Hi,

I was wondering how your big valve heads are going ??. Im considering getting the same thing done.

bump bump, any more info on how your engine is ????