750 big bore kit & cam

[wurlzy]

Hi all, looking at some engine mods and any opinions will be appreciated -
79 650 Special - 33,000miles originally from the States now lives in Australia.

Pod filters and reverse megaphone pipes already on and also performance oil filter/cooler kit from Mikes (Part #15-6504), sump filter changed also.

Wanting to know who has done this and what success you've had, any tips for along the way or anything else I should do or be carefull of.

What I'm planning -

750 Big bore kit from Mikes (Part #05-0750), along with his Performance Cam/valve spring kit (Part #05-0025) and Performance rocker arm set for good measure (Part #05-0037)
While it's apart I'll replace both cam chain guides and chain also.
Heads off so I'll just clean up the internals.
Once all fitted & running I'll take it somewhere and the carbs tuned and running to suit.

Any advise will be appreciated.

Many thanks, Steve.

 

[Sundie]

750 Big bore kit from Mikes (Part #05-0750),

along with his Performance Cam/valve spring kit (Part #05-0025)

Meh. You can spend your money better elsewhere. If you're running 34's, it's not a lot of gain, 38's are better. The stock cam is pretty good.

and Performance rocker arm set for good measure (Part #05-0037)

While these are great, if there's nothing wrong with your current rockers, i wouldn't bother. I'd just get the hex adjusters.

While it's apart I'll replace both cam chain guides and chain also.
Heads off so I'll just clean up the internals.

Always a good plan. Check/lap the valves too, and new valve stem seals.

 

[tx650]

Welcome to Australia.Yes I have done the 750 conversion and I rode one of my mates bike that had one.
Definitely notice the extra grunt and the only problem I seemed to have to contend with was the poor stock braking capability on these dam fine pieces of machinery.
One thing I did was added another front brake (twin discs) and drilled them out.
I have been told that these engines can be taken out to a whopping great 1100cc
Now that's awesome.
Ride Today
Ride Tomorrow
Ride Forever.

 

[tx650]

Just a quick shortnote about the bottom end on these engines,they are huge and not much improvement needs to be done here...They are virtually bomb proof.If anyone has ever pulled one apart they will know what I'm talking about.

 

[Sundie]

1100cc would have to have your heads altered. you'd have like 7 or 8 mm underhang. Nasty for combustion hot spots.

Plus, ~80ish HP is about the top before the bottom end starts imploding, at least on the 477's. 533's are a bit better, but still - if you want that, go buy a newer bike. Less silliness, more riding.

 

[Waldo]

If you are spending the money for a 750 kit and cam, have the crank rebuilt with Mikes rods and main bearings, DONOT for get a new cam chain sprocket on the crank. I went with bronze valve guides, while staying with 650cc.

Waldo

 

[tx650]

1100cc would have to have your heads altered. you'd have like 7 or 8 mm underhang. Nasty for combustion hot spots.

Plus, ~80ish HP is about the top before the bottom end starts imploding, at least on the 477's. 533's are a bit better, but still - if you want that, go buy a newer bike. Less silliness, more riding.

Hi there,the engine I'm referring to was still in the process of assembly and I never got a chance to see it actually running.
I met the guy when I went into his museum and he showed me the engine in his workshop so that's all the info I can give unfortunately but I can remember him saying it was an 1100 now.
I think he built it for off road/drag racing and like you said it might have gone down the quarter mile and disintigrated into a gazillion pieces.....or could be still going strong and breaking world records.
I am no expert on increasing horse power but I should imagine there is a bit more to it than a rebore/resleeve.
Maybe someone that has actually done it can perhaps give more info.
Take care all.

 

[wurlzy]

Welcome to Australia.Yes I have done the 750 conversion and I rode one of my mates bike that had one.
Definitely notice the extra grunt and the only problem I seemed to have to contend with was the poor stock braking capability on these dam fine pieces of machinery.
One thing I did was added another front brake (twin discs) and drilled them out.
I have been told that these engines can be taken out to a whopping great 1100cc
Now that's awesome.
Ride Today
Ride Tomorrow
Ride Forever.

Yeah the stock brakes do leave a little to be desired, haven't gone the twin disc conversion but have replaced the disc with the floating type from Mikes and braided lines front & rear also. Just that alone has made a remarkable difference, not to mention weight loss.......The std disc weighed in at just over 3kg's! and the one from Mikes is only 1.5kg's!

A saving of 1.5kg's of not only unsprung weight but also rotational mass too!

 

[wurlzy]

Thanks for the info on the engine build up too guys, any and all information has and will be taken on board. I'm not one for wasting money or tearing into the engine every 12 months to rebuild, so some sort of reliability would still be nice.

 

[Sundie]

keep in mind, i like the cam - *if* i was going to build an engine that spent most of it's time above 5k. That's where it shines. Otherwise it's actually worse for regular riding/idling. Even with stock gearing, i barely kiss 5k at 140kph or so, so to me, there's no point.