[boris.h]79 GS 550 / 673cc project

[boris.h]

arf I machined a aluminium part, which I fitted while freezing it into the head, with some more loctite sealant. Anyway, the head still leaks a little today, after starting the bike, when cold, but the "leak" (there is no apparent leak neither any smoke but the plug is a bit wet and dark) disapears when hot. The bike runs great.

I do not like using loctite glue, because you need at this place glue that can resist to high temperatures, and, at this place you do not have a lot of material so glue could not "grip" to the head. So that's why I machined a part that came under the spring


thanks for the fairing, it shapes nice to the bike and, I can remove it quickly thanks to the 3D printed parts I made

 

[boris.h]

little update about my bike... gone to 162.5 - 165 - 165 - 162.5, the bike is pulling hard until the end, like an opera singer... I can not imagine the same with bigger pistons... I think, with velocity stacks, a big open exhaust and ported head... it could go above the 80 hp....

 

[boris.h]

Hi all
Long time I did not make any post, because of its poor interest...
OT,
Ended with 165 - 167.5 - 167.5 - 165 and the bike runs great. I am a bit lean between idling and WOT, I am on the top notch so maybe I would have to go up with mains with one size and going one notch down.... but it runs great now, idle to 1100 rpm, going great even at high altitude... as attached a picture at the Mont Ventoux, south of France, a famous place where Tom Simpson died during the tour de France 1967...



see you!

 

[1948man]

Sounds like a really great bike to ride. Your efforts are being rewarded.

 

[boris.h]

yes, for sure!
The next update will be an oil cooler, because of high temperatures in south of france, and the final header I am planning to do by myself

 

[boris.h]

 

[Yozzer74]

Just read all this great build I'm just starting to get parts together for 673 swap

 

[boris.h]

thanks a lot, do not hesitate if you have further questions about this swap, this is working great, for more that 1.5 year. I drove it something like 3000km since the job started.
Keep in mind that you have to get a nice working exhaust (I calculated all the tubes diameters and a 600 bandit exhaust fitted with some modifications), a nice working intake (as you can see, velocity stacks with a grid in front of them works well), here also, the length and the diameter of these stacks is important.

Also, if you get a look on the performance section, there is a thread on performance pistons for this specific swap... if you want to get them, I should advise you to start this BS 34 carbs instead of BS32 ones.

Nevertheless, this swap with 650 standard pistons, if mixture is well adjusted, can give a lot of HP, around 75 hp for my engine, also because the head is fully ported, squish is adjusted to the minimal specifications, etc etc..

If you love mechanic, go with it!