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sungamma wrote:So, if I KEEP the 907 heads and just install the cylinders and pistons, then NO machining is required? Pure bolt on? Want to make sure I get this right before I make the investment.....

Some people already did it.

sungamma wrote:BTW, are the ST2 cams an improvement over stock 90 pieces?

Thanks all.......

They say (my mechanic, too) the ST2 cams are a big improvement for the timing.

Ciao

sungamma wrote:So, if I KEEP the 907 heads and just install the cylinders and pistons, then NO machining is required? Pure bolt on? Want to make sure I get this right before I make the investment.....

Thanks,

Gary

Yes, 100% pure bolt on. If you get new cylinders, just make sure they are for the water cooled engine. It's MUCH easier to have your cylinders bored and plated. If you are in the states Millenium is where everyone gets them done. You will need new base gaskets and o-rings for all oil journals.

You may need some dyno tuning to set up the FI and make sure your not running lean.

The ST2 cams are supposed to be the best for the air cooled motors.

The source motor (ST2) is water cooled, right? I'm looking for COMPLETE bolt on. I'll mess with other stuff down the road. I assume it is smart to use new rings even if the pistons and cylinders are used.....

I'd definitely use all new gaskets....

As for the cams, I'll keep an eye out for either ST2 cams or complete ST2 heads. In the meantime, I'll look into the required headwork to make the ST2 heads fit......

So much for "winter projects". Thanks in advance for the help......

Gary

BTW, do you know what the typical cost is for "bore and replete" for a pair of cylinders?

Overbore, replate and hone will cost about $400. Millenium Technologies is who does them. You can get 30% off that price if you set your self up as a distributor which is amazingly easy. Belive me on this! You send them your pistons and they bore the cyls to fit. Perfect workmanship!

It seems to me a fair price, even if with pistons, con-rods, cams etc. will be a good amount of money.
I'm not sure if the improvement in hps and torque is worth the cost.
All in all, between the 907 and the ST2 engine there is a difference of only 5 hp...
Ciao

I assume it is smart to use new rings even if the pistons and cylinders are used.....

You`ll find the rings very expensive so you might as well buy new pistons instead.
Most do that, I think.
If the bike has no history of high oil consumption, you might as well use the old ones.

persempre907 wrote:It seems to me a fair price, even if with pistons, con-rods, cams etc. will be a good amount of money.

Con rods are not needed to upgrade to 944, just new pistons. The pistons also bump up the compression a bit so the HP and torque are better than 5HP in improvement.

Jeez, in my research, this is getting expensive. Even getting a deal on the pistons and cylinders, I'm getting quotes of $600-$1000USD for the labor plus the cost of rings (haven't checked into that yet), shims ($20-$30 each x plus gaskets etc. Well over $1000 for 5-6 HP. And this still does not include the ST2 cams..... This is starting to look like it might not be worth it especially as my 907 is running fine....... Going to have to think about this some more......

Gary

BTW, will ST2 cams work in stock 907 heads without mods?

Gary

I realized that about 6 years ago and only possibility(for reasonable price!) is to get ST2 heads and cylinders cheaply from somewhere and adopt them with making hole for rev counter sender unit.... Thats why i wanted to forget such modifications to "so old bike", what 907 really is....

sungamma wrote:BTW, will ST2 cams work in stock 907 heads without mods?

Gary

They work! I have them in my 907.... valve clearance adjustments need to do surely..... maybe same time better look also need of new valve quides and valve seats and maybe "porting job" for seats...

I bought a complete ST2 engine, '98 and 17000 miles for $600 in the USA and shipped free to the netherlands and now sittingto be adapted in my 907which has done nearly 60000 km. A couple of Carillo conrods are somewhere around in my shed
I know, I have to do a few jobs but an old lady cranking over 100 HP is just fun.
rear suspension is ok now. front end is done. gold line calipers. full floating discs.
a set of magnesium rims, which are waiting to build in. This all can turn the lady into an angry sheep

Ducbertus

Dont forget to change also ECU with electrics, cause 907 with P7 use 2 pick ups and ST2 with M16 only one...

ducbertus wrote:I have to do a few jobs but an old lady cranking over 100 HP is just fun.

...no matter, it's a little challenge to reach 100 HP with the ST2 engine.
We are talking about an improvement of 17/18 HP.
Ciao