valve clearances

[pasophist]

what are the valve clearances for the 907ie? Am I correct in recalling .10 mm for openers and .00 or approaching zero for closers?

Thanks
Sheldon

[Tamburinifan]

0.00-0.02 all closers,
0.10-0.12 openers intake, 0.12-0.15 exhaust.

[ducbertus]

try to get the closers to 0.00. the valves and seats like that.
the less clearance, the less hammering and a better running bike with longer service interval.
But don't overdo it, the camshaft must rotate freely.
goodluck!

ducbertus

[Finnpaso]

0.10-0.12 openers intake, 0.12-0.15 exhaust.

Gert, WHY intake and exhaust not same? I taught, that normal 907 engine with normal cams shall be both intake and exhaust 0.10mm. At least Ian Falloon's "bible" say so. ST2 is little different; intake 0.05-0.12mm and exhaust 0.05-0.15mm

[ducbertus]

There's a cleart expalnation for this:
the inlet runs cooler by incoming air.
vapourizing the small petrol droplets extracts heat from the metal parts like the inlet duct and valves.
the exhaust is the opposit. burned gasses put into the metal.
whit this difference in the heat housekeeping in the head, the metal expands differently by this heat. ergo; the exhaust side grows bigger as the inlet. therefore also small differences in tolerances.
I hope this explanation is answering your question.

ducbertus

[Finnpaso]

Your explanation is good and i am satisfied to it BUT DIDNT they know such in Ducati FACTORY when they build 907 engines and make those manuals,etc. for it???? Also owners manual say 0.10mm both, intake and exhaust.... Should i be nervous, that i have 0.10mm in inlet and in exhaust? I mean worried about exhaust clearance.

Btw,Have You asked work from Ducati factory?

I adjusted just today my ST2 valves and i put to intake 0.10mm-0.11mm and to exhaust 0.14mm-0.16mm so its very close TO ST2 SPEC'S

[Tamburinifan]

+1 on ducbertus explanation.
Checked, manual f 907 says 0.10 all, my specs are mid 90`s ones.
Maybe Ducati then learned that 0.12-0.15 is better f exhaust,
it`s the same on my M900 manual.

[Finnpaso]

Checked, manual f 907 says 0.10 all, my specs are mid 90`s ones.

Are there "different 907 spec's" around, as Yours is from "mid 90's" and my manuals are from early 90's(both of my 907's are 91 modells). No matter, all say; it should be 0.10mm both inlet and exhaust... I accept different clearances(inlet.and exhaust), but do U really have some specs from MID 90's ??? I am little courious, if Your specs are different than those originals from early 90's, as there in your specs can be another diffrences compared to originals from early 90's...

As i told, ST2 have already "new"(different inlet and exhaust) clearances in manuals, so i trust to those ST2 manuals..... It would be nice to know, how many use "old clearances" in they 907 and how many use "new clearances" and especially have that 0.10mm exhaust clearance made ever problems to anybody/somebody...

I would keep 900 Monster engine out of this, as its air/oil cooled and 907IE is water/air cooled and sylinder /sylinder head temperatures in air cooled engines can be different in front/rear cylinder heads, as water cooled engine runs more "right" temperature (whole engine) (compared to air/oil cooled 2 valve engine). Its well known "problem" in all air/(oil) cooleed carburated Ducati engines that rear sylider runs higher temperatures, and MANY of such bike's carburetors have been adjusted different way in front and rear.

[Tamburinifan]

Meant my specs are mid 90`s 2V in general, not any newer 907 specs.

My exhaust valves/guides/seats was toast on my 907 heads, I`ll go w the ST2 specs on my ST2 heads.
Probably would have used 0.12-0.15 on the 907 heads if they had been OK, maybe those specs are a little kinder
on valves/guides/seats? I don`t know f sure, don`t have that expertise or experience.

Maybe Ducati found out 0.10 were a bit tight and changed it to the ST2?
ST2/907 heads look pretty much identical except rev counter tunnel.

[Finnpaso]

I have heard that ST2 heads were much better with measurements and overall quality compared to 907 heads... Thats why its not so bad idea to add ST2 heads to 907 with that rev counter modification and much better cams. I use also ST2 cams in my "better"(more tuned) 907IE..

Old 907 heads suffer from valve seat and o-ring problems...

[ducbertus]

Hi Annti and Tam. fan.

much of the tolerances put in the manuals has to do with the 0.05 steps of the caliper sizes. this avoids time consuming grinding dow ofthe calipers to the most optimal setting.
the benefit for the customer in the shop is that the bill can be lower, due to the fact that the whole shimming procedure can be done faster.

general problem with Ducati 2V valve guides is that they are too short. normally about 29 mm. due to the head build up the exhaust guide is most vulnerable. Alhough by better materials of the guide there is much to gain. If you make your own guides you can make them 4 or 5 mm longer by carefull measurement and a little altering of the closing rocker. 5 mm on 29 mm is nearly 15 %, which is a lot.

No Annti, I didn't ask for work of the Ducati factory. I have enough to do.
I took a few days off to finish a old VW 2V Polo. I took the job to build in a set of Honda Black Bird carbs! this requires a complete new inlet manifold, which I'm making this week including air box and a lot of other small parts. the goal of this is to have 100+ horsepower on the wheels and > 200km topspeed on the GPS.
Beside that their are a line of projects waiting for me.
like fitting carbon silencers of own production to a Suzuki 1100
building in a ST2 powerplant in my poor 907. ( I want to modify the heads to twin-spark, a small challenge is the water cooling)
So, as you see enough to do

Ducbertus

[Finnpaso]

Hi!

I have to grind quite often those pieces, as i want to be quite exact with those valve things and measurements/clearances...

About guides: I have heard good about these guides: http://www.kaemna.de/cms_en/katalog.htm ... rtikel=508 Anyone here tried?

Some 907 heads suffer from bad material in valve seats, so then have to adjust very often clearances and only way it to take heads away and put new batter material seats and also not so bad idea to port heads same time for better flow....

There are some problems to put 944 ST2 engine to 907: ST2 have only 1 pick up, as 907 have 2, so have to use then also M16 ECU (or some aftremarket) and such mod needs quite alot modifications to electrics. Surely it can be done, but is it wise?.... Its wise, if u have free money and if u are electrician to make all electrical mods and u have friend who own lathe that he can make that rev counter mod to ST2 front head. Remembebering, that Gert have done such rev counter mod in Sweden... That ST2 engine swap sounds easy, but i dont know ANYBODY who have done it to 907IE. One of my friend adopted to Gagiva Elephant 900 Grand Canyon engine and ST2 elctrics with M16 ECU, but he have also knowledge and inertia dyno.... Some have put ST heads to 907, but putting 2 sparks to such heads is complicated, as there are those water chanels in ST2 heads. To 900cc air cooleed engines that is quite simple and some bikes have such mod also here.