It's a long way to 920 type(rary)

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Great info, thanks Yves.

I’m looking forward to your dyno run almost as much as you are...!
 
Hi There,
A lot of work done to day, first finishing Bruno's bike this moning
This afternoon I put the cylinder head off with the engine in the frame, not a easy job in the Seeley frame
I take all the bolts and nuts out but the head stay in place, I give a push with a piece of wood on the exhaust rose and the head rise up.
There was nothing special to see on the 1mm gasket, no oil leaks or compression leaks, Pliobond sealer is realy top of the game, thanks Jim Schmidt!
I clean the cylinder head and cylinder top
I warm up the new 0.6mm head gasket with a torch.
This evening with my Friend John we put the head back on the engine and torque the head and I call it a day...
Tomorow I will put the exhaust, carbs, oil lines, head steady; and adjust the valve clearence, and I hope the salt on the roads will be away, so I can do a road test.
I realy want to do some miles before the dyno on friday
Keep you posted
Yves
 
Yves, let's do a road test together tomorrow afternoon, because there will be rain on Wednesday and Thursday...I will call you in the morning!!
 
Hi There,
To day I finish the bike and did a test ride, after changing the head gasket from 1mm to 0.6mm and the squish from 1.5mm to 1.1mm, I was expecting a lot and I was disapointed, just a bit better...
I have to say that before the test I change the ignition timing from 29 to 27, can that be the reason??
The bike is fast w/o flat spots, but I know my bike so good and I feel that the carbs are to ritch at high RPM
I will know more on friday on the dyno
Keep you posted
Yves
 
Yves, will you post the whole graph?
Gives us a lot more fat to chew on.

Glen
 
yves norton seeley said:
Hi There,
To day I finish the bike and did a test ride, after changing the head gasket from 1mm to 0.6mm and the squish from 1.5mm to 1.1mm, I was expecting a lot and I was disapointed, just a bit better...
I have to say that before the test I change the ignition timing from 29 to 27, can that be the reason??
The bike is fast w/o flat spots, but I know my bike so good and I feel that the carbs are to ritch at high RPM
I will know more on friday on the dyno
Keep you posted
Yves
Click to expand...
The compression ratio increase you made, from 10.1 to 10.6, would result in a theoretical increase in Otto cycle efficiency of just a little over 1% (1.3%), so perhaps not surprising that your perceived seat of the pants improvement was incremental. And as hobot suggested earlier, for whatever reason, Nortons seem to provide impressive performance even without tight squish.

We’re all eager to hear how the dyno session goes, and wish you all the best.
 
Hi WZ507,
I take a look at Otto cycle efficiency, bit difficult for my small brain... and I am always afraid from theorical tuning, I remember when I was a Sidecar racer with the fantastic Yam TZ 750 two stroke, I was looking for the best expansion chamber, so I use the formula from Dr Gordon Blair, after calculation the rersult was that I must use a exhaust from more as 30 feets long, very easy to put on a sidecar...
I am always listening to all the comments about tuning, but at the end of the trail you must make your own experience, and your own feeling is soooo important.
I remember also when I was the team owner in the Jet ski world, there was a man that make reports in a US jet ski magazine about two stroke tuning, you must be at least Werner Von Braun to understand it...
At the World Championship at Lake Havasu city AZ, the man was there with a good rider, but my rider with my engine take the titel in the Pro Modified Class two years on a row, and this w/o using a dyno, it's difficult to explain "feeling tuning" it's like you are inside the engine and understand what the engine says...
So far I don't have this feeling with the 920, test and re-test thats the secret....
BTW: when I make my first road test with the 920 the atmospheric pression was very high and yesterday very low, that of course influance the carb setting and the power
Wish to be already on the dyno to find out
Hope the weather will be dry tomorow, to do a other road test with different ignition settings
Keep you posted
Yves
 
yves norton seeley said:
Yes I will, but I still don't know to where I will push the engine on the dyno: 6.200 or 6.500 RPM maybe?
Yves
Click to expand...

Yves, when I was road racing with 920 engines, I regularly ran them to a 7,000 rpm red line with no problems, so I think you could do so safely for a dyno run. On the other hand, I have broken crankcases when running them at 7200 rpm on a long course (Daytona). But that was before we had Maney cases to use.

Ken
 
Ken, don't forget that so far due to the Belgian weather, Yves' engine has only done about 100 miles since construction. Probably too early to go north of 6000rpm I would have thought.
 
Jagbruno, very few race engines get as much as 100 miles of break in. I can understand not going to 7000, but 6500 should be fine for short dyno bursts.
 
SteveA said:
Jagbruno, very few race engines get as much as 100 miles of break in. I can understand not going to 7000, but 6500 should be fine for short dyno bursts.
Click to expand...
Hi Steve,
I will not go over 6.500 on the dyno tomorow, the problem is that I am very fast used to new power step, and of course the power feeling can be a placebo effect also...
I have the feeling that some horses don't come out the engine and it can be different reasons: ignition timing, carbs setting (probably) or worst camshaft timing
When I was changing the head gasket from 1mm to 0.6mm, the top of the pistons where realy black, to ritch of course;
Carbs adjustements can be very long with Keihin FCR 35, imagine: for low RPM you have a pilot jet, a fuel screw and a air screw, for WOT you have the main fuel jet and main air jet en between at least 15 different needels... after years of using the FCR I am used to the setting of this wonderfull carbs, but it stay a head scratcher.
I will take all the jets and needels I have with me to the dyno so I am pretty sure I will find the setting with the gas analiser from the dyno, I will try different ignition setting also, the good thing is that the dyno never lie.
So tomorow will be the D Day, I hope everithing will be good becouse I did a lot of works to have everyting on the top and spend also a lot of money...
Ruud, the dyno man still have the records from the previous runs (with the 850), good to compare....
If I make a gain of 10HP, I will be more as happy, with 5HP I will be just happy and whit no gain I will hang my zelf on a bonzai tree (remember: I am not far away from being a dwarf)
Wish to be one day older
Keep you posted
Yves
 
Hi Yves,dont hang too much on what the Dyno says tomorrow mate a good result is good but a bad result isn't that bad it just means you need more adjustments as you know.
Just how rich was it?
 
Oh and best of luck with it, can't wait to hear how you get on
 
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Yves,
Good luck,
And don’t hang yourself, we would all miss your posts
Pete
 
baz said:
Hi Yves,dont hang too much on what the Dyno says tomorrow mate a good result is good but a bad result isn't that bad it just means you need more adjustments as you know.
Just how rich was it?
Click to expand...
Difficult to say how ritch it was, but the top of the pistons where black and not from oil, a kind of black velvet, of course I don't arrive at the workshop at WOT
Thanks to all of you for the support
Yves
 
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