ESE's works engine tuner

[husaberg]

Hello. I know there are at least to Posts stating that a motor with a leak in the case, Gasket or Seal, is running rich.
Unfortunately I can confirm that this is true. Had the Problem on my last race event on the German Sachsenring.
And like stated from Wobbly it sized as I went leaner on the main to correct. The surviving side was dark black. So all statements are proved an it was a sad day for me.
Since then I tried to get my head around why the the motor runs rich and what exactly forces the rich condition.
Can someone give an explanation on the effect? That would be great.
Thank you
Regards Siggi

TeeZee some pumper carb tuning tips to go with Wobblys info. Attachment 247635

And here is something if we really cock it up..... ...... piston seizures explained Attachment 247636

One thing I completely disagree with in the piston seizure write up is that air leaks cause a lean condition.
This is utter bollocks, any engine with a case leak will run richer, the bigger the leak the richer it will run.
Caused by the fact that the case "pump" no longer works and the fuel air mixture isnt being transferred thru the ducts.
If the engine is then leaned up to "fix" the incorrect mixture - then it seizes.

I could have got this wrong but when he says air leak could he have been referring to a manifold air leak and if it does will this still cause it to run rich as in your analogy Wob?.
I am not challenging you. Just curious? because I always was lead to believe a manifold air leak runs lean and it always seem to on four strokes.

Piston specs here inc ring peg locations
http://www.pvlsverige.se/vrm/kolvar/kolvar.html

Also below a very old way of securing circlips. Which I think its quite cool. Clever bugger that Phil Irving

A leak between the carb and the reed or any intake will always add air going into the engine and create a lean condition.
A leak anywhere in the case, be it a gasket, a seal, or a pin hole in a casting will cause the engine to run rich.
Problem is that they then seize for no apparent reason when the jetting is then "fixed".
So its always wise to make a set of blanking plates and or use a rubber bung with a bolt that expands it into the pipe manifold, so that a leak down test can ensure no case problems exist.

I think this is what you are looking for.

[Frits Overmars]

Had the Problem on my last race event on the German Sachsenring.... Regards Siggi

Siggi? Siggi who?
Not this Siggi by any chance? Too bad I couldn't make it to the Sachsenring this time, mate.

[breezy]

I think this is what you are looking for.

wobbly, would there be any benefits if you could control the air leaked/added into the crankcase with this richening phenomenon.

[wobbly]

There have been plenty of attempts at " cheating " the rules and allow extra air into the engine when the carb is a spec size, and these do work as
long as you can then retune the A/F ratio correctly.
But the issue with a case leak is that it affects badly the delivery ratio.
With a leak there is less air flow into the case as any pipe effect that pulls down the volume below atmospheric is diluted, and then the small
effect the case compression has on transferring mixture into the cylinder is also reduced.
As I said the engines ability to act as a "pump " is seriously affected,and I cant see any method of harnessing this to any useful end.

[peewee]

I think this is what you are looking for.

would it not be like a straw in a bottle of soda. poke a hole in the straw above the soda and try to suck. seems like you have more air and less soda going up the straw. what am I missing ?

[sispeed]

Thank you for the answers and hints. This is really a great forum with very nice friendly people, willing to give their experience to others.
The no longer effective pumping was what I also thought but could not get it clear in my head.
@Frits: No, not me. I race in the "Klassik Tropy" and not really the fastest rider ;-)
Sachsenring was a great event and an absolute Highlight was the World GP with all the great riders and a lot of 500 2-strokes http://www.worldgpbikelegends.com/
and the best thing they were not parading they were racing, even Jim Redmann with his 84 Years was not slow.
I would be very happy if I could manage to climb on a motorcycle that old.
I don't know if you can see this page without a FB account, but I hope
https://www.facebook.com/SchrauberbudeRacing
Not so up-to-date
http://schrauberbude.de/motorrad/racing.html
and nearly everything only in german
Thank you for your replies and information
Regards Siggi

[ken seeber]

Memory test for you oldies or know-it-alls. I have a question about the very first Yamaha 250 cc race bikes that came out, the TD1A.
Were the cylinder bores hard anodised or (as another memory flash I had), coated with “channel cracked chrome?”
If it was hard anodised, does anyone have any recollection if it was any good or had any problems?
Also, while you are thinking, has anyone had any experience with the Kawasaki WESC (wire explosion spray coating) bores. Was certainly used on some KX125 cylinders.

[TZ350]

Got the carb and TPS sorted, now I can easily change between Carb or EFI simply by switching the fuel between the carb or EFI fuel pump.



Currently the slow speed fuel injectors fire across the bottom of the transfers (illustration A) I am beginning to think that the timing of the squirt to get the narrow band of air/fuel mixture into the cylinder is too difficult and maybe the source of my problems.



I might have better luck by squirting the fuel vertically down the transfer (illustration B) that way a greater area of the transfer volume has a good air/fuel mix in it making the delivery timing less critical. The very successful EFI YZ250 that Flettner worked on had the injectors firing vertically down the transfers. But positing the injectors this way on an air cooled cylinder is hard to do because the fins get in the way, especially the head fins.



Firing through the transfer port window and across the cylinder into the face of the oncoming transfer air stream from the other side may be an even better yet (illustration C). I think this is similar to what Flettner is thinking of doing on his new engine. And it might be the most physically easy way to position the injectors on my air cooled cylinder. It would directly cool the piston crown too.

[husaberg]

Memory test for you oldies or know-it-alls. I have a question about the very first Yamaha 250 cc race bikes that came out, the TD1A.
Were the cylinder bores hard anodised or (as another memory flash I had), coated with “channel cracked chrome?”
If it was hard anodised, does anyone have any recollection if it was any good or had any problems?
Also, while you are thinking, has anyone had any experience with the Kawasaki WESC (wire explosion spray coating) bores. Was certainly used on some KX125 cylinders.

No idea but it would be in the Yamaha twins book which I have but I have no idea where it is.
The info on the TD1A is pretty sketchy at best with even very few pictures of the bike.
One thing I do know is it did have std exhausts that looked for all the world to be off a Triumph twin of the period.
Big brakes that were later used for the B and C
I think the method about the same period of the TD1A was hard chromed iron liners then etched to retain oil, but I have no idea for sure. What it had std.
Edit classic bike or classic racer has about a 5 page spread on them (in about 1992-95ish)

okay google

With this fitment, the YDS1R was now a 30 hp, 100 mph road racer. It was though, unreliable and too heavy to be a winner in the western world of motorcycle racing. The first Alloy barrels had chrome linings, which at the time were by no means perfect. The plating would lift off from around the ports, causing seizures. Ported iron barrels were also used on many Asama’s, before or perhaps while alloy ones were not available, or indeed to stop the seizures!

The engine of the TD1 retained the Hitachi magneto (with red HT leads) and the 27mm Mikuni 276 carburettors. Improved “low expansion” pistons were fitted and the barrels were now anodised. It was the pistons that now had to be carefully run in, as the bores were not easily re-boreable.

As the TD1A was based on the YDS2, the YDS3 lent its’ improvements to the TD1B.

The first 1B’s retained the 1A’s round orange-red fuel tank (known as the watermelon tank in the US), seat unit and general chassis. The rear shocks were improved to stiffer, adjustable units and the forks were again up-rated.

The engine was of course now based upon YDS3 crankcases, with tuned, chrome lined alloy barrels, racing heads, single ring pistons and racing crank. The bulge on the side of the crankcase, which housed the oil pump on the YDS3 was now empty, behind it was only a blanking off plate. The redundant alloy of the oil pump housing was often removed by racers, trying to save that extra bit of weight.

http://www.classicyams.com/productio...amaha-tds.html

for giggles

[Flettner]

Memory test for you oldies or know-it-alls. I have a question about the very first Yamaha 250 cc race bikes that came out, the TD1A.
Were the cylinder bores hard anodised or (as another memory flash I had), coated with “channel cracked chrome?”
If it was hard anodised, does anyone have any recollection if it was any good or had any problems?
Also, while you are thinking, has anyone had any experience with the Kawasaki WESC (wire explosion spray coating) bores. Was certainly used on some KX125 cylinders.

First ones were indeed Hard Anodised but didn't last very well. Next was hard chrome (back etched) straight onto the aluminium bore. Using hydrafluric acid as a pre etch, nasty stuff. There was a need to run cast iron rings against these bores, so also not so usefull when the rings started to get thinner. Then finaly a nikasil type finish with the ring being hard chromed, 'the final solution' as it were.

[peewee]

i wonder if you could machine the sides of a standard piston so there was only a few ribs that contact the cylinder wall. perhaps less friction and more rpm ? tz350 could you try it and see

[tjbw]

Memory test for you oldies or know-it-alls. I have a question about the very first Yamaha 250 cc race bikes that came out, the TD1A.
Were the cylinder bores hard anodised or (as another memory flash I had), coated with “channel cracked chrome?”

....

In mid sixties I watched the Yamaha mechanics prepare engines for the Ulster Grand Prix.

It looked like the cylinders had a steel sleeve. I didn't notice any plating. Using a junior hacksaw
they removed part of the sleeve, about 10 x 3mm, adjacent to transfer port.

[husaberg]

In mid sixties I watched the Yamaha mechanics prepare engines for the Ulster Grand Prix.

It looked like the cylinders had a steel sleeve. I didn't notice any plating. Using a junior hacksaw
they removed part of the sleeve, about 10 x 3mm, adjacent to transfer port.

Sounds like the TD1C gully port.
pic to follow.

[Sketchy_Racer]

i wonder if you could machine the sides of a standard piston so there was only a few ribs that contact the cylinder wall. perhaps less friction and more rpm ? tz350 could you try it and see

Sadly no cigar there, friction is independent of area and by reducing the area you increase the pressure which may lead to failure of the oil film on the cylinder wall causing a mother of all seizures.

Increase lubrication to reduce the coefficient of friction between the piston and cylinder is what we're after, better materials, better oil and more oil film on the cylinder wall.

Perhaps this is why a rich oil mix at 20:1 seems to make more power in our bikes than at 30:1 . Increasing the oil quantity may mean better sealing and less frictional losses??

[TZ350]

Interesting Talk about the TD1C :- http://bridgestonemotorcycleparts.co...?topic=3778.20