ESE's works engine tuner

[Frits Overmars]

SO the ring shape about 4mm larger than the crankpin is only witness marks.... from the rollers....

The internal diameter of the bronze rings is 6 mm (if memory serves) larger than the crankpin diameter; the press fit is at both the internal and external circumferences of the rings.

[husaberg]

The internal diameter of the bronze rings is 6 mm (if memory serves) larger than the crankpin diameter; the press fit is at both the internal and external circumferences of the rings.

OK was it an Aprilia only trick (the pressed in thrust washers) never seen it before but never seen a lot of Euro GP bike cranks either...

[Frits Overmars]

OK was it an Aprilia only trick (the pressed in thrust washers) never seen it before but never seen a lot of Euro GP bike cranks either...

I don't know Husa; I haven't seen it anywhere else. But I did see a solution that I like even better: the Garelli engines had a thin layer of bronze sprayed onto the insides of the crank webs. That way you could make the crankshaft narrower without losing press fit length around the crankpin.

[husaberg]

I don't know Husa; I haven't seen it anywhere else. But I did see a solution that I like even better: the Garelli engines had a thin layer of bronze sprayed onto the insides of the crank webs. That way you could make the crankshaft narrower without losing press fit length around the crankpin.

Great stuff as always and great to see you back on the thread.
Me and rob were jamming up another thread the other day and were wondering what the relationship was with the belly diameter of the pipe for a 2 stroke exhaust.
i was musing it is an expression of the cylinder size with a factor for max suckabilty for want of a better term.
is the diameter just about achieving the required volume....( i have likely got a lot ass about face)
what we were looking for was a way for restrict power output of a two stroke that could be easily measured?

[Frits Overmars]

...wondering what the relationship was with the belly diameter of the pipe for a 2 stroke exhaust. i was musing it is an expression of the cylinder size with a factor for max suckabilty for want of a better term.

Yes, it is about the ratio between suction energy and reflection energy. BTW, I like your word suckability (reminds me of Wobbly's long-standing offer )

what we were looking for was a way for restrict power output of a two stroke that could be easily measured?

I haven't got a clue what you're on about; maybe one must be a Kiwi to understand this sentence?

[husaberg]

Yes, it is about the ratio between suction energy and reflection energy. BTW, I like your word suckability (reminds me of Wobbly's long-standing offer )I haven't got a clue what you're on about; maybe one must be a Kiwi to understand this sentence?

Maybe, the buckets have a 24mm carb restriction for air cooled 125's what had came up (from Dave), was maybe a restriction on pipe belly diameter in order to restrict another engine designs output.

[Drew]

Maybe, the buckets have a 24mm carb restriction for air cooled 125's what had came up (from Dave), was maybe a restriction on pipe belly diameter in order to restrict another engine designs output.

Still a poorly formed sentence.

The question is. Would restricting the chamber diameter on an 85cc two stroke, be a good and easily detectable method for capping the power without making it impossible to get a decent power spread?

[wobbly]

Doubt that the marks on the bronze would be the rollers, as for sure they would be encapsulated by the cage - unless that crank has had a cage failure.
Full complement cage less roller big ends were canned back when we used chainsaws on karts.
I think low mass /high inertia is very much a relative term in the case of the Aprilia crank - what you Frits would describe as "low inertia " in relation to most say MX or kart type cranks
would be way higher than most.
I go back to the historical issues that HRC had when they tried total loss on the RS125, take off the high inertia rotor and replace it with a simple timing disk
and all the overev simply disappeared.
The A kits then came out with cranks full of Tungsten, and suddenly we saw aftermarket so called " heavy " cranks come onto the scene for those liking total loss.
So I think what Jan would be referring to in the testing of low Vs high inertia at Aprilia ,is in reality comparing high with Super high in a normal context.
Maxter have for a while, and now TM are finally getting on the band wagon and have lots of alloy and Tungsten inserts in there so called ' factory special ' crank webs.

Restricting pipe belly diameter is a way of limiting ultimate power of any engine - but a restricted carb is so much simpler.
And even simpler is what we use in the new restricted junior kart engines, a full size pipe but with a specified round restricted
diameter in the pipe flange.
In my dyno testing this gave a virtually linear variation in power.
20mm stock was 10Hp, 17mm was around 7Hp, 15mm was around 5,5Hp etc.
Putting a number on the belly just means someone serious would have to test a dozen different geometry's to find the best compromise - old story of the more rules, the more expense to go fast.

[Drew]

Restricting pipe belly diameter is a way of limiting ultimate power of any engine - but a restricted carb is so much simpler.
And even simpler is what we use in the new restricted junior kart engines, a full size pipe but with a specified round restricted
diameter in the pipe flange.
In my dyno testing this gave a virtually linear variation in power.
20mm stock was 10Hp, 17mm was around 7Hp, 15mm was around 5,5Hp etc.
Putting a number on the belly just means someone serious would have to test a dozen different geometry's to find the best compromise - old story of the more rules, the more expense to go fast.

Are those numbers all done with the same pipe fitted, and were the curves still similar? Essentially, it's just like running the same motor at part throttle, don't two strokes really hate that and go bang?

[pete376403]

The bronze rings are only about 2 mm thick. Their advantage over the usual thrust washers is that they can get rid of friction heat easier and won't vibrate themselves to pieces.
.

I read something (probably by Cameron) that some engine builders use thrust washers/spacers in the piston pin to get the rod centralised on the crankpin, and no thrust washers on the crank pin at all. The logic is that the friction between the rod and piston is much less, ie a small oscillating motion rather than the full rotational motion as would normally be at the crankpin, so less heat generated, and more importantly less heat going into the big end bearing. True?

[wobbly]

The tests with the junior engine were with the identical unrestricted pipe, just a header with a step of varying sizes.
No issue with tuning or reliability at all, just less power each size change.
The curve shape was much the same, but as you went smaller the top end power rolled off faster from a lower peak.
In the end we opted for the step header and a rev limiter, over using a smaller carb as this meant an easy upgrade route to just change the header.
The restricted 65cc engine rev limits to 10,000 the unrestricted goes to 14,000.

Thrusts up in the piston are very rare these days, I think RGV was the last,as sure the friction is less with the small oscillating movement
but lack of sufficient lubrication is a reliability issue.
KT100 Yamaha has the option for both, and the lower thrusts are pretty much universal now due to the alloy washers up the top failing
even when made of 7075 or hard anodised.

[husaberg]

Still a poorly formed sentence.

The question is. Would restricting the chamber diameter on an 85cc two stroke, be a good and easily detectable method for capping the power without making it impossible to get a decent power spread?

Drew the day i decide to have you writing my memoirs, I will of course knowledge your help.
But considering you generally start your own sentences with "look Cunt" it may not pan out that way.


For the record Drew i never mentioned the 85's because it was not pertinent to the actual question.

As for the poor formed, your ugly mug springs to mind........

Ps thanks Wob........

[Drew]

Drew the day i decide to have you writing my memoirs, I will of course knowledge your help.
But considering you generally start your own sentences with "look Cunt" it may not pan out that way.


For the record Drew i never mentioned the 85's because it was not pertinent to the actual question.

As for the poor formed, your ugly mug springs to mind........

Ps thanks Wob........

Look cunt. Hehehehe. Na, been a while since I stopped doing that. Although it was easier to piss people off that way, I now enjoy trolling (or trying to) by presenting the unpopular opinion in a way that nearly makes sense.

Lemme know when we're gonna get started on those memoirs.

Yes, the engine size was not relevant to the question.

Back to two strokes...

I have an RG150 that for the time being will be my road bike till it blows up or I get bored. Is it gonna be more reliable running premix gas, or oiled by the pump?

[TZ350]

I have an RG150 ... Is it gonna be more reliable running premix gas, or oiled by the pump?

2T, be more reliable if you leave it in the shed, last longer that way too. ....

[Drew]

2T, be more reliable if you leave it in the shed, last longer that way too. ....

Awww, you do get me.

Alas that isn't an option for now. It is a free bike, goes good (I think, it's pissing down right now so I don't want to test ride it) and until I can afford another GSXR1000 it'll have to do.