ESE's works engine tuner

[TZ350]

.
All this information about crank/big end oiling is very Interesting .... Thanks.

[guyhockley]

Fath did indeed, and it far more than doubled the crank life.

Suzuki seems to have made the greatest efforts in lubrication, especially on the triples, but I was once approached by a bloke who said I was riding his old "works" bike (MZ250). Sadly, not racers, he had been a dispatch rider for a South Coast (UK) printers and claimed that his other work bike was a GT250 that did 100,000 miles on the original crank before being replaced.

[katinas]

Oh My!
I totally love technical drawings of twostroke stuff!
Where did you get that from? Is there a chance that there might be more? :-)

Regards
Tim

Picture from 2017 RACERS vol. 44 magazine, and I too still enjoy very much, when see such drawings.

For me, the last NSR 250 (98-01) was little bit mystical bike, maybe engine is some copy of Aprilia, but when I nearly touch Kato's bike at 2001 Brno GP on quiet Thursday evening, like it very very much. It was so nice to be around the best strokers, especially as the teams were not so secretive on Thursday evening. For me it was one of the most enjoyable evening

https://www.ebay.co.uk/itm/racers-vo...MAAOSwcmhZlINd

Japanese still releasing special magazine for two strokers

https://www.amazon.co.jp/2%E3%82%B9%.../dp/4777021378

Honda NS 400 conversion to 500
https://page.auctions.yahoo.co.jp/jp...mrjapanfactory

[wobbly]

Cant believe it - I thought I was real clever using staggered length backup reed tensioners to equalize flow thru the reed ports - and there Honda were doing it years ago.

I found a Yamaha style deto button in a box of bits.
Head is 20x2mm , stalk is 10mm with M6 and a couple of slots for 8mm spanner.

[EssexNick]

I'm still at a loss as to just how a deto button works. It clearly goes, I just can't get my head round the concept.
On a different note, can anyone recommend a suitable sealant for use in a fiberglass petrol tank? I'm only planning to use unleaded.

[diesel62]

Hi could you please comment on this piston. I am not sure what is causing the wear above the ring. It is in a maxter kz2 engine. Has seen 15 litres of fuel. The last piston looked the same
I emailed Meteor (piston manufacturer) and got a reply back saying as the skirt was modified that is what the problem is.
The piston has not been modified although the photo is on a funny angle so it looks like the opposite skirt is short.
I have measured the piston against an earlier Vertex piston (measures the same) above and below the ring. Funny thing is that the Vertex piston does not show any wear above the ring.
Any help is appreciated. Cheers

Sent from my SM-P555 using Tapatalk

[wobbly]

The Meteor is obviously expanding more above the ring, and the land is dropping into the Ex port.
You can see the wear pattern that matches exactly the shape of the Ex port timing edge.
The problem may be a very common one in that the manufactures often will grind the Ex duct timing edge too far up, and thus there is very little chamfer left.
Normally this will quickly trap the ring, causing real damage.
This has happened to many so called " factory selected " cylinders , where they seem to be selected, then ground after plating - this should be the other way around.
You may be able to get a some more lead in chamfer with less sharp edge to kill the piston , using an impregnated cotton mop in a die grinder.

[diesel62]

Thank you. I will investigate further

The Meteor is obviously expanding more above the ring, and the land is dropping into the Ex port.
You can see the wear pattern that matches exactly the shape of the Ex port timing edge.
The problem may be a very common one in that the manufactures often will grind the Ex duct timing edge too far up, and thus there is very little chamfer left.
Normally this will quickly trap the ring, causing real damage.
This has happened to many so called " factory selected " cylinders , where they seem to be selected, then ground after plating - this should be the other way around.
You may be able to get a some more lead in chamfer with less sharp edge to kill the piston , using an impregnated cotton mop in a die grinder.

Sent from my SM-P555 using Tapatalk

[Mike Fisher]

Then there's old school...

Not a 2 stroke question but... That looks like a Hurst Airheart master cylinder in the inset photo. Did the Enfiled run a rear disc, or was it a rear hydraulic drum brake, in '65?

[wobbly]

Well here finally is the result of the change to the semi flat top IAME piston with a 1mm edge radius.
The piston is 0.5mm higher, so equivalent to dropping the cylinder 1/2 the radius.
I can see why the MX guys like this mod - added power all the way up the front side ( +1.3 max in this case ) but it drops off past 14,000.
This I believe is simply due to the cylinder being a little low, so I will next jack it up 0.2mm, and drop the insert the same amount down the bore.
But really what needs to happen next is to not move the cylinder, but go with a 1.5mm radius - then depending upon the result even bigger as Frits has alluded to.

[ken seeber]

Wob, good stuff.

Did the spigotted head profile match the radiussed piston edge profile right up to the side of the bore? She'd be sharp edged right at the end, possibly very vulnerable to handling damage and also deto issues.

Why did I say she ? Can't say he in these "enlightened" Ozzie days, so really I should have said it.

[wobbly]

Yes Ken, the spigot matched the piston shape,with a sharp edge at the bore.
I broke the corner with a tiny radius ( easy in CNC ) but once I have tried the other variations of a higher cylinder, and then a bigger radius , the real go is to have a small step at the bore top so the
spigot face is a small flat.
This will make it reliable against deto - but in my case not as vital , as all my fast engines now have no spigot at all.

You really cant say fuck all nowdays mate, but hey , good thing is they cant ban you twice.

[speedboy]

Well here finally is the result of the change to the semi flat top IAME piston with a 1mm edge radius.
The piston is 0.5mm higher, so equivalent to dropping the cylinder 1/2 the radius.
I can see why the MX guys like this mod - added power all the way up the front side ( +1.3 max in this case ) but it drops off past 14,000.
This I believe is simply due to the cylinder being a little low, so I will next jack it up 0.2mm, and drop the insert the same amount down the bore.
But really what needs to happen next is to not move the cylinder, but go with a 1.5mm radius - then depending upon the result even bigger as Frits has alluded to.

Interesting. How many measurements for the average curves?

[RomeuPT]

Well here finally is the result of the change to the semi flat top IAME piston with a 1mm edge radius.
The piston is 0.5mm higher, so equivalent to dropping the cylinder 1/2 the radius.
I can see why the MX guys like this mod - added power all the way up the front side ( +1.3 max in this case ) but it drops off past 14,000.
This I believe is simply due to the cylinder being a little low, so I will next jack it up 0.2mm, and drop the insert the same amount down the bore.
But really what needs to happen next is to not move the cylinder, but go with a 1.5mm radius - then depending upon the result even bigger as Frits has alluded to.

Great!

But changing from a 4º taper used in TM right?!

Thanks

[wobbly]

Each graphed run is 3 averaged.
And yes the change to the radiused semi flat IAME was from a 4*TM.