ESE's works engine tuner

[TZ350]

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Hi Flyincat, very interesting cylinders. Being a temperate climate and not much snow we don't usually see 2T snowmobile engines here. So its very interesting to see what people do with them.

[husaberg]

Hi all, first post here! Greetings from the far side of the pond. Number one, amazing thread and unreal info sharing. Thank you!!

These parts of the world are snowmobile country, so I hope you can forgive me for bringing non-bike material. I've been interested in resurrecting some 70's, 80's, and 90's vintage twin cylinder 2T snowmobile engines, which somehow lead me to the endless 2T info here.

Lohring - having searched and searched for piston port info, I was excited to see you post something recently about a piston port project. Here are some pictures you might find interesting, or not. This is from a Arctic Cat (Suzuki) 500cc twin, case reed, single exhaust port, non power valve motor, ~85-90hp @ ~7800-8000rpm. Not much for performance, but I've seen references that it is intentionally limited in design, and power, to race in a 85hp class. Anyway, the lack of boost port, aside from being case reed, looked quite similar to one concept you proposed. Maybe the port layout is helpful? Just an FYI, but performance shops are porting these engines, along with supporting tuning adjustments, and making 105+hp @8200-8500rpm. I wish I could see a picture of a ported cylinder. There may be a hint in the rear of the cylinder, where it is boxed off. This is the same as the big brother motors (600cc & 800cc), except this boxed in area on the bigger engines houses a boost port along with coolant passages to the crankcase. In this 500 cylinder, there are two coolant passages and a lot of space between them, and space between B ports. Perfect place for a boost port?

Some models of Suzuki artic cat cylinders bolt onto RGV250's. I think its the 660ZRT triple or similar, is it possible to measure the stud spacing to see if it cross pollinates with the say RM250?

[tdc211]

I been playing with pipes and b ports. More so the b port in these pics. Me and a friend had a discussion on the scavinging of this engine. So less B port width was talked about and tried. . It surly was not optimal pipe/head But here is back to back pulls on b port width. Wider b port (no epoxy)
Waz best . But obviously there is a sta difference as well.

Over a year ago. I was building this eng at 34hp with a 790mm pipe. Not big in diameter . Lots comp. Was a easy pipe to obtain and lengthen easily. Always was 20hp at 9000.
One time i decided to mold the b ports better. I always widened them. And epoxy in inner and outer walls in them.
But this one time i added more epoxy in b port. And checked with molds. It was pretty much the same width and length (skinny) till the bore than it got wide. Lots epoxy! It added 3hp at 9000rpm. 23hp @ 9000. More than you can sim with that pipe. I honestly thought dyno was broke. Or the weather station was broke. And hurt peak by 2hp. Same peak rpm. Clutch confirmed dyno result as it had a very hard time holding the pwr. In the mid. i even turned off weather station and inputed the weather. Same thing. Had light detno so i added some export width. Not much diff iin pwr. Probably needed stinger open up. Or head change
Wish i had more time to play with it and see what could be done with it.

Now a year later i know it takes 830mm pipe to make that mid.
With normal looking ports tunnels/with wide ports at bore. And that pipe hurts rpm. Idk. Just a experience i had.

[flyincat]

As a followup to the 500cc snowmobile cylinder pics I posted, here are some of the 'big brother' 600cc cylinder pics. In comparison, note the 600cc cylinder has boost port, powervalve, triple port, 'semi' direct injected cylinder (boost port injected), ~120hp in stock form. It does look like the B port takes up more real estate on the 600 cylinder with the boost port. Just to clarify, both the 500cc and 600cc cylinders are off late models, 2011'ish-present.

TZ350 - you may have seen this video already, but it shows an animation of the boost port injection. It's interesting how the oil is injected into the fuel and runs through the injector. https://www.youtube.com/watch?v=OTGS9kuztcg

[lohring]

I believe the picture I posted as my inspiration was possibly for a snow mobile cylinder. It came from up north ( in North America, not New Zealand). I will need to narrow up the intake port bottoms and increase the intake timing in my cylinder layout. I'll play around with some ideas and lay out the complete engine.

Lohring Miller

[Dutch Fisher]

.......... Other interesting thing from drawings is about EX configuration: looks like one big EX with satellites ,but maybe two big with sat. like on VJ23.
And 3 stages power valve.

As far as i can tell its been a single main ex with 2 aux since the start of the V-4, here's a 1993 cylinder attached, with curious narrowing of the top of the port which could be 'filled' with the static blade of the PV

Honda had formula they used on the narrow angle offset crankpin twins like the bros Hawk and VT500.
If i recall correctly it went along the lines of 1/2 the v angle -90 dregrees equals the crank pin offset to make it think its a 90 degree v twin.

The formulas are : The optimum angular crank pin offset is simply: ( 2 x Av - 180 ) where Av is the angle between the V.
The optimum balance factor is equal to: ( sin(Av) )


Examples: V2 90* = 0* + 100% TZ250(with balancer for rocking couple) RGV VJ22(without balancer)
V2 75* = 30* + 96.5% RS250R nx5/nxa(with bal for RC)
V2 100* = 20* + 98.5% NSR500V(with bal for RC?)
V2 70* = 40* + 94% RGV VJ23(with balancer)***

*** However the VJ23 is 30* offset and has a balancer with an amount of primary? counterbalance on it, with is a might bit strange.


Anyone got the details of the XR95-XR98 Gp250 bike that the marketing hype says the 23 is 'based' on?

[husaberg]

As far as i can tell its been a single main ex with 2 aux since the start of the V-4, here's a 1993 cylinder attached, with curious narrowing of the top of the port which could be 'filled' with the static blade of the PV





The formulas are : The optimum angular crank pin offset is simply: ( 2 x Av - 180 ) where Av is the angle between the V.
The optimum balance factor is equal to: ( sin(Av) )


Examples: V2 90* = 0* + 100% TZ250(with balancer for rocking couple) RGV VJ22(without balancer)
V2 75* = 30* + 96.5% RS250R nx5/nxa(with bal for RC)
V2 100* = 20* + 98.5% NSR500V(with bal for RC?)
V2 70* = 40* + 94% RGV VJ23(with balancer)***

*** However the VJ23 is 30* offset and has a balancer with an amount of primary? counterbalance on it, with is a might bit strange.


Anyone got the details of the XR95-XR98 Gp250 bike that the marketing hype says the 23 is 'based' on?

there was a write up in classic racer about 3-4 months ago
I have a copy but i havent scanned it yet. Not a scan but this will do for now.
Pretty sure i have some period pics.
Attachment 337721Attachment 337722Attachment 337723Attachment 337724

[Norman]

Hi,
In this Racers magazine (No 25) about RGV250 (includes XR95-XR98) there is also some technical information. However, it's in japanese, but to me the pictures looks nice anyway.. I have attached some. Maybe possible to use a "text in picture translation app". I tried that but was not so successful at the time.

As far as i can tell its been a single main ex with 2 aux since the start of the V-4, here's a 1993 cylinder attached, with curious narrowing of the top of the port which could be 'filled' with the static blade of the PV





The formulas are : The optimum angular crank pin offset is simply: ( 2 x Av - 180 ) where Av is the angle between the V.
The optimum balance factor is equal to: ( sin(Av) )


Examples: V2 90* = 0* + 100% TZ250(with balancer for rocking couple) RGV VJ22(without balancer)
V2 75* = 30* + 96.5% RS250R nx5/nxa(with bal for RC)
V2 100* = 20* + 98.5% NSR500V(with bal for RC?)
V2 70* = 40* + 94% RGV VJ23(with balancer)***

*** However the VJ23 is 30* offset and has a balancer with an amount of primary? counterbalance on it, with is a might bit strange.


Anyone got the details of the XR95-XR98 Gp250 bike that the marketing hype says the 23 is 'based' on?

[Dutch Fisher]

Hi,
In this Racers magazine (No 25) about RGV250 (includes XR95-XR98) there is also some technical information. However, it's in japanese, but to me the pictures looks nice anyway.. I have attached some. Maybe possible to use a "text in picture translation app". I tried that but was not so successful at the time.

I can translate with Japanese OCR software, however the pages have to scanned (not photo'd) at hi-res (1920x1080 600dpi) as the jap kanji and kana tend to 'bleed' on anything lower.

[Frits Overmars]

For no particularly good reason I've been exploring the idea of a piston ported cylinder with a boost port for a 26 cc engine. I know it's been done before, see below. My design looks weird and simulations don't show any power gains over a cylinder with no boost but a wider B port. Of course scavenging isn't being modeled. Any thoughts or other ideas?
Attachment 337615 Attachment 337616 Attachment 337617

Lohring, we once tried the Aermacchi system of a C-port, fed from the crankcase through a fat intake divider:
http://www.pit-lane.biz/t7437p75-old...chi-deux-tempsAfter testing it, we filled the lot with Devcon, removed the divider and gained power.

I'd like to suggest staying with your original four-transfer layout. There will be less problems in finding sufficient intake area, less need for additional material, asier to produce, more guidance at the piston ring gap, less wall friction and less heat-excanging surface.



I think this is the post Frits tried to put up - MT

Lohring, we once copied the Aermacchi system of a C-port, fed from the crankcase through a fat intake divider: http://www.pit-lane.biz/t7437p75-old...chi-deux-temps
After testing it, we filled the lot with Devcon, removed the divider and gained power.

I'd like to suggest staying with your original four-transfer layout. There will be less problems in finding sufficient intake area, less need for additional material, asier to produce, more guidance at the piston ring gap, less wall friction and less heat-excanging surface.

[Dutch Fisher]

Looks like this page has become corrupted.
There appears to be a body_id injected into the html code above the div class,
Not sure me saving this will correct it or its a server side muck up.


Edit, nope did nothing, still corrupted, looks like the post above this didn't save correctly.
PM sent to mods 01:25 server time

[Mental Trousers]

Can you guys stop breaking this. I actually had to think about how to fix this one.

[Dutch Fisher]

Can you guys stop breaking this. I actually had to think about how to fix this one.

It wasn't that hard for a man of your talents



Frits, stop putting dodgy html code into the world !

[jacobson_se]

What would be a normal cht temp range on a TZ125 running ELF LMS unleaded?
Hard too find any guidelines for cht.
Wobbly do you measure cht on the KZ?

/Christer

[Frits Overmars]

Frits, stop putting dodgy html code into the world !

I assume you're joking Dutch, but your smiley suggests otherwise.
I posted four lines of text and two JPG-pics; that's all. Nothing I haven't done a thousand times before.