ESE's works engine tuner

[twotempi]

We ditched the copper/fibre head gaskets which used to leak on our Benelli aircooled twin and used Viton "O" rings in a machined groove in the head instead and cured the problem. Not one leak in many seasons.

However a friend machined the groove in the cylinder instead with a too narrow groove and manged to implode the cylinder wall back inside the cylinder. There was not enough material left between the groove and the cylinder bore to support excessive pressure from the crushed "O" ring.

Robs table of "O" ring groove dimensions is available from Seal Imports Ltd. I have found that Murray at the Lower Hutt branch is very helpful - he is also a bike nut which helps - and although I am in Auckland he is only a $4 courier parcel away.

The viton "O" rings are available in two grades - the red one is a higher temp version.

Also there is a "Super Viton" ring available good for a very high temp but very pricey @ $100+ each. Maybe NASA has some shuttle ones left over ??

[speedpro]

Pipeline industries on Rosebank Road have pretty well every regular size viton o-ring made and they are real helpful. They have like a room with racks and racks of orings in plastic bags on hooks.

[Haufen]

One some of the o-ring manufacturers' homepages there are online o-ring groove calculators. Never had a problem if the groove was designed by one of these programs. They also take tolerances of the o-rings into account.

[dinamik2t]

Hello Wob,
I have a question, if you have some time.
Searching backwards, I met with your post here about EGT with Avgas/Unleaded.

How this relates to the bulk temp of the gases in a pipe, in a pipe calculator?
Neels describes the parameter in help files like this:

The software uses this value to calculate the tuned length and it is the average bulk temperature of the exhaust gas in the pipe from the piston face to the tailpipe entry over a complete cycle at the design rpm value.

If the EGT value can be used for this parameter (given avgas/leaded is +200*F over unleaded), does it mean that a pipe designed for unleaded must be shorter?
I have no idea, a 200*F/90*C difference results in ~40mm difference in TL, according to Engmod.


My question is driven by the dyno results of this engine (running pump unleaded). I got my hands on the graph and it's like this
,
-about 1500rpm off- so I immediately thought of lower EGT.
Still, I was able to look at the AFR graph and it was around 13.5~13.7, only past 11k it went through the roof. I tested a little in Engmod to try and produce such a 'deviation'. It seems that such an AFR situation, with ~14adv around 10.5k, could have this effect in power. So I ended up that it was either tuned by a stupid carb/adv tuner or really a lower EGT.
.. so confusing the art of tuning after all.

[wobbly]

Unleaded fuel to make best power likes to be rich and have plenty of advance with low com.
Thus in general a shorter pipe would be needed, as you say due to the lower egt.
But as usuall there is a fly in the ointment in that the FIM race fuel that needs gloves and a respirator, acts differently,and ends up with the same tuned length as was used with ELF124.
But the bulk pipe temp isnt what the egt probe reads in the header, its the average temp and is alot lower overall.

[dinamik2t]

Ok Wob, thank you. Is there a way of tricking EngMod into predicting the right rpm for top power, when using unleaded fuel? So far it seems to predict the rpm range as if the egt was around 650C.

[wobbly]

The biggest thing to realise is that the pipe wall temp seems to work best in the 0 to 100*C range.
I use 50* for most engines running on Avgas.
This is a fudge that Neels hates but works very well.

[TZ350]

More than you ever wanted to know about "O" rings

http://www.parker.com/literature/ORD...g_Handbook.pdf

O-rings are not supposed to be compressed or squashed in the groove, they are supposed to be 'displaced' & the groove allow the space for it to deform.

True....



Static "O" ring groove design.

[F5 Dave]

Wow that looks like a read & a 1/2, I'll need to find some time to go through that, good post.

[TZ350]

Originally posted by Husa

The variator interests me as I would like to fit one to the Beast.



By moving my engine forward the variator assembly looks short enough to fit into the chassis with a jack shaft for the chain.

If anyone knows what this one is off I would love to know.

[husaberg]

Originally posted by Husa

The variator interests me as I would like to fit one to the Beast.



By moving my engine forward the variator assembly looks short enough to fit into the chassis with a jack shaft for the chain.

If anyone knows what this one is off I would love to know.

http://www.aaenperformance.com/snow_clutch_parts.asp
http://www.aaenperformance.com/snow_clutch_roller.asp

bUT look under snowmobiles failing that Argo or john deere (can't remember what the old 6 wheeler was)(later gator the old 6 wheelers) they all have similar CVT's hp'ed to suit. i remember the argo are set to rev real high and had a 2 stroke std (well some of them did)
Before you start though try going around corners in netural to see if you like it though.
interestingly I was going to post some stuff on the 70's Husky 4 speed auto set up but can't find all the info. I haven't googled it though.
Why not a slipper KTM 50 style always on the pipe. Much like a chainsaw setup.

[speedpro]

Snow mobile.

I've already investigated them. The Canadians have some lovely billet stuff with roller bearings and different ramp angles etc etc. Some of their snowmobiles are making over 300hp using turbocharged 2-strokes.

Check this place out - http://www.aaenperformance.com/snow_clutch_roller.asp

They run the sleds on the drag strip as well using titanium tracks with rubber bits on the outside.

Check out the 1&5/8th belt good for over 300hp and also their racing engines.

[richban]

Originally posted by Husa

The variator interests me as I would like to fit one to the Beast.



By moving my engine forward the variator assembly looks short enough to fit into the chassis with a jack shaft for the chain.

If anyone knows what this one is off I would love to know.

Try find yourself a Gilera runner 180 one. Should cope with the hp fine. Also lots of good bits for them. I might have an old vespa one in the shed will have a look. I replaced it with an adjustable malossi one. Was never beaten when the lights went out. They are quite big and heavy. Even the fancy ones.

You will need a nice rear brake. If you are hoping to make it easier to ride think again. Corner entry and exit are hard work. Also the delay from throttle to drive is a bitch. When you set the clutch up to launch hard for starts it also means that it can be quite brutal when you twist it on to full noise.

When I raced my scooter I spent the whole time wishing I had gears.

[husaberg]

Try find yourself a Gilera runner 180 one. Should cope with the hp fine. Also lots of good bits for them. I might have an old vespa one in the shed will have a look. I replaced it with an adjustable malossi one. Was never beaten when the lights went out. They are quite big and heavy. Even the fancy ones.

You will need a nice rear brake. If you are hoping to make it easier to ride think again. Corner entry and exit are hard work. Also the delay from throttle to drive is a bitch. When you set the clutch up to launch hard for starts it also means that it can be quite brutal when you twist it on to full noise.

When I raced my scooter I spent the whole time wishing I had gears.

I have no doubt posted the Monotrack stuff somewhere if not i will do. it had one back in the early 70s based on a snowmoble were avant-garde at the time (Mag monoque disk all around mag wheels funny air forks belt rear drive etc)but no match for the TZ750's. From memory the rokon had one (probably the same guy) i think the weird 2wd bike about the same time as well had on too.

[wobbly]

Forget that shit - get a 30Hp aircooled on track that runs like a clock all day!!