ESE's works engine tuner

[Frits Overmars]

Frits.
Would it be possible to display your latest version of FOS exaust concept ?

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[porttiming124]

thank you Frits

[peewee]

hey guys i picked up a 68x64 banshee mono block. its unplated with lower roof heights than a cub so theres a bit more freedom of port shapes and such. ive got engmod for assistance but still its only my hobby. oof drag pipes is what ill install. do you have any cyl advise before i bugger it all to hell ?

[aljaxon]

Al , a fat pipe will have way less wave amplitude as it enters the rear cone section. Thus what would be considered a very sharp rear cone of say 24* on an 80 Dia
belly section , would hardly develop any reverse pulse energy on a 118 Dia.
Thus the thin pipe would have no overev , and the fat pipe would act like it had only a 20* rear cone ie better frontside and overev power, by default.

that makes so much sense.

now why didnt i think of that....

[aljaxon]

Al, all I see there is heaps of room for a radiator and an auxiliary turbo water pump. Some time with a hacksaw. . .

..

tempting....
ive even got a stihlsaw

[wobbly]

There are a few issues with this setup. Its a CPI Cheetah Cub that has been machined incorrectly with low ports - thats good as they have dumb transfers that open all together
and the setup had no attention paid to what the Blowdown STA was , even though the original had the main port opening at a real high 82* ATDC.
The cylinder responds real well to normal stagger , as it has no PV, and the A transfer roof is too shallow to start with.
Pay attention to where BDC of the ports actually is when you mock it all up - if the ports are low , that probably means the all the port floors are well below BDC , not good.

But the real issue is the crank - what is it.
Luckily this is set up for the 120 rod and a TRX piston, but none of the cranks I have seen in +10 are balanced even close to correctly for the long rod and heavy piston.
The next issue is the the case has to be trenched big time for the rod swing and then they are not reliable at all unless the case is welded.
Another possibility is there are a couple of billet cases being made , but the Mattoon is pretty agricultural.
Best to use straight cut gears and the extra plate clutch from Hinson - get the spring loaded type as the rubber button version is said to handle 100Hp - but it cant unless you make your own urethane buttons.
Put roller mains on the outsides.
And depending upon your end use , the RZ gears go straight in , and Nova make a 1st/2nd/3rd close ratio set to go with the 4/5/6 that are spaced well.
The Banshee gear set splits are horrible.

[JanBros]

I'm going to try to add an EGT sensor to my dyno.
at what distance do you place the EGT sensor in the pipe Wobbly ?
and what temp are you shooting for ? and is that temp BMEP-dependent or universal ?
or do I have to figure out the ideal EGT myself ?
(it's for not high BMEP air-cooled 50cc).

sorry if this has been asked already, but I can't find anything using the search and the google-site-search function no longer works on this site.

[wobbly]

Make sure you have a fast / exposed tip probe that sits on the header centerline - 3X bore from piston ( square engine ). I use Stinger probes from EGT Industries , they are the only
probes with a guarantee - used literally hundreds of them. Only just recently had a failure and that was the internal wire connection failing after 5 years use.

The actual egt is totally dependent upon the compression and the ignition timing used to suit the fuel.
But as I have said 100 times as you jet down one size at a time you will see a pattern of egt increase / jet size - say 20*C per jet.
As soon as you go down one size and the egt hardly increases, if at all , then that is the deto limit.

You may not loose power at the deto limit , but it sure as hell isnt safe going there.
There is an RAD / jet chart on my Wobblypipes FB page showing 3 different egt for max power just short of deto for 3 different fuels - same ignition timing , same compression.

[peewee]

There are a few issues with this setup. Its a CPI Cheetah Cub that has been machined incorrectly with low ports - thats good as they have dumb transfers that open all together
and the setup had no attention paid to what the Blowdown STA was , even though the original had the main port opening at a real high 82* ATDC.
The cylinder responds real well to normal stagger , as it has no PV, and the A transfer roof is too shallow to start with.
Pay attention to where BDC of the ports actually is when you mock it all up - if the ports are low , that probably means the all the port floors are well below BDC , not good.

But the real issue is the crank - what is it.
Luckily this is set up for the 120 rod and a TRX piston, but none of the cranks I have seen in +10 are balanced even close to correctly for the long rod and heavy piston.
The next issue is the the case has to be trenched big time for the rod swing and then they are not reliable at all unless the case is welded.
Another possibility is there are a couple of billet cases being made , but the Mattoon is pretty agricultural.
Best to use straight cut gears and the extra plate clutch from Hinson - get the spring loaded type as the rubber button version is said to handle 100Hp - but it cant unless you make your own urethane buttons.
Put roller mains on the outsides.
And depending upon your end use , the RZ gears go straight in , and Nova make a 1st/2nd/3rd close ratio set to go with the 4/5/6 that are spaced well.
The Banshee gear set splits are horrible.

hey mate ill put up some drawings they gave me with the cyl. ive not yet had a chance to drop them on the bottom end but i hope the trans floors arent well below the piston top edge. that would be completely dumb.
the common piston looks to be a 68mm blaster style but i suppose the banshee style could be used with a 5mm cyl spacer.
crank i have is a +10 billet with 115 rods made in house by crank works and roller bearings across the board. the rods look miles stronger than common 115 rods. i thought of 125mm rods but that opens a can of worms like needing expensive after market cases. my factory cases are trenched for rod swing. its not super deep so i hope it will be fine structurally.
also got hinson straight cut gears with springed basket. gearbox is 2-5 overide with billet 2nd
when you say normal stagger do you meen A open first then B then C ?

[wobbly]

Aha , so the Serval is a different animal , maybe those port timings are low with the BDC in the right place - I had not seen that actual setup sheet before.
The 68/64 normal Cub is set up with a 120 rod and a option TRX piston.
Shit thats a very short rod on a big stroke - even the original RD400 with the 62 stroke was limited by those short 115 rods.
But yes stagger with the A opening first , the next two the same lower height and the boost lower again - works very well.
Having the ports all low like that makes it easy to get all the STA numbers correct very easily as its not plated.
And my choice would be the Banshee piston with the 5mm spacer to get some case volume happening.
CrankWorks are just as bad as plenty of others at using all the same components for a huge bunch of different combo's of stroke/rod/piston - so check what the BF actually is.

[porttiming124]

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Hello Frits.
What is the way to measure the length of the Exaust runner according to you?

[Frits Overmars]

Hello Frits.
What is the way to measure the length of the Exaust runner according to you?

I do it like this, with the depth gauge of the caliper in the top corner of the exhaust port, against the piston.











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[porttiming124]

Thank you Frits

[TZ350]

.


Stroked crank, pin hole welded and re machined for 45mm stroke (thanks Flettner).

This is to go with a big bore kit to make an F4 95cc, Suzuki RG50 engine with a rotary valve conversion.

To get close to 50% ballance factor I needed to make the counter weight heavier.

Managed that by removing a small amount of material on the crank pin side.

It is always a worry drilling holes here as it may loosen the crank pin. Anyway I kept them as shallow as possible and crossed my fingers for luck.

[F5 Dave]

Um, so like a 52mm piston?. That one in pic looks smaller. What kind of barrel? A mate got an RG80 out of Germany, but it looked horrible .
Awfully oversquare, but would be superlight engine.
Oh yeah sorry for delay shipping parts but hard to get near po ATM.