ESE's works engine tuner

[Michael Moore]

This info from NTN and INA on crankshaft needle bearings may be of use:

http://www.ntnglobal.com/en/products...f/2300E_03.pdf

https://www.schaeffler.com/remotemed...pi94_de_en.pdf

[TZ350]

TZ350, do you have a fuel pressure regulator on your EFI system? What pressure do you run, and what is the pressure swing?

Yes, a bypass pressure regulator. 3.5bar and no noticeable pressure change from idling to full load. The fuel pump provides more than enough volume of fuel and the surplus passes back to the tank.

[Yow Ling]

My 50 and the 80 from which my 97 is developed, both had 12mm gudgeon pins in the same 17mm rod eye, so needles of 2.5mm diameter. No problems revving to 14,000.

I'm just wondering if the smaller contact area of the 1.5mm needles will increase the pressure on the eye and the pin, like stiletto heels do on a carpet compared with flats.
I'll certainly be doing checks after every meeting for a while.

Hi Lodger, what piston do you run in your 80? Is it a GE3G cylinder?

[lodgernz]

Hi Lodger, what piston do you run in your 80? Is it a GE3G cylinder?

Hi Mike. No, it's a GJ1G (CRM80 I think), bored out to 53mm with a KT100S kart piston. Stroked as well.

[lodgernz]

This info from NTN and INA on crankshaft needle bearings may be of use:

http://www.ntnglobal.com/en/products...f/2300E_03.pdf

https://www.schaeffler.com/remotemed...pi94_de_en.pdf

Nice! Useful data. Thanks Michael.

[Yow Ling]

Hi Mike. No, it's a GJ1G (CRM80 I think), bored out to 53mm with a KT100S kart piston. Stroked as well.

Ahh thanks KT100 was on my list, there are lots of stock pistons that didnt look great for 14,000. I have a nsr50 and a GE3G to put together

[speedpro]

I think one problem with using KT100 pistons is the process where a piston which is only a very small amount larger is fitted after a hone, and then the next one and the next one and so on. The bore changes shape slightly each time it's used and the hone simply changes the surface texture. I think it would be worthwhile to have the bore ground in a cylindrical grinder every 2nd piston to maintain it's cylindrical shape and remove any taper that may develop. I quite like the look of the Burris pistons but don't know that they are actually any better. They can certainly extend the life of a cylinder due to the increased clearance required versus say a Yamaha piston. there might be some slight difference in the shape of the crown requiring a different head.

[lodgernz]

I think one problem with using KT100 pistons is the process where a piston which is only a very small amount larger is fitted after a hone, and then the next one and the next one and so on. The bore changes shape slightly each time it's used and the hone simply changes the surface texture. I think it would be worthwhile to have the bore ground in a cylindrical grinder every 2nd piston to maintain it's cylindrical shape and remove any taper that may develop. I quite like the look of the Burris pistons but don't know that they are actually any better. They can certainly extend the life of a cylinder due to the increased clearance required versus say a Yamaha piston. there might be some slight difference in the shape of the crown requiring a different head.

Thanks Mike, duly noted. This has been a simple overbore to match the supplied piston, so that shouldn't be an issue this time. I'll bear it in mind for future replacements though.
I make my own head inserts to match whatever piston I'm using, so that also shouldn't be a problem.

[lodgernz]

Ahh thanks KT100 was on my list, there are lots of stock pistons that didnt look great for 14,000. I have a nsr50 and a GE3G to put together

Lucky you! Great engines.

[shnaggs]

Yes, a bypass pressure regulator. 3.5bar and no noticeable pressure change from idling to full load. The fuel pump provides more than enough volume of fuel and the surplus passes back to the tank.

If you are running a regulated return system what if you plumb the top side of the regulator (boost reference) to the pipe??? This is how a lot of turbo 4T adjust the fueling as boost rises and falls...maybe it would work the same with the pipe on the 2T. As pipe pressure rises, so would fuel pressure and hence more fuel. If the pipe collapses then pressure would also, so the fuel pressure would drop as a result.

[Yow Ling]

If you are running a regulated return system what if you plumb the top side of the regulator (boost reference) to the pipe??? This is how a lot of turbo 4T adjust the fueling as boost rises and falls...maybe it would work the same with the pipe on the 2T. As pipe pressure rises, so would fuel pressure and hence more fuel. If the pipe collapses then pressure would also, so the fuel pressure would drop as a result.

I think the purpose of the manifold pressure referenced regulator is not to supply more or less fuel but to keep it constant, if you have 3.5 bar of fuel pressure and 1 bar or boost the rail pressure has to increase to 4.5 bar to counter the 1 bar on the nozzle, and likewise if you have vacuum in the manifold the rail pressure decreases to maintain a constant pressure at the nozzle, this means the computer does not have to account for these changes electronicly

[jbiplane]

More information, (from a fire engineering not automotive site).

Eagerly awaiting the results of Wobbly's tests with ceramic matrix, thermal coatings.

What would be best gasket material - cylinder to header? BTW chainsaws use thermal screen beetween muffler and cylinder.
Possible as well cover header by simple basalt tape
https://www.amazon.com/Titanium-Basa.../dp/B0022QOY0C

Question. For simple muffler and 2-stroke. What is optimal stinger diameter for simple lightweight exhaust systems?
Or what optimal back pressure in muffler?
Saw one interesting idea http://www.dragonfly75.com/motorbike/stingersizing.html

[paul gane]

Can anyone help me with an ignition timing map for a TZ250 5F7

[wobbly]

The cylinder to do the Exhaust Port thermal barrier coating test has been at HPC for over week ,and they now say it wont be done till mid next week.
I to am hanging out for the result, and will have it on the dyno the same day it arrives.
The deto sensor will tell immediately if it goes into destruction mode or not.

Re stinger size and pressure.I have measured several engines and found that 2.5psi at full noise seemed to be a constant.
But the process is a bit counter intuitive in that less pressure in the pipe ( ie a big stinger ) renders the pipe less "efficient " at low rpm.
Thus when the return wave comes back to the piston face too early at lower speeds this reduced pressure also reduces the power loss due to the wrongly timed stuffing process.
Increasing the pressure ( a smaller stinger ) makes better power higher up.
This is used in the Jetski world to good effectby having a oversize stinger, and using a rpm controlled solenoid, water is than dumped into it to increase the back pressure at higher engine speeds.
PWM valve control makes it even better.
Easy way to size a stinger ( or nozzle settup ) is to look at the Mach number in the restriction using EngMod, 0.8 Mach works best every time.

[Haufen]

The cylinder to do the Exhaust Port thermal barrier coating test has been at HPC for over week ,and they now say it wont be done till mid next week.
I to am hanging out for the result, and will have it on the dyno the same day it arrives.
The deto sensor will tell immediately if it goes into destruction mode or not.

I suppose a pre-test with flange and part of the header wrapped might give a hint on the result of the coated exhaust port. I would expect the effect to be the similar but not as large as with the coated port.