T500 porting

[Vintageman]

sqish band clearance

You changed the head too? not using the stock dome?

That Suz bulletin look easy and me still thinks if you cut the changes in Ex and Intake height it may be decent.

Tz375,
What did you do for porting. I know if plan to drag competitively than you may keep it secret. Reading your post it seems like you raised transfers a lot?

ja-moo.

I think for you its degrees.. (e.g 90 degree on exhaust). I am not sure what a stock early T500 cyl port timing is in degrees. Suz never published like Kaw did. I never calculated (but same a later Gt750 me thinks) I think you like to widen Ex port too. But honesty I don't see reeds adding any power (maybe low end grunt) You would need to have a very large reed cage ... dual row petals etc.
You could always just increase port area on piston ported engine. I think top end piston ported can be easier to get the same area and value. Maybe you add the extra port in the back too?

I am too fat too. If i tried to ride the Ronax with those low handle bars my stomach would not let my short arms reach handle bars.

I would like to see someone make a twin 350cc liquid version 7 speed

Do you guys know what I mean by direct injection. No unspent fuel short circuiting out exhaust port from transfer during scavenging! That is huge!

Now you still have the oil that burns. Not as much. so I wonder if this 2 stroke engine could pass emission levels USA. doubt it
If they added an oil ring and then the oil that pooled in the bottom use a version of SRIS but don't reburn, just collect.

Maybe not too many people left remember 2 strokes anymore so no motivation for manufactures to produces (e.g. Yam RZ350 take 2)

Fun stuff

[Zunspec4]

Hello Vintageman.

I am using centre plug heads. These were supplied by Pete Odell and are machined from a cast blank.

Cheers Geoff

[ja-moo]

ja-moo.

But honesty I don't see reeds adding any power (maybe low end grunt) You would need to have a very large reed cage ... dual row petals etc.

You are correct, they don't add power, BUT they do add in powerband width. And you can port harder and still have plenty of grunt. I will also say, that you incorrect on reed size, mine fit right in the port, and product more than enough power. I can take my ported 500 kawi triple (not known for torque anyway) and take off in 4th gear at 5500 ft. of altitude.

You could always just increase port area on piston ported engine. Not the same at all, you will never get a PP to have the powerband of a reeded motor.

I think top end piston ported can be easier to get the same area and value. Maybe you add the extra port in the back too?

Yes, one or 2 depending on the cylinder design.

[SpecialK]

ja, et al,
If one were to consider adding "thru-piston" (a) Tx boost port(s) in the T500 barrel, there is only 24mm chordal of space available. This is due to the 30 degree rotation of the porting layout of the barrels which now brings the piston wrist pin boss into play which is perpendicular to the crankshaft thrust axis. This minimizes the available "boost port area" by 30 degrees. On top of that, the available piston window height is very small due to a large 1st ring land dimension which if I remember correctly is >6mm ... which causes the port window top edge to be placed at ~ 7+mm from the piston timing edge. After removing the 2nd ring from the piston, the total height of the window ends up no more than a few mm's @ BDC (because @ BDC you do not want this window to open to the intake duct). With a matching boost port "pocket if you will" cut into the liner, this approach will provide some degree of piston dome cooling which is good, yet there is minimal "flow" through this short window to support appreciable scavenging. However, reliability is a good thing to persue though when pushing engines, so there is some benefit. Now if there were single ring pistons with a reduced 1st land height available for the T500, then that makes things better ...
Zun,
I sent you some info a few weeks back to your email. I'm not sure you received it ... it may have landed in your junk folder as I haven't heard whether you received it or not.
Cheers,
Ken

[Zunspec4]

Hi Ken,

I'll have a look for it. Picking up engine #1 in a few days so I'll post a few photos when it's back on my workbench.

Cheers Geoff

[irish1]

Boost ports, I asked this question and somehow I posted it in the wrong place. What will happen if the slots in the piston are exposed at bdc, will it run this way? If the piston is replaced with stock one will notch in cylinder wall be a problem? Also do you think it would be a good idea to ask these questions first. Thanks for any replies.

[ja-moo]

If you cut in a boost port, you have to use a reed valve conversion. Some try boosts with worm feed cut on the liners, but that's a lot of work for very little advantage.

[irish1]

Thanks for the reply ja-moo, perhaps I didn't explain my question clear enough, I didn't cut a port from the intake through to the cylinder and make a "boost port" like a reed valve engine. What I did was cut a notch in the cylinder the same hight as the transfers and angled up to slightly off center of spark plug and made a horizontal opening in the piston just below the ring lands. So my long winded question is if this slot in the piston is exposed at bdc what will happen, would it run or would I loose crankcase pressure and reduce performance.

[ja-moo]

Ah, ok. Everything "open" at BDC will bleed crankcase compression out. And if you mean by "open", open to the intake port, yes it will case big losses in power.