Early T500 Port Measurements, Anyone have for later T500?

[Vintageman]

Ouch.

Good news got someone on this board to measure a cylinder

Bad news. Not confident the early intake port was really designed by Suzuki to be 3mm lower than later.

Have to get some more guys to make a few measurements to verify pattern...

When I get to my 75 T500 I'll take its meaurements.

ConnerVt don't you have an early set of cylinders?

[ConnerVT]

Have an early set ('71) by the bench downstairs.

Late model set on the bike.

Can check the measurements on my early set, will be a few days. (12 hour shifts at work)

[Vintageman]

ConnerVT and brewsky

ConnerVT
Yuk, I thought 10 hrs was bad
Also measure oil hole position please (See end of this reply for my data)

brewsky,
Did you get a chance to measure oil hole position on your 74 yet?

All.

When I looked at brewsky pic of the later intake versus my early ports they do look longer and narrower just as we measure. Can't use oil hole as visual reference for it confuses.

So now I am thinking they move oil hole too. If left too far from port it won’t mix with fuel as good and not spread about. Surprise they left that method of oil versus tube in intake itself.

Anybody else have a Later T500 cylinder with intake casting divider and the timem please measure intake port dimensions






The hole is an ellipse. Had to paper trace position since calipers won’t fit in bore. I set cylinder on flat surface (Kitchen table ) and tracing paper edge is squared to that so is top of liner. After tracing I make square line to hole so I am not measuring on an angle
As before I measured from top of liner to bottom of hole and top of hole
For my early T500 right cylinder,
Top of Liner to bottom edge of oil hole:
4.455" = 113.57mm
Top of Liner to top edge of oil hole:
4.390" = 111.51mm
Center in between two readings

[argo1974]

I have an early and late cylinder set both in 1" over before me. I can confirm the early cylinders having lower intake port floor with 104mm. On late cylinders, I measured 101,6mm. Intake port roof is 79mm on both set. BTW, T500 pistons despite of their type (windowed or GT750 style) have only 75mm skirt height. That means, intake port roof is overrun by piston skirt at TDC couple of mm.

[Vintageman]

argo1974:

Thanks.

I think you'll find that the later port width was widened too. If true maybe they tried to keep static area the same and/or compensate for loss when adding divider.

[brewsky]

ConnerVT and brewsky

ConnerVT
Yuk, I thought 10 hrs was bad
Also measure oil hole position please (See end of this reply for my data)

brewsky,
Did you get a chance to measure oil hole position on your 74 yet?

All.

When I looked at brewsky pic of the later intake versus my early ports they do look longer and narrower just as we measure. Can't use oil hole as visual reference for it confuses.

So now I am thinking they move oil hole too. If left too far from port it won’t mix with fuel as good and not spread about. Surprise they left that method of oil versus tube in intake itself.

Anybody else have a Later T500 cylinder with intake casting divider and the timem please measure intake port dimensions






The hole is an ellipse. Had to paper trace position since calipers won’t fit in bore. I set cylinder on flat surface (Kitchen table ) and tracing paper edge is squared to that so is top of liner. After tracing I make square line to hole so I am not measuring on an angle
As before I measured from top of liner to bottom of hole and top of hole
For my early T500 right cylinder,
Top of Liner to bottom edge of oil hole:
4.455" = 113.57mm
Top of Liner to top edge of oil hole:
4.390" = 111.51mm107.5mm
Center in between two readings

Added mine in RED above:

[argo1974]

I have late type std. bore cylinders on the shelf with 41,2mm exhaust height and 102mm intake height.
I don't know what model year they are off but they seem to have altered exhaust porting by 1mm (40->41mm).

Argo

[Vintageman]

FYI,

I did change my 75 T500 cylinders to early style. Yes, the early intake was lower by at least 3.0mm and not as wide as shown in this post's history when measuring other cylinders. I was going to change the intake Air boxm etc. to match early, but kept all later stuff for original looks

I did not have to change jetting at all... all throttle positions are fine.

No BS. The bike runs very different. It has more mid and top end. It has a slight power band where before mid to top transition was flat and would run out of breadth. Somewhere there are two period magazine reviews, same publisher, and when they tried the later versus earlier test they were disappointed in powe rloss. I can't find them right now again but, I agree it is as they stated now I have tried both

It is "fun" to drive. I "feel" no loss in bottom end. I can hold 50 MPH at 3K rpm. 3.5K RPM it will hold a few degree incline just fine. I am sure it must have last some but if it did it still lugs well. No worries, very nice sporty 2 stroke street bike!

I think the later cylinder could even be "Better" for it is wider. Maybe just shave the skirt of piston 3mm (if enough material to remove). If you did not like it just replace pistons

Well I think the intake port timing is the main difference. I don’t think there is much difference in air boxes. I think the main jetting is mainly because the earlier carbs are Homo type and later are not.

I am pleased Thanks for everyone’s help in finding out what was the difference beteww the early and the Later T500