Difference between Late and Early model Cylinders....

Jughead · Post by **Jughead** » Tue Jun 16, 2009 10:06 am

What are the Port Differences for the Early and Late model T500 Cylinders? All I can see is the Big AZZ Bridge that splits the Intake in the Late model ones.I know the Later ones ran the longer intakes.I found a set of Later Model ones in my parts stash the other night and I figured I would use those for my Reed Conversion since I'm trading my Late model 72 T500 off in the next few weeks.

muzza · Post by **muzza** » Wed Jun 17, 2009 4:31 am

Hi juggie, hope you are well mate

The later jugs are identical except for the bridge in the intake port which you can easily cut down or in your case take out.

The intake length was modified by a bolt on manifold.

Jughead · Post by **Jughead** » Wed Jun 17, 2009 7:14 am

Thanks Muzzy.I couldn't remember what the specifics was.I don't mess with the later bikes and I din't have a set of spare early cylinders loose to compare them too.

Kris Bernstein · Post by **Kris Bernstein** » Tue Aug 25, 2009 1:03 pm

Any pictures of the T500 reed cylinders?
Any porting specs?

Thanks

Kris

husson73 · Post by **husson73** » Thu Aug 27, 2009 2:39 am

later are sadly detuned

on T 500
was the other way for the Buffalo later 3 HPmore

Jughead · Post by **Jughead** » Thu Aug 27, 2009 5:00 am

Haven't had a chance to work on them yet.Need a little welding done on them before I start carving.Guys I work with said they'd Tig them one day when I brought them down to the Shop.

Suzukidave · Post by **Suzukidave** » Thu Aug 27, 2009 10:42 am

Instead of building up the rear of the 500 cylinder with weld as you did before my suggestion would be to mill back the intake side of the cyl like Tom did on his 250 till you get a flat surface big enough to mount the reed blocks to , this also gets the reeds / carbs in closer .

ja-moo · Post by **ja-moo** » Thu Aug 27, 2009 2:08 pm

Suzukidave wrote:Instead of building up the rear of the 500 cylinder with weld....

It's not a weld fill, just a bit of filling in. Juggy's conversion will be total "stealth"........

Any guesses on which reed block is good for just under 100 crank HP on a 500?..........

There is a secret "hint" in the picture........

Suzukidave · Post by **Suzukidave** » Thu Aug 27, 2009 2:16 pm

Good deal John , it high time one of the Suzuki guys tried one of your reed setups

ja-moo · Post by **ja-moo** » Thu Aug 27, 2009 2:47 pm

Suzukidave wrote:Good deal John , it high time one of the Suzuki guys tried one of your reed setups

A few guys bought kits through the years, but this time they will get installed....LOL

tygrant351 · Post by **tygrant351** » Thu Aug 27, 2009 5:39 pm

what are the major benefits to fabing up a reed induction system? This T500 is actualy the first piston port motor i have owned. everything else im familiar with is the reed induction on sleds, stand up jet skis, dirt bikes and what not. so maybe a better question is what are the hold backs of a piston port motor??

ja-moo · Post by **ja-moo** » Thu Aug 27, 2009 10:14 pm

tygrant351 wrote:what are the major benefits to fabing up a reed induction system? This T500 is actualy the first piston port motor i have owned. everything else im familiar with is the reed induction on sleds, stand up jet skis, dirt bikes and what not. so maybe a better question is what are the hold backs of a piston port motor??

The holdback is the reversion in the intake track. Without a reed valve, part of the intake charge is pushed back through the carb, reducing power and causing double carburation, as fuel is picked going in both directions in the carb. So you get a extra rich mixture and inefficient crankcase compression. This gets worse as you add intake duration for more power.

The reed valves stop the reversion, traps all the intake charge in the crankcase, allows for maximum intake duration and allows for extra ports off the intake for more transfer area........

Jughead · Post by **Jughead** » Thu Aug 27, 2009 10:51 pm

Hmmm Anybody want a Job.They can have half mine.

Hopefully things will slow down long enough until I can Progress enough to start on the conversion.

tygrant351 · Post by **tygrant351** » Fri Aug 28, 2009 6:49 am

Ja-moo, makes total sense, i actualy thought that might happen when i first looked at a piston port motor, I remember thinkin hmmmm. thanks for the answer, how much can one gain from adding reeds to a motor like the t500, what else has to be done

edit also when its done do you cut the piston skirts down? would make sense if the port opened sooner right?

tz375 · Post by **tz375** » Fri Aug 28, 2009 7:49 am

Tygrant,
The way to think about reeds is that they allow you to raise the state of tune without all of the harmful side effects.

Just fitting reeds won't make much difference to most motors in terms of power. On some it will improve the bottom end. If the reeds are small they will tend to restrict flow and top end performance, and too large and they barely open, so that's not a lot of use either.

So if you intend to tune a motor especially if you want more intake duration from shorter piston or from dropping the floor of the intake port, reeds help to avoid a big loss of tractability.

Reeds do not open instantly, but take a finite time to open and close. Stiff reeds are even harder to open and are better for race motors because they don't flutter as much as less stiff reeds.

Sometimes, smallish reeds that open very wide can flow better than big reeds that don't open as easily. Reed block angle also effects the way a reed flows.

On a TZ race bike reeds cost power but make teh bike easier to ride. A TZ700 makes about 90HP with reeds and with a pair of TZ350 cylinders with identical porting it makes about 115, but it's almost unrideable.

It's not the difference in top end that makes the difference, it's the way it comes on the pipe - the sudden transition from inefficient to efficient at lower revs.

But in a high performance two stroke that's rideable, reeds are a must.

It all comes down to porting and intended use.