Ports - GT750

[tz375]

Thanks, I remember reading that when I got my first GT750 basket case a few years ago. There are better porting answers than that, but it makes fun reading.s

[stevegt738]

Well my next rebuild has been made more interesting .

[tz375]

So I pick up the set of L barrels ported to my specs late this week and in the meantime I have a set of A barrels at the machine shop being shaved. the A are already bored and honed and the ported ones need to be shaved by about 4mm and bored and honed, so they can wait for me to buy the winning lottery ticket.

The A's were slightly cleaned up to remove all bar 12mm of the intake bridges and the exhausts were cleaned up but the ports are more or less stock, so that should give me a baseline for the three different sets of pipes lined up to test. Then I can swap over the barrels and repeat the exhaust tests and then I'll work out what to do next. (make some custom pipes, change to 34 flats?).

We have the hypothesis, now we need to test it

[oldjapanesebikes]

We have the hypothesis, now we need to test it

Interesting - I may have to stick my head in the door next time I'm down that way to get a closer look at what you are up to !

[tz375]

Please do. But remember that if you find out what I'm up to I'll have to kill you (after you let me know what I'm up to. ).

Not much going on really, but I'd be happy to show you around. Of course, most of the stuff "going on" is in my head, so not a lot to see.

[water cooled]

Richard,

I need to get those chambers to you. I'll send them UPS this week but they dont have the exhaust nipples and have the hole for the EGT....I think Dave has a claim on them after you are done testing.

[tz375]

Thasnks Kevin, EGT holes are good if it's for a Westach triple EGT. I have one of those waiting to be put into action.

Nipples. Obviously I didn't stay abreast of exhaust technology.... Are they available from Jemco?

R

[tz375]

So I decide I have heard enough election coverage and needed a break from work so I snuck out to the shop to fit pistons and slide on the baseline cylinder block. First piston goes on easily but I manage to drop a circlip from #2 right into the crankcase. I saw it for a moment, but now it seems to be between the crank wheels and the crankcase, so it's out of sight with no way to get to it.

If all else fails, I have to completely strip the motor, so I'll leave it until I feel calm and them I'm sure it will offer itself up like a good little vegemite. Maybe I should have stayed in bed this morning.. Grrrr.

[Suzukidave]

So Richard were you able to get the C clip out ?

[tz375]

No yet. I'll try again later on when I have more time and patience.

[water cooled]

Richard,

I did exactly the same thing and dropped one into the center cylinder. Here's an easy solution....hit the back side with compressed air...but be ready to catch it on the way out.

Kevin

[water cooled]

By the way, I try to keep a breast of all component terms and references but even more important I pride myself on my ability to recognize and fully understand just how rare three nipples can be.

[two-stroke-brit]

No yet. I'll try again later on when I have more time and patience.

try a thin magnetic stick from autozone or the like.
good luck.
mark

[tz375]

Tried compressed air and it just hid and tried the magnet on a stick but no sign of the little beast, so I started to pull side covers and the alternator off, so the motor would be lighter to remove. Just as I got to tthe last outer cover off, I had a last peek inside and there was one tiny part of the circlip showing, so in went the magnet to catch it and I rotated that around as I turned the crank backward, out it came. Nice and easy.

On went pistons and rings and didn't drop the clip this time and slid the barrels down over the pistons and it all went really well. The barrels are catching on the dowel part of the front outer studs, but that will pass. No carbs on yet, but just for giggles I slipped on a stock head and head gasket and used just a few of the 8mm studs and a set of old plugs and boy does this thing have a lot of compression. Not sure what it will be like when I get the head back from the machine shop where they are taking 30 thou off the head to go with the 30 thou off the barrels ( some top some bottom) .

I may have to get a longer kickstarter in lieu of the shorty RM450 aluminum kicker I fitted. Only time will tell. Now to get all those bits I removed back on the motor.

Of course, this is just the more or less stock but re-bored and cleaned up, baseline set of barrels. After I get it running and test a few things I have to swap barrels to fit the "good" ported barrels. You just know how much I'm looking forward to that.

Thanks all for the suggestions.

[two-stroke-brit]

sounds like a ton of put on and take it of again.
but you will get great comparrison results.
so are you keeping the total hieght of the two barrels the same presumably allowing for a spacer plate etc.?
do you have to have gaskets on top and base of said plate or do you go with a silicon type seal.?
and are you using the later model thinner head gasket?.
cheers mark