TCE Tommy Crawford 3 in 1 GT 750 comments please!

[ja-moo]

I prefer Bell's book. They both have all the basic information on how a 2 stroke works. For porting or pipe design, you really need to get computer generated specs from a good program.

[dyrberg123]

I prefer Bell's book. They both have all the basic information on how a 2 stroke works. For porting or pipe design, you really need to get computer generated specs from a good program.

What program are to prefer?

[D&D CHASSIS]

NOT two stroke wizard......
TSR is good stuff....

[tz375]

I agree with D&D. Wizard is no good for pipe design.

TSR ( Tom Turner) is good if you can get it

Bimotion from Billy Avarsson in Sweden is excellent

MOTA from IWT in Australia is an excellent simulation tool

EngMod2T from South Africa is also excellent

I use Bimotion and MOTA.

Jennings book was very good but it was written a long time ago and much has been learned since then. There;s a small book by John Robinson that's good and Bell is excellent and gives examples of the range to aim for.

[dyrberg123]

Thanks for your comments, i truly am gratefull. Is there anybody no we are on it that could tell me a bit about where to get porting tools, and what to buy and what not to buy? I see a guy he's a aussie from Down under selling set´s on fleebay - do not know if those are any good?

[tz375]

http://www.ccspecialtytool.com/" onclick="window.open(this.href);return false; is the place to go for porting tools.

If you are just doing one or two engines, it's cheaper to send the barrels and heads to Pete O'Dell in the UK or EBOS in Sweden. Both have excellent reputations. I'd suggest talking to them about your project and costs to do what you want.

There are a few great 2 stroke tuning guys in Australia and in the US there's Scott Clough, Tom Turner (retired) and then there are guys like Eric or myself and a few others who port a few barrels.

If you are just looking for a slight improvement and not a full race motor you can probably just add a spacer, widen the exhaust with a file or dremmel and be done with it. DG pipes are not perfect but they are a great street pipe and really cheap. The trick on the early "350" was to use a 6mm barrel spacer and machine the same amount off the top. I had a chance to take a short ride on one like that with stock pipes years ago and it was pretty fast and still easy to ride. If you want to do it yourself, you should start with a port map of your cylinder and work out what port shapes and size you need and work from there.

[dyrberg123]

http://www.ccspecialtytool.com/" onclick="window.open(this.href);return false; is the place to go for porting tools.

If you are just doing one or two engines, it's cheaper to send the barrels and heads to Pete O'Dell in the UK or EBOS in Sweden. Both have excellent reputations. I'd suggest talking to them about your project and costs to do what you want.

There are a few great 2 stroke tuning guys in Australia and in the US there's Scott Clough, Tom Turner (retired) and then there are guys like Eric or myself and a few others who port a few barrels.

If you are just looking for a slight improvement and not a full race motor you can probably just add a spacer, widen the exhaust with a file or dremmel and be done with it. DG pipes are not perfect but they are a great street pipe and really cheap. The trick on the early "350" was to use a 6mm barrel spacer and machine the same amount off the top. I had a chance to take a short ride on one like that with stock pipes years ago and it was pretty fast and still easy to ride. If you want to do it yourself, you should start with a port map of your cylinder and work out what port shapes and size you need and work from there.

Hi, thanks. Actually the port job tools i aske about is for a T350, so maybe i should remove it from this thread, but what the heck The early 350 you speay about was that a T350? You think i should try 6mm plate underneath, skimme the same amount of the top and maybe lower the intake the same? Daniel

[tz375]

Daniel, don't worry about the threadjack. It happens all the time.

What 350 was it? Not sure I want to say it was 315cc so what model does that make it? It was raced as a stock bikes and looked stock but was very fast and easy to ride (on the street). It was blue with straight fins so let's guess it was a 69 T350. Now I think about it I wonder if it had 64mm pistons in it and if so which ones? Would R5 or TZ350 pistons fit with a slight overbore I wonder

I do not suggest making any changes until you have measured the ports and decided what timing you want. Spend time planning the change and then do it. I was playing with a GT550 the other day and just for fun I decided to see what a 2mm spacer would do (no other changes) and then 3mm and so on and I stopped at 6mm and it was interesting to see the results. If I was serious bout a spacer that thick I would go back and model the changes more accurately.

MOTA allows you to change the port open timing (and area) in the software without changing duct dimensions, but if you raise a port roof on a cylinder, the area does change. I didn't bother correcting that - I was after a quick indication of how far I could push before the results became counter productive. You need to work the data first. Bell's book will give you a quick idea of how soft a stock motor is and how much it could/should be changed.

[dyrberg123]

Thanks. I will have a look at it soon. I just bought a top end on ebay, just run in (according to seller ) on 5th over bore, wiseco pistons and squish modded Kawa h1 heads rinning o,45" in clerence and app 45% of the bore. Volume is 18,5cc - 2,5 cc less than stock. Does that sound okay? My intentions is to fit it, i run chambers and PWK 28 flatslides, and see how its behaving. Then do some mapping and go through the Graham bell book formulas and see where it takes me.