Suzuki 2 Strokes

Hi I recently got into motorcycles after a ten year hiatus and got a hold of quite a few bikes for cheap.

Anyway, I've been reading through the different threads and I came across the possibility of retrofitting a T350 top end on a GT250 lower end. I have never worked on two stroke engines so I may ask some Barney level questions here.

My questions are: -What parts do I need to source?
-Cant I just bore out the GT250 cylinders to 62mm?
-Is there any difference on the exhaust ports from the GT250 to the T350?
-Would I need to get T350 carburetors or are they the same as the GT250A intake ports?

Any help and advice is greatly appreciated.

I successfully did the same many years ago. Back in the mid 80s

I'm unsure if you can bore out the 250 barrels as I used 350 barrels instead.

The carbs for the 350 are larger as well as the exhaust system. So you will need to source different carbs and exhaust pipes. Apart from that it all fits perfectly.

It seems reasonable enough. I was going to in34mm mukini carbs since I am planing on doing some porting and chambers.

All that is holding me up really is I can't find a left cylinder. So I'm holing off on buying the parts until I can find one.

What are some part suppliers for these bikes?

I've found a few overseas, but I was hopping someone my be able to point out some I may have not come across yet.

LaVolpe wrote:My questions are: -What parts do I need to source?
-Cant I just bore out the GT250 cylinders to 62mm?
-Is there any difference on the exhaust ports from the GT250 to the T350?
-Would I need to get T350 carburetors or are they the same as the GT250A intake ports?

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just bore out the GT250 cylinders to 62mm NO
Is there any difference on the exhaust ports from the GT250 to the T350? -> Wider port. Tad less height and outlet is a larger thread... GT250 exhaust will not work
Would I need to get T350 carburetors or are they the same as the GT250A . The T3xx cylinders are designed to accepts T350 carb stud spacing. We are talking 32 mm versus 26mm/28mm. I have been using either T350 carbs or T305 and jet to latter t350 specs (little less on main). You might be able to use something else for carbs... 28mm flat side, 28mm rounds or fit 32mm aftermarket maybe use same jetting as OEM???. But the Jet Needle is obsolete (Latter version is). You good work out new carbs but will take time to jet it in.

You need the T350 heads and gaskets
You need T350/T305 Oil pump requires more flow for same rpm
If you run T350 carbs need heat isolation spacer (obsolete).
The T350 Clutch spring are stiffer than 250 (clutch will slip without them once into power or atl east when running chambers )
T350 vibrate more and you should puts vibration bushing to rubber mount your handle Bars like T350 did to avoid hand buzz from longer rides. It really works! Just get upper triple tree from T350/T350(?) for parts and fabrication the bushing into the GT250 triple tree.
You need T305/350 Y boot gt250 carb mouth too small (you can make it work by cutting out the two little inner rubber short tubes carefully.
You should use either T305 (least restrictive of all, well more noise at least than T350 airbox). The GT250 Air box inlets most likely too restrictive versus T350
T305 cycls are just as good as T350 if not better
You can put RD400 D&G chambers on them... Higgspeed has a set for T350

I have done this conversion a few times and have two of my bikes this way now plus one 1971 T350. of all my bikes I tend to ride these the most. Light, handle well and with T305/T350 engine enough power to cruise interstate 65-70 mph even in the hill off VT

These parts are getting very hard to find (Cylinders, carbs and pump)

He was down in the $6xx range once ->
http://www.ebay.com/itm/Suzuki-T305-T-3 ... f9&vxp=mtr" onclick="window.open(this.href);return false;

From what You are saying, it seems more practical for me to just buy a T350 or T305.

Thanks for all the advice.

I am just going to make a GT250 based engine.

I'll most likely do a ported GT250 cylinders and RG250 pistons. Seems like the best bang for the buck.

I think you are making a good call. If you enjoy the hassle, fine, but if you like to fix (or restore) and ride, then as you say.
Occasionally, posters will ask 'how can I make my GT380 faster?', to which the stock answer is 'get a GT550'
You definitely can improve each of these bikes but it can be hard work and its as easy to spoil as improve all-round performance. For me, how they feel is every bit as important as the number on the speedo. My GT380 is great fun and all I've done is to fit GT550 carbs to it. I don't know if the performance is really higher, but it runs so joyously like this.
Whatever you do decide, enjoy!
Mike

I would say the GT550 carbs on GT380 does boost power, based on now it will slip my clutch as I go past though +6000 rpm at WOT. Never did that before. Of course I don't have a dyno chart

Back to 250

For me decent shape GT250s were easier to find than the older T350. But stuff is out there you just have to look and be patient.

If you want a fast Top end mainly (you can't have it all with these old bike) 250cc machine GT250 get the 76 and up GT250A/B... suz had done all the work for you. That bike is very quick and top end pulls hard. But those cylinders don't fit the earlier T250/GT250 KLM. I see a lot more GT250 A/B doner bikes than I do T305/T350

What is special about RG250 pistons?

What might help a little is if you find a piston where the cut out is wider and matches transfer case inlet.... Not sure how much you want to change inlet timing. The EX port you could raise a little but too much all you have is top end and in my opinion if you use it short crank life. You could EX widen it a little.

I think the best is to leave stock (or clean up and keep port changes to 1mm or less). And, 1/4- 1/2 mm off head... or just leave as is (or just get spare parts and play/try as much as you want)

There is one thing if I recall some later 26mm GT250 carb slides are too long and fall short of WOT. I forget but there are slides (T250?) that are shorter and allow WOT.

The T350 air box as stated is less restrictive than GT250 and still less noise by far than PODs and easy to jet in(don't think I had to do anything). But many people think PODs are cool .

Then or just add chambers if you want some upper mid to top end power. Designed chambers alone can do what raising EX port does without killing bottom and mid power. Not much choices for chambers available commercially. The D&Gs for RD400 work well for me on T350/T305 and a broad tuned pipe on RD400. My R5 has same EX timing as GT250 KLM (32mm- 54 mm stroke) and the D&G RD350 gave it more top end without me needing to make EX port height 29.5mm as Rd350 and dare I say the R5 piston ported has stronger upper bottom/mid range end/ maybe top too than stock reed valve Rd350

What I am saying is the D&G RD350 may be good tune for GT250 KLM.


Fun Stuff

^ Not suprised to hear your DG pipe success on the Suzukis. I run a DG RD350 pipe on my Blaster bike. My brother and I half joked about putting a set on my Titan. They are cheapish and readily available.

Alright there a lot of good information here, but I am really new to the two stroke world so You guys are really pushing me to do some good research.

So I have two more questions.

-Would chambers for the RZ350 work on a GT250? (With some modding of course)

https://www.denniskirk.com/dg/street-ex ... 442183.sku" onclick="window.open(this.href);return false;

If these don't work I'll just go with Higgspeed

-Also Do parts from the T250 work on the GT250? It was rated at 33hp. While the GT250 is supposed to have 30hp.

Hi.. You could also try this link

viewtopic.php?f=5&t=10385&hilit=royal+kick+in+the+ass" onclick="window.open(this.href);return false;

That one i did a few years back with help and sparring from members inhere, still have it and it still amazes

Well I'm back, So I went the practical route and decided to start with a T350R. I feel like I got a decent deal on it.

http://r.ebay.com/bOqtMg" onclick="window.open(this.href);return false;

So the project takes a new direction, with this being the the Main focus and the GT250k donating any missing pieces

The plan is to make it road worthy and see what happened from there.

Looks like a good deal unless you have to pay a lot for shipping.

Would be wise to ask him to reassemble the carb, except for the broken float.
And put the carb back on the bike + tape up the carb openings.
This way you won’t loose any of those parts & will protect the motor internals from the elements.

Actually I'll be picking it up in person, it's cheaper and give me a chance to visit some friends and relatives.

So total cost with fuel will be about $550

In a worst state than that, it would be well over £1000 in the UK.

True and thank You for the vote of confidence. However You Englishmen love Suzuki Two Stroke bike in general.

A lot of parts I end up having to get from retailers from the UK for that reason.