Suzuki 2 Strokes

Hi guys.

I am really close on buying a GT 185 from Germany, but its restricted, so my question is where is it restricted so i can localise the parts needed to deristrict it prior reciving the bike...

I have searched the hole bloody internet, on english and german as well to see what was done to kill the power on these little crackers, but cant find anything.

so please help me out with info..

Thanks

Never heard of a 185 being restricted.
Start with setting it up properly - timing carbs etc.
Make sure the carbs open fully and there aren't any restrictions in the exhaust.
Some mopeds had a washer welded in the engine end of the exhaust as a restrictor.
Also check that the baffles aren't clogged up.

By restricted do you mean the power it has from the factory? That is how the factory tuned it stock?

For a 185 it is not that lame, tuned kind of enduro-ish . I had 1972 Yamaha CS5s which are 200CC piston ported engine as well with extra finger type transfer ports. I always thought it was faster than my 75 GT185, but in reality it was not. My son and I would drag and me being 40-50 pounds heavier, whichever one I road i was a little behind.

But with that said the 185 is ported mildly with tiny ports and carbs

My GT185 currently has Jemco race expansion chambers (came as kit). Those really changed the power characteristics... A Top end machine, some bottom, no mid range. I wish they were not so top end.

The stock 20mm carbs are bored to about 22mm (be careful how you do this for you can't turn down idle speed... shift the bore up towards slide some). The first part of the intake is opened to match larger carb bores. I run 2mm OS pistons, I run 0.020" copper head gasket versus the 0.040" (helped midrange). Stock timing (helps midrange). The exhaust port I did not raise but cleaning it up I might have inadvertently raised it by 1/2mm. The port was square shaped and I widened it oval shaped (that truly helped and a good mod by itself) The piston shirt is shaved ~ 1.5mm. I changed gears 2 - 5 to be that of a Suzuki TM100 close ratio. They were too far apart before and engine would fall out of power band in-between shifts unless you revved high before shifting. Not anymore!

You can drive this bike easy at 4000-5500 rpm with similar torque to stock, between 5500 and 6500 RPM it is doggy and not good if you have a bit of hill to manage, from 7500 RPM to 10500 RPM Damn! no hill stops it and it becomes crazy powerful for a 185

Its just a little 185 ... too small, but fun for short little excursions. It was a better for longer rides stock and I think just the wider exhaust port, 2mm OS bore and 22 mm carbs alone keep that stock feel but add power everywhere. depends what your goals are.

How is your T350 with RD heads and EX port at 29.5 mm height if I recall. I blew mine up end of last last seasons. too many over revs beyond 8000 RPM where it loved to be (my Ex was about + 30mm) Man it was fun for a few thousand miles.

The bike is almost back together now with new to me T350 jugs, rebuilt crank and I only raised EX port to 32mm (~1/2mm) and widened a little. Skirt shorted 1.5mm (this engine likes that IMO) and 0.020" off head and 1.0mm OS piston from T305 which has wider transfer windows than the T350 piston.

fun stuff

Hi guys,

Thanks for replying.

The bike is as many i Germany restricted from the factory to 11kw/15hp witch makes it A1 leagal, originally its supposed to have 20/21 i think.

From what i have heard and found out by now the piston skirts / windows are a bit different altering the inlet as its piston ported, and the top gasket is thicker changing the compression ratio from 8:1 to 6:1 but i have no documentation to back me up, would wish i had a parts book with a German appendix.

So please see if you can come up with any info on this to me...

About the t 350, it runs really really well, low end and mid range is not that bad, no boggin and the the devil put his hands on it when hitting 6500, its just so smooth like it was ment to be with these mods. I also think the pwk 28 helps the low end due to the 28mm keeping the velocity speed rather fair at low rpm compared to 30 - 32mm round ones. But as they are flat slides the also allow high flow.

Only noticeable thing is when i have raced it hard and comes to a redlight, going to idle i have to flip the throttle to "clean its throat ", think i have a pile of fuel in the crank house...

Cheers

The only analogy I have is the Yamaha RD350 in India: Rajdoot or something they called it. As you noted it had lower compression and milder port timing.

At one time USA GT185 parts ala eBay were abundant and cheep. I am thinking you need a new set of cylinders, pistons, and heads and simply compare things once you receive them. I suspect that is it. I think Highspeed makes chambers for the GT185 and they don't look racy more broad power. My T305/T350s with D&Gs don't have midrange issues like the gt185 with Jemco race pipes.

I think the OEM 32mm carbs works extremely well on T305/T350. Some how Suz did a good job with that carb fitted to that engine. I suspect 28mm works well too. I run stock air box but they are from a T305 not later T350. the earlier one has better breathing design but much louder but still looks stock.

Even stock heads the engine never pings and when I tore down the engine no signs of pre-detonation on pistons I run 87 octane . Nice piston wash about ports so jetted OK. So why I am trying 0.020" off stock head this time, maybe I have to run 91 or 93 octane... we'll see

However this is the third or forth crank (big end bearings always) I have blow up due to sustained high revs be it a modded 250,305 or 350. I tried to find a better BE bearing this time and came to the conclusion the diameter is too small for those types of forces at high RPM . Sure it is easy enough to put in cranks, but tired of thinking it going to blow and when it does most likely I am moving fast... unsafe. Trying for a little more power earlier in RPMs this time while still being reliable.

I think the key it to machine the case and put in a yam crank if you want to get high RPM power safely
http://www.t20suzuki.com/" onclick="window.open(this.href);return false;. I have a spare engine and may try this and reuse my 30mm EX port cylinders.

fun stuff

Hi!

dyrberg123 wrote:The bike is as many i Germany restricted from the factory to 11kw/15hp witch makes it A1 leagal, originally its supposed to have 20/21 i think. ...
From what i have heard and found out by now the piston skirts / windows are a bit different altering the inlet as its piston ported, and the top gasket is thicker changing the compression ratio from 8:1 to 6:1 but i have no documentation to back me up, would wish i had a parts book with a German appendix.

When this bike was sold in Germany, there wasn't "A1"-drivers license yet.
Motors were reduced in power due to insurance-classes.
Can't imagine Suzuki would have produced special cylinders and pistons for Germany, at the low sales of this motorcycle there. I think it is more likely that a German accessories supplier or the official importer has offered appropriate conversion kits. In official retrofit that would have to be written in the registration papers.
possible conversions, e.g.:
Other rubber intake flange with reduced aperture diameter
Reduced passage at the entrance of the exhaust manifold by a ring welded therein.
(so done also at the "german" GT380 with 27hp(PS))

Markus

Hi guys.

Vintage man, nice link to the t20 page, actually i was offered one the other day for cheap money, maybe i chould get it - damn i am an addict

Marcus, thanks for your answer, I guess you are right, it also have zu gross hubraum to get in the A1 cat

The guy selling the bike says different head gasket and other pistons, does that sound possible.?

Cheers guys

Hello!

dyrberg123 wrote:...The guy selling the bike says different head gasket and other pistons, does that sound possible.?...

A thicker head gasket to reduce compression and power sounds possible. "Other pistons" could mean anything: next oversize after piston seizure, aftermarket pistons etc. It is not clear, and less likely that the "other pistons" were built in from the beginning.
What is written in the registration documents about a power reduction? (For example, a specific exhaust or exhaust marking) Can you get a copy of the vehicle registration document (german "KFZ-Brief") in advance by the owner? That might be helpful.
Also possible that performance-reducing components were already removed, but the corresponding entry in the papers has not been changed. (to "economize" insurance premium)
I think, it will not be so much difficult to find and remove reducing-parts, if there are any.
grtnx
Markus

Hi Markus,

Thanks for your help, i changed the pistons and a std gasket set and wow what a change... Looks like the height from pin to crown where slightly different, so it could be right. Wether it is made like that from factory or not is hard to say, could be bad copy or wrong pistons as well.

But problem solved, so thwnks for the input.

Cheers u all