Transmission gear Interferance fit?

[Vintageman]

Hello,

I am thinking about changing my GT185 transmission gears to a closer ratio set from TM125/100 gears. I think gears will work. To my surprise one of the gears is pressed on. I guess it is, I am not sure but, asking if this makes sense that it is pressed on. I suppose it must be and on very tight (no three jaw puller will get it off?). It is 2nd drive gear.

It is Item 3 here->
http://www.buymotorcycleparts.com" onclick="window.open(this.href);return false; Search Suzuki, 1975, GT185, Transmission, then see figure

It is the small gear bottom left in this picture on ebay ->
http://www.ebay.com/itm/76-Suzuki-GT-18 ... eb&vxp=mtr" onclick="window.open(this.href);return false;

Here is one looks like off ->
http://www.ebay.com/itm/NOS-OEM-Suzuki- ... d0&vxp=mtr" onclick="window.open(this.href);return false;

Since it is a separate item no dogs, no key way or splines and affixed to shaft I suppose it must be pressed on? Can take the torque applied? Make sense? Here is my thinking. Let me know if I have clue here

I do have access at work to an old large hand mechanical rack and pinion press (maybe I need to buy a decent little home hydraulic shop one). Not sure how much force is needed. Shaft is only ~14mm. It looks like I need to rest on 5th gear (item 6) while I push down on shaft. Item 6 is 5th gear and it spins free and is only 0.013" (use this # when I press back on) from item 3 that is pressed on. Since item 6 is wider in diameter I must use it to press off item 3. I wont have too much to rest on (everything below item 6 not as wide but close), but, expect that gear 5th gear is strong

Any advice before I attempt this? For example I will need to find a short round stock less than 14 mm. I suppose even aluminum should be OK. Need just long enough to pass depth of item 3 to get fully off shaft. Putting it back on should I cool shaft and heat gear on nor worries. Press it on an put the 0.013" gage as a stop with item 6.

Just surprise this one item in the hole assemble is pressed on. Other than item 2 which is the shaft and first gear is made with that shaft as one item. Every thing else comes a part nicely after this one item it appears.

Thanks

[yeadon_m]

I am not at all sure whether this applies to your specific application but I recall reading among the many Suzuki T and GT bulletins that indeed one of the cogs is pressed onto the shaft and Suzuki set a fixed number of times the gear could be pressed off and on before the shaft itself was to be replaced. Also states thread lock stuff needed. Struck me also as an odd choice of method of fixing, but I'm not an engineer.
Cheers,
Mike
ps: for the GT550 for example, see bottom of p32
http://oldjapanesebikes.com/mraxl_GT_Re ... 50-28.html" onclick="window.open(this.href);return false;

[Vintageman]

yeadon_m,

Perfect!

I almost could not believe my own eyes.

Maybe loctite Red is the same stuff stated in Bulliten? I'll see

Three removals max it says. I may buy a new gear at least.

Seams like cooling shaft and heating gear some may be a good idea too when reassembling.

Thanks

[Vintageman]

I bought the stuff Suzuki calls out for reapplying gear. Still available and at my door for under $10.

I pressed the gear back on shaft all was tight and surfaces were in good shape when removed.

The TM100/TM125 gears have steeper angle dogs and sliding gears have a chamfer versus straight across like GT185 spur gears. I suppose this was done to assure your don't miss a gear racing the TM in a quick hard shift. All else the smae. The TM gears are on the GT185 shafts. I am confident it will work in the GT185 (still need to insert into my bike... stored in my shed awaiting snow to melt to get to it).

Could not change first gear set since the drive gear is integral with shaft, but did change 2-5.

The old ratio was
1st 2.75
2nd 1.8125
3rd 1.25
4th 1
5th 0.8

New will be
1st 2.75
2nd 1.588
3rd 1.25
4th 1.045
5th 0.913

I plan to run a 15 tooth front versus 14 and maybe a tooth smaller on back too. !st will be a little tall, but just give a little run and hop on.

With the Jemco pipes on the bike it made the engine very peaky and powerful top end hit. These are race pipes and sure can see how a pipe can change things on a 2 stroke. However, if you did not over rev before you shifted it dropped out of power band. Ratio too wide.

I plan to install this gear set (work or fail I will update this post) and maybe widen and lift the exhaust port some as we have been talking with the RD400 barrel post.

[tz375]

I didn't know that JEMCo made a GT185 pipe. Is it a race pipe and if so do we know what it was copied from?

Their T20 pipe is an old school race pie and is not good for the street. Normally I wouldn't suggest more exhaust duration if the engine is already peaky, but it might bring it closer to what the pipe was designed for and that may stretch the top end. If compression is low it might be a good time to raise it.

[Vintageman]

Tz375.
From a post of mine couple years ago, you did say raise compression and I did and only went 0.020" Stock is 7.0:1 and might be what 7.2:1 now?

I used a copper head gasket at 0.020" versus stock one at 0.040: I could take another 0.020" off head without need to change shape. Check squish clearance

The pipe hits real hard at 7000 RPM. Just like a switch. My bike seams to stop revving at ~ 9500 rpm pulling. Maybe at that rate I can't get out the exhaust gas fast enough? That exhaust port is the low power squared up shape style.

Since 2.0mm oversize wider on exhaust maybe only? In between 5500 and 7000 it runs like poop. Better with air box on here. Funny runs very well 5000 rpm and under. So if you shift and fall into that range uck! Since I street ride it was annoying and since removed pipe and was going to sell bike. Then had this brain fart idea.

The pipe is a kit. You have to put it together. I think two were done Iwe know of

http://www.youtube.com/watch?v=NJSIxujKfzk" onclick="window.open(this.href);return false; (mine before I raised compression and bored carbs and first part of jugs intake 10%)

http://www.youtube.com/watch?v=Evx1_iy9yVo" onclick="window.open(this.href);return false; (pop in a wheelie!. this made me go get mine

I have close up pics of it, Jon Easton wanted me to take for him when customers ask how . I will attached when I get home and find them again.

I coined it "race pipe" given how it looks (short, fat belly, steep cone angle in back and how it behaves. I think Jon Easton did say it was intended for racing but, never told me what it was tuned for specifically.


Mike

[tz375]

Connect a compression tester please and tell us what cranking compression is now.

I'm not a big fan of the 2mm approach unless I worked out that 2mm is the right number. It could be too little or too much.

A square top exhaust makes more power and noise that one with a curved roof and the same port timing. A flat roof creates a stronger pressure wave which helps power at one specific RPM and hurts everywhere else.

The lack of bottom end and steep step in the powerband suggests that it is a race pipe and may be out of step with port timing and area.

[Vintageman]

Unfortunately that bike is packed away tightly and can’t get to it unless I pull a few bikes out of its path. Too much snow in the way to do that.

What I mean by square is the vertical side. You know like the pick in Bell's book that reference as low power shape. I know (read at least) a straight top little chamfer gives a nice sharp pressure wave which pipes like when piston passes it.

I got a set of extra of low mile GT185 gears when I did the swap over with TM100 set. Wanted to make sure it would work ahead of splitting case.

Close ratio transmission will help keep me in power that power band. It wants to run 6500 and up effortlessly if I can keep it there.
I once put an old YZ100 top end on a DT100 Yam and same exact problem. Soon as you shift feel right out of power band

I’ll get compression. And, when I pull the bike apart I will measure all ports and note deck height etc. I will also use a degree wheel so not a hypocrite about always asking for data like that.

Again 5000 RPM and under bike runs just like it has stock pipes. 7000 to 9500 pipe kicking butt. In-between is horrible. I think hear the reflection is coming back while transfers are open. The longer intake length air box is just creating a little flow inertia to fight back. Better, but still suck there. More length I will probably loose top end?

I was hoping for a little more RPM. If road racing pipe, I am thinking another 5000-7500 rpm may have been expected. Limit to my ignition maybe but my other bikes points have no problem 10000-10500 RPM. It feels to me like I can’t shed old gas in time. We’ll see what port timing is soon.

http://i266.photobucket.com/albums/ii25 ... /003-4.jpg" onclick="window.open(this.href);return false;
http://i266.photobucket.com/albums/ii25 ... /004-5.jpg" onclick="window.open(this.href);return false;

http://i266.photobucket.com/albums/ii25 ... us/009.jpg" onclick="window.open(this.href);return false; (sold these unfortunately)

[tz375]

Interesting looking fat pipes.

When it gets warmer, we'll have top measure those pipes and the ports and few other things and work out what's going on.

The pipes actually look almost like the fat pipe on an RS125 Honda that peaked at around 12,000 or so. Something may be a little out of synch but sometimes that works too.

[Suzukidave]

Those are nice looking pipes

[Vintageman]

just an update The TM100/TM125 gears worked out real well with these pipes. you can exchange 2-5 from gt185 to these from the TM. 1st gear is integral to gt185 shaft so can't change. makes a wider step between 1 and 2nd (TM). kind a feels like my 73 gt550 does which I think sucks too

but what counts is when your are going. Second, Third, Fourth and Fifth for example are all closer together and don't need to over rev to keep bike on the pipe. much more enjoyable to ride

Oh I bet it will still do 80 mph.

Its a little crap, but man it sounds fierce, those pipe when they kick in full starting at 7500 can't stop it. 5th gear 7500 rpm is ~+70mph as geared. run a smaller 38 tooth rear versus the 41 to get a 5% lower overall then stock which make sense power higher and >1000 more useable rpm than stock.

thanks