GT185 fuel/air questions

[markc522]

First off, my name is Mark. I am new to the GT's but happy to have one. I hate my 1st post is a question, but I'm at the last straw. Sorry, but here goes.

Trying to get an old 185 back on the road. Its a '74 with 1400 original miles. Its by no means a show bike, but it is pretty clean.
I am stuck and need help. What is choke on/off?? On = Up? On = Down?

(When I say 'choke up,' I mean choke lever in the upward position, and visa versa)

Symptoms:
-Bike runs and starts choke up or choke down, but on one cylinder.
-Choke up = right cyl firing fine, left is dead
-Choke down = left cyl firing, right dead
-Minor adjustments to throttle stop (with choke down) has yielded both cyls run (not sync'd but at least both firing) then the bike slowly fades off and dies.
-I can flip the choke while its running and get it to switch firing cyl.
-side note: I have been tinkering a little here and there, and one time, one time, it ran fantastic. It was peppy, it was sharp, and apparently it was an accident, because nothing was right. Carbs were off, tank was dirty, no fuel filter, choke lever in down position, cold night, late, dark, and angry neighbors. BUT it made one super lap around the neighborhood, and I loved it.

Things I have done:
-Check fuel, installed a clean clear in-line fuel filter and new hoses. Clear filter lets me visually see fuel flowing.
-Petcock is in rough shape. I took it apart, cleaned it and made it have steady fuel flow on reserve position (I know this is wrong, but its a solid flow, and that's what I am working with. Flow is weak in the on position)
-Exhaust baffles removed, 2 stroke wrap material added, and baffles reinstalled
-degreased gunk from tank, looks like its been coated, but its not real good. the filter helps me monitor and see fuel is as clean as can be with this setup.
-I have taken off the carbs, cleaned an re assembled. twice. new float bowl gaskets. Floats adjusted. Carbs dipped, anything rubber went into a rubber friendly dip.
-New exhaust header gaskets, old ones were leaking and allowing large amounts of 2 stroke oil to run down the pipe and eventually drip off about the foot pegs, messy.
-Bike run with tank cap on and off and in the 'loose' position. no difference noted in any option
-Terrible ground in the wiring loom. Replaced the ground, visually checked wires that next to the melted ground.
-New air filters (I only thought there was one, apparently there are two?? One on each side of the box?)
-new plugs, twice.
-pilot screws set at 1 turn out. Not messed with after that. I need it to start and run before fine tuning.
-throttle stop screws, This is where I am all over the board trying to get it right.
-set throttle cables at each carb to be close to 1 mm play
-adjusted oil pump cable after adjusting throttle stop cables


Again, I am sorry its typical newb 1st post.

[markc522]

Got it. Choke lever in the up position is off. Tore the carbs apart again and soaked them. Noticed pilot jet on the trouble maker cyl was cruddy. An all night soak, and back in this morning. The bike is alive and running! Fires right up, no choke. Dialed in carbs per the Haynes manual and she seems to be running great. She's a little weak, top speed I got to today was 65 per the spedo. I weigh 225 lbs.
I have to keep the revs upward of 5500 to maintain anything over 50 mph, and I find that top gear is somewhat useless unless cruising down hill. From a stand still, getting going is a little tough. Maybe it's a clutch issue. Shifting is tad weak. Seems like there is a little slip.

[titan performance]

Great fun little stroker.......you will enjoy it once you have ironed out the gremlins. I cut my biking teeth on this stuff in the seventies and had the best fun of my biking life on similar little bikes.

[markc522]

Here she is. I have done loads of polishing on the chrome bits trying to remove 40 yrs of gunk. The chrome is scratched and scuffed, not perfect, but at least Im getting the stains and small rust spots off.

This is exactly how it sits right now. I need new blinker lenses and the pegs have been bent up into the pipes and thats about it. I think Im going to leave it original. I was considering touch up paint here and there, but now, I will give it some elbow grease and polish, and where it ends up is where it will stay.

Not sure if my carbs fell out of sync, (things couldnt be better yesterday), but today, the trouble cylinder (right) started running a little weak. I will adjust the carbs again and see if the screws are just vibrating themselves out or something.

[Flywheel]

Nice bike! Check the petcock again for debris. Mine was so loaded with rust that it impacted the flow, the first circuit to be starved of fuel is the right side. BTW unless someone replaced the gas tank, side panels, and pipes, your GT185 looks to be a 1975.

[Vintageman]

My 75 gt185 was weak (sounds like yours) until fresh bore. I weigh 215# birthday suit. In a slight tuck (limited by my oversized gut) I had the little bugger 80mph so probably 75 mph true. Tach about 8000 rpm. There was no tail wind nor was it down hill. Fairly flat nice road nice calm day. Even though yours has 1400 miles wonder if some rust on walls for example?

But, the bike is little and if there is ~ 4% grade to climb you can do it lugging in 5th +50 mph or drop to 4th and thrash to +60 mph. Bike likes to run at 50mph OK all day long. best I drive is 40 MPG

You bike looks nice... it should run a little better I think... check timing and use 1975 specs.

Since that amazing run I have added chambers, 2mm OS bore, over bored carbs ~10%, open intake passage to match, 1/2mm thinner gasket and now gears 2-5 from a TM100/TM125 with closer ratio to match peaky chamber behavior mated 38 rear tooth vs 42 for about 5% more rev top gear, 1/2 mm off Ex port, 1mm wider, and 1.25mm off skirt. The latter mods (TM100/TM125 and on) are waiting to be tried soon as I get spare my pistons from UK any week( ) now I hope. I'll be delighted if it still does 80 MPH. First, I hope it still shifts

[jeremyevison]

Hi Mark currently in the process of a GT185 build myself, il post some pics soon! Just going over the loom and wondering about the ground wiring you mentioned you replaced? It may be a bit of a simple question but where do you have the ground attached - to the engine or the frame? Cheers

[Coyote]

Sweet little bike. I'm envious. I'd like to know how it melted the ground without blowing the fuse? It take a lot of heat to melt wire jackets. That heat always come from a direct short. That's the purpose of the fuse -- to prevent that from happening.

[GT750Battleship]

Hi,lovely looking bike,you may want to pull the pipes off & give them a good internal clean ! a big problem for two strokes.....don't ask me how I know...I've just spent a month on a GT750 with problems...I couldn't find...I'll find out for sure this morning after refitting the pipes !!
Cheers,
Roger