TS185 Stalls only in fifth gear, 4K RPM

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Phoenix
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Suzuki 2-Strokes: TS185

TS185 Stalls only in fifth gear, 4K RPM

Post by Phoenix »

Have a 1975 TS185. Rebuild engine, new rings, crank bearings and crank seals. Carb has been rebuilt. Plenty of gas and spark. Bike starts and runs great thru all gears (RPM up to 6K) except for fifth gear at 4K RPM +. The bike dies.
When the bike dies in fifth gear at 4K RPM +, I pull in the clutch and the bike remains dead until I slow down and restart (rolling start) at a lower RPM. Again, only a fifth gear issue. If I keep the bike under 4K RPM in fifth gear, rides great all day long. What is the issue??
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by sportston »

We might need a bit more info.
My first thought would be that perhaps you have an incorrect carb float height. I would check that first.
I would say it is most likely a carburation problem.
Can you show us the colour of the plug after a few miles ride?
What does the air filter look like? Is it a standard air filter or aftermarket cone type? Is it clean? If it has a foam element has it been soaked in oil?
Has your engine been ported? It may be you have the wrong size jets, if so.
Has the needle got the c-clip in the correct groove?
karl pa
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by karl pa »

sportston wrote:My first thought would be that perhaps you have an incorrect carb float height. I would check that first.
I would say it is most likely a carburation problem.
I agree, you should also check that you have good gas flow from tank and the tank cap vent is open.
I once had a fuel line break down inside and had a piece of rubber restrict the flow to the float bowl.
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GTandcbr
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by GTandcbr »

I'm not sure does the ts185 have a diaphragm gas tap? If it does then a sticking tap is my guess ? I once had a very similar problem which was solved by cleaning out the gas tap.
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ConnerVT
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by ConnerVT »

GTandcbr wrote:I'm not sure does the ts185 have a diaphragm gas tap? If it does then a sticking tap is my guess ? I once had a very similar problem which was solved by cleaning out the gas tap.
I was thinking about this as a possibility.

Quick check - switch the petcock to Prime, and see if it resolves the issue. This will eliminate a weak vacuum diaphragm opening as an issue.

It is certainly OK to run the motor in Prime. Carbs won't overflow if the carb floats are operating correctly.
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by karl pa »

ConnerVT wrote:
GTandcbr wrote:I'm not sure does the ts185 have a diaphragm gas tap? If it does then a sticking tap is my guess ? I once had a very similar problem which was solved by cleaning out the gas tap.
I was thinking about this as a possibility.

Quick check - switch the petcock to Prime, and see if it resolves the issue. This will eliminate a weak vacuum diaphragm opening as an issue.

It is certainly OK to run the motor in Prime. Carbs won't overflow if the carb floats are operating correctly.
I don't believe the TS 185 came with a vacuum petcock, according to parts book it has the same manual petcock as the GT185, not saying one couldn't be fitted.
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GTandcbr
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by GTandcbr »

I suggest the next time this occurs do not restart the bike. Pull the spark plug and see if it is wet. If the bike is overfuelling it may kill the spark. Open the drain plug on the float bowl is there fuel in there?
98 carb Blackbird and GT550j
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by sportston »

karl pa wrote: you should also check that you have good gas flow from tank and the tank cap vent is open.
I once had a fuel line break down inside and had a piece of rubber restrict the flow to the float bowl.
+1 on that. Definitely should check fuel flow.
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Suzuki 2-Strokes: TS185

Re: TS185 Stalls only in fifth gear, 4K RPM

Post by Phoenix »

Dear All:
Thank you for the idea's.
The plug currently is slightly dark in color (black), but electrode area more brown color. May be running a little rich. No diaphragm in carburetor (Mukuni V series). Air filter is original design with a new filter element. Carburetor rebuild parts from a Keystone carburetor kit and believe all proper size for jets. Needle has the C clip at center notch. Don't know if engine has been ported.

One more potential factor....I recently reinstalled the exhaust pipe to seal a leak (oil residue) at the head using a standard exhaust gasket and high temp gasket sealer (silicone). Not sure if the stall problem was present prior to exhaust fix. I also cleaned the inner exhaust pipe / baffle with hot water and detergent.

The Next plan of action:
1. Will check venting at gas cap, but I don't see restriction in gas flow.
2. Remove filter element, clean with gasoline and re-oil.
2. I'm going to get the bike to stall in fifth gear, roll to a stop, and then check the plug to see if I have excess gas or oil. This is a good idea.
3. Remove the carburetor and check the float height. I set the height last time the carburetor was apart, but my Clymer repair book had various dimensions listed and I may have set incorrectly.

Also have a 1975 GT185....it's a great bike. Does the bike normally exhaust more blue smoke from left side during start up?

Stay tuned for the TS185 fix.
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by GTandcbr »

I take it you replaced carb jets with 'keyster' kit :( could be the source of the problem. They don't have a good reputation . I would always recommend genuine Mikuni to make sure it's right.
http://www.3cyl.com/specs/suzi2float.jpg" onclick="window.open(this.href);return false;
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by karl pa »

GTandcbr wrote:I take it you replaced carb jets with 'keyster' kit could be the source of the problem. They don't have a good reputation . I would always recommend genuine Mikuni to make sure it's right.
Never tried keyster, but many say not to use them.
Phoenix wrote:Also have a 1975 GT185....it's a great bike. Does the bike normally exhaust more blue smoke from left side during start up?
I would think you have a weeping check valve on left side oil lines, some of mine smoke pretty good till cleaned out.
Other thing is the GT185 uses left carb choke circuit to feed the right carb, my right cylinder takes a little to fire when cold.
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by sportston »

Keyster kits sometimes have the wrong size jets in as they don't always take into account the variances of different models very well. However if they have the correct numbers stamped on the jets then they should fit in my experience (Though some may disagree with me).
I would research what the correct size jets are and compare if the Keyster kit contains the correct sizes. Having said all that, I still think you should recheck the fuel flow and float level. Judging by the colour of your plugs it sounds like you might be running a tiny bit rich. This could be caused by incorrect jetting or by poorly adjusted float level.
I'm not overly familiar with your particular model, so I don't know the settings for your carb. You mention that your jet needle is set to the middle setting, this is a good starting place, but is not always the correct setting for every bike. It might be worth experimenting with needle height. Perhaps try dropping the needle one notch and see what happens, if fuel is flowing well and setting the float height hasn't fixed the problem.
I would not recommend using silicone sealant on the exhaust/head joint. If bits break off it could clog your baffles. You mentioned cleaning your exhausts with detergent and water. It won't do any harm, but it is not likely to remove thick carbon deposits. Try caustic soda for that.
It seems like you have a good plan of action, judging from your list. I would suggest checking your Clymer manual carefully for carb settings. It may be that Suzuki fitted more than one of type of carbs during the life of your model, so try to make sure you get the correct settings for your model of carb.
Good luck my friend. Keep at it and you'll get there eventually. We'd love to see some pics of your bike if you get the chance.
Ciao
Tom
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Suzuki 2-Strokes: TS185

Re: TS185 Stalls only in fifth gear, 4K RPM

Post by Phoenix »

Thanks again for the ideas.
- Ran the bike for two days and plug burning more dark milky brown, so not too bad.
- Was able to stall the bike for the first time at 6K RPM in fourth gear. Can repeat the stall in fifth gear @ 4K RPM.
- When bike stalled, I coasted to a stop without restarting and removed the plug...no soaked plug ((excess gas)...plug looked good.
- Gas cap venting appears good, no obstructions.
- Going to remove the air cleaner and see if that makes a difference before moving into the carburetor for needle adjustment, float re-adjustment and inspection of the jets (keystone vs Mikuni).
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Re: TS185 Stalls only in fifth gear, 4K RPM

Post by sportston »

Looks like a lovely fun bike.
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Suzuki 2-Strokes: TS185

Re: TS185 Stalls only in fifth gear, 4K RPM

Post by Phoenix »

Dear All:
- Pulled air filter, cleaned and re-oiled.
- Pulled carburetor and disassembled. One issue found after disassembly was a damaged o-ring. The o-ring basically seats between the needle jet and main jet, in a pocket in the bottom of the fuel bowl). A damaged o-ring will allow the fuel in the bowl to pull directly into the needle jet along with fuel coming from the main jet. Damage to o-ring may have occurred during earlier assembly operations when installing the fuel bowl onto the main carb body. When reassembling the carb, seating the o-ring into the pocket of the fuel bowl is tricky.

I removed the aftermarket (Keyster) needle jet, jet needle and main jet and replaced with Mikuni parts. Carb is a VM24SH and used a 125 main jet, 25 pilot jet. Checked the float level and re-set. Carb back into the bike, adjust air screw, and test drove for an hour.

Bike runs much better, more responsive. Bike still dies briefly / hesitates in fifth gear, at a slightly higher RPM (4.5K to 5K RPM) and if I'm gunning the throttle. If I ease back on the throttle a little bit, bike responds and runs. Also, if I accelerate slower in fifth gear and creep upon the RPM's, bike appears to run fine. Pulled spark plug, milky brownish color. Put in a new plug. Next step is to try adjusting the clip setting on the jet needle..move clip up, less fuel. Clip down, more fuel.

It almost appears as though too much gas is overwhelming the carb when gunning the throttle in fifth gear @ high RPM's. Need to think about this for a few days...
Best Regards
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Last edited by Phoenix on Wed Dec 26, 2018 10:02 pm, edited 1 time in total.
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