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PostPosted: Thu Nov 07, 2019 3:07 pm 
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Suzuki 2-Strokes: T500
Alan H wrote:
The rev counter doesn't work when the clutch is in too - or the oil pump - so don't sit in stalled traffic for ages with the clutch lever pulled in!


Thanks to both Karl and Alan for that info...had no idea...that's a goofy arrangement. I wonder if anybody has damaged their bikes because of that!?!?!


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PostPosted: Thu Nov 07, 2019 3:43 pm 
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Location: southeast pa
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Suzuki 2-Strokes: GT
When you try shifting, does the shift lever go through full travel or does it hit against, does it move easy or hard? you may need to pull clutch cover and make sure shift shaft arm is engaging on shift drum properly.

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76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe


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PostPosted: Thu Nov 07, 2019 5:35 pm 
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Suzuki 2-Strokes: T500
karl pa wrote:
When you try shifting, does the shift lever go through full travel or does it hit against, does it move easy or hard? you may need to pull clutch cover and make sure shift shaft arm is engaging on shift drum properly.


Hi Karl,
It moves, but not as fully as I would expect. It feels like it is binding at the end of the throw. It feels the same for both up and down shifting. We're pulling the cover, as you suggested, right now to check alignment and function.


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PostPosted: Sun Nov 10, 2019 8:03 am 
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Location: southeast pa
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Suzuki 2-Strokes: GT
Grey_Ghost wrote:
We're pulling the cover, as you suggested, right now to check alignment and function.

Did you find any issues in shift shaft or drum, shift pawl ? If not I am afraid it could be in transmission, shift forks or gears binding. Hopefully someone else may know of something else to check.

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76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe


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PostPosted: Mon Nov 11, 2019 8:53 am 
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Suzuki 2-Strokes: T500
karl pa wrote:
Grey_Ghost wrote:
We're pulling the cover, as you suggested, right now to check alignment and function.

Did you find any issues in shift shaft or drum, shift pawl ? If not I am afraid it could be in transmission, shift forks or gears binding. Hopefully someone else may know of something else to check.


Sorry, busy weekend...Just got a chance to sit down and reply...

When we pulled the clutch cover, we found the shifter shaft was offset by one tooth so the transmission was always in between gears and couldn't quite finish its shift. We tapped the shaft out half an inch, re-centered, and pushed back in and it works like a charm! I was very worried something had gotten missed during assembly and we would have had to pull the motor. That would have been terrible...

We got the carbs all tuned up (Thanks ConnerVT for your carb tuning tips!!) and the bike starts on the first kick and quickly settles into a nice idle. The Higgspeed pipes sound AMAZING!

We still have a few minor tweaks and fixes here and there, but we will work those out over the next couple weeks. My son took it for its first ride around the neighborhood on Saturday and came back with a huge grin on his face! :D The timing worked out well, too, because it was also his 18th birthday yesterday.

He will get it inspected this week with his license soon thereafter. The weather here is still pleasant so he hopes to get some miles on it before the snow arrives. I will get a few pictures of it posted out in the sun this week so you can get a decent overall of the finished project.

Again, thank you all for your support, wisdom, and encouragement! We hope you have enjoyed following the build as much as we have had doing it. We couldn't have done it without you!


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PostPosted: Wed Nov 27, 2019 10:30 am 
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Joined: Wed Jul 10, 2013 12:04 pm
Posts: 1078
Country: England, UK
Suzuki 2-Strokes: FZ50, GP100, RG125 Gamma, GT380, Bandit 1200S
Its so good to see it finished. It looks terrific! Well done mate. That is a nice tidy job you and your son can be proud of.


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PostPosted: Fri Dec 20, 2019 3:47 pm 
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Thanks Sportston, we appreciate the compliment!

I do have another question I could use some help on...the oil line between the tank and pump leaks and I haven’t had any luck getting things sealed up (the swiveling union at the pump’s banjo fitting leaks as well as the hose connection at the tank fitting). Seeing how OEM/replacement parts are non-existent, has anyone out there had any experience fabricating an alternative arrangement to get the oil to the pump?

Thanks in advance!!


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PostPosted: Mon Feb 24, 2020 9:14 am 
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Howdy all,

As winter begins to release us from its grip, we have been buttoning up some of the little miscellaneous tasks to get the Titan street ready for spring. We finished modifying the oil supply line between the tank and pump, mounted the seat, got the turn signals and brake lights sorted out and functioning, and mounted the mirrors.

We just took the bike out on the road for the first time last weekend and ran into an issue with the engine. The bike starts and idles beautifully. In the garage it revs nicely. However, when we get it under load on the road, it falls flat at 4500 rpm. Up to that point, it pulls strong and smooth, but when it hits 4500 rpm, it just falls on its face. I have not changed any jetting in the carbs from when I bought it, and I assume the jets are stock. It is using the stock airbox, too.

I am hoping its just a clogged/restricted passage somewhere as the carbs were pretty sketchy when I pulled them apart originally.

Any other thoughts or ideas where we can start?


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PostPosted: Wed Feb 26, 2020 5:07 am 
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Joined: Sat Sep 05, 2015 3:14 pm
Posts: 256
Location: southeast pa
Country: us
Suzuki 2-Strokes: GT
I would think the main jets could go up a couple sizes since you installed chambers, and/or check float levels, if fuel bowl level is low, it can cause fuel starvation at higher rpm, but I must admit I am not good at tuning carbs.

_________________
76 GT185
77 GT250
77 GT380
76 GT500
73 GT550
73 GT750
74 GT750
71 T250 scrambler
75 T500 cafe


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PostPosted: Sat Mar 07, 2020 5:52 pm 
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Joined: Wed Jan 18, 2012 8:01 pm
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Location: North of Albany, NY
Country: USA
Suzuki 2-Strokes: T500R (now), T500M (40 yrs ago)
Grey_Ghost wrote:
We got the carbs all tuned up (Thanks ConnerVT for your carb tuning tips!!) and the bike starts on the first kick and quickly settles into a nice idle. The Higgspeed pipes sound AMAZING!

I have carb tuning tips??? Who knew??? :ssh:

Not sure what post(s) they came from, but I just share the hundreds of hours spent trying to make my old girl run reliably well.

I haven't visited here as much recently - life gets in the way sometimes. But glad I was some help in your project, and I have been checking in from time to time. Your results look great - congrats on your perseverance. :up:


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PostPosted: Sun Mar 08, 2020 5:58 pm 
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Location: North of Albany, NY
Country: USA
Suzuki 2-Strokes: T500R (now), T500M (40 yrs ago)
After I posted yesterday, got to thinking I didn't give any advice to help with your issue.

First, be sure that all of the usual is sorted - carb and all carb passages are clean, float height set correctly, original Mikuni brass (no aftermarket kits!), throttle cables adjusted correctly (full open/close travel, slides in sync with each other), no vacuum leaks. With that out of the way...

If you are hitting the wall at 4500RPM, with throttle open full, you need to decide if you are getting too much fuel, or too little. For if you are turning 4500 and the throttle is wide open, the idle jet and the needle jet are contributing nearly nothing to the mixture. You are full on Main Jet at this point.

If you have too much fuel, the motor bogs down and starts 4-stroking - not firing every cycle due to a rich mixture. Sometimes rolling off the throttle a little bit will pick things up, and it feels like you can squeak a few more RPM when you roll it back on a little more. For this, you go down a size on the Main Jet, and try again.

But seeing you added pipes, you probably are seeing the opposite issue. The bike just hits the wall at 4500. Not like it is running bad/off (gurgling/bubbling/maybe it will, maybe it won't), but just plain runs out of steam. And it kinda is - it is running lean, and just doesn't have enough fuel to push it any harder. Time to go up in your jetting. And if the wall is 4500, I would start by going up two sizes on the Main Jet (2.5 x 2 = +5) and seeing how things behave.


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PostPosted: Tue Mar 10, 2020 7:29 am 
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Suzuki 2-Strokes: T500
Thanks for the tips ConnerVT, the tuning of carburetors is still a dark magic for many of us!

I do have a couple additional questions...We pulled the carbs off the bike and are sending them out for powder coat this week and during the tear down I looked at the jets and saw the main jet was a 150 but did not see any markings on the needle. The carb rebuild kits were for the Mikuni VM32SC. When I look online (ozebook.com) the main jet size for a T500M is 97.5 and the needle is a 5FP17-3. All the sizes for the other bikes listed call out a 150 and 5FP8-3, respectively.

Could this be part of the problem? Do I need to get the listed 97.5/5FP17-3 parts or keep the 150/5FP8-3? Or do either combination work as long as the part groups match (i.e., they work as a matched set)?

In addition to the powder coating we've got the mirrors mounted, brake lights and switches wired up and functional, seat fully mounted, fabricated a shock-mount license plate frame and light, and completed other miscellaneous bits. Right now, I think, getting the carbs done are the last tasks. I think it really is almost finished!

Oh, one other question...Do any of you know where I can get custom (or shorter) length brake cables? The conversion from stock bars to clip-ons has left us with a front brake cable that is about 12" too long. I would love to get one a bit shorter.

Thanks for all of the help!


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PostPosted: Tue Mar 10, 2020 9:01 am 
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Location: North of Albany, NY
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Suzuki 2-Strokes: T500R (now), T500M (40 yrs ago)
Ah... The pull of the black hole which is the T500 carburetor. :shock:

There is always confusion about the T/GT500, as through its production it had three different carburetors (All of the Mikuni VM).

For the initial 1968 model, it had a VM34.
From 1969 to 1972, it had a VM32 "Homopressure" (more on this in a moment.
From 1973 to 1977, it had a conventional VM32.

So what is the difference between a Conventional and a homopressure VM32? The bodies of the homopressure carbs vent the fuel bowl internally to the bell of the carb, where a conventional one vents to the outside world. The quick tell is if the carb has external overflow tubes sticking off it - if it does, it is a conventional VM32.

Suzuki's experiment likely had two goals - by making the bowl pressure part of a feedback loop, it was hoped to be less susceptible to differences in altitude (where tuning is different in the mountains vs at sea level), and perhaps smoother performance. That they bailed out of the idea in 1973 (when also making some other minor engine design changes) shows it wasn't the greatest of their ideas. But then, they also put a rotary engine on a motorcycle.

The difference in the Main Jets for these two types (150 vs 97.5) is because the fuel bowl has less pressure when vented to the internally. The difference between the pressure pushing down on the fuel vs the top of the jet makes less fuel move through the jet. Not unlike taking a shower, and someone flushes the toilet - flow from the shower head decreases. To make up for this, you need more flow (bigger pipes).

As this is a 40+ year old motorcycle, and the aftermarket kit companies can't be bothered to understand the difference, they just sell it one size fits all.

I recommend staying far away from these kits. I have bought several from different manufactures, and measured the parts vs genuine Mikuni parts. None were close to a match, and some kits just had totally wrong parts (ask my wife about the two gallons of gasoline on out garage floor).

Stick with genuine Mikuni brass. Main and Idle Jets are still available, as well as fuel valve and seats. Needle Valve and Valve Needles are no longer available - there are solutions, but more than I'll cover here. The two Valve Needles are pretty much interchangeable, one is a bit richer at small throttle openings (I don't remember which).

A good source for Mikuni brass is Dennis Kirk at around $6 for a pair of jets. I usually buy several sizes, to try out to see which behaves best. The T500 seems to always have a hole somewhere, never perfect across all speeds/loads/throttle, but such is life in the analog world. Want perfect? Buy a Busa. :lol:

https://www.denniskirk.com/mikuni/carburetor-jets


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PostPosted: Tue Mar 10, 2020 11:42 am 
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So, to make sure I understand correctly...If I have the later model carb (has an external overflow tube which mine does) then I need the smaller jet (along with the corresponding needle)? So a 97.5 jet and 5FP17-3? Plus possibly increasing the main jet size to account for the pipes?


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PostPosted: Tue Mar 10, 2020 12:36 pm 
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Location: North of Albany, NY
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Suzuki 2-Strokes: T500R (now), T500M (40 yrs ago)
Correct. I rather talk about early vs late model carbs, by identifying if it has external vent hoses, rather than going by year. Many of these bikes have bits on them which they never left the factory with. Mine is a 1971, with a 1973 motor, but with the 1971 carbs, intakes, and airbox. Always something squirrelly going on.

So a late model carb (the one with vent hoses) has a stock 97.5 Large Round Main Jet (Mikuni 100/604 Main Jet - N100.604-97.5). I would start at least 2 sizes up (102.5) and wouldn't be surprised if you go up another, given she is flat @ 4500RPM. Plus it is always better to err on the side of too much rich than being lean.

At $6 a pair of jets + ~$8 postage, you can have 5 sets from 97.5 to 110 of genuine Mikuni brass for about $40.

edit: Here is a link to Suzuki's Service Bulletin, which has the carb specs from 1971-1975. You can see the shift from the 150 to 97.5 Main Jet (as well as Valve Needle and more). What I found interesting is that from '71 to '72, they also had different Needle Valves spec'd. Me thinks they already knew they had issues with the homopressure carbs, and were tweaking as they went along. Come 1973, the specs stayed the same until the 2-stroke 500 was discontinued.

http://www.ozebook.com/compendium/techbuls/SerBulletin%20Specifications%206-9.pdf


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