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post #1 of 87 (permalink) Old 08-17-2018 Thread Starter
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Unhappy New YSR owner

Just got my first YSR, its a GT80 conversion.
The bike is gorgeous.....but unfourtunately, it does not make power like it should. It has the Calamari pipe, Mikuni 20mm round-slide, 5 speed. Compression is good (120 psi cold) but it wont hit the powerband like it should. It had a 240 jet in it, I went up to 270 and got a little better but still NOT running like it should.

Any advice would be great.

I spoke with Team Calimari, they said I should be running a 180 jet max, if Iím running 240-270 jet its a sign of an air leak that is being compensated for with a bigger jet.

Please help??

Rich
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post #2 of 87 (permalink) Old 08-17-2018
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post #3 of 87 (permalink) Old 08-17-2018
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sounds like your carb is to big my 150 dirt bike has a 19mm carb just for reference I whould try a smaller carb to get the air velocity up

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post #4 of 87 (permalink) Old 08-17-2018
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Re: New YSR owner

Welcome to the forum...

Your problem is either electrical related or you don't know the full scope of a GT80CC engine...The reason for the conversion is the GT80 is similar to the YSR50/80 except not as hard to do a topend rebuild and easy to do the swap...

Anyways if TC said you could have an AL its possible...

You need to get plugs and plug off the exhaust and intake then pump the mill up with 10psi of air using a leakdown tester through the sparkplug hole with engine rotated to BDC piston position and at the same time you should have bubbled soappy water and an acid brush to test around the seals which require the removal of the flywheel on the side that sucks air...

Ive seen the crank bearings n the case go bad and allow the crank to hit the inside of the jug causing cracks in the crankcase.........

Engine type:Single cylinder, two-stroke

Power:4.90 HP (3.6 kW))

Torque:6.10 Nm†(0.6 kgf-m or 4.5 ft.lbs) @†7200 RPM

120 psi is peanuts for power especially when it's ported for trail riding and beginner riders....You need about 180-200psi and alot more aggressive porting along with blueprinting, crank stuffing, etc to boost power and torque on them..

My YSR had a 1979 TS 125cc 6 speed streetbike engine conversion that I modded to 20hp from the bone stock 12hp...It had zero problems in the power dept...lol

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Last edited by CAM2; 08-17-2018 at 08:17 PM.
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post #5 of 87 (permalink) Old 08-21-2018 Thread Starter
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Re: New YSR owner

CAM2

I changed out the left crank seal. Capped off the intake and exhaust. Pressurized the crankcase through the spark plug hole, no leakage to speak of. I called Team Calimari and they gave me exact specs on the 20 MM roundslide. Turns out I have an incorrect needle installed in my carb , but I cant see how this would make the bike run so poor at wide open. I have gone up and down in jet sizes. 170, 180, 240, 270, 340. It pretty much runs the same. Still trying to figure it out. Any advice will be helpful.

Thanks
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post #6 of 87 (permalink) Old 08-21-2018 Thread Starter
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Re: New YSR owner

CAM2

I had 120 psi compression on a cold engine, Team Calamari said thats fine for the GT 80. I will check on a warm engine and post again soon.

Thanks
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post #7 of 87 (permalink) Old 08-22-2018
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Re: New YSR owner

Quote:
Originally Posted by Planefixer4 View Post
CAM2

I changed out the left crank seal. Capped off the intake and exhaust. Pressurized the crankcase through the spark plug hole, no leakage to speak of. I called Team Calimari and they gave me exact specs on the 20 MM roundslide. Turns out I have an incorrect needle installed in my carb , but I cant see how this would make the bike run so poor at wide open. I have gone up and down in jet sizes. 170, 180, 240, 270, 340. It pretty much runs the same. Still trying to figure it out. Any advice will be helpful.

Thanks


Does the engine smoke alot?

What are you using for reeds?

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Last edited by CAM2; 08-22-2018 at 06:17 PM.
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post #8 of 87 (permalink) Old 08-22-2018
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Re: New YSR owner

Quote:
Originally Posted by Planefixer4 View Post
CAM2

I had 120 psi compression on a cold engine, Team Calamari said thats fine for the GT 80. I will check on a warm engine and post again soon.

Thanks
Sure 120 psi is good for a bone stock GT80 engine...It's got under 5hp...

Maybe I should ask you a question and maybe it will sink in on the point I'm trying to make about the GT80 engine and why I went with a 12hp stock TS 125cc engine swap instead. .

Which would you bring to a racetrack. ..?..Hyundai Elantra or Corvette Stingray...

Just know you have the Hyundai of 80cc engines....

My YZ80 engine bone stock has 10 more hp than that GT80 and now it's pumped up on methsnol it's pumping out about 22hp

The reason why the extreme changes make little differences is because the engine is weak and anemic...

Putting a larger carb on your application won't yield a topend powerband...putting a smaller carb will because it will increase velocity....I'd be putting a PVHA 14dd,,a 16mm carb or even a PVHA 17.5mm carb..

https://www.gasbike.net/products/gt8...clone-assembly

https://japan.webike.net/YAMAHA/GT80/761/mtop/

If you want perfrmance out of a dog you must build it accordingly..

You must bump the compression and do some power porting to get that engine in the 9 -10hp range to do any real tuning....
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Last edited by CAM2; 08-22-2018 at 06:53 PM.
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post #9 of 87 (permalink) Old 08-22-2018
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120 PSI of compression that's perfect for a Briggs and Stratton you can use it to mow the yard lol even the Harbor Freight Predator motors have more than that I'm not trying to be mean but a hundred twenty that's laughable if I were you I'd take that thing apart and figure out a way to Pump That Thing Up

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post #10 of 87 (permalink) Old 08-23-2018 Thread Starter
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Re: New YSR owner

CAM2 , Sir

Your responses seem to be the most honest and educated. Thanks. I am new to the YSR scene and I appreciate your continued input. I have a few more bits of info and questions. Maybe we could do a phone conversation sometime soon, as it would probably help me much faster than this messaging method. Just so you know, I live in Florida, USA. I bought the bike on EBay and the seller was in Tennessee. So, once I won the auction I was committed. Anyway....

Here are the bits of info and questions:

1. The original owner was an avid motorcycle and YSR/NSR owner. He had about 4 other YSRís and a few Japan imported NSR 50/80ís. He also had a total of about 25 other motorcycles/atvís in his garage. He was rather wealthy and he told me he loved working, riding, and collecting bikes. I was impressed with his shop and his collection. He was also a pilot (owned his own plane). I was actually amazed at his love for bikes and tinkering.

2. I asked him about why did he go with the GT80 conversion and he explained to me that YSR 80 engine parts are very hard to come by so thatís why he did the GT80 conversion. He said its a popular option because of easy engine mounting and plug-and-play electrical connections.

3. I asked him why is the GT80 was only rated at 5hp and the YSR50 was 7hp stock. He explained that the YSR had better ports and an expansion chamber exhaust. He explained that a GT80 motor with a good pipe on it and proper tuning could easily match a YSR80. It made sense to me.

4. I have tinkered with 2 and 4 stroke bikes and jet skis , I know what proper jetting and good compression can do for a motor. I had a Yamaha 650 Superjet jet ski that blew me away after I did a port-match job on it, milled the head, and increased the jet sizes. It was insane. It hit the rev limiter the instant you hit the throttle!!

So...Now, a few questions:

1. What is a safe compression number for me to aim for with this motor. Iím getting 120psi on a cold engine right now. Previous owner said it was a fresh top-end. Team Calamari said thatís a good number. I want this bike to be street rideable on pump gas. 91-93 octane is what we have here in Florida USA.

2. Is milling the head to bump the compression up a bad idea?

3. The bike has a Mikuni Round-Slide 20mm carb on it now, the previous owner gave me a nearly new Mikuni Flat Slide 24mm, do you think I should consider installing/tuning with the 24mm or just stick with the 20mm for better overall street-use considering Iím planning on using pump gas (91 octane). I have easy access to 100 octane aviation fuel, but I want ease of use and reliability.

Thanks, hope to hear back soon.

Rich
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we both told you the same thing get a smaller Carby to get the velocity up and yet you still want to flood your week little engine out with a bigger Carby than what you have right now...
Like I said befor my 150 has a 19mm Carby on it for reference...
Try a 15mm Carby...
120psi of compershon is week...
No one cares how many bikes the guy you got it from has or how mutch money he has they all probley run like sh1t...
it won't start making good power untill you hit 150psi 175psi will give you some head room for wear and tear that's about 15:1 still okay for Pump Fuel if it were mine I'd be trying to hit 200 PSI...

Aftermarket piston and rings machining the head porting polishing base gasket deleting restuding changing the timing are all in your near future...

Like Cam2 said ( a little nicer then me ) just throw that engin away and get a 125cc or a china CDI 150 off a tao tao something like that is mutch better for makeing power...

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Last edited by MrKitty; 08-23-2018 at 11:57 AM.
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post #12 of 87 (permalink) Old 08-23-2018 Thread Starter
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Re: New YSR owner

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Im assuming your 150cc was a four stroke??
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Yes my 150 is a 4-stroke with that said you still don't have enough vacuum to run that big of carburetor on that tiny little engine but don't worry obviously I can tell you're stubborn so go ahead bolt on that 24 millimeter carburetor don't come crying back here complaining that you have fuel drooling out of the air intake side 😛 you can complain on that 1990s style squid website lmao

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Last edited by MrKitty; 08-23-2018 at 07:59 PM.
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Re: New YSR owner

Going to a bigger jet or bigger carb is not going to make you go faster. Lean is fast, rich is slow, too lean and you will burn up the engine. You might buy a Wiseco hp piston and ring set for $100, hone your cyld if it is good, and porting the cyld would help too. The high compression piston will give you more power.

Empty Pockets Racing: The difficult we do, the impossible takes longer.....
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post #16 of 87 (permalink) Old 08-24-2018 Thread Starter
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Re: New YSR owner

Dear MrKitty

I appreciate your advice. However, you seem cocky and rude. This may be because you really know your stuff or because you just like to annoy people. However...., since buying this YSR (GT80 conversion) and doing a fair bit of research; I have heard nothing other than people say that a 20mm Mikuni VM is the appropriate carb size for a 80cc 2-stroke. So, I am GENTLY asking you to stop being a fly buzzing around annoying me. I will learn from my own mistakes. I have spoken with Team Calamari, and I would trust what they say rather than you. No offense intended.

PS....how long have you been in business and paying employees working on 2-strokes?

Thank you, and have a nice day

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post #17 of 87 (permalink) Old 08-24-2018 Thread Starter
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Re: New YSR owner

EPR....

YUP, understood. Work in progress, turns out that my carb has the wrong needle in it. I just got the correct size today, will install and test ride tommorow. Please follow this thread if you want, as I will post my learning experience as I go. Do you own a YSR also? They are a gorgeous little animal.

Thanks
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Re: New YSR owner

Quote:
Originally Posted by Planefixer4 View Post
CAM2 , Sir

Your responses seem to be the most honest and educated. Thanks. I am new to the YSR scene and I appreciate your continued input. I have a few more bits of info and questions. Maybe we could do a phone conversation sometime soon, as it would probably help me much faster than this messaging method. Just so you know, I live in Florida, USA. I bought the bike on EBay and the seller was in Tennessee. So, once I won the auction I was committed. Anyway....

Here are the bits of info and questions:

1. The original owner was an avid motorcycle and YSR/NSR owner. He had about 4 other YSRís and a few Japan imported NSR 50/80ís. He also had a total of about 25 other motorcycles/atvís in his garage. He was rather wealthy and he told me he loved working, riding, and collecting bikes. I was impressed with his shop and his collection. He was also a pilot (owned his own plane). I was actually amazed at his love for bikes and tinkering.

2. I asked him about why did he go with the GT80 conversion and he explained to me that YSR 80 engine parts are very hard to come by so thatís why he did the GT80 conversion. He said its a popular option because of easy engine mounting and plug-and-play electrical connections.

3. I asked him why is the GT80 was only rated at 5hp and the YSR50 was 7hp stock. He explained that the YSR had better ports and an expansion chamber exhaust. He explained that a GT80 motor with a good pipe on it and proper tuning could easily match a YSR80. It made sense to me.

4. I have tinkered with 2 and 4 stroke bikes and jet skis , I know what proper jetting and good compression can do for a motor. I had a Yamaha 650 Superjet jet ski that blew me away after I did a port-match job on it, milled the head, and increased the jet sizes. It was insane. It hit the rev limiter the instant you hit the throttle!!

So...Now, a few questions:

1. What is a safe compression number for me to aim for with this motor. Iím getting 120psi on a cold engine right now. Previous owner said it was a fresh top-end. Team Calamari said thatís a good number. I want this bike to be street rideable on pump gas. 91-93 octane is what we have here in Florida USA.

2. Is milling the head to bump the compression up a bad idea?

3. The bike has a Mikuni Round-Slide 20mm carb on it now, the previous owner gave me a nearly new Mikuni Flat Slide 24mm, do you think I should consider installing/tuning with the 24mm or just stick with the 20mm for better overall street-use considering Iím planning on using pump gas (91 octane). I have easy access to 100 octane aviation fuel, but I want ease of use and reliability.

Thanks, hope to hear back soon.

Rich
You have researched very well....Can I ask one thing..?

Where are you located..?..Where you sit at sea level aswell as ambient temps batometric pressure etc have an effect on tuning too

I've done mods to my bikes that others have done and those mods don't work as intended.

Team Calimari is a really good source....They were alot better when the race scene was booming through the roof though....

Usually there's a proper atomizer to go either the needle..Some of those 20s have 4 stroke atomizer tubes in them..

I call my local airport aswell as use my fuel on shelf unit....

100 octane would only be warranted if you get the compression in the,respected are of around 12:1 compression..

I'll keep tabs on the thread...

Good luck and take care

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post #19 of 87 (permalink) Old 08-24-2018 Thread Starter
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Re: New YSR owner

CAM2

I am at sea-level, Florida.

Thanks
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post #20 of 87 (permalink) Old 08-24-2018 Thread Starter
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Re: New YSR owner

CAM2

I spoke with Team Calamari,

They gave me the exact specs for my 20mm Mikuni. Needle receiver is supposed to be a 239 0-6 (and it is) , and the needle is a supposed to be a 4J13. My carb came with a 4F10 needle installed. I ordered the correct one. I installed it.....test run later today after the beer buzz wears off.

Keep ya posted!

Thanks
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