1974 T500 Jetting

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steved57
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Suzuki 2-Strokes: RM125 RM250 GSXR750 GSXR1000 T500 Titan

1974 T500 Jetting

Post by steved57 »

So I have a 1974 T500 that I've done pretty much a frame up restoration (didn't split cases or repaint tank/side panels) but as far as engine went .010 piston using stock Suzuki piston/rings and have stock air cleaner and stock pipes - I am assuming the carb's are original - they are Mikuni and all I can find is 153 14 stamped on them = the bore (cylinder side) is 32mm

The jetting in the bike is

97.5 main jet
30 pilot jet
E5FP8 needle - 3rd clip from top

Bikes starts very easy but just doesn't seem to have any power - and checked that the slides are in correctly

I did all this several years ago and haven't messed with it since (till today) I came out in the garage a while back and all the fuel was on the floor so I am ordering oem Mikuni float valve/seat VM28/163-2.5 which I found suggested in here and while apart want to try and get jetting dialed in so any input would be highly appreciated


Thanks

Steve
Current Bikes
1974 Suzuki T500 Titan
2018 KTM 300 XC
2017 KTM 1290 Super Duke GT
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Indy650
Around the block
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Joined: Tue Jul 03, 2018 4:32 pm
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Suzuki 2-Strokes: '74 GT250

Re: 1974 T500 Jetting

Post by Indy650 »

this webpage might help you out.according to that you might have the wrong needle. I would ride it and do a plug reading to get a baseline. Its best if you can tell how its running while riding it but not many people can. Its nice though these days theres the internet and you can read about how a bike acts when lean or rich at different throttle positions and rpms. when I was growing up it was all trial and error lol.
Also take your elevation and temperature into account with jetting.
Vintageman
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Re: 1974 T500 Jetting

Post by Vintageman »

The carb float may have a hole and sinks.

One thing that can happen if your first time (or not paying attention) working on engine with left and right piston you may have crossed them. I think it starts well and idles when crossed but any throttle it won't take the fuel. If you look into intake carb port at piston bottom may be able to tell (should see only bottom of piston horizontal flat , no cut out for transfers... maybe). Rotax air cooled twins had left and right and I never swapped them :ssh:
Current Bikes
74 GT250 (T350 upgrade),
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Indy650
Around the block
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Joined: Tue Jul 03, 2018 4:32 pm
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Suzuki 2-Strokes: '74 GT250

Re: 1974 T500 Jetting

Post by Indy650 »

Not sure why my above link disappeared?
Im unsure why they made the transfer ports like they did requiring different pistons. it cant be just to help with the exhaust angle but I just don't see an advantage to it.
Vintageman
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Joined: Tue May 18, 2010 5:38 pm
Country: USA
Suzuki 2-Strokes: Suz, Yam, Honda, Kaw.
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Re: 1974 T500 Jetting

Post by Vintageman »

Vintageman wrote:m unsure why they made the transfer ports like they did requiring different pistons. it cant be just to help with the exhaust angle but I just don't see an advantage to it.

The reason piston are angled like that IMO is to get rid of exhaust side heat. If you look at T500 cyl where they butt to each other there are no cooling fins... allows for narrow engine design as well The Exhaust side has the majority heat and putting the exhaust port at an angle like that allow the EX port side of cyls to be cooled better and symmetrically with heat removing fins. Rotax did that in the 70s on the F/C engines too.
Current Bikes
74 GT250 (T350 upgrade),
76 GT250 (T350 upgrade),
71 T350,
70 T350,
74 GT380,
75 T500,
73 GT550,
75 GT750,
72 Yamaha DS7 (R5 upgrade),
77 Yamaha RD400 (Daytona Cyls),
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