Franken-bike 250 what's what?

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daxman
To the on ramp
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Suzuki 2-Strokes: A100 GT250 & 4t Yams!
Location: Brussel County, England

Franken-bike 250 what's what?

Post by daxman »

Spotted this bike http://www.ebay.co.uk/itm/Suzuki-gt250- ... 3938380536 on ebay which looks interesting. I especially like the pipes - anyone know what they are? Also the motor is curious - no ram-air head(s) on a ram-air bottom ?? How well do these work on premix as I see the auto-lube pump is blocked off.
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jabcb
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Suzuki 2-Strokes: 69 T350 thru 75 GT750
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Re: Franken-bike 250 what's what?

Post by jabcb »

Its built from parts for different model years of the T250 & GT250.
The oil tank & side cover are from a T250.
The cylinder head looks to be from a 76-78 GT250. The 73-75 GT250 has the ram air cover but the later bikes don’t.
The carbs look to be from a T250 or 73-75 GT250.

The crank main bearings get oil directly from the oil pump. The crank would have to be rebuilt with the intent of running on premix for it to be adequately lubricated by premix.
Those bearings are not going to last very long when run on premix without the crank mods.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
daxman
To the on ramp
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Suzuki 2-Strokes: A100 GT250 & 4t Yams!
Location: Brussel County, England

Re: Franken-bike 250 what's what?

Post by daxman »

Indeed..

'Hustler' side panels actually look quite cool on this machine I think.

I wasn't aware the later one piece head would fit the earlier motor.

Interesting about the premix situation - out of interest what mods need to be made to lube the crank mains with pre-mix..
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jabcb
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Suzuki 2-Strokes: 69 T350 thru 75 GT750
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Re: Franken-bike 250 what's what?

Post by jabcb »

I agree that the metal side cover & oil tank from the T250 looks better. The bike has a T250 gas tank, which also looks better.

The crank has oil slingers that route the main bearing oil to the connecting rod bearing. Those would need to be removed for premix only. I don’t know what else would be required.

One of the crank bearings is lubricated by the transmission oil. Suzuki switched that for the later GT250s. So the cranks & right oil lines for the 73-75 & 76-78 models are not interchangeable.

The T250 & 73-75 GT250 have flange mounted carbs. The 76-78 GT250 has spigot mounted carbs & carb holders. Don’t know if those setups are interchangeable.

I don’t know what mix & match combos are possible. Perhaps he has a 73-75 GT250 crankcase + cylinders + carbs, and a 76-78 crank + cylinder head. And he went premix because of Suzuki’s crank main bearing oiling change.

The bike might be worth buying if you can get it cheap enough & are willing to do the work to get the bike reliable. I think the motor should be disassembled so you can figure out what you have & what is needed.

What it takes to get the bike street legal might be another big issue. Where I live, the title goes with the frame & they don’t care what motor you have.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
dollydog
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Suzuki 2-Strokes: several gt250 ramairs

Re: Franken-bike 250 what's what?

Post by dollydog »

think you'll find the engine is a gt250a or b, as the cylinder head won't fit the earlier models - the stud spacing is different. he's put longer carb studs in and used the t250/ramair carbs and insulators, [you can tell this because it has the pull up type tickover adjusters and not the screws the 250m had], which i thought was a bit stupid, being as the later model uses a 28mm carb instead of 26mm, in fact, i think the early t250 used 24mm. frame is t250, forks and wheels are gt250. fork yokes are t250 as the gt250 stem is too long. just thought of something, and i know this is right because i've tried it, you can't fit a gt250 ramair engine in a t250 or t350 [the one i tried] frame, as the mounting points for the engine/front downtubes are slightly different. you can't fit the ramair covers as they hit the front downtubes. i'd also like to know where he had those exhausts from :D first thing i'd do is either fit a t250 engine [don't like the 'a' model engine] or an oilpump. these suzuki pumps are usually 100% reliable, so why take it off? if he just wanted to save weight, then why fit the oil tank? :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
daxman
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Suzuki 2-Strokes: A100 GT250 & 4t Yams!
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Re: Franken-bike 250 what's what?

Post by daxman »

Thanks chaps - fascinating stuff. I'd buy it if I didn't still have my 'A' to get going plus my other various bike and car (and house) projects... :roll:

Cheers

PS no clues on those pipes though ?
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