missing mid-range! Can you help find it?

General discussion about Street two-stroke Suzuki motorcycles.

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daxman
To the on ramp
Posts: 348
Joined: Thu Nov 07, 2013 1:59 pm
Country: United Kingdom
Suzuki 2-Strokes: A100 GT250 & 4t Yams!
Location: Brussel County, England

Re: missing mid-range! Can you help find it?

Post by daxman »

jabcb wrote:Service Bulletin GT-32 lists the changes going from the early GT250s to the GT250A http://www.ozebook.com/compendium/techb ... 027-33.pdf

Service Bulletin GT-35 lists the mid-model-year changes for the GT250A: http://www.ozebook.com/compendium/techb ... 034-39.pdf

They also had a timing marks snafu with the early GT250A. See Service Bulletin GT-30: http://www.ozebook.com/compendium/techb ... 027-33.pdf
Many thanks - I checked engine and frame numbers and it appears my 'A' was built after these mid-year changes. Nevertheless I will re-check carbs when they re next off. The spare (VM28SS) carb I have shows a pilot/main combo of 30/110 !
daxman
To the on ramp
Posts: 348
Joined: Thu Nov 07, 2013 1:59 pm
Country: United Kingdom
Suzuki 2-Strokes: A100 GT250 & 4t Yams!
Location: Brussel County, England

Re: missing mid-range! Can you help find it?

Post by daxman »

Hi All

After all thie carb talk i checked the timing and think I might have had it too far retarded. Next sunny day I'll give it a road test and see what we got. I can also try out the 2017 CB125R master cylinder i fitted - just couldn't get any 'pedal' with the old one even after a rebuild..

Cheers
Vintageman
Expert racer
Posts: 1483
Joined: Tue May 18, 2010 5:38 pm
Country: USA
Suzuki 2-Strokes: Suz, Yam, Honda, Kaw.
Location: New Hampshire

Re: missing mid-range! Can you help find it?

Post by Vintageman »

daxman wrote:just couldn't get any 'pedal' with the old one even after a rebuild..
You could not get all the air out i take it? Air bubbles that won't come out easily can be the problem ... takes some tricks to get it all out and can be a PIA.


Did you change timing?

If didn't help, How are the rings/cyl walls?


One of these came up near me, just have had time to go get it. Keep it 250 or stick a T350. Think I would leave it 250 for a while. Little rocket. keep it pegged
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),
daxman
To the on ramp
Posts: 348
Joined: Thu Nov 07, 2013 1:59 pm
Country: United Kingdom
Suzuki 2-Strokes: A100 GT250 & 4t Yams!
Location: Brussel County, England

Re: missing mid-range! Can you help find it?

Post by daxman »

Hi Yes

I've change the timing - using an old spark plug tapped with an M8 x 1mm bolt - 2 turns from TDC = 2mm !

Compression seems Ok and teh the bike has som pep.. Ar some point it will require a 'proper' rebuild but I
need to find the enthusiasm..

Cheers
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