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 Post subject: t350 carbs??
PostPosted: Sat Feb 17, 2018 5:58 am 
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I likes them jubblies
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Joined: Wed Oct 15, 2008 11:19 am
Posts: 2257
Location: OL BLIGHTY uk
Country: uk
Bikes owned: tracer 700
theres a guy on F/B who has a t350 but no carbs. will a 250 fit if jets are change etc.
if so what size jets etc will he need?

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 Post subject: Re: t350 carbs??
PostPosted: Sat Feb 17, 2018 7:14 am 
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To the on ramp

Joined: Fri Aug 11, 2017 7:09 am
Posts: 260
Country: england
Bikes owned: several gt250 ramairs
hi john, they will fit, but are too small. the t305 and t350 use 32mm carbs - not 26mm.
pilot jet is 30 [same as 250]
main jet is 112.5 - oddly enough nearly every carb i've rebuilt for the gt250's has had 112.5 main jets in them already :wth: make of that what you will :D
cheers, dd.
p.s. 32mm mikuni vm's are hard to find and VERY expensive if you do find some. the last pair i saw on e.b. went for £160 and the engine went for less :roll:

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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.


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 Post subject: Re: t350 carbs??
PostPosted: Sat Feb 17, 2018 9:53 am 
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Joined: Mon Nov 03, 2008 10:47 am
Posts: 5981
Location: Illinois
How different are the 350 carbs from say the 32mm carbs on a GT750? I assume that jets are different, but what about the bodies?


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 Post subject: Re: t350 carbs??
PostPosted: Sat Feb 17, 2018 11:25 am 
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Moto GP
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Joined: Mon Dec 13, 2010 4:32 pm
Posts: 3231
Location: southwestern Pennsylvania
Country: USA
Bikes owned: 69 T350 thru 75 GT750
The T350 carbs are flange mounted.
Its also a pretty tight fit — you can only get to one of the float bowl drain screws.

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BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 73 project
T350 69, 71 & 72 project
T250 72
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE


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 Post subject: Re: t350 carbs??
PostPosted: Sat Feb 17, 2018 11:28 am 
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World Superbike
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Joined: Thu Feb 16, 2012 11:50 am
Posts: 2141
Location: The Republic of South Yorkshire
Country: England
Bikes owned: GT550s GT750 GSX1400 and lots of spares
Remember that a GT550 is 1.5 times bigger than a T350.
Not sure what manifold is on a T530 but can 550 carbs be made to fit?
I know that bore sizes are different, but???????
Details from 1972 service manual.
Attachment:
Suzuki service manual 1972 P6.JPG
Suzuki service manual 1972 P6.JPG [ 182.81 KiB | Viewed 1212 times ]

Attachment:
Suzuki service manual 1972 P7.JPG
Suzuki service manual 1972 P7.JPG [ 127.37 KiB | Viewed 1212 times ]


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 Post subject: Re: t350 carbs??
PostPosted: Sat Feb 17, 2018 3:05 pm 
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To the on ramp

Joined: Fri Aug 11, 2017 7:09 am
Posts: 260
Country: england
Bikes owned: several gt250 ramairs
or buy a pair of pwk flatslides from china :D about £40.
or there's a new pair of vm32's on eb usa - $250 inc post :?
if you try hard enough you can make anything fit and work :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.


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 Post subject: Re: t350 carbs??
PostPosted: Sun Feb 18, 2018 4:11 am 
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I likes them jubblies
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Joined: Wed Oct 15, 2008 11:19 am
Posts: 2257
Location: OL BLIGHTY uk
Country: uk
Bikes owned: tracer 700
thanks.info has been passed on. :up:

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If I wanted to make a life-long career out of
working with the mentally retarded I would
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 Post subject: Re: t350 carbs??
PostPosted: Sun Mar 04, 2018 11:01 am 
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Joined: Tue May 18, 2010 5:38 pm
Posts: 1405
Location: New Hampshire
Country: USA
Bikes owned: Suz, Yam, Honda, Kaw.
I think you could make 250 carbs fit by elongating flange slots. I would also think it would be jetted close to correct as is. But I never tried... been in same situation, but eventually find the T350/T305 carbs

It would probably run very well with 26mm (Yam RD400 using 28mm for example), however the 32mm on that 165cc per cylinder t350 is a unique experience, one of its claim to fame per Suz. When the bike can take it, it really adds well to the experience.

Use 26mm from T250...keep looking for T350 carbs.

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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,


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 Post subject: Re: t350 carbs??
PostPosted: Sun Mar 04, 2018 3:27 pm 
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To the on ramp

Joined: Fri Aug 11, 2017 7:09 am
Posts: 260
Country: england
Bikes owned: several gt250 ramairs
a pair of gt250a carbs, with the rubber flange mounts should bolt straight on. these are 28mm mikuni vm's. after what i've experienced using these carbs, a good start would be 112.5 main jets and #30 pilot jets. whether you use the t350 insulators is up to you :D depends on whether you're using the standard airbox?
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.


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 Post subject: Re: t350 carbs??
PostPosted: Sun Mar 04, 2018 3:49 pm 
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On the street
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Joined: Mon May 23, 2011 4:23 am
Posts: 49
Location: Maleny, Queensland, Australia
Country: Australia
Bikes owned: Suzuki T20-250-350-500, DL650
I tried 250 carbs on my 350 and they just killed performance. Look for 350 carbs.


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 Post subject: Re: t350 carbs??
PostPosted: Sun Mar 04, 2018 5:58 pm 
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World Superbike
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Joined: Thu Feb 16, 2012 11:50 am
Posts: 2141
Location: The Republic of South Yorkshire
Country: England
Bikes owned: GT550s GT750 GSX1400 and lots of spares
A GT380 is 2.5 250s - same bore and stroke, whereas a GT550 is 2.5 305s - ish. Same bore, longer stroke
Check pistons for starters. Somewhere between really, but gives a starter.
350/305 was 36hp - /2 x 3 = 54. GT550 50hp, but more torque at lower revs. Close enough to be ballpark Shirley?


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Suzuki service manual 1972 P13.JPG
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 Post subject: Re: t350 carbs??
PostPosted: Tue Mar 06, 2018 5:36 pm 
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Joined: Tue May 18, 2010 5:38 pm
Posts: 1405
Location: New Hampshire
Country: USA
Bikes owned: Suz, Yam, Honda, Kaw.
joethebike wrote:
I tried 250 carbs on my 350


Was the stock jetting close enough.

joethebike, did you do any mods to a t350? You are the expert for sure.

I am thinking running 1.5mm to 2.0mm Pistons getting cc up to 325cc or 335cc respectively. maybe widen ports same proportion looking for couple HP and lb/ft (this is what I want)

What do you think about ignition timing. Suz gives nominal setting and range/window for more retard or advance. I run a little more advance and really seams to help midrange torque. I hit redline street riding and no problem so far (no marks on piston at all)

If you jet mains one size down it helps mid, but don't get that extra fuel for max top end or cooling (important) so all mine are 112.5 (late jetting setup)

Thoughts on T305. It seams like the racer of the two? but less ccs. I am running a 1.0mm OS T305 piston in std bore T350 the transfer cut outs wider match better. Thicker rings. Never dynod, but wonder why they made cut out smaller on t350 piston (fuel economy or just worked better) The t305 in T350 works well and MPG seams the same.

The intake timing looks very short. Gives max low end torque for piston port. I have shaved 1 mm to 1.5mm and that does clearly seam to allow mid to top end to be achieved easier. Can't feel any diff bottom, but suppose there is theory (below 5000?)... if you compare intake time to 250 the t305/t350 is so much less...

Early T350 vs late T350 cyls. Suz added the two extra Exhaust passages, but put them too low to be of value? I have seen a few cylinders where they are just plugged with carbon, tells me of little value. Suz narrowed the main port too, lower half a bit versus early cyls, more oval to accommodate those little ports. You can widen ports a bit but not much before you hit the the little port opening.. widen on top half.

The T305 air BOX has more air passages, top and bottom than T350. Sure hurts your ears. I have one bike using just lower T305 part of air box and T350 top Half way between. That was they key to ear pain

run D&G chambers . Stock pipes worked OK too but D&G help top a tad. works better if you raise x port, but that killed bottom and mid even when just short of 2 mm. Dang it had top end... while the crank lasted

Anything else? I know leave it alone, nice as is.... wish it was closer to 350cc, my Yam R5 similar port timing has more midrange torque for highway riding.

but i ride the t350 more than other bike i own

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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,


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 Post subject: Re: t350 carbs??
PostPosted: Wed Mar 07, 2018 12:58 am 
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On the street
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Joined: Mon May 23, 2011 4:23 am
Posts: 49
Location: Maleny, Queensland, Australia
Country: Australia
Bikes owned: Suzuki T20-250-350-500, DL650
I may have had some expertise in riding the 350 but small modifications were the cause of much pain when racing the bike in stock production form so I stuck to running the motor in original condition, just bored out to the allowable .05mm oversize.

Using the bike as my ride to work transport led me to experiment with smaller T250 carbs hoping to gain some extra bottom end torque but the end result was simply to lose power and toque everywhere through the rev range. Suzuki knew best when it came to 35mm carbs on the 350.

I can't offer any expertise on port timing or differences between the 305 and 315 barrels but can say that I did race with the ignition timing set at 3mm BTDC and 110 main jets.
A peculiarity with the bike under racing conditions required the air screw set to half a turn out only, otherwise it would ping excessively on the overrun. On the open road today I still have to set the pilot screw rich to stop a tendency to ping when rolling off the throttle. That's with 110 main jets and needle clip 2nd from the bottom.


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 Post subject: Re: t350 carbs??
PostPosted: Wed Mar 07, 2018 3:47 pm 
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Expert racer

Joined: Tue May 18, 2010 5:38 pm
Posts: 1405
Location: New Hampshire
Country: USA
Bikes owned: Suz, Yam, Honda, Kaw.
joethebike wrote:
3mm BTDC and 110 main jets.


I agree is all around the best, with strongest mid. It is OK even up to full rated advance... run 93 if nervous. I use 87 Octane no worries I run B7 heat range plugs ...bit hotter than old cooler B77 Suz spec'ed. so far no issue, but could be if wot extended time I suppose.

T305 and T350 have same port timing other than the difference in Ex port design as mentioned on Later T350. I would think the wider cut out pistons on T305 must add a smidgen power, but worse emissions. The freer flowing air box on t305 probably gave a tad more top.... just too noisy for average rider.

I was comparing more the T250 Intake timing versus t305/t350. The T350 has very short intake port time where the t250 is more typical of other 250-350 twns of error, if I recall. Maybe 6mm height difference if I recall. When you did the 1mm off skirt to address factory tolerances, I can say that bike sure likes another 1mm on intake timing for better mid an top end. I think it pivots the torque curve around 5K so loss at 4k trivial. much more area under the curve and gives over rev which let chambers take advantage.

The factory allowed 1mm OS. Wiseco did a 1.5mm OS and 2.0mm OS, I think at 1.5mm the piston hits case or something and needs to be ground to fits 2mm = 335cc vs 315cc must add a couple lb/ft. noticeable. Oh the wisecos from error have the dyke top ring. what I can see it is lower than the top of stock piston (~1mm?) and can cause longer Ex port timing... That kills all but peak my experience, but <mm may not be too much. Need to recheck. P. Miller has modern wiseco he had custom made and claims he is getting in some 1.5mm OS for a whopping 330cc. I just bought set of t350 cyls off ebay!

I agree if too lean pilot and back off from higher RPM pings. I run stock pilot stock setting fresh needle jet and jet and all is well. Not a CV carb, kind of large carbso there are spots in throttle position don't make sense for all possible engine load. Richer pilot solves but just makes running slow awful. Temp that day makes diff. I may turn in half turn if cool day...The later T350 heads versus earlier has more surface area and better cooling I suspect

One of my favorite bike to ride. 6 speed!

Thanks

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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,


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