T350 pipes

[roostking]

Just picked up a 71 T350 and want to put a set of pipes on it. Saw that a set of DG pipes from an RD will work. I can get RD 350 and RD 400 pipes, I would think the 350 pipes would match up the best but the bike I saw had the 400 pipes on it. Anybody have an idea if it has to do with the exhaust port diameter or if that was just what was on hand. Don't have much knowledge on the RD's but would think the 350 and 400 exhaust port would be similar size at the flange. I'm thinking the 350 pipe volume would match up better than the 400 but don't know for sure. The RD 350 bore and stroke are very close to the T350.

Also the RD used bolt on flanges and the T350 has screw on flange. Any idea how to modify the pipe to the T350 setup.
Kind of thinking of sliding the screw on part on the pipe and then welding some sort of flange or washer to the end of the pipe like the stock pipe.

Any help or comments are appreciated.

Thanks

[Vintageman]

I would use RD400 D&G has larger pipe near engine.... 350-400 D&G cone sizse when i compared were the same within 1/2 inch (mfg tolerances?). It's more about exhaust timing.

You need to get GT380 screw on flanges for example. and weld the D&G flane on to it.. the gt380 fits T350 cyl exhaust threads

Search my posts (and responses to others) such as member dyrberg123.

I have put d&G 400s on GT250s, T305 and T350 top ends The work well (real nice on 29.5mm Ex height like 76 and up gt250... same as Rd350 height and all have 54mm stroke). Works decent with 32mm ex height too like T350. and all bikes and maintain good broad street manners.

Also search youtube "Suzuki GT250 sound chambers" two of my bikes show up. read T305 top end comments ... it has some info too, but my posts reply are better if remember

[roostking]

In my search I think it was your bike that I saw the Youtube vid of.
Ok so the 400 pipes has a bit larger head pipe diameter than the 350 and this will fit up with the T350 exaust port diameter better? Do you know the diameter of the 350 and 400 head pipe?

Not sure if it's mfg tolerances or differences due to the larger engine pumping more air. That was my concern with the 2 pipes that the 400 pipe would be too big to work properly on the T350.

Funny that you mention the Gt380 flange as I was looking at the T350 last night I thought it looked close to the GT380 flange. I was thinking you could bolt the DG flange to the 380 flange but welding would be the fine as well. Good thing I kept my old GT380 pipes as I can use the flange from them.

My only concern with the DG pipe is that they seem to hang fairly low. Is it an issue ?

I'll do some more searching for your posts.

Thanks

[roostking]

Just thinking out loud but I'm just a bit confused as to why the RD 400 pipe would be a better fit when the RD350 engine bore and stroke seem to be a closer match to the T350.

I know the 400 pipe works as you have done it but have you tried the 350 pipe to compare performance between the 2 ?

How would you describe the pipe performance (rd400) on the T350?
I'm looking for a bit more snap but don't want it to be too peaky. a wide powerband with more power across the board is what I'm looking for. From reading some of your posts that's what the DG rd400 pipe seems to do. just wondering if the DG rd350 would be better or just peaky.

[rngdng]

I imagine Jemco has patterns for the T350.......



Lane

[Vintageman]

Your right I bolted RD400 flange to GT380 flange There is more to than that and in the post (bad grammar and all) You’ll figure it out. I welded to my GT250A flange for my GT250A I had spare exhaust to sacrifice

I have D&G for Rd350 and RD400. I put them side by side for I had the same concern as you. Same dia pipes just 1/2 inch ¾” at the most variation in length. I would say its mfg tolerance only. Don't see have 1/2 or even 3/4 inch or so would make a difference given overall length of section. I think the Rd350 flange dia being smaller is more a limitation choking exhaust even if it was.

I am no pipe design expert but I think it’s about Ex port timing in degrees, not bore and stroke
I am not sure how Rd350 compare with RD400 in degrees, Again pipes so close in design reason told me trivial. And if RD400 is less timing than RD250 it’s a better fit for stock T350 at 32mm Ex
D&G told me it’s a very old fragile jig they use to make them (call them and see if same base jig). The one who designed it is long gone

Yes pipes hang too low unless you cut. If you check out the post you see I cut the Rd400 pipes just below the double wall part that goes over flange. I re-welded the double piece back on for good seal. The seal on Rd400 is better than single Rd350

Also the hanger on the RD400 is in a better spot than RD350. I only had to weld a short tab to reach rear foot peg for mount. I am lazy. Before you re-weld double wall back on you may want to fit pipe to bike then tack double piece. I do have to pull up a little when I hook to rear foot peg. Pre-fit will reduce that need. Well, don't need spring to hold to flange I think dryberg123 got fancier at fitting in tight and may have re-angled a section interface. I can say they are just as close to ground on my Suzukis as they are on my R5 and Rd400. being under frame you don't want to go off roading.

How do they work? The don't seam to give as much boost on a T350 as RD350 Pipes do on my R5 nor as much boost as D&G Rd400 do for my RD400. It really wakes up my Yams dare I say as much as 15% if not more (don’t laugh). I heard they cut out too soon maybe peak at 7500 RPM, but on my R5 I can easy peg my factory tach (10,500?) Stock exhaust redline of 8000 bike was out of breath I can get 9500 out my RD400 easy. If peak 7500 it shows they are broad.

On the T350 maybe not as much same boost also true with stock T305 cyls. On the GT250A with its 29.5mm Ex height it works better. That little shite is a rocket. I recently ported my T305 Ex port to < 30.5mm if i recall. Now the Rd400 D&G pipes sound very crisp and boost more similar to what they on my Yams. So I think the D&G are a better fit when exhaust port time get closer to 90%. I think the Rd400 may be a little less than Rd350 timing with it 29.5 mm Ex, Daytona RD400 is much less.

I don't think Jemco has a set for T350. HiggSpeed does, but judging book by its cover D&G looks better at performance.

What is nice about D&G is broad power band. At one point on Yam board D&G was a link to either to either Spec II or Moto Carrera. They compared their pipe to D&G. D&G had a bit less peak (2-3 HP if I recall) but over a narrow peak. The D&G had more power at many more other RPM points. So area under curve greater with D&G. That is important if you street ride. I think they pulled the data for can’t find again (Ripley’s believe it or not).

So in expensive. So easy to fit. Even a cave man can do it

[roostking]

hey thanks for the info. I get what you mean by mfg errors. that's great info.
I tried Jemco but they don't make a T350 specific pipe. I asked if they could make a weld up kit but no answer yet.
A few cuts to make it fit are no issue unless it a big change but from what I can see the yam and suz are fairly similar.
So the RD 400 pipe it is at appears to be a better fit with all things being equal between the two.

[tz375]

DG pipes resonate at around 8,500 with RD350 exhaust port timing. Radical changes in timing will move that up or down a little but not as much as you might expect. On a 305/350 Suzuki with such a small exhaust port, that peak is down around 7,000 on stock exhaust port opening timing and as the port is raised so is the peak RPM until the pipe starts to limit peak revs.

DG are not the "best" pipes in terms of peak HP but are an honest pipe that makes good power everywhere and with some porting they can help to wake up your bike - as well as the neighbors...

[smokin_blue]

I designed my pipes for my bike as a GT-250 with a peak at 7,000. I later bolted T-350 top end down on the GT cases and ran the same pipes. I don't remember if there was any difference in the port timing (both were stock) and the bike ran and pulled well as a 330.