New VM 34 with Titan Chambers tuning help

Getting your blazingly fast Suzuki powerplant to perform even better!

Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan

Post Reply
fltchop
Still in the Driveway
Posts: 6
Joined: Thu Nov 09, 2017 6:56 pm
Country: United States
Suzuki 2-Strokes: 1970 t500

New VM 34 with Titan Chambers tuning help

Post by fltchop »

Looking for a safe proper starting point for jetting and ignition timing .

This is my first two stroke build .

Here is what we have for a set up .


1971 Titan 500:

Stock stroke

+ 2mm weisco pistons

Bill Bune ported cylinders

Bill Bune polished and shaved heads

Newtronics Ignition

Mikini VM 34mm carbs (new aftermarket) with K&N cone filters.

Long aluminum intake manifolds

Titan performance expansion chambers


Looking for a safe base timing position and jetting as well as spark plug heat range .

I did get the bike running and the bike is loading the pipes up with allot of oil/ fuel

I’ve played with the jets a bit, but before I go in circles I was hoping to get some advice and direction, thanks so much !

- Wayne
Craig380
Expert racer
Posts: 1250
Joined: Mon Dec 01, 2008 2:52 am
Location: Manchester, UK

Re: New VM 34 with Titan Chambers tuning help

Post by Craig380 »

Hi and welcome!

Timing-wise, I'd be tempted to be cautious and retard a little from the stock setting, especially with the shaved heads. I don't know what the standard factory setting is, but I'd be tempted to retard it by 0.2mm for safety while you get the carb settings dialled in.

I'd also be tempted to run one grade colder plugs than stock too, again just to give a safety margin. Also, Platinum or Iridium plugs give a more reliable spark, are much more resistant to fouling and don't cost THAT much more than stock plugs these days (and you only need 2 of 'em :lol:).

In terms of a jetting baseline, I'd speak to the guys at Titan as they have built bikes themselves with K&Ns etc, so they should be able to give you a ballpark.

Keep us posted!
1976 GT380 - wounded by me, and sold on
2006 SV650S - killed by a patch of diesel and a kerb in Feb 2019
2017 SV650 AL7 - naked and unashamed
fltchop
Still in the Driveway
Posts: 6
Joined: Thu Nov 09, 2017 6:56 pm
Country: United States
Suzuki 2-Strokes: 1970 t500

Re: New VM 34 with Titan Chambers tuning help

Post by fltchop »

Will do ! Thanks for the info .
fltchop
Still in the Driveway
Posts: 6
Joined: Thu Nov 09, 2017 6:56 pm
Country: United States
Suzuki 2-Strokes: 1970 t500

Re: New VM 34 with Titan Chambers tuning help

Post by fltchop »

So just to confirm plugs would be B9 iridiums (instead of B7) and timing would be 2.4mm BTDC

Does that sound right ?


Thanks again for the help -

Wayne
Craig380
Expert racer
Posts: 1250
Joined: Mon Dec 01, 2008 2:52 am
Location: Manchester, UK

Re: New VM 34 with Titan Chambers tuning help

Post by Craig380 »

Going one grade colder on the plugs should be enough, if the stock plugs are B7 then B8 should be fine. Two grades colder might be too cold ...

I don't know what the stock ignition timing is for the T500, but if (for example) it is 3.4mm BTDC, I would try setting it at 3.2mm for safety.
1976 GT380 - wounded by me, and sold on
2006 SV650S - killed by a patch of diesel and a kerb in Feb 2019
2017 SV650 AL7 - naked and unashamed
Zunspec4
Expert racer
Posts: 1087
Joined: Tue Dec 16, 2008 11:37 am
Country: UK
Suzuki 2-Strokes: T500R, SV1000S, TS125, Seeley T500
Location: Trowbridge UK

Re: New VM 34 with Titan Chambers tuning help

Post by Zunspec4 »

I run VM34 carbs on one of my race engines. Maximum timing advance I use is 2.9mm BTDC when running with premium grade unleaded. When testing at the dyno I start well safe at 2.4mm BTDC and work up, if necessary, from there.

Plugs - I use NGK B10EGV, I doubt you will need to go that "cold" but if it's not fouling plugs no need to worry.

Main Jet - I would start at a well safe 260 - 280. again time on a dyno which can read your air/fuel ratio will get you heading in the right direction.

Iridium plugs - recently heard they are not the optimum choice but darn if I can remember why :D .

One thing is certain and that is when deviating from a std. set-up you have to be ready for a bunch of testing to get things right. Over the past 5 years I have collected an impressive range of Mikuni main/pilot jets, carb slides etc. to make the changes we needed.

Cheers Geoff
fltchop
Still in the Driveway
Posts: 6
Joined: Thu Nov 09, 2017 6:56 pm
Country: United States
Suzuki 2-Strokes: 1970 t500

Re: New VM 34 with Titan Chambers tuning help

Post by fltchop »

I’ve decided to use a innovate dual wide band O2 sensor kit to help with safe tunning .

What would be the ideal location for the 02 sensor bungs ?

I’ve read that they should be at the fattest / widest part of the expansion chamber and mounted at 12 O’clock / straight up and down .

Does that sound about right ?
fltchop
Still in the Driveway
Posts: 6
Joined: Thu Nov 09, 2017 6:56 pm
Country: United States
Suzuki 2-Strokes: 1970 t500

Re: New VM 34 with Titan Chambers tuning help

Post by fltchop »

Ran the bike on the Dyno today .

It only made 43 HP at the rear wheel ?

I figured it would be 50 HP at least .

I ended up with 240 main jets and the A/F was in the 12’s

Started out with timing at 2.4 mm BTDT and moved up in small increments to 3.00 mm BTC with less than 1HP gain , So I’ll move it back down .

Anyone have any thoughts on the poor performance ? Too small of a pipe ? More compression ? Kinda lost at this point .
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: New VM 34 with Titan Chambers tuning help

Post by jabcb »

Can’t help on the motor issues but FYI on the plugs.

NGK has discontinued the B8EGV & B9EGV. Best to get an inventory now while you can if they are your preferred plugs.
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
fredvincent
Still in the Driveway
Posts: 4
Joined: Wed Dec 30, 2015 12:14 pm
Country: UK
Suzuki 2-Strokes: TS250, GT500
Location: Leigh-On-Sea

Re: New VM 34 with Titan Chambers tuning help

Post by fredvincent »

When I first read your thread, two things stood out - conical filters and titan chambers.

The K & N's could cause you a few problems with setting up the carbs - most people use foam pods to reduce any turbulence caused by the design of the small K & N's.

I will probably make myself unpopular now by suggesting that Titan (and Higgspeed) chambers are made to fit and look good rather than to provide any more performance, particularly with ported barrels (which sound like are OK being Bill Bune).

I would have thought it best to talk to Bill if he still around and maybe look at Jemco who seem to have a good reputation - after all, it's only money!

Good luck.
Indy650
Around the block
Posts: 84
Joined: Tue Jul 03, 2018 4:32 pm
Country: Usa
Suzuki 2-Strokes: '74 GT250

Re: New VM 34 with Titan Chambers tuning help

Post by Indy650 »

I also think titan pipes are made to look good but also they are made for a stock or mostly stock engine. Your power output is around what I would expect with those pipes you might be able to creep over 50hp with tuning though. Also I agree with fredvincent if you have those short little k&n filters i would switch to uni pod filters or try fitting the larger k&ns if you can. they make angled boot k&n's that can help with space issues. As for exhaust recommendations the only way to go with a modified engine is a custom set of pipes built to you porting specs. It can be hard to find a good pipe builder but they are still out there. Also depending on your mechanical knowledge you could build your own. I've built race pipes for my snowmobiles for a few years now and done a few bikes. If your good with math and metal fab buy a good pipe builder software and the tools and after a few sets youll have a set of pipes that blows manufacturer pipes away. The most important part is taking your port area and timing into account when building an exhaust.

edit: if you are interested in building your own pipes I use MOTA software its a few hundred bucks but its well worth it. Also I can give you a link to a cone building software where you can design and print out templates for your cones.
Zunspec4
Expert racer
Posts: 1087
Joined: Tue Dec 16, 2008 11:37 am
Country: UK
Suzuki 2-Strokes: T500R, SV1000S, TS125, Seeley T500
Location: Trowbridge UK

Re: New VM 34 with Titan Chambers tuning help

Post by Zunspec4 »

Hi fltchop,

Here is the dyno graph for my race engines, one with 34mm carbs the other with 38mm carbs:
Image

The red curve is the 34mm Mikuni VM carb engine, This engine had almost std. porting. The exhaust had been raised by 1mm but pretty much std. after that. What it also had were:

1. Straight cut primary gears (worth maybe 1-2 bhp)
2. Centre plug squish heads (squish set at 1.3mm which is quite wide. Worth maybe 2-3 bhp))
3. Fully programable digital ignition (Not really needed on a T500 engine, simpler ignitions like PowerDynamo more than adequate)
4. Custom made expansion pipes costing 800 GBP (worth maybe 5-6 bhp). These are now being re-worked to raise the resonant rpm range by another 1000 rpm to suit the more adventurous porting on the 38mm engine.

AND, a whole lot of attention to detail to the c/cases, transfer tunnels, port shape, compression ratio, inlets etc. etc. etc. by my tuner Graham File. The 34mm would make a stonking road engine but crikey it would be an expensive one (but then, when has that ever stopped a determined build lol :lol: ) With the modified pipes I am hoping for 65 bhp (ish) at 8700 rpm (ish) with Max Torque in the upper 40's.

In conclusion after that ramble, don't be disappointed with power you are getting. Yes, 43 bhp at the rear wheel is pretty decent for a road T500. I would look for an alternative for those pod filter though, just because they can make setting up the carburation a bit of a trial.

Cheers Geoff
fltchop
Still in the Driveway
Posts: 6
Joined: Thu Nov 09, 2017 6:56 pm
Country: United States
Suzuki 2-Strokes: 1970 t500

Re: New VM 34 with Titan Chambers tuning help

Post by fltchop »

Thanks so much for all the info guys !

Very much appreciate it , I’ll work on setting up some better flowing filters for sure !!
Post Reply