T5 Malossi optimization advice needed

[Juti]

Hi All,

I have read your stories for a while with google translator. Now I'm looking forward to hear your opinions and advices/tips/tricks to achieve the next level.

I have fitted a tuned T5 engine into my Gl frame (VLA1T). Setup is following:

- Malossi 172 (timings 194/131 with 6mm thick base plate, 68 degrees wide exhaust port, modified original piston)

- MMW head with 1.25mm squish (piston surface comes ca. 1,40mm over the cylinder)

- Worb5 "lippenwelle" crank with 56.5mm stroke and 110mm rod

- MMW Cosa2 "Spider" clutch

- MMW2 membrane with Boyesen Pro reeds (all the corners and surfaces smoothened and polished)

- Mikuni TMX35 (270 main, 15 idle, 53 needle) + Ramair filter

- Mikuni 20l/h vacuum pump

- T5 original electrics + 1000g flywheel (Parmakit Race is coming for the next season if nothing better/reasonable is available)

- NSR Race exhaus + Koso EGT

- heavily modified casings, enlargened and polished ports matched to the cylinder

- original PX200 Lusso transmission (going to replace it with T5 4th and 21 teeth clutch sprocket)

Few pics, a poor quality port map and a dyno curve:

VLA1T with candy green paint:

Preliminary portmap (all the red areas are already grinded off);

Slightly optimistic dyno curve run with 3rd gear (maybe 31hp is accurate, hard to say without a reference engine):

And one sound sample from dyno run:

And now comes the big question: What should be done next? More torq and more power is the goal but how? Of course the NSR Race exhaust is quite brutal and comes alive at high rpms and that's why the torq at low rpm is not so high. I have already thought about to order Parmakit variable ignition system and maybe a new modified head from Gravedigger. What do you think about the timings/blowdown time? Should I modify those somehow? And what about the ports inside the cylinder; I only have Dremel with 90-degree angle so any grinding applicable tips for my tool are appreciated

Front wheel is already really light but still I want more

I have also a problem with my TMX35. It floods at high rpms. It seems that the fuel pump creates too much pressure when the engine is running at high rpm and at the same time the vacuum connection (connected to the MMW membrane) creates a high underpressure into the vacuum pump. Does anyone have the same problem and is there a solution to decrease the fuel pressure between the carb and pump? I have a return line back to the tank but I think that the height difference between the pump and tank is too high and that's why the carb floods..? There is fuel flowing back to the tank but the resistance at the carb is lower, maybe?

Thank's in advance! You guys have a great forum. Hopefully the message in English is not a problem.

Chiers from snowy Finland,

Juti

[T5Pien]

Hi All,

I have read your stories for a while with google translator. Now I'm looking forward to hear your opinions and advices/tips/tricks to achieve the next level.

I have fitted a tuned T5 engine into my Gl frame (VLA1T). Setup is following:

- Malossi 172 (timings 194/131 with 6mm thick base plate, 68 degrees wide exhaust port, modified original piston)

- MMW head with 1.25mm squish (piston surface comes ca. 1,40mm over the cylinder)

- Worb5 "lippenwelle" crank with 56.5mm stroke and 110mm rod

- MMW Cosa2 "Spider" clutch

- MMW2 membrane with Boyesen Pro reeds (all the corners and surfaces smoothened and polished)

- Mikuni TMX35 (270 main, 15 idle, 53 needle) + Ramair filter

- Mikuni 20l/h vacuum pump

- T5 original electrics + 1000g flywheel (Parmakit Race is coming for the next season if nothing better/reasonable is available)

- NSR Race exhaus + Koso EGT

- heavily modified casings, enlargened and polished ports matched to the cylinder

- original PX200 Lusso transmission (going to replace it with T5 4th and 21 teeth clutch sprocket)

And one sound sample from dyno run:

And now comes the big question: What should be done next? More torq and more power is the goal but how? Of course the NSR Race exhaust is quite brutal and comes alive at high rpms and that's why the torq at low rpm is not so high. I have already thought about to order Parmakit variable ignition system and maybe a new modified head from Gravedigger. What do you think about the timings/blowdown time? Should I modify those somehow? And what about the ports inside the cylinder; I only have Dremel with 90-degree angle so any grinding applicable tips for my tool are appreciated

Front wheel is already really light but still I want more

I have also a problem with my TMX35. It floods at high rpms. It seems that the fuel pump creates too much pressure when the engine is running at high rpm and at the same time the vacuum connection (connected to the MMW membrane) creates a high underpressure into the vacuum pump. Does anyone have the same problem and is there a solution to decrease the fuel pressure between the carb and pump? I have a return line back to the tank but I think that the height difference between the pump and tank is too high and that's why the carb floods..? There is fuel flowing back to the tank but the resistance at the carb is lower, maybe?

Thank's in advance! You guys have a great forum. Hopefully the message in English is not a problem.

Chiers from snowy Finland,

Juti

tmx-floods - whatever

how did yout mount the pump ? ( draw a picture ) is the "thing" in the tank closed

Mikuni TMX35 (270 main, 15 idle, 53 needle) + Ramair filter

try a run without the ramair

the mainjet seems to be allright, the 15 idle is maybe a little bit to small try 17,5 or 20 - a leaner needle ( 55,56) could work better between 3000 - 5000 upm

[barnie]

Terve,

what is the ignition timing right now?

[Crank-Hank]

- original PX200 Lusso transmission (going to replace it with T5 4th and 21 teeth clutch sprocket)

65 and 21 tooth clutch is not a good combination for the material: especially with your engine power

DRT has no cosa 21 tooth clutch for a 65 christmas tree

Bearbeitet 10. Dezember 2012 von Crank-Hank

[Juti]

tmx-floods - whatever

how did yout mount the pump ? ( draw a picture ) is the "thing" in the tank closed

Mikuni TMX35 (270 main, 15 idle, 53 needle) + Ramair filter

try a run without the ramair

the mainjet seems to be allright, the 15 idle is maybe a little bit to small try 17,5 or 20 - a leaner needle ( 55,56) could work better between 3000 - 5000 upm

Here's a pic from the pump assembly (the pump is almost at the floor level mounted on to the lip under the tank):

- blue arrow = vacuum connection from the membrane

- yellow arrow = return line to the tank

- purple arrow = Y-connection

- red arrow = fuel line to carb

- green line = line from the tank (hi-flow tap in the tank)

What is the "thing"?? I'm confused

Vespa is already in pieces so the next tests are done during the spring. I'll test the bigger idle and also leaner needles.

Terve,

what is the ignition timing right now?

Terve,

Ignition timing is 16-17 degrees BDTC considering measuring tolerances.

65 and 21 tooth clutch is not a good combination for the material: especially with your engine power

DRT has no cosa 21 tooth clutch for a 65 christmas tree

Yeah, you're right. Material strenght is one of my concerns also. One option is to replase the primary at the same time. I'm going to buy at least the repair kit for it so maybe it would be best to buy DRT primary with straight teeth and proper clutch sprocket. What combination is recommended? Now the 4th gear is waaaaaayyyy too long while shorter gears are pretty much ok. Top speed at 3rd is almost 120km/h but after switching to 4th gear the speed does not go any higher if there's no downhill ahead..

Bearbeitet 10. Dezember 2012 von Juti

[barnie]

...

Terve,

Ignition timing is 16-17 degrees BDTC considering measuring tolerances.

...

is this already optimized to the knocking limit?

[T5Pien]

What is the "thing"?? I'm confused

the thing

[Juti]

is this already optimized to the knocking limit?

No or not in purpose if it is.. It was set up according to Malossi's instructions. Actually this is the first time I hear the term. How it can be optimized to the knocking limit?

[Juti]

the thing

Well, it's not closed.. Is it possible that his can cause the flooding? If so I need to go under the blanket and cry a bit...

[barnie]

Just use GOOGLE ... yksi, kaksi, kolme and you got it !

[T5Pien]

Well, it's not closed.. Is it possible that his can cause the flooding? If so I need to go under the blanket and cry a bit...

i don´t think this has an effect to the flooding, but for a errorfree run this is necessary. i think the flooding have somthing to do with this :

http://www.mikuni-topham.de/ENGLISHSITE/Technical%20data/Schwimmerst%E4nde.pdf

do you understand what this meens ?

[T5Pien]

did´t you fit a reducepiece ( f.e. a mainjet ) in the fuel-loop. i saw that you put the loop back to he tank but this dosen´t matter - you need a reducepiece

[Juti]

did´t you fit a reducepiece ( f.e. a mainjet ) in the fuel-loop. i saw that you put the loop back to he tank but this dosen´t matter - you need a reducepiece

No, I don't have this reducuction piece in the loop. This piece (main jet etc.) was also mentioned at Finnish forum but I was sceptic of it's purpose. If I put it in to the return line this should increase the pressure at carb? Well, this needs to be done at the same time when I close the "thing". Thank's!

I did get the message from the file above. Floating height for TMX35 needs to be 20mm. I need to check that. Good tip.

It seems that I need to do more homework. Luckily we have a long winter ahead.

[T5Pien]

I did get the message from the file above. Floating height for TMX35 needs to be 20mm. I need to check that. Good tip.

It seems that I need to do more homework. Luckily we have a long winter ahead.

this problem should be solved in 10 minutes !

ps: very nice & clean welding at the enginecase for the big reedintake of the mmw 2-intake

[audiard2]

impressive broad of power at high revs but sounds like deep space emptiness till 7500... wouldn't like to be your clutch basket when it kicks in......

Bearbeitet 11. Dezember 2012 von audiard2

[Crank-Hank]

Looks good

I'm curious if the cylinder feet stays stable. Years ago someone here had it opened as wide as here shown and it cracked some month later. It was the boostport side: it is swinging the most because of the missing side support (at the ports). He saw the crack at a revision so fortunately the part did not broke (fell off)

I would be very precised to try to avoid any tight corners, better are wide round corners.

May be I find the topic/pics

Bearbeitet 10. Dezember 2012 von Crank-Hank

[Crank-Hank]

Found it:

http://www.germansco...__p__1066107283

and here later

http://www.germansco...5293-t5-malossi

Ok, nearly 2 years later

Kandi shouts: the cylinder was still running with the missing part!

Bearbeitet 10. Dezember 2012 von Crank-Hank

[Juti]

Yeah, I've read the first one. This was almost a year ago before I chose my own path.. But the next one I have never seen. Damn, hope my cylinder stays in one piece. I need to pay attention to the boost port side. "Luckily" the boost port window is almost untouched.

And about the dyno curve; I forgot to mention that the dyno shows too high rpms. Maybe +1000-1200rpm too much at high end according to max. speed at 3rd measured with GPS and gear ratio.

Thank's, really good points so far! Any tips for improving the performance? Timing adjustment, exhaust etc...?

[Tyler Durden]

Ref. to the flooding, have you mounted a smaller needle valve as recommended by Topham? http://www.mikuni-topham.de/ENGLISHSITE/ENGLISH/Frame_English.html

[barnie]

I ´d recommend a spark advance something like that:

[Juti]

Ref. to the flooding, have you mounted a smaller needle valve as recommended by Topham? http://www.mikuni-to...me_English.html

No I have not. This will be done! I don't know why I have missed this instruction.. I was so eager to get the motor running last spring so these kind of instructions were not noticed by me. Lessons learnt; think again before you hit the kick start.

I ´d recommend a spark advance something like that:

Great, thank's a lot barnie! There seems to be a quite similar pre-adjusted curve in the Parmakit Race set. Is Parmakit with 1000g flywheel the best set for this setup or should I think about something else? Currently I have HP4 flywheel with original T5 electrics. Electrics are working fine but honestly speaking the HP4 is a piece of cr*p. At least I need a better 1000-1200g flywheel and programmable CDI so maybe the Parmakit is the best (easiest) solution..?

[Crank-Hank]

Forget all spark advance kits available for PX (Parmakit, Polini etc) - they are all not fitting well on a T5 crank! Trust me!

Vespatronic has a T5 kit now which I think is very good. But comes with a 2kg flywheel (I like it!)

[Juti]

Forget all spark advance kits available for PX (Parmakit, Polini etc) - they are all not fitting well on a T5 crank! Trust me!

Vespatronic has a T5 kit now which I think is very good. But comes with a 2kg flywheel (I like it!)

Yes, I know. My current HP4 is for PX and it works but does not fit like I want. I have been watching this T5 Vespatronic for a while. Only problem is the flywheel weight. It should have less mass around it.. I have Vespatronic installed to my other engine (VLA1T casings with Polini 177) and that has worked really well. Heavier flywheel could bring more torq to low end but I'm seeking for explosives, not touring mode.. I have lightened T5 original flywheel ca. 1650g and if you compare that to HP4 the difference is huge. Throttle responce is like from another planet.

Any ideas to make the Vespatronic flywheel closer to 1000g? Is there any material to grind off? Or where could I get proper 1000g flywheel for T5? Then I could use the CDI with variable ignition if that can be purchased separately..?

[Crank-Hank]

You don´t think you can remove the ring like on any other Vespatronic?

I would bet

[50s-bastler]

Did you double-check the ratio on the dyno? It doesn't sound like 12k rpm to me.

[Juti]

Like I wrote earlier the dyno shows too high rpms. Actual figures are roughly 1000-1200rpm lower than curve shows. Max. speed at 3rd is 120km/h according to GPS and two different dynos so the max. rpm should be somewhere between 10300-10500rpm (based on my current rear tyre and 3rd gear ratio).

Crank-Hank; PM was sent for "Vespatronic". Let's see what is the reply..

[audiard2]

i'm riding the vespatronic for T5 with a 1kg flywheel and it's night and day..... I just can't figure out why they designed it with such an heavy weight?!

Bearbeitet 11. Dezember 2012 von audiard2

[Crank-Hank]

The 2kg Vespatronic is heavy like original: it was designed for everyone except of extremly revy engines

And who don´t likes it: just get rid of the ring....

[audiard2]

a pity they don't supply it with a 1,5-1,6 kg flywheel.... it leaves you no choice but to get rid of the ring cause 2,2kg is definitly a non compromise weight...

Bearbeitet 11. Dezember 2012 von audiard2

[Juti]

Do you guys know what is the flywheel weight after the ring is removed? 1000g or more?