210 Malossi Worb 5 gearing

[Jack221]

You have a Polossi then, 8.800rpms for a torquey cylinder like yours is an excellent result. The new Malossi kits, especially the Sport version are going on that direction too...i like revvy kits, this one modified by Worb has plenty of potential i hope i can fully exploit.
By the way, i closed the engine today with 22/65, didn't have 67-68...this should be a good ratio to start with... As soon as i'll put it back on the frame i'll try the set up i have in mind, let's see how far i can go! Thanks for the good tips! I might get back for some more!

I guess you have fitted the barrel by now. Did you check your main transfer port open and exhaust open degrees?

[santacama]

Hi all! Im building a PX200 engine, here are my engine specs:

Malossi 210 Worb5,
ported crankscase,
57mm flowed crank,
JL righthand,
Keihin pwk 35,
Tassinari vforce4 reed block.
Malossi head

with the standard base gasket and no head gaskets:
Exhaust 175* (enlarged 2.5mm per side) Transfer 120*, Squish 0.8mm

im waiting to close the engine because i'm not sure about the right gearing. which gearing would you recommed for this set up?
Has to pull the fourth with no esitation in every condition. Also some good tips about best set up (transfer exhaust etc...) would be much appreciated.

thanks

I will not worry a second about the gears, you are going to have plenty of power ..... 120/175 ..... I am running 130/190 with a standard PX 200 gear box and short 4 gear and it pulls like a train: Malossi 221, MMW Head, RD reeds, Keihin 35 AS (45, BGN 2, 148) RZ Mark 2...... You are going to need my fat cousin sitting at the front to keep the front down.

Squish better 1,00 to 1,20 mm.

[225worb]

Ive managed to to put some miles on my MHR set with new head and my set up revs out now even though im running a gear kit, it use to rev out before with my old worb5 top end ( with added transfer) but not as quickly ....
\ill keep it as it is as im not wanting to stick a wider/bigger rear tyre and modify the cases etc..

[Noplastic]

Ive managed to to put some miles on my MHR set with new head and my set up revs out now even though im running a gear kit, it use to rev out before with my old worb5 top end ( with added transfer) but not as quickly ....
\ill keep it as it is as im not wanting to stick a wider/bigger rear tyre and modify the cases etc..

Hi i dont have a MHR but i do have a Worb5 and a Sport..and i had exactly the opposite feeling, the worb 5 is revvier and revs quicker than the sport... I tryed both on a rotary valve engine with a long stroke mazz crank. The Sport could pull taller gearing but as i said before wasnt so revvy slightly revvier than a Polini buth less torquey, a bit of a compromise.

I meausred both today with 0.5mm base gasket and this were the results:

Malossi sport: 177 120
Malossi worb 5: 173 115

Question: What is more relevant in terms of high rpms, the height of the exhaust port or the width? Cause the Worb 5 has 173 height but is 2.5mm larger than the Sport on each side...

Initially i wa sure the Worb 5 was the one for this engine but now im confused...

@225worb: What do you mean by "gearing kit"..and whats the Worb 5 extra transfer you're talking about?
@santacama: what type of Malossi is yours?

[Jack221]

Noplastic, Are you sure about these degrees? They seem very low. Can you just tell me the millimeters from the top of the barrel down to the ports?

Very very generally about ports;
The degrees between the top of the exhaust port and the the top of the main transfer port (blowdown duration) is important. More is higher rpm and less torque.
The degrees of open duration of the main transfer ports makes revs. More degrees, is more rpm, is more power, until you have almost no torque.
The wider the exhaust port is in its first 10 to 15 degrees of opening increases everything, including fuel consumption

[Noplastic]

Noplastic, Are you sure about these degrees? They seem very low. Can you just tell me the millimeters from the top of the barrel down to the ports?

Very very generally about ports;
The degrees between the top of the exhaust port and the the top of the main transfer port (blowdown duration) is important. More is higher rpm and less torque.
The degrees of open duration of the main transfer ports makes revs. More degrees, is more rpm, is more power, until you have almost no torque.
The wider the exhaust port is in its first 10 to 15 degrees of opening increases everything, including fuel consumption

I measured them dozen times with the Pinasco timing disc i normally use...They seem to be too low to me too..especially considering that i fitted the 0.5mm gasket at the bottom of the barrel!! It's also true that each casings are different from another...
They should be pretty reliable thou if compared to those taken by scooter center: http://blog.scooter-center.com/malossi- ... l/?lang=en
If you look under the stroke 57 table they say that Malossi standard measures 110/173/31 (blowdown) against Sport 109/177/33 (blowdown).
What really differs from my measurements is the big difference between the worb5 transfer (115) against the Sport transfer (120). Compared to the Scooter center measurements they should be nearly the same instead.

In summation...considering that the transfers between the two barrels are the same (like scooter center states) which top end i use for my purposes (getting tons of rpms high in the rev range to fully exploit the power of my large carb) ? the one with the lower but wider exhaust port or the one with the taller but narrower exhaust port?

hmmm ok maybe is better if i try both and find out by myself?

[Jack221]

No two engines are the same when it comes to fitting barrels. Too many tolerences are added together. Like you say try both barrels running on the road and see how they go. If neither is as revvy as you hoped then change to a race 60mm crank and try them both again

[Noplastic]

*thumbs up!*

[225worb]

Ive managed to to put some miles on my MHR set with new head and my set up revs out now even though im running a gear kit, it use to rev out before with my old worb5 top end ( with added transfer) but not as quickly ....
\ill keep it as it is as im not wanting to stick a wider/bigger rear tyre and modify the cases etc..

Hi i dont have a MHR but i do have a Worb5 and a Sport..and i had exactly the opposite feeling, the worb 5 is revvier and revs quicker than the sport... I tryed both on a rotary valve engine with a long stroke mazz crank. The Sport could pull taller gearing but as i said before wasnt so revvy slightly revvier than a Polini buth less torquey, a bit of a compromise.

I meausred both today with 0.5mm base gasket and this were the results:

Malossi sport: 177 120
Malossi worb 5: 173 115

Question: What is more relevant in terms of high rpms, the height of the exhaust port or the width? Cause the Worb 5 has 173 height but is 2.5mm larger than the Sport on each side...

Initially i wa sure the Worb 5 was the one for this engine but now im confused...

@225worb: What do you mean by "gearing kit"..and whats the Worb 5 extra transfer you're talking about?
@santacama: what type of Malossi is yours?

Hi
I mean an up gearing kit ( cant remember the teeth pitch though)
The worb cylinder and standard cylinder has the finger port in the middle of the 2 boost ports, all ive done is drill inbetween the 2 ports to create the third boost port...
seems to work !!!

I HAVE BY THE WAY MY OLD WORB 5 CYLINDER FOR SALE .....IT WILL NEED REPAIRING (replate) OFFERS
OR CALL
07971 671943
Thanks Nik

[Noplastic]

treyd them all: Worb 5, Sport and Mhr, the result is till the same hits a brick wall at 8000 rpms . Top speed 125-128km maybe 130 i dont know.. (approx 80mph) i run a 23/65 with z36 and 20teeth drt cluster, so the ratio its more or less like a 23/65 with z37. The JL righthand doesnt rev as high as i want. My set up is now: Mhr cylinder with standard base gasket, Sip head, 1,2mm squish m Jl righthand... any ideas?

Or should i be happy with that?