MHR REPLICA VS MHR VS METRAKIT SP/ HM

[ex-racer#2]

After playing around trying to squeeze as much as I can on the cheap from a stock BW's cylinder (Minarelli verticle) it is time to look at going big bore. I am looking to retain the oil pump and make it reliable as this is my primary transportion when weather allows it. I usually put 5000km on it a year.

Here in Canada I can get the following kits from local suppliers and would like some help in figuring out which way to go:

Airsal $199.95
Mhr $469.95
MHR replica $359.95
Metrakit HM $223.61
Metrakit SP $319.49
Prices are in CND$ just for comparision.

I already have a Technigas Next R pipe, 17.5mm Del-orto, Malossi vario, and just got Malossi gears but have yet to attempt to tune for them. Before the gears I was hitting 78-83 and topping out at 95kmh on the flats when weather was just perfect.

 

[DME3]

I would go for the airsal or metrakit HM, the others are way to high reving for your exhaust!

 

[ex-racer#2]

I would go for the airsal or metrakit HM, the others are way to high reving for your exhaust!

Based on the Metrakit website the differance between the HM and SP is 1000rpm. I can always add a new pipe if that is needed later. The main issue is streetable setup to run oil injection.

 

[Pallenaldo]

My Stalker had max rpms at 12000rpms with MK SP. During acceleration the rpms was 11,2k-11,6k rpms.

The SP kit delivered about 11-12hp - would be my guess.

 

[adas]

Aloha, I am currenty using a Malossi Replica stock tuning and this is my strongest cylinder. It is also "de-tuned" (I have a 42mm stroker crank and so the ports are 1.5mm lower and giving less duration.) I have used Polini Evo, tuned malossi, airsal, TP and some Chinese clones and none have the torque and in city power that this stock replica has. I have a tuned malossi replica that does not have the torque and power that this stock one has. --- don't ask me why! Maybe the combo with Yas 16. frank

 

[scootertrog]

ex-racer,
Is your oil pump adjustable? If it is not, then I'd definately go with the Airsal, because the other cylinder kits are just too expensive to chance a lubrication problem. Also, a larger carb would be recommended with any of these cylinder kits, but the Airsal is the least powerful of them all, and could be run with your carb, but again even it would benefit from a 19 or 21mm carb.

Adas,
No fair comparing cylinder torque if you have a stroker crank.

scootertrog

 

[DME3]

17,5mm carb can do fine with all these cilinders. Bigger carb just gives more power (especially on the MHR).

I woul mix my own fuel if I were you. The oil pump just doesn't give enough for these kind of cilinders.

If you realy want to keep the oil pump instead of mixing yourself, I would go for a Polini 70cc cast iron cilinder or another low reving cilinder.

 

[DME3]

Aloha, I am currenty using a Malossi Replica stock tuning and this is my strongest cylinder. It is also "de-tuned" (I have a 42mm stroker crank and so the ports are 1.5mm lower and giving less duration.) I have used Polini Evo, tuned malossi, airsal, TP and some Chinese clones and none have the torque and in city power that this stock replica has. I have a tuned malossi replica that does not have the torque and power that this stock one has. --- don't ask me why! Maybe the combo with Yas 16. frank

I'm not familiar with stroker cranks...
Usualy cranks have a 80mm conrod. Does a stroker crank have a 85mm conrod?

Or is it a completly different thing?

 

[ex-racer#2]

17,5mm carb can do fine with all these cilinders. Bigger carb just gives more power (especially on the MHR).

I woul mix my own fuel if I were you. The oil pump just doesn't give enough for these kind of cilinders.

If you realy want to keep the oil pump instead of mixing yourself, I would go for a Polini 70cc cast iron cilinder or another low reving cilinder.

The mixing of fuel is not a big issue. The issue is having enough of it as the BW tank is tiny. I am really not into doing a trip into the city and having to mix while at the gas station or carrying extra oil and something to mix it in. Sure I can mix it in the tank but it is such a pain. If i had to go that route I would make a larger tank to eliminate the issue of mixing on the go. My best range with the 12mm stock carb was 90km. With the 17.5 and my other mods it has dropped to 65-70km. This range is just too short if I have to mix.

 

[ex-racer#2]

I'm not familiar with stroker cranks...
Usualy cranks have a 80mm conrod. Does a stroker crank have a 85mm conrod?

Or is it a completly different thing?

A stroker crank has the crank pin further away from the crank center which increases displacement by lengthening the stroke. Depending on the increase in stroke you may have to use a shorter rod or shim up the cylinder with a plate to reduce compression or prevent the piston from hitting the head.

Aside from clearance issues with the piston /head the RPM potential is reduced as the piston speed is much higher at comparible RPM with a stroker crank. (The piston has further to travel in the same time period. (RPM)) The advantage of the stroker crank is more "flywheel" effect as it is much harder to accelerate or to slow down a crank with more weight or larger leverage from piston. (Increased distance from crank pin to crank center allows more leverage.)

 

[DME3]

You can also use the more low reving cilinders with a 12mm carb. It won't give as much performance, but fuel consumption will be less.
Note that a 70cc cilinder uses more fuel than a stnd cilinder.

From your list, I would choose the Airsal (if you'll keep the oilpump). An other exhaust will give more power, think of Yasuni R or Giannelli Shot. Things won't break if you trow a dip of oil in the tank before you refuel and use good oil!

 

[bws_racing]

im driving whit an mhr replica and an technigas rs 70.. i made my squish to 0.6 i had a 21 mm carb whit size 88 in it.. now im driving whit 17,5 whit size 60... big fuel diffrence.. but hes a lot faster...

 

[ex-racer#2]

You can also use the more low reving cilinders with a 12mm carb. It won't give as much performance, but fuel consumption will be less.
Note that a 70cc cilinder uses more fuel than a stnd cilinder.

From your list, I would choose the Airsal (if you'll keep the oilpump). An other exhaust will give more power, think of Yasuni R or Giannelli Shot. Things won't break if you trow a dip of oil in the tank before you refuel and use good oil!

I have yet to see Yasuni or gianneli available here in Canada. One issue I have with mail order or internet ordering is warrantee. My first Technigas pipe broke where the headpipe meets the expansion chamber. Because I bought it locally I had a new pipe in my hands and installed within 2 days. No additional shipping charges or anything. The importer had a whole batch that were crap and we all got new pipes.

 

[DME3]

Other good 70cc exhaust are: Technigas RS70, Polini for race, Top Performance Nardo, Stage 6 Sport, Bidalot S2.
There just has to be one of those in Canada

 

[ex-racer#2]

Other good 70cc exhaust are: Technigas RS70, Polini for race, Top Performance Nardo, Stage 6 Sport, Bidalot S2.
There just has to be one of those in Canada

Technigas yes! We can also get leo vince and now metrakit.

Look at Canada on a map. Compare the size of the country with the population of 30-35 million people and you can see why scooters are not very popular here. Other than the big cities we are pretty spread out. Because of that we don't sell many scoots and therefore don't get the same selection of aftermarket parts locally. Plus many scooters and the parts go by different names /part#'s here. I can't find a Technigas RS70 but I can find a RS and NONE. The NONE is supposed to be their racing/ 70/80cc pipe with spigot and spring mounts. (My mistake NONE only avail for horiz minirelli)