fa2st cyclinder for mini quad

Hello all,

I spent a while on the phone talking with a couple of guys here in the US that have done basically what Im attempting. What ever happened to the Unison Racing guy?????


Well anyways I spoke to a guy with the same ATV and he also was not happy with the poor stock cylinder. He tried a couple of 47.6 mm cylinders and used a 42 mm stroke crank yielding almost 75 cc.
He has the spacer plates already machined up (about $40.00, quite fair).
His first cylinder was a Metrakit and he had poor low end performance with this and it seemed that the porting was all over the place from cylinder to cylinder (same model).
His second cylinder was a Hebo Manston (flat top piston) and he had great results with this set-up. The pricing for this cylinder seems good at about $400.00 or so US. Is this Hebo Cylinder similar to the Polini EVO I or II in performance and price??

Thanks again for all the help all.







damm i just typed a long reply and i was logged off :(
Well anyways here some of the info you asked for
the 45mm crank i have is out of taiwan and has a outer dia. = 77.8mm Also the taper on the stator side is of the larger jog style. So please check what your new PVL ignition is? If its for a 50cc (39.3mm) crank it wont work. Also you have to take into account that the larger "stoker" cranks out of taiwan are usually ment for the "JOG 90" style trans, meaning the spline is larger with less teeth. So if you are using a stater motor, the Pulley and ramp all have to match your new crank.
You can swith the crank to that of the 50cc style as ( most of italian cranks are) and still use all the same flywheel, ramp and etc.... on that crank. From what i gather you have all the "jog 90" style trans and stator so not sure what direction to recommend you take now? Sorry but it is a confusing set up that you are going for? Let me know if you still want the crank, i got a few left.
 
Hebo Manston has skyhigh port timings as it is & nikasil plating & piston quality isn't the best as i have read from these forums, for that same amount i'd rather get an MHR Team 7T, Polini Evo1 & tune it.
 
Hebo Manston has skyhigh port timings as it is & nikasil plating & piston quality isn't the best as i have read from these forums, for that same amount i'd rather get an MHR Team 7T, Polini Evo1 & tune it.

The Manston 1 had bad qualitly parts. The Manston 2 is a nice cylinder.
If you wanna use a stroker crank, get a Metrakit SP.

Better to make a normal 70cc engine with a speed7t setup. Put's out 21 hp easily.
 
Motors tested and runs ?

We are no on our 3rd build and can not seem to keep belts from breaking and shredding to pieces. We need help with the port timing I think. We have a motor that will rev to 15500 with no issue and has a very tight power curve. Making all the power at 10600 - 12000 and hits way to hard in the mid range. Nothing on the bottom or on the top. This thing will pull the wheels off the ground at 11000 and fall flat at 12000?
We like the 45mm crank and would like to stay with it.
Here are a list of issues now.
1 reeds are coming apart on ends
2 need a broader power band
3 need to get more than 1 lap on a belt (using 6.5grm dr pulleys)
4 running at 126* F with no heat issues and seems to be to much cooling and needs to be choked to long 20 min is not even warm yet
5 carb is bogging at fast push of gas 180 main and 45 idle smaller was more bog
6 we have been running on vp110 at 2% o2
7 Keeps melting belts and shreds every one we put in it?
I will be porting the last motor in the next few days any one have some ideas?
I do think that with the spacer we need to move the ports way down from were we have been.
I will be on every daty and post all findings.
 
What carb and what cylinder do you use?

What reed are you using and which tickness reedpedels?

Which brand belt do you use?

Can you post a dyno graph?
 
We are no on our 3rd build and can not seem to keep belts from breaking and shredding to pieces. We need help with the port timing I think. We have a motor that will rev to 15500 with no issue and has a very tight power curve. Making all the power at 10600 - 12000 and hits way to hard in the mid range. Nothing on the bottom or on the top. This thing will pull the wheels off the ground at 11000 and fall flat at 12000?
We like the 45mm crank and would like to stay with it.
Here are a list of issues now.
1 reeds are coming apart on ends
2 need a broader power band
3 need to get more than 1 lap on a belt (using 6.5grm dr pulleys)
4 running at 126* F with no heat issues and seems to be to much cooling and needs to be choked to long 20 min is not even warm yet
5 carb is bogging at fast push of gas 180 main and 45 idle smaller was more bog
6 we have been running on vp110 at 2% o2
7 Keeps melting belts and shreds every one we put in it?
I will be porting the last motor in the next few days any one have some ideas?
I do think that with the spacer we need to move the ports way down from were we have been.
I will be on every daty and post all findings.

1. Find something other than Taiwann reeds or change them more frequently. I believe reed tips fray where the most flow is traveling.
2. Pipe Reeds and port timing are out of sync.
3.Need overrange system , with wider belt rate dat more feet per second. Also airiate the heck out of the LH Case.
3b. It's a race motor, run it for only the 3 to 5 laps then let it cool down.
4.Jetting is off, could be lean at pilot needle and main.
5. If it's a Kehin , go to the needle chart and really sort out your jetting problem. For the 70cc's it will require more stall than your are offering and also a very rich bottom to mid transition. (If it idle's long at start line it should load up.)
Lunatic transfer timings and exhaust duration will also aggravate this as will a junk pipe.
6. VP is plenty good enough by itself or mixed 50 / 50 with 87 octane.
7. Heat. Period. Also not enough range on pulleys.
8. Porting. What exactly are you asking for? Port duration numbers. What are your duration numbers so far?
Would this be Mr. George from Lubrizoil?
 
Last edited:
1 reeds are coming apart on ends
use malossi reed block,it has rubber seats and will tolerate petal thickness down to 0.25mm without chipping or fraying,if hard plastic or alloy block youll need 0.35mm to 0.40 minimum to get good life from them

2 need a broader power band
raise transfers to get 27 blowdown or better to deck the ex duration down to 180,s lengthen header pipe and retime ignition

3 need to get more than 1 lap on a belt (using 6.5grm dr pulleys)
polini or malossi overrange will sort this.

4 running at 126* F with no heat issues and seems to be to much cooling and needs to be choked to long 20 min is not even warm yet
it will get warm enough when set up and running to its best

5 carb is bogging at fast push of gas 180 main and 45 idle smaller was more bog
extremely fine tune the mixture screw and check on bite rpm as it may be double rich prior to coming onto pipe ? does it cure problem with the choke on if so richen up

6 we have been running on vp110 at 2% o2

7 Keeps melting belts and shreds every one we put in it?
I will be porting the last motor in the next few days any one have some ideas?
I do think that with the spacer we need to move the ports way down from were we have been. ?
what italkit cylinder you now on, is it triple exhaust port and what ex and tr duration are you running at present
 
all i can say is wow, tried to keep up with things but as i`m not as technical as i would wish i have a few questions, please bare with me as they might of already been asked.

we run both marinelli or jog engines in our quads (unison) i have a few queries that are slightly differant.

our quads are 98cc but i dont mind dropping the cc etc to get more power.

i heard mention of various cylinders etc the 2fast and 7t, i am looking for info on how to acheive the best set up, i dont mind changing casings cranks etc etc but torque is important, so can any one give me a description of what parts i would possible need and how to acheive a very good base set up to start with, i sorry if its a bit repetative but i`m desperate because there just doesnt seem much info available in the uk

thanks
 
all i can say is wow, tried to keep up with things but as i`m not as technical as i would wish i have a few questions, please bare with me as they might of already been asked.

we run both marinelli or jog engines in our quads (unison) i have a few queries that are slightly differant.

our quads are 98cc but i dont mind dropping the cc etc to get more power.

i heard mention of various cylinders etc the 2fast and 7t, i am looking for info on how to acheive the best set up, i dont mind changing casings cranks etc etc but torque is important, so can any one give me a description of what parts i would possible need and how to acheive a very good base set up to start with, i sorry if its a bit repetative but i`m desperate because there just doesnt seem much info available in the uk

thanks
under the DUTCH section you can chose the subthread "projecten", here you can see lots of scooter with really fast setups,
Most of the time, the chosen set up from the drivers and creators of the project will be given at the first page of the project.
You can use this list as an indication for your setup.
 
I know this topic is old but I just wanted to say this is one of the most informative topics I have ever stumbled across!!

I have a son that is moving from 50cc Quads to 70cc Quads next season in the Extreme Dirt Track Series over here in the states, He won the 50cc class and I'd like to see him win the 70cc class this coming year or maybe two 70 class's even lol.

I have a few questions about these two packages you guys were talking about if possible?

Our quads are DRR brand quads and use the Minarelli based engines. The 2 Fast kit is very very interesting but from what I understand it is an 80cc kit and they do not offer a 70cc kit for the Minarelli based engines? I am having a hard time fin ding information on this, just bits and peices here and there so any good usefull info would be very much apreciated.

Then the Malossi 7T-T kit, this uses the 13mm pin but I seen someone said earlier in thsi topic that it will fit all 12mm cranks due to it coming with a special pin bearing, I called Joe @ Richelle a Malossi Dist here in the states and he was far less than helpful in knwoing what I would need to order to build that motor and didn't even seem to want to help.

Basiclly I'd really like to know what all I would need to run both of these setups as far as Cranks, Top Ends and anything special I may need to be a legal 70cc or less bike.

We are runnign a Malossi 70cc Air Cooled 10mm top end now that runs very well, this is on his practice bike but runs strong so I am happy with Malossi's quality and performace to this point.

Thanks in advance for any help I can get on this, Corey
 
I know this topic is old but I just wanted to say this is one of the most informative topics I have ever stumbled across!!

I have a son that is moving from 50cc Quads to 70cc Quads next season in the Extreme Dirt Track Series over here in the states, He won the 50cc class and I'd like to see him win the 70cc class this coming year or maybe two 70 class's even lol.

I have a few questions about these two packages you guys were talking about if possible?

Our quads are DRR brand quads and use the Minarelli based engines. The 2 Fast kit is very very interesting but from what I understand it is an 80cc kit and they do not offer a 70cc kit for the Minarelli based engines? I am having a hard time fin ding information on this, just bits and peices here and there so any good usefull info would be very much apreciated.

Then the Malossi 7T-T kit, this uses the 13mm pin but I seen someone said earlier in thsi topic that it will fit all 12mm cranks due to it coming with a special pin bearing, I called Joe @ Richelle a Malossi Dist here in the states and he was far less than helpful in knwoing what I would need to order to build that motor and didn't even seem to want to help.

Basiclly I'd really like to know what all I would need to run both of these setups as far as Cranks, Top Ends and anything special I may need to be a legal 70cc or less bike.

We are runnign a Malossi 70cc Air Cooled 10mm top end now that runs very well, this is on his practice bike but runs strong so I am happy with Malossi's quality and performace to this point.

Thanks in advance for any help I can get on this, Corey

you came to the right place.

for a 70cc class legal setup just get the regular MHR Team 7T cylinder kit (31 12642) with the 12mm pin piston & a Malossi RHQ pin12 crankshaft (53 8009) so you can use your existing transmission. no need to buy that overpriced MHR Team crankshaft just to raise the crankcase compression, you can do just that with clever mods to the crankcase without spending hundreds of $'s.

this kit will require major modifications to the crankcase bcoz the cylinder skirt of the Team cylinder is oversized to make it stronger (MHR cylinders have thinner cylinder skirts).

for pipes if you can fabricate a yasuni C21 spec for the quad it'll be the best pipe you can bolt on to your MHR Team 7T kit even if the cylinder ports are highly tuned.

are you using an inner rotor ignition like the Malossi Selettra or PVL ignition? what parts have you got on hand? maybe you can still use them with the 70cc setup.
 
you came to the right place.

for a 70cc class legal setup just get the regular MHR Team 7T cylinder kit (31 12642) with the 12mm pin piston & a Malossi RHQ pin12 crankshaft (53 8009) so you can use your existing transmission. no need to buy that overpriced MHR Team crankshaft just to raise the crankcase compression, you can do just that with clever mods to the crankcase without spending hundreds of $'s.

Ok great, I actually made a topic asking opinions on that kit. What kind of "clever mods" do you recommend, I have searched the internet looking for detailed info on stuffing the cases and so on but with no luck. Is the MHR crank allot more $$ than the RHQ?

this kit will require major modifications to the crankcase bcoz the cylinder skirt of the Team cylinder is oversized to make it stronger (MHR cylinders have thinner cylinder skirts).

So the Malossi (31 12642) will require the major case mods then? Sorry for the confusion.

for pipes if you can fabricate a yasuni C21 spec for the quad it'll be the best pipe you can bolt on to your MHR Team 7T kit even if the cylinder ports are highly tuned.

I feel very confident that I have the resources to make the pipe work lol, I hope anyways lol, I also have a guy here in the states that is very very handy with making pipes so I should be able to conqure that task one way or another.

are you using an inner rotor ignition like the Malossi Selettra or PVL ignition? what parts have you got on hand? maybe you can still use them with the 70cc setup.

I have a Digital PVL I just bought for this new build, the other 2 bikes we had to run stock ignitions being in the Stock/Limited class but I do also have some adjustable CDI boxs and Bando Coils.

As for parts I have several thousands of dollars in parts and spare parts to keep these bikes up and runnign to their best potential but I plan to buy allot of new for this next season like all Malossi clutching rather than the KOSO, DR. Pulley and Stock we ran all this year and last. Pipes I have stock one, a few different 90cc quad pipes and access top several customs. Carbs, I have several from Custom 23mm OKOs with blades installed to 28mm PWKs and all in between including several Keiin PE's 20-28.

The clutching I plan to try and use will be the Malossi over range kit 6112811 and their Delta clutch and Wing bell. The clutching we used this year I noticed allot of wear to the faces and the the clutch shoes dont always seem to make full contact with the bell/drum surface, hopefully the Malossi stuff will be better.

The bikes weigh around 200 pounds roughly and my boy is about 65 pounds, do you think this cylinder will need some tweaking?

Very sorry for all the questions its just rare that I find such a place full of such knowledgable people and I can use all the help I can get.

Thanks in advance, Corey
 
Ok great, I actually made a topic asking opinions on that kit. What kind of "clever mods" do you recommend, I have searched the internet looking for detailed info on stuffing the cases and so on but with no luck. Is the MHR crank allot more $$ than the RHQ?

i have my own method of stuffing the cases with epoxy, where & how i do it is my secret but here's a piece of advice, the MHR Team 7T 70cc likes to have a very high primary compression, you can port the cases for better airflow from the reedvalve to the transfer ports but that lowers your primary compression too much so you must bring it back up by stuffing the dead spots inside the case. i tried lowering the primary compression but it didn't work very well.

the cost of an MHR Team crank will get you 3 Malossi RHQ crankshafts & the RHQ is one of the better crankshafts out there, if you wish to buy a crank with MHR Team specs for less than half the price get the Polini Evo2 crankshaft, a very solidly built crank with the same conrod & driveshaft as the Team crank.



So the Malossi (31 12642) will require the major case mods then? Sorry for the confusion.

yes, it will require major case mods (boring & match porting), such is the price in the quest for ultimate performance.



I feel very confident that I have the resources to make the pipe work lol, I hope anyways lol, I also have a guy here in the states that is very very handy with making pipes so I should be able to conqure that task one way or another.

good for you then, if you can get a yasuni pipe you can copy & adapt to your ATV it'll be the best pipe you can have save for a custom job.



I have a Digital PVL I just bought for this new build, the other 2 bikes we had to run stock ignitions being in the Stock/Limited class but I do also have some adjustable CDI boxs and Bando Coils.

i used to run Malossi Selettra inner rotor ignitions on both our Yamaha Jog dragscooters & they worked ok but it gave inconsistent performance on our setup so we tried the Kundo PVL inner rotor ignition & the result was awesome. we chopped a few tenths off our best time & it revs solidly all the way to overrev unlike the Selettra. just make sure you feed the engine with at least 100 octane high quality unleaded pump gas, if rules allow you to run VP racing fuels i suggest you do so, fuel is cheaper compared to detonating a piston & the quality & consistency of pump gas is always suspect.

As for parts I have several thousands of dollars in parts and spare parts to keep these bikes up and runnign to their best potential but I plan to buy allot of new for this next season like all Malossi clutching rather than the KOSO, DR. Pulley and Stock we ran all this year and last. Pipes I have stock one, a few different 90cc quad pipes and access top several customs. Carbs, I have several from Custom 23mm OKOs with blades installed to 28mm PWKs and all in between including several Keiin PE's 20-28.

The clutching I plan to try and use will be the Malossi over range kit 6112811 and their Delta clutch and Wing bell. The clutching we used this year I noticed allot of wear to the faces and the the clutch shoes dont always seem to make full contact with the bell/drum surface, hopefully the Malossi stuff will be better.
The bikes weigh around 200 pounds roughly and my boy is about 65 pounds, do you think this cylinder will need some tweaking?

Very sorry for all the questions its just rare that I find such a place full of such knowledgable people and I can use all the help I can get.

Thanks in advance, Corey

for the MHR Team 70cc kits you must run the Overrange tranny system as the powerband will be way up in the rev range (8000 to 15000rpm depending on tuning), using the standard sized tranny will make it work outside its range & severely compromise acceleration & topspeed, the wider belt of the Overrange tranny makes it handle the hp these high strung engines make, a narrower belt will succumb to the abuse sooner but that doesn't mean the OR belt will last longer, i've snapped new OR belts with less than 500kms of use. replace the belt if it has worn -1mm from new.

the Delta clutch & Wing bell is the best & most popular combo being used especially for drag & circuit racing, the Delta maybe cumbersome to setup at first but when you master how it works & how to set it up for racing conditions it is the best clutch out there, even Metrakit has copied their clutch & works just as great. the Wing bell is must as you need the reinforcing ring to keep the bell round for consistent clutch engagement & the cooling fins provide for a cooler running tranny.

if you decide to get the Evo2 crankshaft get the Polini Evo SS9 vario kit (it comes with 13mm/16mm hubpins & backplate) & just buy the Malossi Overrange rear pulley separately, i used to run the MHR 2000 OR vario kit but i replaced it with the Polini Evo SS9 vario kit & it ran much better (more consistent rpms over a wide range of temps), the MHR 2005 OR vario kit works just as well but it will only work with the Malossi RHQ crank (13mm spline) & with the MHR Team crank as it comes with the correct backplate for it.

whichever vario kit you get make sure you stock up on rollers, lots & lots of them, with the kind of abuse you'll be doing you'll be running through a few sets every few races.

i've been using Keihin PWK28 carbs on both my MHR Team 70cc & 2Fast 80cc dragscooters, both have VF3 reedvalves, they are the best reeds i have tested & used so far, my high revving engines never missed a beat with these reeds, minimal to no blowback.

for quads i'd run the kit as it is save for cleaning up the ports with a dremel o foredom tool with a diamond burr, do not polish the ports & that includes the exhaust, these MHR Team 70cc kits are peaky as it is. it's different when you run a 90lb dragscooter (100lb rider) vs a 200lb quad, you need torque & lots of it in your application.

i hope this is enough info to get you started, if you need more info just shoot me a PM.
 
Back
Top