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.