90 MPH Mini Bike Engine Build / Tillitson 236R

hey guys it's lewis here this is a new 90 mile hour combo it's similar to the old uh 78 mile an hour and a quarter build which was on my motovox i'm gonna have a video of that and the proof of the bike doing the pass so after the proof video i uploaded another video of the motovox walkaround video and in that i went over the combo build so i went over exactly what was in the motor and i still had people ask me on that video what the engine build was like did you not watch the video so um i'm not going to judge you or anything because when i watch some youtube videos i usually skip over i try to find the specific part i need and you probably just skipped over it but i'm gonna tell you the combo right now and then i'm gonna i'm gonna get to this build so the old um the old build was a full non-hanging motor stock board stock stroke at 212 cc so the bottom end was a arc billet rod arc billet flower with stock timing which was 32 degrees um it had a dyno 308 cam stock side cover and stock side cover bolts um stock gas tank with two little vent holes the top end was a stock head that came with it stock valves stock retainers stock keepers 26 pound springs a mikuni manifold with a 26 millimeter okiyo card from ebay a walbro fuel pump stock head bolts and the stock spark plug i ran my pulse from the valve cover because i had no venting on the block and it was on 93 octane so that's the old build oh with stock uh stock rockers and stock push rods turned just under nine grand which was 87.70 and the gear ratio was a 1264 with 16 and a half inch tires with a 145 pound rider so that was the old combo the new combo is a little bit bigger bottom end a very similar head the only difference is more spring pressure a bigger cam uh more head flow and more compression so specifically the bottom end is what increases the power um in this build the head is still very similar still a stock valve size head it's not a big valve head so and that's probably limiting me a little bit too um now going to to more flow and staying with stock valves is just um i'm just on a budget right now so this is the head i had available and they flow pretty damn good for stock valve head so the combo is a 236 cc build which is the bottom end it's a tilson block so if you go on on google right now and you type ec carburetors 236r kit you'll see this bottom end it's basically a tilt sum block so notice there's no there's no um brackets to fit the gas tank this is my own bracket that i made and it's a very rigid with gussets it's a very rigid strong block so it has gussets on the bottom and top around your cylinder um and it's a two millimeter overboard than than a stock so it's two millimeters bigger than the stock uh stock bore of a 212 um and a little more stroke than a 212 crank it's a stroker so the kit basically comes with a stroker crank a lightweight piston and a billet rod comes with gaskets side cover and that's about it i have a um a custom grind precision precision cam in here which you can't really buy you can't buy online you have to go through johnny berry specifically through facebook it's a very high duration cam and it makes most of the power up top in the around 9000 rpm that's where most of the power is gonna be so between eight and nine grand um this is the thing that i don't like about hydration cams and they go to their power up top and they're a little bit a little bit slower off the line so compared to my old cam which was a 308 cam um with mid duration if you'd say which was 244 duration um or 240 244 i think see the 244 to 46 duration uh compared to this which is at 270 duration so it moves the power band way up you do lose slight slightly slightly off the line or slight torque but you gain at a top and that's what i wanted with this build so it's a custom grind precision cam um with a 329 lift on the intake 333 lift on exhaust and 270 degrees of duration now why more lift on the exhaust if you keep the exhaust lift higher or duration higher it'll carry the power a little bit better so um if you want more torque run less lift and less duration on the exhaust side and you might lose a little bit of of power up top but it'll lower your power band down so you have to play with this um read online read some forums just that's how i gather my info um it's basically trial and error and a lot of reading a lot of reading so that's basically the bottom end it's a 236r kit from tilton 2.835 board which is 72 millimeter i forgot the exact size on the crank which is i think the 2.285 or 2.283 i'm not exactly sure um full studs side cover studs head studs which are a must um at least for the head and yeah stroker crank stroker cache crank the billet rod that comes with the kit 72 millimeter board the piston it's a lightweight flat top piston that came with the kit and these cranks take a clone clone flywheel so this is an old flywheel that's at like 28 degrees and i use a timing key to get them up to 32 degrees because i'm running 100 octane pump fuel so that's my bottom end now the top end is a very similar head very similar carb at the same exact carb actually same exact fuel pump they're just brand new because i sold my other bike um the only difference is the head has been milled a lot more the old head wasn't milled at all this head is a um i had 85 thousands taken off this head and it's around 13 and a half to 14 cc chamber it's a little bit more porting and a lot more valve um a lot more spring pressure so my old um the old valve springs were 26 pounds these are 32 pound duals you don't need much spring pressure with this because this is a stock valve head and the rtc non-hemi head valves are super light they're five millimeter stems and they're extremely extremely strong for stock valves i don't worry about them i don't worry about them breaking anything and you can get the the dual um dual piston dual piston dual spring retainer and all that from ec carburetor themselves so um and they'll bolt right onto the stock valves work phenomenal i have champion rockers with chromoly push rods and if you need a cheap set of rockers these things will handle a ton of pressure and they're very strong for for cast 30 rockers they're extremely strong now i have a lot of venting done to this notice i took the baffle out of my my valve cover because i want more i want more positive crankcase pressure to get out i want to free as much power as i can out of this so the more pressure pressure i can get it's not oil pressure this is positive crankcase pressure from the piston which creates a lot of pressure on the inside and if you free that pressure if you can get it get it out it frees up power to where your your crank and just um doesn't have to fight it so it might sound might sound confusing if i explain it it's just um it just frees up power notice i think the baffle like i said this is jb world around fittings and this will run two lines to my catch can um you have to keep an eye on your oil volume in the bottom end because um it tends to push a lot of oil out of here which is totally normal because the baffle is out obviously and it's kind of like a free flow out but the way i run my lines is kind of like a circle and it pushes most of the pressure out and most of the oil will come back in so i make my lines go up instead of go down that way the oil can get feedback to the head and i don't lose as much you will lose slightly a little bit but you don't lose as much as if you were to run your lines go down running down so um ported head let me show you guys the port most people don't show this but i don't care there you go and i pour all my heads i pour all my heads um if you guys are looking for someone to put your heads hit me up on instagram i have my own ads on facebook too um whatever you need i don't do any machining to the head i can get it milled um they do charge a little bit local they charge around fifty dollars to mill ahead because there's no small engine machine shop around me it's mainly like car guys or car shops so they do charge a little bit more but if you were to ship it out to somebody who builds engines they'll charge me like 20 max to to mill your head so um it's cheaper if you go through an engine builder than if you were to do it local um i don't do any big valves um i don't have the machines to do that so i only port stock valve heads or if you were to send me a big valve head i'm more than happy to work on it for you i just can't put the seats in and do all that work so um if you have a head that you want ported 100 i guarantee i guarantee better performance 100 i have a lot of vouchers i'm not trying to sell myself or anything but the head work is very important and i've been doing this enough to know where to port how to port so um yeah that's basically it this is not really also if you can find the biggest exhaust you can the biggest at least a 25 id stage for the first like 25 millimeter stage the first stage um the more gas you can escape out the the more fresh air it can pull in so most people think bigger exhaust will lose some torque um it depends on your build with this build i'm trying to get as much exhaust out so it pulls as much fresher and um yeah that's about it it's not really complicated it's very simple it's all in your gear it's on your tire height and it's on the rpm so yeah i hope this helps you guys have any questions leave them in the comments see

Channel: LS Mini Bikes

Views: 6,545

Rating: 4.9503107 out of 5

Keywords:

Id: 3Lt3cXb_xOY

Length: 11min 21sec (681 seconds)

Published: Thu Nov 19 2020