I never knew they made a rotary that small. Should have scary top end speed on that little short wheel base bike! Can’t wait to see the first run , be safe boys 👍🏻
Fundingo11...That was the NORMAL wheelbase at one time, you had to have big ones to race the real fast ones as a kid: you guys now days have got it easy !. Trev NZ & I go back to the 60's....
Awesome build! I would add some sort of chain tensioner though. That chain from the engine to the jack shaft was bouncing around something fierce. Keep up the great work guys! Can't wait to see you guys giving her a rip.
D 12 (Diesel)...My thoughts exactly, that gold made in China Chain won't last 5 minutes with all the unsupported backlash it has. It looks pretty but buy made in America & Keep your cuntry working !PS it's not even a metric chain:. Their there own metric size to make you buy more of their products.....same for gas welding gear made in China.. you've been warned ! Trev New Zealand home of Indy car Champ Scott Dickson.
id go for a rear drum break after market because if you make the brake connected through chains to the wheel, when you brake or pop a chain its game over, no brakes . A rear drum or disk set up will be safer. love the work !
Those long unsupported jack shaft mounts will be ok for a little while as long as it does not get much use. They concentrate a lot of load on the lower connection point.
Yeah or a super charger. You can actually get small superchargers for very cheap on eBay. Not the electric fan ones these get driven off of the chain. Kinda cool actually.
i didn't even know they made a rotary this small. it sounds awesome! i'd put a tensioner on the clutch to jackshaft chain if i were you. it has a little too much vibration for me. being as it will be all chrome, it will be kinda like a mini captain america from easyriders. put the gas tank from a pit bike on it, paint it in the german flag colors, and dub it kapitan deutschland, since sachs is a german mfg company. it'll definitely be one of a kind.
Engine to Jack shaft chain sure was bouncing around a lot might want to add a tensioner sprocket or you may be slinging chains, sick build, can't wait for maiden voyage
Sounds good in paper, the problem is chains still stretch and things move, ridged things holding malleable objects eventually fail, adding a spring idle tensioner will always have consistent tension on the chain until it's maxed out , why do you think your car has the same setup... why don't you just stop while your not ahead
I just relized this was uploaded 13 hours ago and I kinda surprised bc it seems that no ones making mini bike vids anymore and im glad you guys are, thanks
For some odd reason this reminds me of the cart we built using a washing machine motor and a car battery back in the day lol Love the rotary fellows nice work 👍👌
You're probably going to lose a fair amount of power through that jackshaft with the tiny sprocket on the primary side (not to mention a serious amount of side load on it). May be better to go with a little bit larger sprocket on the primary side of the jackshaft, and a little smaller wheel sprocket to compensate. That jackshaft 'stand' won't last long without running some support pipes down to your lower frame rails to box it in. Otherwise, it should be a fun little ride.😉
Awesome work except that little fuel tank. I thought they said previously they were trying to go original as possible it needs the original tank or it will just look stupid.
Very cool build! Whats the rpm range of that rotary though?? Im assuming much higher than a predator. If so, you might need a much bigger sprocket on the jack shaft to increase your gear ratio because that thing might be geared to do 60 mph and not have much acceleration! One more thing you might consider is the "lock-up" rpm of the centrifugal clutch, Because of the higher rpm of rotaries, the idle speed of that engine might already be locking up that clutch so either much stronger springs in the clutch, lighter weights in it, or you might have to install the clutch on the jack shaft once you lower the gear ratio to the jack shaft! Defiantly do some on the ground testing before putting more work into this! very excited to see this frame chromed!!
from what i could find online, the max rpm or that engine is 5K so with your gear ratio (6.1:1) that should put you around 32 mph top speed. Not as bad as I thought! Might be in the clear if your idle rpm isnt too high!
Josh...the chain lube would ruin the disc pads in 1 minute but good idea though if he doubles up & does the same on the opposite side of the rim & same on the front wheel too - you get upto 70% of your braking on the front compared to just the rear only !.Cheers Bud Trev NZ
@@trevinskiking2165 I mean, unless you’re applying chain lube by the gallon centrifugal force would keep most if not all of it off, sprotors do exist and do work pretty well
@@tenderblender945 When I was MX racing we would soak our chains in a hot pan of Moly grease (Liquid) let it slowly cool & dry - there was natural sling off. You can lose up to 30%HP with an improperly lubed chain.T 🙃NZ
@@tenderblender945 I get your point but I didn't say OIL , I said MOLY GREASE: a + 2 HP increase - another of my speed secrets hard earned: Isky Trev NZ
Why didn't you just run the pipe out under the seat vs sticking out the side? Got all that room under there, makes it less likely you'll burn your leg or hand on it picking the bike up. Jut curious.
I'll be "that guy",...'again'LOL. 1.That's so freaking Awesome !.2.Seriously going to need to change to a belt drive as that revs so high at idle.3.Please Never try to drive this without full body protection.It may kill you.It Will be that dangerous.Best wishes for your continued health,and success.
@@finrennard3402 Nah just move engine slightly to off center or modify rear wider. Those are non issues. Whats more likely is that due high revs they need to gear it with second set, but that even that would be solved with CVT