aprilla/rotax LC engine .

[henri]

ive decided to lessen my workload an get on with some of my own background projects for myself . ive had this barrel an pcker plate near on a year now ,time to get on with it .IMG_2261 by henri briggs, on Flickr  .
its a aprilla-rotax 140cc set up , capable on smallframe cases of upto 45bhp depending on the size of carb an exhaust valve setting .IMG_2262 by henri briggs, on Flickr   .
an heres the cases for it , been heavily welded an decked/altered to fit the packer plate an barrel on .1st job a dry build with dummy bearings an see what squish is going to be .as i know i'll have to make another spacer to allow for cases being decked again to cure a porous weld situation .again they have been back from engineers for 2 months just sitting in my shed .H

[henri]

so dummy bearings into cases an mount the crank .IMG_2264 by henri briggs, on Flickr .
packer/conversion plate nxt .IMG_2265 by henri briggs, on Flickr .
then piston an barrel , an check deck height ,as cases have been decked had to sit barrel down on 4 washers on studs to get a negative deck height with no gaskets .IMG_2266 by henri briggs, on Flickr .
then solder in bore on top of piston an head on , getting a 2mm squish .with the washers raising barrel being 2mm thick ,quick maths an 1mm gasket gives me a nice squish .IMG_2267 (1) by henri briggs, on Flickr .
whilst together popped the cooling jacket cover on ,so can put in a frame an workout water pipe runs an inlet&exhaust fitment .H

[henri]

time for a quick trial fit of the exhaust .IMG_2282 by henri briggs, on Flickr .
H

[jonnysnatchsniffer]

nice, looks like a 123 rotax with the rave in it, hope it came with a 34mm manifold instead of the 24 they put on some of them

[henri]

managed to get a few hours in on this one last week ,got the new bits for internals so a dry build to check clearances an rubs.IMG_2484 by henri briggs, on Flickr .
that went all ok so carried on a built the bottom end .IMG_2493 by henri briggs, on Flickr .
i'd chosen newfren 27/69 primary gears with the vmc hardened basket to go on them ,an a 5 plate vmc hard work clutch rated too 40bhp+ .IMG_2498 by henri briggs, on Flickr . an that proved to be a right tricky bugger to fit ,none of my pullers/compressors would fit .so ended up adapting a small CC 4 stroke valve compressor to work ,which was a bit fiddly . nxt onto the top end ,an saving up for a pneumatic exhaust valve an a 34mm carb .H

[henri]

forgot to say ,i chose a long arm clutch cover with the crimaz geared plunger to go on this engine .so the usual game of replacing the rollers into bearings commenced ,a few harsh words later an it was built. an with a 1mm gasket clears the clutch nicely .IMG_2439 by henri briggs, on Flickr    .
H

[henri]

a couple of rainy days an i got an hour or two in on this one .IMG_2541 by henri briggs, on Flickr .
top end on ,after the faff about of individually altering every packer plate securing screws ,they where interfering with the barrel skirt . then a trial fit of the ignition ,to find because of welding the fly needs machining . before mine this was a race engine,so ran a internal rotor no lights ignition .so need to get the outer ring machined off the vmc billet flywheel for it too fit . shame i didnt get a non-billet one as thats ring is a pressed fit .H

[henri]

the 1st of no doubt many dry builds .IMG_2584 by henri briggs, on Flickr .
an the first of many problems .IMG_2585 by henri briggs, on Flickr .
looks like frame tube is getting altered to get clearance for the plug an exhaust valve .H

[tren]

I love the aprilia rs 125 rotax engine..
I have a complete engine in my shed...
When the powevalve opens its something else love it...
Can't wait to see your build comlpete

[tren]

If you need any aprilia bits pjme is the place ..
You probably know any way..

[henri]

finally got time to mock up the new inlet to move the 34mm carb inside the frame instead of out the bubble .IMG_2727 by henri briggs, on Flickr .
just had to tell people i wasnt going to be home over the mod weekender ,an then turn my phone off . H

[henri]

got my inlet welded up over last weekend , an then opened up the inlet hole an blended it to the reed cage stuffer .IMG_2777 by henri briggs, on FlickrIMG_2778 by henri briggs, on Flickr .
next is out with the engineers blue an fine grit on a mirror an make sure its still flat an will seal . an a general clean up an polish before fitting . also altered the flywheel to fit an stator base plate too around the welding on cases for transfers . so very close to a 1st start up ,hopefully this week ,time allowing .H

[henri]

engine all plumbed in .IMG_2794 by henri briggs, on Flickr .IMG_2795 by henri briggs, on Flickr .
still need to alter frame to get more clearance over spark plug .H

[henri]

first start . IMG_2797 by henri briggs, on Flickr .
too small a pilot jet , an a choke half on to compensate ,an needs to be timed up . but it starts an runs .H

[henri]

whilst waiting on new bigger pilot jets its time to get on trial fitting the fibreglass rear end . an working out fixings for it an the cdi/regbox/water pump .IMG_2808 by henri briggs, on FlickrIMG_2809 by henri briggs, on Flickr .
an work out mounts for a rear hugger to stop rear wheel throwing shit all over the carb .IMG_2810 by henri briggs, on Flickr .
just need a dry not too windy day to do the welding needed .H

[henri]

next piece of the puzzle has arrived .IMG_2836 by henri briggs, on Flickr .
the adjustable exhaust valve that runs off exhaust gas pressure , was needed to check clearances 1st before altering frame .H

[Wayne Miller]

Wow! That’s my old engine, I’d recognise it anywhere. It’s the same barrel, packer plate inlet and exhaust! I had two barrels tuned by Mick Abbey, the other one is long gone. Has it still got the same gearbox? If so with 27/69, the pipe will rev to 9500rpm and it’ll do 80mph 👍🏼👍🏼👍🏼 I had some fun building and riding that thing. I’ll keep popping back to see how you get on. It sounded awesome back in the day, would love to hear it roar again. Best of luck with it bud. Did it come with the ignitech power valve control system?

Wayne

[Wayne Miller]

Can’t really hear it hear as I’d only just finished it. I took it out the following day and smiled for hours

[ozoap]

Haven't been on here for a while. Nice work H.
Wayne, I still have your old Sprint frame and reverse barrel pipe.

[henri]

Dec 19, 2023 22:44:08 GMT Wayne Miller said:

Wow! That’s my old engine, I’d recognise it anywhere. It’s the same barrel, packer plate inlet and exhaust! I had two barrels tuned by Mick Abbey, the other one is long gone. Has it still got the same gearbox? If so with 27/69, the pipe will rev to 9500rpm and it’ll do 80mph 👍🏼👍🏼👍🏼 I had some fun building and riding that thing. I’ll keep popping back to see how you get on. It sounded awesome back in the day, would love to hear it roar again. Best of luck with it bud. Did it come with the ignitech power valve control system?

Wayne

its got 27/69 primarys ,stock pk loose gears an a benelli short 4th tree in it now .all i got was bare cases ,crank,exhaust an the barrel an packer plate from the racer david bristow . and a power valve controller of unknown make , i considered using it ,or a stepper motor triggered through relays from the change an redline lights on a tacho.so it would be a 2 step valve that was programmable . also thought of a thumb choke deal ,marked "bimble" "thrash" and "kamikaze" for the 3 settings .but settled on the simplest type which runs off exhaust pressure ,so barrel needs a hole drilling to provide this .H