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Aprilia RS257


wazrs257
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Hi all. This is my first post with pics n all, so bear with me.

Have been a bit bored since taking my project RS257 to the exhaust builder (3 weeks ago, he said it would be a week! Grr!), so thought I'd start a thread to show what I've been up to so far.

Started with this, "almost" an RS125 rolling chassis, bought off the bay as an impulse buy. I'd always thought the RS had a good chassis (Baby Bimota!), but was crying out for MORE POWER!!

4474350950_fca22723cf_o.jpg

A couple of days later I got an e-mail from my brother about a Rotax type 257 Kart spec engine for sale. This was procured post haste, and within a couple of hours was sitting in the chassis

4622483018_1c2215642c_b.jpg

More pic's and details to follow!

:eusa_dance:

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Does the kart spec engine have a PV?

Hi all. This is my first post with pics n all, so bear with me.

Have been a bit bored since taking my project RS257 to the exhaust builder (3 weeks ago, he said it would be a week! Grr!), so thought I'd start a thread to show what I've been up to so far.

Started with this, "almost" an RS125 rolling chassis, bought off the bay as an impulse buy. I'd always thought the RS had a good chassis (Baby Bimota!), but was crying out for MORE POWER!!

4474350950_fca22723cf_o.jpg

A couple of days later I got an e-mail from my brother about a Rotax type 257 Kart spec engine for sale. This was procured post haste, and within a couple of hours was sitting in the chassis

4622483018_1c2215642c_b.jpg

More pic's and details to follow!

:icon_salut:

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the kart engines have the pneumatic powervalve systems, well the 125 ones do, so i'm guessing its the same for this engine. Have you made any of the mounts yet? is it a pretty much straight fit?

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Do you mean the Rotax Max engines?

the kart engines have the pneumatic powervalve systems, well the 125 ones do, so i'm guessing its the same for this engine. Have you made any of the mounts yet? is it a pretty much straight fit?
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According to the paperwork I've got from Rotax, the kart spec engine didn't have a powervalve. The bike spec engines (Type 257GS/287GS) did have a powervalve though. They're single cylinder engines of 249.8 or 253.5cc with a 6 speed box, although some later kart engines are 5 speed due to a rule change. As standard they're about 50 brake, tuned approx 63ish. The top ends are the weak point on these engines, the cylinders crack, the one on my bike at the moment has been welded. Strangely, my engine's fitted with a 38mm Delorto, rather than the usual 39mm, I'll know what difference it makes when I get it on a dyno.

I've made & re-designed the engine mounts about 4 times, before I was happy to get the exhaust made. I managed to screw up the last but one set of front mounts by drilling a hole oversize by mistake, after having spent 4 hours chain drilling, filing & polishing them by hand! :tumbleweed: I made sure the mounting holes were correct before i finished the last set!

This is an early pic, showing mk1 mounts:

4622095796_26341b7b44_b.jpg

The radiator plumbing in that pic was a bodge. The waterpump on the 257 is on the left, but the outlet from the rad is on the right, so a pipe was run across the engine between the two. The rad has now had the outlet pipe moved to the left hand side giving a straight run to the pump. Also, the engine was positioned too low, meaning the sprocket/swing arm spindle relationship wasn't right, also now corrected.

These are the final versions made from 8mm HE30 aluminium.

http://farm5.static.flickr.com/4001/462479...3687e1687_b.jpg

I'll get some more pics up when I 've sorted them on flikr

:D

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this looks really good and I will be following this intently, i've have pretty much a second rolling chassis in my shed so this could be something that I could do. do you have any drawings for the mounts or were they made by eye. I reckon you should make the bike to the new model, like my race bike, it will be different to the other 250 engine conversions that are out there.

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I have got drawings (on autocad) for the mounts, but each hole only needs to be a bit out and the third one's miles out! I ended up drilling the engine bolt hole & one of the frame one's, then bolted it on & centre drilled the second frame hole in situ. The engine's held at the front and at the swing arm spindle at the moment, not sure what to do with the head mount. The barrels can be weak enough as it is, without the aditional stress of being solidly clamped to the frame, when all it wants to do is vibrate.

I'd originaly set a budget for this build but after buying a fully adjustable Wilbers race shock & then a lathe (cos I got bored with waiting to get spacers made at work!), the budget got thrown out of the window!!

Im waiting for a phone call from the guy thats doing my pipe to see if it will be ready to pick up tomorrow, fingers crossed!

How it looked the last time I saw it!

4626835104_da1ff92a63_b.jpg

:beerchug:

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so you are going for the old model style bodywork then. do those wheels have the holes at each end of the spokes?

i may be interested in those drawings if they can be printed off.

I need to look for a new shock for my racebike as the stock one is not up to it either.

for the mount situation have a look at my friends racebike, its a 500cc engine but the concept is the same.

RS 500

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The bodywork's just some I picked up cheap, though I do prefer the 2001 shape bikes. A full set of black ARD bodywork will be fitted when I've put a few miles on the bike & have had chance to iron out the inevitable creases! The wheels are open castings on one side, but no holes. I intend to fit a set of 2006-on wheels when I get chance.

I was following your mates thread, thats going to be lethal :beerchug: Very nicely done, although I think that silencer has way too small a bore for an engine that size.

I'll probably leave the top mount until I can get my spare cylinder braced/strengthened. Basically, they can crack around the base flange, new ones are £500 so dont really want to take any riscs with the only two I've got!

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for the mount situation have a look at my friends racebike, its a 500cc engine but the concept is the same.

RS 500

OOH OOH OOH I'm doing one of those next.....what KTM motor is it?

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OOH OOH OOH I'm doing one of those next.....what KTM motor is it?

it was a very complicated build, cost him a fortune he used to race aprilias and his dad tunes and rebuilds them so they have quite a few spare parts, i'm not sure what engine it is but there cant be that many ktm 500 2t engines? i would of thought they would use the same for a few different bikes. but it is a beast though

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The bodywork's just some I picked up cheap, though I do prefer the 2001 shape bikes. A full set of black ARD bodywork will be fitted when I've put a few miles on the bike & have had chance to iron out the inevitable creases! The wheels are open castings on one side, but no holes. I intend to fit a set of 2006-on wheels when I get chance.

I was following your mates thread, thats going to be lethal :eusa_whistle: Very nicely done, although I think that silencer has way too small a bore for an engine that size.

I'll probably leave the top mount until I can get my spare cylinder braced/strengthened. Basically, they can crack around the base flange, new ones are £500 so dont really want to take any riscs with the only two I've got!

maybe you could look around some kart forums and see if anyone on there has any barrels for sale? thats what i do for my rs, I have a shelf full of rs barrels as they are so expensive to buy brand new. ahh damm no holes mean they are not SP wheels (if they were i would be begging to buy them off you) 2006 wheels look really nice, ive got one on the front so that i could use the 06 forks and I plan to get a rear at some point.

that rs500 is so loud (motogp loud) that he wasnt allowed to run it on a trackday at cadwell

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I've just got back from picking my bike up, thourght I'd put up a couple of pics of the finished pipe.

4632020740_06513d3cfd_b.jpg

4631423177_6fb213a528_b.jpg

This pic shows the modified rad

4632022062_b768f5d620_b.jpg

No Devon, they're Race Services Direct rearsets. Was going to get SES ones, but these were quite a bit cheaper.

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very nice all the same, how long before its up and running?

I just need to make up the centre & rear mounts for the exhaust and then plumb the rad in, then its time for a brief 'road test'! I want to get it finished/mot'd by end of june for the Shoulder of mutton pub meet, which is only about 15 miles away from me.

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I made up the exhaust mounts & rad pipes tonight, then fired her up!! It started really easily considering it hasn't been run for about 9 months, I'm a VERY happy bunny!

On the down side, even though its fitted with a 75mm diameter x 400mm long silencer, its not exactly quiet. I think most of the noise comes from parts resonating, in fact, a couple of parts worked loose just during warm up. Time to crack open the thread lock!

;)

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Congrats on firing it up again, it's looking good. With two strokes almost as much noise is emitted by the expansion chamber resonating as the tailpipe. An easy way to reduce the noise is to wrap the pipe in some of that exhaust wrap insulation stuff. It deadens it down quite a bit, also if it's not already then make sure the pipe is spring mounted at the barrel and there is plenty or anti-vibration damping in any other mounts because they crack pretty quickly if they're solidly mounted. Ask me how I know...

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I made up the exhaust mounts & rad pipes tonight, then fired her up!! It started really easily considering it hasn't been run for about 9 months, I'm a VERY happy bunny!

On the down side, even though its fitted with a 75mm diameter x 400mm long silencer, its not exactly quiet. I think most of the noise comes from parts resonating, in fact, a couple of parts worked loose just during warm up. Time to crack open the thread lock!

:icon_puke_r:

I like your pipe, great to see a well made custom pipe for a change. Who did the design/fabrication? That should have a satisfying 'ting ting ting' noise from the pipe itself.

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Congrats on firing it up again, it's looking good. With two strokes almost as much noise is emitted by the expansion chamber resonating as the tailpipe. An easy way to reduce the noise is to wrap the pipe in some of that exhaust wrap insulation stuff. It deadens it down quite a bit, also if it's not already then make sure the pipe is spring mounted at the barrel and there is plenty or anti-vibration damping in any other mounts because they crack pretty quickly if they're solidly mounted. Ask me how I know...

The pipe is sprung at the head, and I've managed to use the standard RS125 centre rubber mount. I asked the guy who made the pipe about exhaust bandage, & his opinion was that it would keep in more heat & therefore affect the power characteristics. Apparently the extra heat can affect the pulses in the pipe and raise the revs that peak power is produced at. Mine had been designed to peak at 10'250 rpm. I had intended to use exhaust bandage to quiten it down, but he's been designing and building 2 stroke exhausts for 35 years, so at the moment Im going to leave it as it is.

I was going to take it out for a sneaky test ride tonight, but as wednesday's bike night round here (More P.c plod around!) I think I'll go into the garage, fire up the lathe and turn an adaptor to fit the Scitsu temp gauge sender instead.

:rolleyes:

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You're right about the increase in exhaust gas temperature moving the power up the rev range. It also causes the pipe to rot a lot quicker because the bandage will hold moisture next to the metal so it is a bit of a last resort.

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You're right about the increase in exhaust gas temperature moving the power up the rev range. It also causes the pipe to rot a lot quicker because the bandage will hold moisture next to the metal so it is a bit of a last resort.

couldn't you routinely dry the exhaust out?

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couldn't you routinely dry the exhaust out?

That would mean stripping the bandage off pretty much every time the bike is ridden. Raw mild steel pipes rust very easily, mine had two rusty hand prints where I'd held it to fit it, within a couple of days of fitting! I've wiped it over with WD40 now, so hopefully it should be ok for a while.

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If you're going to run it bare then you can keep the corrosion at bay by scotchbriting the pipe then rubbing duck oil into it. Doesn't burn off the same as WD40 but smokes like hell when you first put it on!

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Just got back from its first (unofficial) road test! FAIL!!!!!

I managed to foul the plug and it wouldn't burn clean, was four stroking like buggery! Then about half way round a four mile loop, the nut holding the throttle cable into the slide vibrated loose & I ground to a halt! With no tools on me it was a long hot push home.

Better luck next time. Hopefully.

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Ahh I fell foul ('scuse the pun) of the vibrations today, one of my exhausts came off! Luckily I was only doing 15mph or so. As for the fouling of the plug what sort of plug are you using? And what pre-mix ratio? It's easy to put too much oil in thinking it's safer but it leans the mixture out and causes all manner of other problems including fouling plugs.

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Ahh I fell foul ('scuse the pun) of the vibrations today, one of my exhausts came off! Luckily I was only doing 15mph or so. As for the fouling of the plug what sort of plug are you using? And what pre-mix ratio? It's easy to put too much oil in thinking it's safer but it leans the mixture out and causes all manner of other problems including fouling plugs.

Off the top of my head I think its an NGK B9EG, 10's are recommended. Its an old ex-race plug, so I think its overdue a change. Running 33:1 pre-mix, I used to run 25:1 on my LC's years ago, so this isn't overly 'rich'. I'll try again tomorrow, with a fresh plug, & after checking the whole bike for loose nuts!

Strokers :), but are more high maintainance than women!

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