DizzyRebel
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Registered: 2nd Jan 09
Location: Lincoln
User status: Offline
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Danny had complained of low compression and sought after my services to give his pocket rocket a clean bill of health. The logical remedy was a new set of piston rings, so he ordered a new set of genuine rings and head/base gasket set. The parts arrived on wednesday so we decided thursday would be the date of attack.
The service history stated a full service and top end rebuild in february, but as we came to find out it wasnt as mechanically sound as the ebay add had led him to belive.
Well at 10am this morning the happy chappy turned up and my door and we wasted no time and begun to crack on! It wasnt long before obvious signs of neglect and bodgery were apparent. I first spotted this:
The front engine mount bolt was missing its nut and flapping about, although not terminal it prepared us for what else was in store.
Next up after draining the coolant and removing the cylinder and head bolts (that looked like they hadnt been touched since the day it was first assembled 9 years ago) i removed the cylinder to reveal the cause of the low compression:
The piston was scored badly and showed signs of partial seizure, inspection of the barrel showed signs of wear but luckily it was still useable. It turns out this was the culprit:
This is the main oil feed into the carb nipple and it has a huge split in, the previous owner/cowboy had tried to bodge it up with some rubber/tape/silocone/mastic concoction that was allowing it to leak and consequently starving the engine of oil. It looks like we caught it just in time otherwise the damage could have been much much worse. you can see the bodge is this photo if you look at the oil feeds closely:
I also noticed the powervalve blade and housing had been assembled in much the wrong way, and that the blade was seized inside the exhaust port and the cable had snapped. I later removed and freed this up.
However now we had a dilemma as the piston was shafted and we only had replacement rings. A quick browse on the internet revealed an aprilia piston stockist in beeston, notts (about 40 miles from lincoln) so without haste we jumped in his car and sprinted off to GT motorcycles to pick up a piston. Upon arrival i have to say the shop was an absolute shit hole and the service wasnt very pleasant or helpful at all, none the less we got our bits and swiftly left for a much needed toilet stop!
In no time at all i had the engine back together ready to put the carb, airbox and newly 'professionally bodged' oil feed line back into place:
So without haste i continued to put the bike back together, fixing other bodge jobs along the way. Also fitted a new speedo drive whilst we was waiting for the oil pipe to set.
After filling it up with coolant it was crunch time, would the new piston be ok in the worn barrel? Sure as hell i worked my magic and it fired up on the first press of the button, it sounded nice and crisp (or 'fucked' as danny describes a 2 strokes sound) and it was ready to roll after the coolant system was bled:
So i sent him on his way after he crossed my palms with gold. after shakedown he reported back to me as it running well, so i was pleased with the result! I guess the morale of the story is take somone with you who knows their game to view an ebay purchase before you commit to it, as this little one had a fair few niggles and could easily have cost the purchase price again in repairs of he didnt bring it to me as soon as he did.
Just keep your peepers on the road now danny and stop watching your rev counter! 
[Edited on 09-04-2009 by DizzyRebel]
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_Allan_
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Registered: 24th Mar 04
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Nice one Dizzy, and nice write up.
The previous owners was clearly a muppet, why and try and bodge a simple pipe that could be replaced 
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dannymccann
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Registered: 9th Aug 06
Location: Doddington, Lincolnshire
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I learnt loads today though, absolute star, wasnt expecting such a large write up either. Still cant believe how shit that oil feed was 
edit - this lad knows his shit too, I reckon he could of almost done it with his eyes shut the way he was going round the inside of the bike, especially in the tight conditions he gave himself to work with
edit 2 - and now I have a speedo too, no more guessing the mph as im going through the Gatso's 
[Edited on 09-04-2009 by dannymccann]
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Ben G
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Registered: 12th Jan 07
Location: Essex
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thats a lovely looking bike 
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DannyB
Premium Member
Registered: 6th Feb 08
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I really wish I was as mechanically minded as some people on here 
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Ben G
Member
Registered: 12th Jan 07
Location: Essex
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quote:
Originally posted by DannyB
I really wish I was as mechanically minded as some people on here
but you're not so you'll just have to live in envy of these people, much like i do
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DizzyRebel
Member
Registered: 2nd Jan 09
Location: Lincoln
User status: Offline
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quote:
Originally posted by dannymccann
I learnt loads today though, absolute star, wasnt expecting such a large write up either. Still cant believe how shit that oil feed was
edit - this lad knows his shit too, I reckon he could of almost done it with his eyes shut the way he was going round the inside of the bike, especially in the tight conditions he gave himself to work with
[Edited on 09-04-2009 by dannymccann]
Well at least its sorted now mate, was easier than doing a crank and conrod on it too! Im glad i know my shit too, after doing 50-60 of these in my time id be worried if i didnt know my way around one lol! The oil feed was epic though, only a true retard could have put it back together like that!
PS you look nothing like your avatar, i thought those bunny ears were the real deal
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DannyB
Premium Member
Registered: 6th Feb 08
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rofl Ben
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Luke
Member
Registered: 9th Dec 05
Location: Oxford Drives:Corsa B C20LET
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Nice read there mate. Top work indeed.
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Ojc
Member
Registered: 14th Nov 00
Location: Reading: Drives : Clio 197
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Brilliant mate.
Full power? Is that a full Arrow system or just the end can?
Dizzy, when me and my mates fitted the Arrow systems to our Aprilias we found that we lost bottom end acceleration but gained a big chunk mid range, common?
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dannymccann
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Registered: 9th Aug 06
Location: Doddington, Lincolnshire
User status: Offline
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According to Dizzy (not me, I know shit all) its a standard system with just Arrow end, which is the best combination.
Not full power at the minute due to the broken power valve cable, although now I have a speedo im quite surprised at how quick it is
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DizzyRebel
Member
Registered: 2nd Jan 09
Location: Lincoln
User status: Offline
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Full power bike, minus pv cable lol
Yeah the arrow system gives an illusion of 'fake' power, much like a vtec. It moves the power band further up the rev range and makes the bike feel more peaky. However on the dyno it shows the true effects. B2B with standard the arrow pipe moves the power band further up the rev range and shortens it somewhat, but actually it looses some top and bottom end power in the process.
The best combination is a pre 2000 expansion chamber and arrow end can, as the end can gives an extra 2bhp over stock on the dyno being straight through. The expansion chambers are rare now as most have rotted away, this lucky chap has the genuine one though so once it hads a new pv cable on it it will fly!
[Edited on 09-04-2009 by DizzyRebel]
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_Allan_
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Registered: 24th Mar 04
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It is for the 125 but I had a full arrow system on my RS250 and it pretty much improved the flow right through the power range. Plus sounded the nuts 
On the downside corroded like fuck a the mere hint of moisture. Had to get the headers and pipes coated right up to the Carbon/Kevlar cans. Looked ace though and amazing weight saving over the OE system.
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Sunz
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Registered: 12th Jan 07
Location: SE England
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if you upgraded the full exhaust you couldn't just bolt it on and go/
Carbs will need setting up etc, rejetting or so Ive found personally.
Get the damn cable then 
looks nice, will be good for the summer.
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DizzyRebel
Member
Registered: 2nd Jan 09
Location: Lincoln
User status: Offline
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quote:
Originally posted by Sunz
if you upgraded the full exhaust you couldn't just bolt it on and go/
Carbs will need setting up etc, rejetting or so Ive found personally.
Get the damn cable then
looks nice, will be good for the summer.
Yeah they need down jetting to give them some top end back, but need the port timing altering to work correctly with the arrow pipe. They come with a 120 main jet in the box now to fit with the pipe iirc.
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Ojc
Member
Registered: 14th Nov 00
Location: Reading: Drives : Clio 197
User status: Offline
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Another question Dizzy.
The pre 99 RS125's as per this
When they started phasing in the bubble shaped rear ended ones in 99, we found the older shape was faster in every aspect, acceleration/top end. They were all standard.
The new ones were just slower.
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Ojc
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Registered: 14th Nov 00
Location: Reading: Drives : Clio 197
User status: Offline
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(and I know that's a pic of a 50cc)
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richc
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Registered: 24th Mar 07
Location: Ilkeston
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As regaurds Dizzy knowing his shit...
I was just thinking,
Being a bike mechanic, he will know 2 stroke aprilias like the back of his hand
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jr
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Registered: 20th May 02
Location: Kent
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nice one dizzy
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DizzyRebel
Member
Registered: 2nd Jan 09
Location: Lincoln
User status: Offline
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quote:
Originally posted by Ojc
(and I know that's a pic of a 50cc)
Yeah the old ones had a 123 rotax engines as opposed to the updated 122 type engine in the post 99 bikes. Port and head design was slightly better on the 123 and the biggest difference was that they fitted a 34mm carb to them whereas the 122 comes with a 28mm carb for the euro emissions regs.
The 123 is faster, but it isnt as reliable as the 122 as certain aspects of it were flawed in design. With some minor porting and flat top piston + head kit coupled to a boyesen reedblock, 34mm carb and JL pipe the 122 can be made into an absolute screamer.
Ps i had a 50 exactly the same as that as my first bike lol.
And yes, i do know them like the back of my hand - most of my first years training was done on one!
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richc
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Registered: 24th Mar 07
Location: Ilkeston
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Tbh though, i think they are only unreliable, and they get into the hands of the young chavs who dont put decent oil in then, and thrash them from cold!
(not saying your a chavy danny, but at some point, it probably owned by one
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Ojc
Member
Registered: 14th Nov 00
Location: Reading: Drives : Clio 197
User status: Offline
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quote:
Originally posted by DizzyRebel
quote:
Originally posted by Ojc
(and I know that's a pic of a 50cc)
Yeah the old ones had a 123 rotax engines as opposed to the updated 122 type engine in the post 99 bikes. Port and head design was slightly better on the 123 and the biggest difference was that they fitted a 34mm carb to them whereas the 122 comes with a 28mm carb for the euro emissions regs.
The 123 is faster, but it isnt as reliable as the 122 as certain aspects of it were flawed in design. With some minor porting and flat top piston + head kit coupled to a boyesen reedblock, 34mm carb and JL pipe the 122 can be made into an absolute screamer.
It's only taken 10 years to find out the answer as to why the older ones were faster and now I know.
Thankyou.
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sand-eel
Member
Registered: 15th Mar 07
Location: carluke/braidwood--IRNBRULAND
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I love working on 2 strokes, they are so simple
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Ojc
Member
Registered: 14th Nov 00
Location: Reading: Drives : Clio 197
User status: Offline
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quote:
Originally posted by sand-eel
I love working on 2 strokes, they are so simple
They are, my mate had an 80cc AF1. That thing was a beauty to ride, I prefered to ride that than the 125. It was fairly quiet, it used to just be so smooth and it would do 80mph (on the clocks)
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22B
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Registered: 9th Sep 04
User status: Offline
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quote:
Originally posted by sand-eel
I love working on 2 strokes, they are so simple
agreed, on my Yamaha YZ 125 I can strip it down and have a new piston in within 25 mins, as long as the barrel doesnt require a rub down. Can do a complete clutch change in no time, infact pretty much any job can be done with minimal time, as long as you know what your doing.
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