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YR5 Upgrade project

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redeem ouzzer
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PostPosted: 23:04 - 13 Dec 2017    Post subject: Reply with quote

While my YR5 was in bits getting it's dodgy side stand bracket fixed I decided to pull the clutch cover off and investigate the somewhat erratic clutch assembly. Didn't find anything obviously wrong with the clutch Sad

But did discover a primary gear in the process of eating it's way through the clutch side crank seal :o

https://i.imgur.com/5kbFrGX.jpg

https://i.imgur.com/tngyazg.jpg

https://i.imgur.com/Hgb9IIm.jpg

The later RD's use ribbed crank seals so this can't happen, and it's fair to assume Yamaha changed the design for a reason. I've taken the plunge and sourced a set of later cases from an RD250B, which also gives me the bonus of a Euro spec 6 speed box with close ratio 4th / 5th / 6th, certainly a desirable modification!

The bottom end I bought had some damage from a previous chain break so so it's away getting welded, then I can get on with building what is hopefully the definitve engine. I'm also well on with rebuilding the rolling chassis after the stand repair, going for clipons this time, lighter headlight brackets and a new clock setup (couldn't be arsed with Koso / Acewell shit so homebrewing something with various old Yamaha bits that should work well and cost sod all). Pics to follow over xmas.
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stevo as b4
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PostPosted: 00:27 - 15 Dec 2017    Post subject: Reply with quote

That's a pain, having to rebuild a low mileage well set up motor and with new cases. But I bet your glad you found out when you did about the munched up crankshaft oil seal, as it could have got nasty if it failed on track maybe.

Im in a similar position when I get my KMX back from the pipe builder, I'm going to have to rebuild the top end with a brand new OEM cylinder and piston, as the 500mile old rebuilt motor has a liner fitted. Its running ok, but is down on power by about 2bhp or so.

Not worth what I'm spending on aftermarket parts to improve performance, to throw away that kind of power, which while it's a trivial amount, on a 125 it's quite a significant number.
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redeem ouzzer
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PostPosted: 00:04 - 01 Feb 2018    Post subject: Reply with quote

I've been busy but most of it's been waiting for my tuner / fabricator to work his magic.

Crusty 250B euro spec bottom end complete with Smilered top case from broken chain.

https://farm5.staticflickr.com/4675/39301755024_4dc28f4e73_k.jpgIMG_3845

And after blasting and artisan level repair. Looks better than original.

https://farm5.staticflickr.com/4748/39301753534_a7800a9b38_k.jpgIMG_3938

Engine is back together (Vito crank, top end and gearbox bearings from original engine combined with 6 speed CR box and dropped in new casings with later crank seals) and back in the frame.

Major point of consternation has been the clocks. The chinese specials originally fitted looked good but didn't work and the rogue battery issue took out most of the LED's. I toyed with the idea of using a Koso or some shit but it's a lot of money. So I came up with this -

Butchered original clock bracket in unholy matrimony with a 250/400E clock bracket. 250/400E Speedo, TDR250 tacho using LT pulse from coil (seems Yamaha do the calculation for wasted spark in the clock rather than the CDI so it reads fine), i couldn't get any tacho to respond to the pulse from the Zeeltronic unit. Light unit from egay.

https://farm5.staticflickr.com/4750/26138482338_1b2ef070dc_k.jpgIMG_3955

Test fitted ok, wiring harness made. I've stripped it to paint all the metal work and will fit it properly at the weekend. Also in the photo note presence of clip ons and preload adjustable fork caps, because race bike.

While speaking to my tuner about the upper case fail it transpired he had a set of the Indian 350 barrels in his cupboard that never made it onto his 250 special. Price was agreed plus cost of doing the same tune onto them before collection. Once i get them decked and some pistons sorted i'll have a spare top end of the same spec so if i have any issues or it needs a rebore I can just swop barrels.

https://farm5.staticflickr.com/4745/39979516302_7c7b608637_z.jpgIMG_3935
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trevor saxe-coburg-gotha
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PostPosted: 13:54 - 01 Apr 2018    Post subject: Reply with quote

There's a similar bike w/ track mods in last months Practical Sportsbike.

https://www.greatmagazines.co.uk/covers/large/w300/current/pracbikes.jpg
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redeem ouzzer
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PostPosted: 22:19 - 02 Apr 2018    Post subject: Reply with quote

trevor saxe-coburg-gotha wrote:
There's a similar bike w/ track mods in last months Practical Sportsbike.

https://www.greatmagazines.co.uk/covers/large/w300/current/pracbikes.jpg


Yeah I saw that. Almost identical to mine Wink
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stevo as b4
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PostPosted: 23:45 - 03 Apr 2018    Post subject: Reply with quote

How much of the gains you saw in performance do you feel can be attributed to the tuned cylinders alone?

I'm stopping at 125 tuning at std port maps, as I just want to see what everything else can do for my engine and see the best numbers I can, before fitting a ported 191cc top end and starting again.

Silly way to waste money, but I'd only go buying new or more bikes if I didn't mess with it until my curiosity has been satisfied.

Would you go to a YPVS lump in yours if you wanted to develop it further, or do you have a line to draw under it too?
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redeem ouzzer
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PostPosted: 21:13 - 08 Apr 2018    Post subject: Reply with quote

stevo as b4 wrote:
How much of the gains you saw in performance do you feel can be attributed to the tuned cylinders alone?

I'm stopping at 125 tuning at std port maps, as I just want to see what everything else can do for my engine and see the best numbers I can, before fitting a ported 191cc top end and starting again.

Silly way to waste money, but I'd only go buying new or more bikes if I didn't mess with it until my curiosity has been satisfied.

Would you go to a YPVS lump in yours if you wanted to develop it further, or do you have a line to draw under it too?


I think the tuned cylinders make a hell of a difference, as well as the JL pipes. You can’t make power without revs and the JL pipes extend the rev range which also fits in with the easier breathing from the bigger ports. The ignition makes it a) more reliable and b) gives the ability to ease some of the peakiness which will always be an issue with a massive fixed exhaust port and huge expansion chambers. It’s still fucking useless below 7k in higher gears but before fiddling with the curves it had a huge hole at 5.5k where it would buck and stutter. I can also back it off near the redline to help cooling and reliability. The squish is a bit big at the moment, it wants to be 0.9mm but it’s about 1.2mm, so that’s a job to do. Other than a dyno session once the squish is done that’s about it, possibly a switch to YPVS reed blocks. Once you cross the 60bhp rubicon on an aircooled you start poking the unreliability god with a big stick as well as making it even more horrible to ride.

Funnily enough I was considering the YPVS route in the bath earlier, but narp, I want it to maintain its aircooled routes and then you’d be looking at R1 front ends and monoshock rear, which defeats the point as you’d be better off buying a 3MA or 3XV.
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Hahadumball
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PostPosted: 10:34 - 28 Apr 2018    Post subject: Reply with quote

we know youre getting on a bit dan but can we have more pics and updates Mr. Green Mr. Green
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redeem ouzzer
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PostPosted: 18:04 - 08 May 2018    Post subject: Reply with quote

Despined_By_Ex wrote:
we know youre getting on a bit dan but can we have more pics and updates Mr. Green Mr. Green


Demanding c**t Laughing

Due to my GSXR400 being a complete bitch that decieded after winter it wouldn't crack 65mph I had a quandry with a Bennetts trackday at Donnington at the end of March. It was cheap (£85.00) and i was tempted to save the van hire and not go. I wasn't planning on taking the 350 as I wanted to sort the squish and get it back in the dyno. However the realisation i couldn't cancel my hotel room and the fact i rode it the week before and it didn't break coerced me into taking the old bastard.

https://farm1.staticflickr.com/912/28106754628_fbb42fb1be_b.jpgIMG_4062 by Ian Brandon Anderson, on Flickr

She did fine, Donnington is a fast circuit and small bikes get crucified round there if you know what you are doing. Bastard headers still blow slightly but I had no issues other than the fact it's peaky as fuck and therefore a bit dangerous in wet / drying conditions (first session was a bit hairy, took care tapping it on in 2nd and 3rd).

Future jobs are sorting the squish, getting the heads dowled and possibly doing yet something else with the clocks. But as it's together and running nothing will be happening untill later in the year, i plan to take it to the Isle of Man for the classic TT.
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redeem ouzzer
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PostPosted: 08:51 - 23 Jun 2018    Post subject: Reply with quote

I took it to Cadwell for the Classic Bike Trackdays weekend (along with my now fixed GSXR400).

It worked pretty well, I split the sessions equally with my 400, ended up doing 170 miles / 78 laps over the weekend, and i basically thrashed it till the shift light came on in every gear without an issue.

https://farm2.staticflickr.com/1836/42913632152_da3838befa_b.jpg

https://farm1.staticflickr.com/899/29090717288_88611ed4be_b.jpg

However my ground clearance issues are not solved...

https://farm2.staticflickr.com/1814/42061571905_a58d502d34_b.jpg

To be honest i'm pretty dissapointed in the JL pipes. They are pretty to look at but they still deck out, i can't stop them leaking from the headers for more than a few hundred miles and they need a sympathetic noise tester. My plan is to get Mick Abbey to make me a set of bespoke pipes over winter with the focus on ground clearance and also increasing midrange.
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Suntan Sid
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PostPosted: 08:33 - 26 Jun 2018    Post subject: Reply with quote

That's a real bummer with the clearance and fitting problems on the pipes, the bike does look exceptional though! Thumbs Up

You have a PM.
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