YR5 Blyton Park 30/7/20

[D Peacock]

Took my YR5 to the annual 2t Big Bang event at Blyton Park. Was the only AC there but bike proved quite a draw 




Some GoPro footage here - https://youtu.be/utLqJlU2XAY

[5port]

Bike looking good!  Vid has  age blocker.

5port

[D Peacock]

Bike looking good!  Vid has  age blocker.

5port

Thanks 

Vid should be ok now, for some reason they default to age restricted unless you choose otherwise when uploading.

[5port]

Thanks Dan!   Enjoyed that.  What is the build state of the motor/pipes/comp?

Cheers

5port 

[5port]

Engine sound sweet.  You seem to use 8 as your change up revs, saw 8.5 a few times.  Obviously flexible, pulling from 5 on occasion, jetting sounding nice!  I am guessing these are a medium porting spec cylinders?  You said you were going back to standard heads, I guess also the 28mm Mikunis, foam filters and Mick Abbeys pipes?  What reeds? And plugs?     Sorry, to ask but keen to know!

5port

[D Peacock]

Engine sound sweet.  You seem to use 8 as your change up revs, saw 8.5 a few times.  Obviously flexible, pulling from 5 on occasion, jetting sounding nice!  I am guessing these are a medium porting spec cylinders?  You said you were going back to standard heads, I guess also the 28mm Mikunis, foam filters and Mick Abbeys pipes?  What reeds? And plugs?     Sorry, to ask but keen to know!

5port

Hi 

Barrels are Mick's "fast road tune", 31K pistons  standard heads, standard head gasket setup but dowled to ensure dead centre on assembly. Reed setup is bog standard RD, 28mm Mikuni VM carbs, pipes are Mick's to suit the tune, can't remember where the ignition curve ended up to be honest but i can download it if interested. Shift light is set at 8500rpm with hard rev limit at 9k. Sometimes forget how torquey it is until I watch these clips back or let someone else ride it! This is the latest dyno curve I have, with the current pipes and porting but tight squish, I think it's better with standard heads as it will rev on past peak instead of stopping dead (nor suffer from engine melting detonation).



I would like to get it on the dyno again just out of interest. It would be possible to get more peak out of it with further work on porting and heads but you'd pay a penalty on overall flexibility, currently the powerband is as wide as a standard bike but the peak is 50+ bhp rather than 30! Also 110mph is plenty quick enough for me with drum brakes, steel frame and crossply tyres!

[5port]

Great Dan!  That track doesn't seem to let you get 6th?  Think ratio's there, 3rd dropping 8 to 6.5, 4th 8 to 7, 5th - not getting 6th before braking?  Like you say, very flexible.
Yes, normal thoughts would be that it should rev better with slightly lower CR. 
Reeds.  Yes, Ed Erlenbach and Dale Alexander say don't go mad on reeds, until the tunning actually needs better.  I have done my £50 upgrade to YZ125 Yamaha plastic petals with flowed cages, supported by Ed.  However, I am hankering after buying the complete YZ85 reeds new, again Ed says his best upgrade/value option, single petal, just very minor relief of reed housing and bolt-on. Hmmm, tempted to put some in the box for the next level!
Overall, nice measured riding!  The bike ran well. Nice to see a quiet track.  How do you get on with the sound checks?

Cheers

5port   

[D Peacock]

Blyton is mega twisty, I wasn’t counting gears while riding but yeah I would be surprised if I got 6th. Could of stuck a 15t front sprocket on I guess but it was just a fun run out and the only track time I’ve had this year.

Supposedly there is a drive by limit at Blyton but I’ve never known it tripped    noise is a worry, I was right on the 105db at Cadwell last year and that’s running the long Tyga cans  the guys at Cadwell generally test at 5500rpm as they know 7000 is a bit high for an old tech 2t, I’m fairly sure it would be over 105db at 7k.

[5port]

Blyton is mega twisty, I wasn’t counting gears while riding but yeah I would be surprised if I got 6th. Could of stuck a 15t front sprocket on I guess but it was just a fun run out and the only track time I’ve had this year.

Supposedly there is a drive by limit at Blyton but I’ve never known it tripped    noise is a worry, I was right on the 105db at Cadwell last year and that’s running the long Tyga cans  the guys at Cadwell generally test at 5500rpm as they know 7000 is a bit high for an old tech 2t, I’m fairly sure it would be over 105db at 7k.

Thanks Dan,  I will be packing my TZ Ally cans carefully.  Gotta be a bugger to pay for everything and fail noise! 

5port

[Motty]

Thank you for posting the youtube link, I missed it when it was originally posted, I've just enjoyed a 15 minute ride on a lovely summers day