collapse

www.dimecitycycles.com


www.restocycle.com

www.CITYLIMITMOTO.com

www.jadusmotorcycleparts.com

www.bisonmotorsports.com

www.speedmotoco.com

www.lostapostlejewelry.com

www.cognitomoto.com

www.townmoto.com

www.sparckmoto.com

www.Moto-Madness.com

www.pistonsociety.com

www.steeltowngarage.com

OUR ADS ARE FROM SUPPORTERS OF THE COMMUNITY - CONSIDER TURNING YOUR AD-BLOCKER OFF FOR WWW.DOTHETON.COM

Author Topic: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp  (Read 14489 times)

Offline JadusMotorcycleParts

  • DTT SUPPORTER
  • *
  • Posts: 847
    • Jadus Motorcycle Parts
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #100 on: Mar 03, 2018, 06:36:34 »
About the rocker pads...  I actually did the measurements with both versions of the rockers and came up with the same results.  As with any good measurement, I took it several times then took the average - same for both.  I did this because I always thought this particular bike made slightly more power than the black one and I thought it might have had something to do with the rockers - if the ratio was slightly better, the valves would get a little more lift = a little more air fuel mixture = a little more power.  But this was not the case.  Goes to show how accurate the butt dyno is haha.

Not sure about the 5.5mm valve guides, probably is.  Thing is, Chris makes everything custom to each application anyway, so he'll turn some up in the right material and size.  Yeah, I am happy with the decision about SS instead of Ti.

Current power falls off at about 7800rpm but will rev to 9000rpm.  I basically want to be able to rev to 10000 and have power all the way up to 9500.  I think this is achievable with the weight loss program.

Yeah, will be lightening the rockers - I covered this a few pages back in the thread   :)

This amount of research is usually very unnecessary (unless rebuilding an engine to non stock spec) but I am treating it as an educational process and I am super passionate about it so it's all just really interesting to me!  I have read a few posts on your blog too, looks like you take a similar approach! 

Offline Sav0r

  • Posts: 547
    • ChrisLivengood.net
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #101 on: Mar 03, 2018, 10:02:05 »
The butt dyno is pure confirmation bias. Anybody who has ever worked with data acquisition knows this to be true.
Sav0r the adventure.

Visit www.chrislivengood.net to get more information on my RD350 dubbed Mia Wallace as well as my other projects and snafus.

Instagram

Offline JadusMotorcycleParts

  • DTT SUPPORTER
  • *
  • Posts: 847
    • Jadus Motorcycle Parts
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #102 on: Mar 13, 2018, 19:42:15 »
While preparing and packing up the head to send away for machine work, I decided to see if I could remove the tach drive system entirely.  The answer is yes.  But then there is nothing for the tach-plug I have made to push up against and it sinks into the hole in the head too deep to form a seal.  So I put it back in!  It will not be driven anyway because the cam regrind I got was done on a non-tach drive cam (missing the worm gear drive).  Anyway, if anyone was curious, this is what the assembly looks like...

Offline Eleganten

  • Posts: 115
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #103 on: Mar 14, 2018, 18:48:04 »
Why not just drill and thread a hole on the top side. Then make a aluminum plug with a flange and a plain hole? Worst outcome would be oil leakage in case the bolt unscrews and the plug comes off.

Hit me up if you want one done and Iíll squeeze it in at work.


Sent from my iPhone using Tapatalk

Offline JadusMotorcycleParts

  • DTT SUPPORTER
  • *
  • Posts: 847
    • Jadus Motorcycle Parts
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #104 on: Mar 15, 2018, 16:02:07 »
A custom plug could definitely be a solution!   You work with CNC machines?

Offline JadusMotorcycleParts

  • DTT SUPPORTER
  • *
  • Posts: 847
    • Jadus Motorcycle Parts
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #105 on: Mar 17, 2018, 12:34:43 »
A cool day for the project yesterday - I went in and picked up the parts from the machinist/engine refurbishing mob!

The rebuilt crank looks amazing, nice to know the bottom end is fresh and strong when I put extra stress on it.  He swapped out the bearing for a brand new one as well - this is a part Yamaha doesn't list on the spare parts program (rather it is a part of the crank half assembly), but he managed to source the correct one and replace it!  Woohoo.

The bored up cylinder looks really nice as well, finished with the typical cross hatch honing.  The guy said he shot for the middle of the suggested clearance tolerances and that came out at 0.075mm or something - pretty much what der_nanno suggested.  He also explained the difference in these tolerances vs the factory specs for the factory piston... Also what der_nanno mentioned a few pages back.  The stock piston is cast and expands less than a forged/machined piston like this new custom one is.  He also said that because of that, the engine might be a bit noisier than stock when it is cold - until the engine gets to temp and the piston expands and comes into it's working diameter spec.

The machined starter drive gear looks great too.  This actually ended up costing more than I thought - because it is hardened it couldn't just be turned down in a lathe with a bit, rather it needed to be ground down in the lathe with a grinding stone.

Offline der_nanno

  • Posts: 358
  • Faster!
    • Greasy Greg
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #106 on: Mar 17, 2018, 20:33:14 »
I may admit that I am an engineer by trade...  ;)

Nice to see, that your engine is coming along nicely.
Real freedom starts with the freedom of thought.

My Blog:
http://greasygreg.blogspot.co.at

My Mule TR1.1 build here on DTT:
http://www.dotheton.com/forum/index.php?topic=75458.0

My Turbo TR1.1 (XV1000) build here on DTT:
http://www.dotheton.com/forum/index.php?topic=72571

My XS Triple Sidecar build here on DTT:
http://www.dotheton.com/forum/index.php?topic=74211

Offline JadusMotorcycleParts

  • DTT SUPPORTER
  • *
  • Posts: 847
    • Jadus Motorcycle Parts
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #107 on: Mar 18, 2018, 15:25:25 »
Might need to pick your brains for the next job...  Assembling the crankcases.  Which sealant do you recommend?  Yamabond #4?  I heard 3 bond is the same product/manufactures the Yamabond.  Anyone use anything else?

Offline Eleganten

  • Posts: 115
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #108 on: Mar 19, 2018, 08:55:37 »
A custom plug could definitely be a solution!   You work with CNC machines?

I got 3 of them at workHowever I would turn it manually in the lathe and mill since that would take way less time since our 5-axis ainít running at the moment.

Just send me a drawing and your address and Iíll try to sort it out for you.


Sent from my iPhone using Tapatalk

Offline der_nanno

  • Posts: 358
  • Faster!
    • Greasy Greg
Re: Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp
« Reply #109 on: Mar 19, 2018, 11:25:59 »
Anyone use anything else?

I use Elring Dirko HT (red), with great success. Especially as it's a lot cheaper overhere and it comes off very easily with just a bit of Acetone. And a little bit goes a very long way, i.e. a tube will last you several engine cases.
Real freedom starts with the freedom of thought.

My Blog:
http://greasygreg.blogspot.co.at

My Mule TR1.1 build here on DTT:
http://www.dotheton.com/forum/index.php?topic=75458.0

My Turbo TR1.1 (XV1000) build here on DTT:
http://www.dotheton.com/forum/index.php?topic=72571

My XS Triple Sidecar build here on DTT:
http://www.dotheton.com/forum/index.php?topic=74211