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So this is where I belong!

23593 Views 116 Replies 20 Participants Last post by  davemosstuning
I put my intro up but added ?'s on my race bike that I want to get 50bhp out of. Those ?'s should have gone here, so the entire season long thread will stay here with pictures!

I've no real idea what I have and scoured Mr. Scrooge's thread and the FAQ database for questions on pistons, head gaskets etc. I've gathered a lot of information on the web as well, but now I need more guidance.

Will engine numbers give me the year of origin and therefore tell me if I have a 17 or a 19 version? If so, is there a link/site I can go to in order to check those engine numbers? I gather there are ways of recognizing heads from Mr. Scooge's page so I'll look at those carefully when the heads come off.

I have 2 engines to build - the 3rd is currently in the race bike but tired. One needs pistons - NOS or OEM? I'm not an engine builder, so I'll post lots of pictures and that will help others doing the same thing. Every nut and bolt will come apart - that is a definite.


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I've bought some NOS pistons that are unknown to me in terms of use/quality/durability as I can't find any new OEM, no matter what country in the world I search. Can't
If anyone has any leads on pistons, I would appreciate the assistance. Over standard bore is fine too!
Wiseco HIGH-PERFORMANCE PISTONS from Barton Powersports

Red book racing (LSR, Canada) look on facebook , sleeved down a 250/4 Yam, using Wiseco pistons (special order low comp), the same Wiseco pistons folks tell you are NOT available in small sizes (forged) the above piston size table tells a different story
Maybe slight mods would be needed in the valve pocket dept, but late model 50/80cc 4 valve single pistons look promising ?
Has anyone tried these in their engine?

Piston Piston Rings for CBR250 MC22 Size Std 4sets | eBay
Yup, I'm using them now,,,,,,,,,,,,,,,
Thanks very much for posting this information up. That makes me feel better about the purchase of the pistons. We'll measure everything very carefully indeed to be sure for the race engine obviously.

I'll move on and get into the Wiseco info now.

Again, thank you!
The wiseco pistons have a LOT less skirt than the CBR slugs do, so they would be a lot lighter (balance ?)
Remember to make sure any pistons you choose have 13mm pins (thats the hard part to find info on)
Pin center to crown, critical dimension,,I think this was in the "too hard basket" for manufactures , but if you have one on hand, I'm sure you could do the math.
That's a great point on piston balance based on dimensions and a shorter skirt. That could get very ugly in a hurry. I think I will box up a piston and send one off to see what they have. That will leave me 3 other pistons to send to other manufacturers at the same time. Thanks!
One of my OEM pistons has flown to the USA.Germany, back to the USA , then from Woosner to JP, back to Woosner, a road trip to Bonneville, then back to Oz with a mate, who forgot to bring it to lake G this year, maybe it'll be reunited with me next year (I hope it took photos)
Final race report and results posted:

2014 Race reports | Feel The Track

The final class standings are in that report? Curious to see if I won the championship? Read on .........

It has been a remarkable year indeed and thanks again to Evan at SA Motorcycles in Adelaide who saved my season with a junk yard motor.
How did the coolant temp go ? Did you go with my recommendation (the un tested one ) when removing the thermostat ?

Didn't have the time and the machinist flaked on the build. @#$%^&*. That being said, I have another person very interested in the project in general who may be up for learning a lot about this engine/cooling system/ignition etc. Thomas and I are going back and forth with PM's on getting my iginition changed for next year based on all his work and learning. I can see winter being mad as I have very little time for this with travelling so much in the southern hemisphere through the end of February.
If only Thomas could copy his brain onto a thumb drive,,lol,,,(your blood is worth bottling also Thomas)
I'm getting 99 degrees C from the coolant returns from the head after a mile after a warm up , I keep forgetting to feel the radiator temp :mad:.
Best I start using my full face helmet,,my face starts flappin' before I get into 5th gear making vision limited,,,,,,,
End of race season review

What started out as a pipe dream with the mini blade (not that kind of pipe.....) ended with a championship in the first year of trying. It was a bold claim to the prior owner that I'd get the championship as I'm not a binary rider. I personally need to progress through learning and fear management and that takes time in understanding the bike and pushing it along with chassis and suspension revisions to make it work better to support faster lap times. Add in that I never practice as I'm too busy helping other racers with suspension support all weekend (other than 4 laps Sunday morning to check everything works), and that makes the achievement even more humbling as the riders in this class are top notch with finishes often in the .5 of a bike length range over start finish. It is not unusual to have the top 5 riders separated by less than one second.

I did not doubt the ability of this bike - let's make that clear. Given what stock suspension and swing arm offers in terms of flex, the build revisions of RVF forks and triples and the CBR400RR swing arm made the handling of the bike far more predictable. Those changes matched the rigidity of the frame and brought a very even platform to the track to push harder with. That did therefore expedite learning dramatically, but the that kind of learning is also very high risk indeed as you have no idea how the bike will talk to you when things go pear shaped/turn to custard. All part of the racing game of risk and reward right?

So what does that mean for this winter?

It means that the bike will come down to the frame and be rebuilt from the ground up with new everything including all chassis bearings, bushings etc if they are available. The original engine has been stripped as you have seen in this thread and the parts sent away for REM/cryo. There are many suggestions on the table as to what to do with the engine:

- light head porting
- removal of scissor gears
- acquisition of a lighter flywheel
- MC19 cams
- other as yet not discussed engine changes via Mike Norman of GForce when he looks at the engine very closely.

I would be happy to read about what others have done to their engines and the +ve/-ve effects of those changes. I don't want to blow up a brand new motor given parts are so scarce and I need longevity not outright BHP. I can learn to be a better rider and lose more weight (to a point) with a focus on being a better rider. To that end I am committing to practice days where I won't be coaching 1-1, working on suspension etc. Just me, the bike and a test plan.

It has been a remarkable year indeed and thank you all for following this project. In between touring Australia and New Zealand this winter teaching and coaching with workshops and suspension schools, I'll have to find time to get the bike built prior to the end of December.
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Do you have any spare intake boots for 94+ machines? I am in the u.s. and am hoping to avoid waiting weeks for parts from AU/JP/EU.
No spares unfortunately thebeefsalad. Sorry about that
Work starts next week on the race engine. All the parts are back from Cryo treatment and cylinder boring for the oversize NOS pistons off eBay so we will start with the head/porting and general clean up. MC19 cams will be installed and the valve seats will get a 3 angle cut.

Our big headache will be rod and crank case bearings that seem to be unavailable no matter where in the world we look. Any assistance there would be appreciated.

I'll post pictures as we work on it sporadically over the next month.
Looking forward to this!
please include lots of photos and info on the engine build!
Just about to go to my first track day with a new set of MC19 camshafts installed in my RR, took a bit of playing around to get the carbs tuned properly with them, low vacuum at idle and midrange made the motor run really rich, but after about 8500rpm it tries to pull your arms out of their sockets! Can't wait to see how it runs at the track!

(I removed the scissor gears while I was at it, it's a little bit noisier but I don't mind... if it gets a little bit more top end power then I'll be happy!)
Any more news on your bike Dave? I know you've been busy, travelling etc. Was gutted I couldn't come down to Cycletreads to catch up with you the other weekend. Hope you're doing well though! :)
Right then......

Yes I deserve a royal bollocking for being away so long. Cliff notes to save time

- All motor parts back from processing, currently in Los Angeles and awaiting their return to the race shop in Milpitas some time this month
- no photo's available to me yet of the parts so I will take them when I see them
- eBay pistons are MASSIVELY heavy compared to stock so we are looking at testing hardness and possible machining for weight reduction
- head porting started, 50% done

- need to follow the links for bearings so thank you for those

Round 1 race report here: 2015 Race reports (2014 below) | Feel The Track

Used the stock air filter for Round 1 and need to dyno the bike compared to the foam air filter that was in it to see what the differences are. Rides much better with the stock air filter.

More coming in the next few weeks so thanks for your patience and your support of this thread!
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