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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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First action item - pistons. Mike will be on that Monday morning for OEM ones.

I purchased some NOS pistons off eBay, but they are MC19 pistons, not MC22. Poor attention to detail on my part. I paid $100 for them delivered, any one need them? According to Mike, he'd use them in any engine.

$80 USD plus shipping.
Good 'ol Chinese :poop: , have a look at the pins & clips, no way I'd use them, but I have these pistons in my engine, with ceramic thermal barriers, so far, they are doing the job.
CP Pistons will make you a set of forged Cibbie pistons, they once had a MC19 sample of mine, but at $500 EACH , bare, I couldn't bring myself to get 'em made
PS a set of OEM pins and clips from CML cost more than the Chinese pistons, with rings/clips/pins, but I trust 'em
The radiator is being removed tomorrow and being taken to a business that makes heat exchangers work more effectively. One of the staff is a racer that I tune for and he believes he can bring the running temp down from 80C to 60-65C. No idea how long it will take but we have 4 weeks until the bike needs to be ready.

The good news, the muratic acid wash/rinse of the radiator clearly helped!

Race pictures due in the next week.
race images from round 3


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Trophy's are always good!
Just took the cylinder upper case with pistons to a machine shop for the .75 overbore. ETA 2 weeks hopefully. Head being ported around the same time so pictures will be taken of before and after Stuck with rod and case bearings, all now N/A unless anyone has a secret stash or source for a bearings manufacturer?

That means one more race on the Adelaide engine.

radiator due back tomorrow and they found small fractures in it so it is now sealed up tight and pressure tested to 20psi with no leaks. Hopefully the pressure test didn't create any new cracks lol.
There was a slight delay on getting the radiator back in, but now the bike is back together! Fontana radiator repair did a great job in all aspects of keeping me informed, high quality work and great turn around time. Don't hesitate to use them! I need to get the bike onto the dyno before the race weekend (2 weeks away) just to make sure there are no surprises at all that I can deal with now, not on the race weekend.......


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Thanks for the tip on bearings. I'm also going to contact Performance Coatings (performance) to see what we can do with the OEM bearings. Worth asking the question! I'll let you know what I find out.
I would be prepared to give the Chinese shells a go, providing they are uniform shape,size and installed with correct clearance (+ a bit for racing applications), after all, a film of oil provides the means of isolating metal to metal contact, not the shell.
hey mate, nice work.

always good to see someone sinking money into making these little cibby motors work harder.

OE comp ratio of an MC22 L/N engine is 11.5:1 and MC19 is 11:1. If you fit a 22 head to a 19 block you will actually go down in compression due to the difference in piston/chamber shapes. this worked out to be about 1cc which is huge when you consider the chamber squish volume is about 4.9cc to start with on an MC22.

if you try a 19 head on a 22, the piston will actually strike the quench pads on the side of the chamber. this is a less than ideal scenario lol, so i would advise against that course of action.

as for the cams, i have more sets of camshafts than i care to admit and there is no rhyme or reason to the markings. they appear to be batch marks and my only educated guess is that they are based on the journal grind diameters not the actual lobe grinds. the difference between the grinds is half a millimeter extra lift on the MC19 camshafts over the MC22 L/N. The timing on open/close for both is identical but on such small camshafts .5mm is nothing to laugh at.

also, if you have any gear which is marked KAZ-G [CDI or head] get rid of it as it is the HP limited post 94 gear. the short block from a post 94 engine is fine but the head is a piece of shit. with tiny 26mm ports and choked out cams it is pretty useless in an engine you want to see gains from. though to be fair, it does have potential for torque tuning applications as opposed to peak HP but there just isnt enough displacement for any real gains there.

controversial, but i also recommend removing all of the scissor gears off your cam gear train if it is a race bike. why? less rotating mass. less contact friction.

as for knife edging the crank, i would personally advise against this unless you intend on having the crank balanced professionally afterwards WITH the weights of the piston/rod assembly bolted onto the big ends. i suspect that you would have to add some rather hefty mass back onto the crankshaft to dampen a lot of the inherent harmonics out of it afterwards. maybe just polish the shit out of it for a little less splash resistance, but not that it would achieve much.

finally, if you insist on running without a thermostat, please put a restrictor the size of the open thermostat into the housing at least. these motors LOVE to cavitate their coolant without them. your impeller will thank me later...
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finally, if you insist on running without a thermostat, please put a restrictor the size of the open thermostat into the housing at least. these motors LOVE to cavitate their coolant without them. your impeller will thank me later...
Yep, what he said, I replaced the thermostat with an alloy plate, same size hole in the center as the internal coolant hose size, so far so good.
I tried 2 thermostats, but neither would open fast enough resulting in boiling coolant in the head return pipes, with a cool radiator.
Tiny :hail: 's to Moot's wisdom
Sorry for being away but the race report from the last round is here:

2014 Race reports | Feel The Track

The next race weekend is in 4 days, so I will have to wait for the following week to do some very careful inspection using Mr. Mootavic's sage guidance. I'm hoping I don't find that I have everything I don't need on the race bike and then need to buy a lot more parts. That being said, SA Motorcycles in Adelaide sent me some MC19 cams from an actual MC19 engine (the wrecking yard is very close to them) so there's a step in the right direction.

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 find valve springs and bearings either. Has anyone tried these in their engine?

Piston Piston Rings for CBR250 MC22 Size Std 4sets | eBay

The wrecker engine that is in the bike will get me to the end of the year with 2 races left, then I'd like to build a 'proper' motor for next year over our winter with all the bells and whistles. I'd like to do it right the first time, but suspect pistons might be very expensive if they grenade.

If anyone has any leads on pistons, I would appreciate the assistance. Over standard bore is fine too!

Cheers everyone and I'll let you know how the race weekend goes!
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As I don't have a thermostat to use as a guide for measuring, can I get the plate dimensions from you please? Thanks in advance!
This is what I found on the head that we have (see pic). We measured the intakes where the carbs seat and they are 26mm. This is the original race engine that made 40bhp. I'd like confirmation that this is the head we do not want.


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Dave - you should investigate comiming to Australia for the International Island Classic - there is a pretty large USA contingent that sends their kit over in containers. You may need to remove a little bit of the fancy kit from your bike to be eligible for 250 production - standard suspension, and old school race glass (we have moulds so that is easy to source). Would be quite awesome to race against some internationals in the Period 6 250 Produciton class!


I was told that the container was full earlier this week as I was planning to head over. Interesting coincidence.


Wait - perhaps there might be a bike I could "rent" for the event? I can't image it is stock suspension? Stock on the outside versus the inside? Tell me more about the stipulations for suspension if you'd be so kind or point me in the direction of the rule book. I'll be in NZ then doing a DMT Jan and Feb suspension school tour so it would be a quick flight over! Planning on being in Aussie November and December. Putting the trip together now for Darwin, Brisbane, Tasmania, Adelaide and Perth.
Good to hear your coming back to Tas Dave, hopefully I can get in a setup day with you this time!
Motorcycling Australia is our governing body http://www.ma.org.au/

There is the Barry Sheene Festival of Speed http://www.barrysheene.com.au/

Sorry I can’t dig up a good link to the Island Classic
Round 6 race weekend with AFM is complete and the race reports are posted. Enjoy!

2014 Race reports | Feel The Track
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