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Completely blown engine

19K views 34 replies 14 participants last post by  tartan_warrior 
#1 ·
So here's my sob story. Riding at COTA this last Saturday, in the second session my CBR600RR starting blowing a little oil from a hairline crack in the clutch cover. (Crack was caused by getting t-boned while racing in NOLA the prior weekend.)


So I switched to my CBR250R. Second session out on the little blade, going down the long back straight, shifting up into 5th, there is a large "clunk" and then grinding. I pull off and get picked up by the sag wagon. Putting the bike in the trailer I notice my belly pan is about 1" deep in oil. Taking it off the trailer, I notice that there is a 3" hole in the front of the crankcase - I can easily see into the internal workings of the piston and shifting stuff. Doesn't look good. Pieces of metal all mixed in with the oil in the belly pan.


I'm going to take the motor out and let a mechanic look at it to see the Takagawa big bore kit parts are salvageable. If not, I then need to decide whether to put in a stock engine (about $5-600 on ebay) and sell it (which would require some title work, as I never transferred title and just rode it on the track), or part it out.


In which case I need to decide on what the next ultralight track bike will be. Maybe a KTM390; Ninja 300? I love the cornering of the CBR250R, but any 250 is now underpowered and can't compete in the class.


The good news is I was able to fix my CBR600RR that night and ride all day on Sunday.
 
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#4 ·
Holy crap. That's nuts.

I wonder if the big bore kit proved too much over time for the lower internals? Maybe since you'll have it apart, you can do the 300r crank/piston/balance shaft swap with the big bore kit. I'm sure the internals on the bottom end of the 300r is a little beefier, but who knows.
 
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#8 ·
I hear ya! Are there many racing mods for R3's yet?


I was running the Jettuning 11,800 rev limiter. That could have contributed (although I don't think I was much over redline, if at all). The overbore kit could have contributed also. I'll know more once I have time to remove the engine and take it to the shop to diagnose what can be saved.
 
#11 ·
Actually, I kind of update my previous statement. Seems someone on ADV riders forum has done it on the CRF250L, which as we know uses the same engine. Seems the crank/balancer is a complete drop-in swap.

The CRF250L Owners thread - Page 707 - ADVrider

But, it seems there are some case strengthenings that happened as well on the engineering side that we can't implement; how extensive they are remains to be illucidated. In addition, and I have no idea because I don't own one (Shisoshin, where are you!!! :laugh:), that the O2 sensor was removed from the head. The cams are also different and the flywheel.

CRF250 desplacement mods> CBR300? - Page 2 - CRF250 L/M - ThumperTalk

Again, I suppose I can only confirm the crank and balancer is a drop-in swap, but whatever else was changed has yet to be confirmed by a full-fledged swap.
 
#12 ·
I am betting wrist pin pulled out of piston or pin failed...just think of the forces involved when that piston is doing 11500 rpms, that pin and piston pin bosses have to stop that piston from traveling upwards and yank it down 11500 times a minute or 190 times a second
 
#13 ·
I am 100% positive it was the wrist pin. Same thing happened to mine. I didnt blow a hole in the case, but it did a lot of internal damage. I would look into the Duke 390, More HP lots of aftermarket parts available still light weight and flick able. Rode friend of mines a few months back, plenty of power for the track. Take one for a test ride you will love it.
 
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#15 ·
I would look into the Duke 390, More HP lots of aftermarket parts available still light weight and flick able.


Do you mean the KTM RC390? I've been looking into it. (I beat one on my CBR250 in my last race, but with equal riders it would have blown me away. 3 other did blow me away.)


I've never heard of a Ducati 390. Am I missing something cool?
 
#18 ·
There are some differences between the 2015 KTM 390 duke and the 2015 KTM RC 390. RC stands for race competition, so it has lower bars, stiffer suspension, and more bodywork.
.

The 390 Duke is similar the CB300f, less fairings, 5" (125 mm) higher handlebars.
 
#21 ·
Ari Henning from Motorcyclist magazine dropped the 300s engine on his multi-trophy winning 250, and he's still winning. I asked him if its a direct swap or if it involved extensive mods and he said it was as good as swapping the old 250 engine for a new one. Needed a new crankshaft and crankcase.
Somebody here listed the overall changes the bike underwent from 250 to 286cc
CRF250 desplacement mods> CBR300? - Page 2 - CRF250 L/M - ThumperTalk
 
#23 ·
Ari Henning from Motorcyclist magazine dropped the 300s engine on his multi-trophy winning 250, and he's still winning. I asked him if its a direct swap or if it involved extensive mods and he said it was as good as swapping the old 250 engine for a new one. Needed a new crankshaft and crankcase.
Somebody here listed the overall changes the bike underwent from 250 to 286cc
CRF250 desplacement mods> CBR300? - Page 2 - CRF250 L/M - ThumperTalk
That's the link I just posted a few posts ago. It doesn't say exactly what the guy changed when he did the swap besides the fact the crank and balancer drop right in. There is the supposed list posted of all the changes, but nothing confirmed. No idea what the changes to the crank case were, or what they could be without a clean-sheet redesign of the manufacturing. My thoughts were due to the 286cc displacement, that's as far as they could go in the EXISTING crankcase with stroking it (minimal parts redesign), so I have no idea what crankcase changes were implemented.

Would probably be easier and cheaper to just drop an entire engine in with the ECU and call it a day.
 
#24 ·
Interesting. So, when mines go Kaboom I'll just drop the CBR300r/f Engine into the 250.
 
#27 ·
OK - I apologize if I'm being a bit pedantic, but the link is for a CRF250, and I want to make sure I'm not wasting money before buying a 300r engine.


Can someone confirm that a 300r engine will bolt right into the 250r frame? If so, I think I'm going to buy a 300r engine and ECU as the first step. After that I'll research the 349cc kit.


Again, can anyone confirm that the 300r stock engine (with ECU) will bolt right in to the cbr250r frame without modification?


Thanks in advance.
 
#30 ·
Here's a partial list of part numbers for the 2012 CBR250R and 2015 CBR300R. It looks good in general - the component numbers (first string of numbers) match (except for the frame, but that's probably because the 2015 only sells a Frame Set while the 2012 sells just the Frame). However, the Parts Classification Numbers (second string) are different in some cases. I'm not sure if that means the parts themselves are different, or if this is just an internal Honda classification for which bike they go on.


Any help? Thanks.




Part
CBR250
CBR300
Left Crankcase Cover
11341-KYJ-900
11341-KYJ-900
R Crankcase Assbly
11300-KYJ-901
11300-K33-001
PLATE, R. FR. ENGINE HANGER
50351-KYJ-900
50351-KYJ-900
PLATE, L. FR. ENGINE HANGER
50361-KYJ-900
50361-KYJ-900
STAY, R. COWL (LOWER)
64315-KYJ-900
64315-K33-D00
STAY, L. COWL (LOWER)
64325-KYJ-900
64325-K33-D00
FRAME
50100-KYJ-900
50010-K33-D00
 
#29 ·
The engines are the same physical size; not sure if the ECU has the same plug or not. Likely Honda changed it, but Shisoshin has a 300r and could probably confirm that for you.
 
#31 ·
A couple of updates on my dealings with Ari. First, he's incredibly knowledgeable and helpful.

Second, the 300 engine does bolt directly to the 250 frame. But the 300 engine doesn't have a place for the O2 sensor, as that screws into the header pipe on the 300 (not into the header as does the 250). Most people who would do this change don't use the O2 sensor anyway, because they've replaced it with a PCV.

The 250 ECU will work with the 300 engine (although you'll need a PCV and a custom map).

Jett Tuning's custom PCV is the same for the 250 and the 300. So if you use Jett Tuning's PCV on your 250, it will work on the 300. I highly recommend it.

I don't have a complete list of parts for the 250/300 that are interchangeable, but it seems that most are identical, other than cams (different base lobe diameters), balance shaft, clutch hub and transmission.

Millenium Technologies in Wisconsin makes a bore kit for the 300. 78mm Wiseco Hi-comp piston. Increases the 300 to 300.8 cc (from the stock 286 cc). However, the 78mm Wiseco slug is made for the 250, so it has a much higher dome (and thus compression ratio) than is acceptable for the 300. You have to remove a lot of material from the piston dome to lower compression to a usable 13:1 in a 300 engine.

Ari has convinced me to stick with the CBR250 for racing. Even with a lot of work, it will never have as much top end speed or HP as a Ninja 300, R3 or RC390, but it handles better than any of them and with Ari's help I think I'll be able to get a new engine that is reliable (again, don't get the Takagawa) and can keep me close enough in the straights to pass again in the twistys
 
#32 ·
Final update, unless you let me know you want more info...

I get my new, fully race built engine delivered on Monday. Mount it on the bike, install a new map to my pcv, change the sprockets to adjust for more power and low end torque and, hopefully, race at Cresson next weekend! Still looking to show the ninjettes and duke 390s that the little Honda can go fast.
 
#33 ·
Nice one bro. Good luck on the track :)

Edit: Would you be willing to share your map data?
 
#34 ·
Would you be willing to share your map data?
Do you mean the actual map, or the dyno results? The map I'm going to use this weekend is from Ari and I would need to ask his permission. Probably wouldn't be much help anyway, since its for a heavily modified engine. And I won't have dyno results until I get my own map, which I plan to do in the next month.
 
#35 · (Edited)
No problem bro.

I was just interested to see the actual map. Mainly to see how different it is from my bike running with the Juicebox & full exhaust system. Mainly the deceleration values. If it is confidential. I totally understand. :) I still feel my map is a little lean on deceleration.
 
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