Honda CBR 300 Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
Just picked up this bike with known bad engine. Tore the top end off and the rod is toast on the crankshaft. I saw one other post similar. Previous owner changed the oil and ran it 2000 miles, then it tied up on the freeway. I thought perhaps it had seized the piston, but the piston/bore look fine, although the camshaft lobes are looking a little starved for oil. Dunno if I can get any warranty assistance as I am now the 3rd owner in 7k miles. Looks like a new crankshaft is in the $250 range, but obviously a whole teardown has to happen and all engine oil passages need to be flushed thoroughly.
Bill "MrHonda" Silver
 

Attachments

·
Registered
Joined
·
1,389 Posts
Looks like you know what you're doing - so it shouldn't be too much of a problem. Good luck, and keep us posted!
 

·
Premium Member
Joined
·
5,461 Posts
There's a lot of discoloration on that piston from over heating, a lack of oil would be my guess. It seems to be around the small end of the connecting rod.
Parts seem to be cheap for these bikes so depending on what you paid for the whole bike, you may have a bargain on your hands once you get it running.
Is the rest of the bike tidy?
 

·
Registered
Joined
·
75 Posts
Have you considered buying a used motor? The model is still considered new, but there might be one online for $300-500 off of a crashed CBR. If you decided to fix that motor, you should bore it out a bit enough to hit close to 300cc depending if you have enough material to remove.

I had an old Ninja 250 that I bought for $1000, it had a damaged motor, but I had a set of "high-comp 2mm oversize-pistons" laying around. Long story short, by the time I was done with the engine it was putting out 32hp on stock exhaust. It had more room for improvement but I moved on to a different project. You have the engine out already, might as well build it up a bit.
 

·
Registered
Joined
·
2,083 Posts
Just picked up this bike with known bad engine. Tore the top end off and the rod is toast on the crankshaft. I saw one other post similar. Previous owner changed the oil and ran it 2000 miles, then it tied up on the freeway. I thought perhaps it had seized the piston, but the piston/bore look fine, although the camshaft lobes are looking a little starved for oil. Dunno if I can get any warranty assistance as I am now the 3rd owner in 7k miles. Looks like a new crankshaft is in the $250 range, but obviously a whole teardown has to happen and all engine oil passages need to be flushed thoroughly.
Bill "MrHonda" Silver
Wow that's toast. The Honda Warranty is on the bike for 1 year from the date of sale. Doesn't matter how many owners there have been. Not sure if they have a mileage limit for the year tho? But if they do I doubt it's less than 7000 miles. Thing is since you have it opened up already I'm not sure if they would cover it now
 

·
Registered
Joined
·
2,083 Posts
Have you considered buying a used motor? The model is still considered new, but there might be one online for $300-500 off of a crashed CBR. If you decided to fix that motor, you should bore it out a bit enough to hit close to 300cc depending if you have enough material to remove.

I had an old Ninja 250 that I bought for $1000, it had a damaged motor, but I had a set of "high-comp 2mm oversize-pistons" laying around. Long story short, by the time I was done with the engine it was putting out 32hp on stock exhaust. It had more room for improvement but I moved on to a different project. You have the engine out already, might as well build it up a bit.
They do sell a bore kit for the 250r, forget what it brings it to but I am pretty sure it is even higher than the 286. However, I've also heard people have had problems with the kit
 

·
Premium Member
Joined
·
3,009 Posts
... If you decided to fix that motor, you should bore it out a bit enough to hit close to 300cc depending if you have enough material to remove...
These cylinders can't be bored, as they are not made with a steel sleeve (it's known as a Nikasil cylinder). Which is why Honda doesn't offer oversized pistons & ring sets for these bikes.
 

·
Premium Member
Joined
·
3,009 Posts
Just picked up this bike with known bad engine. Tore the top end off and the rod is toast on the crankshaft. I saw one other post similar. Previous owner changed the oil and ran it 2000 miles, then it tied up on the freeway. I thought perhaps it had seized the piston, but the piston/bore look fine, although the camshaft lobes are looking a little starved for oil. Dunno if I can get any warranty assistance as I am now the 3rd owner in 7k miles. Looks like a new crankshaft is in the $250 range, but obviously a whole teardown has to happen and all engine oil passages need to be flushed thoroughly.
Bill "MrHonda" Silver
When you removed the oil filter cover, was the filter previously installed backwards?... that would explain the oil starved cam lobes.

Over the past few years, we've seen a number of CBR250R owners who have inadvertently installed the oil filter backwards, which then toasts the top end in short order.

As kiwi rider said, parts are relatively inexpensive for these bikes... if you are located in the U.S., you'll want to check out HondaEastToledo.com for discounted prices on OEM Honda parts.

It looks like you have the 'know how' to do the rebuild yourself, so if you bought the bike cheap you may very well end up with a bargain.
 

·
Registered
Joined
·
75 Posts
These cylinders can't be bored, as they are not made with a steel sleeve (it's known as a Nikasil cylinder). Which is why Honda doesn't offer oversized pistons & ring sets for these bikes.
Nikasil can be re-plated again or bored out and re-plated to maintain tighter tolerances. Some people that dislike Nikasil sleeve over it. If what you say is true regarding OS pistons, I don't know why Honda would not have oversize pistons for the bike? Engine damage can still occur? But assuming the engine is maintained right it can last a very long time with Nikasil.

I had no idea Honda used Nikasil on the 300r. They must want to keep the bike as light as possible by having the pistons, liners, and block in aluminum.
 

·
Registered
Joined
·
75 Posts
They do sell a bore kit for the 250r, forget what it brings it to but I am pretty sure it is even higher than the 286. However, I've also heard people have had problems with the kit
Same here, I heard about the stroker kit through the Ninja forum, but I already had pistons laying around. These bikes can get expensive to hop-up :)
 

·
Premium Member
Joined
·
3,009 Posts
Nikasil can be re-plated again or bored out and re-plated to maintain tighter tolerances. Some people that dislike Nikasil sleeve over it. If what you say is true regarding OS pistons, I don't know why Honda would not have oversize pistons for the bike? Engine damage can still occur? But assuming the engine is maintained right it can last a very long time with Nikasil.

I had no idea Honda used Nikasil on the 300r. They must want to keep the bike as light as possible by having the pistons, liners, and block in aluminum.
A new OEM cylinder costs less than $100 USD: http://www.hondaeasttoledo.net/OEMp...NDER/CBR300R-15-THA-3AC/2Y14K33F11AK334E0500A

... and the OEM piston & ring set is also very inexpensive: http://www.hondaeasttoledo.net/OEMp...TON/CBR300R-15-THA-3AC/2Y14K33F11AK334E1600AA

With these low parts prices, it doesn't make sense to spend time and money machining & re-plating a CBR250R/300R cylinder.

By comparison, if you look at the current prices for a new OEM cylinder on an older air cooled Honda XR, you can see why they would offer two OS piston & ring set sizes for those motors... sleeved cylinders are expensive to manufacture. So while you can re-sleeve those XR cylinders, by the time you're done it can easily cost 1/2 to 2/3 of what the complete new cylinder costs.
 

·
Registered
Joined
·
75 Posts
A new OEM cylinder costs less than $100 USD:
With these low parts prices, it doesn't make sense to spend time and money machining & re-plating a CBR250R/300R cylinder.

By comparison, if you look at the current prices for a new OEM cylinder on an older air cooled Honda XR, you can see why they would offer two OS piston & ring set sizes for those motors... sleeved cylinders are expensive to manufacture. So while you can re-sleeve those XR cylinders, by the time you're done it can easily cost 1/2 to 2/3 of what the complete new cylinder costs.
But my point was the Nikasil plated cylinders can be bored out and re-plated, when you said "These cylinders can't be bored, as they are not made with a steel sleeve (it's known as a Nikasil cylinder). Which is why Honda doesn't offer oversized pistons & ring sets for these bikes." I have done it on my radio controlled cars & planes. It's just a matter of preference.
Check this out:http://www.powersealusa.com/repair-process/

As far as prices it really depends on the person. Last time I paid $320 to have my 4 cylinder MR2 sleeved, that's 80 per cylinder including the sleeves that the machinist will provide. It should cost no more that $100 on the CBR since it's only 1 cylinder. The O.P. doesn't know exactly what else is damaged with the motor, but with the parts and service added, it's gonna cost a lot more than $250 done right out the door. If you wait long enough you can buy a perfectly good engine online for maybe $300-500.

That's why I mentioned to the O.P. that it might be better to buy a used motor if money was an issue. Rebuilding an engine is never cheap. If he doesn't have the basic & special tools like a straight edge, micrometer, and all the necessary tools, then it's better to leave it to a machinist. Even if you spend the money to increase displacement, it's a lot better than buying a slip-on/exhaust because you can feel the power throughout the RPM and not just peak power. Good luck to O.P.
 

·
Premium Member
Joined
·
3,009 Posts
But my point was the Nikasil plated cylinders can be bored out and re-plated, when you said "These cylinders can't be bored, as they are not made with a steel sleeve (it's known as a Nikasil cylinder). Which is why Honda doesn't offer oversized pistons & ring sets for these bikes." I have done it on my radio controlled cars & planes. It's just a matter of preference.
Sorry for the confusion. I should have written that differently: That this cylinder doesn't have a steel sleeve (which could be readily bored to an existing oversize piston), is why Honda doesn't offer any oversized piston & ring sets for this engine. Whereas Honda cylinders which do have a steel sleeve, will typically have at least two OEM oversized piston & ring sets available.

Sure, you could in theory bore and then re-plate these particular Nikasil cylinders to an oversize, but then where will you easily be able to source an oversized piston & ring set that will be 'drop-in' compatible with the all of the other stock OEM engine components?


... As far as prices it really depends on the person. Last time I paid $320 to have my 4 cylinder MR2 sleeved, that's 80 per cylinder including the sleeves that the machinist will provide. It should cost no more that $100 on the CBR since it's only 1 cylinder. The O.P. doesn't know exactly what else is damaged with the motor, but with the parts and service added, it's gonna cost a lot more than $250 done right out the door.

That's why I mentioned to the O.P. that it might be better to buy a used motor if money was an issue. Rebuilding an engine is never cheap. If he doesn't have the basic & special tools like a straight edge, micrometer, and all the necessary tools, then it's better to leave it to a machinist. I think the O.P. mentioned the cam lobs being scored as well. Good luck to him.
I agree, if one could find a used motor in good running condition for a reasonable price, that would probably be the way to go.

I wasn't implying that a rebuild could be done for $250. Those links to the parts listings were just to reference the relative cost of the cylinder and piston & ring set, as compared to the cost of boring, sleeving, re-plating, etc.

IMO, a realistic cost of parts only to do a quality rebuild on one of these engines would likely run in the area of $550 to $650 USD.
 

·
Registered
Joined
·
75 Posts
^No worries,
Right now the CBR 300r is a new model. Eventually aftermarket companies like JE will have pistons for it. But I'm pretty sure they can make you a custom piston set exclusive to your specs right now if you really wanted one. That's what I had to do to a few of my custom built engines, the down time is 3 weeks for 4 pistons and should be less for 1.
 
1 - 14 of 14 Posts
Top