New CBR 300 Is Born

[ll2]

Hi guys, just found this tread.

Took possession of my new CBR 300 white red and blue yesterday, 136 k

very nice to ride, never rode the 250 so i can not compare it, sorry.

im 105 kg and the missus with a back pack brought it up to 160 kgs

and still very responsive, hade it up to 145 kph, was more there but did not want to push to hard

I gave it the hard break in for the first 75 km, then replaced the oil, 10 w 30

I was surprised to see the oil was black with particles

next upgrade is tyres, IRC'S are rubbish, the back was kicking out today while gearing down

pics to follow as its raining now

congrats and happy rides.

i really like the handsome design of cbr300r.

Plus it was feeling nice when i sat down one at motor show. Light and slim, a cool city warrior!

Write more impression time by time about it, thanks.

[Dakling]

Does anyone know off the top of their head if there are any significant changes to the frame or suspension on the CBR300 vs the CBR250 or is it basically just a stroked engine and different cosmetically?

I am seeing on some sites that guys are putting big bore kits on CBR250s that take them up to 305 cc. Some are also planning on trying to fit the crank from a CBR300 into the bored out 250 which would take displacement up to 350cc. All this could be done for a bit over $500 using kits and an OEM crank from a CBR300. Likely need to get a aftermarket ECU tuner to get everything working together properly but it would be an interesting project. If the crank replacement turns out to be problematic you would still have the bore kit taking you to 305cc vs the CBR300 true displacement of 286 cc.

I am thinking if you bought a somewhat tired CBR250 for 70,000 and put 30,000 into it you would have a pretty nice bike. Granted it might be less reliable than a new stock CBR300 but you would save 35,000 baht and end up with a more powerful bike. I do realize that you would get a lot less resale for an older, modded CBR250 than a newer stock CBR300 so if you think of full life cost the CBR300 would be the better option financially.

Another option would be to buy the CBR300 and after a year or two put the big bore kit on it. Cost more up front but if you only planned on keeping the bike for 3 to 5 years then you would get more on the resale. With a 22% increase in displacement you could see the stock 300 going from 30 to 33 or maybe as much as 35 hp if you do the ECU work and help it to breath a bit.

I know that after putting in the kit on a new CBR300, ecu remapping etc. I am getting close to CB500 prices but this might be a fun project. Thoughts anyone?

[charlie42]

How much is the big bore kit ?. I know for the older model car 150 it's close to 40,000 baht ?

[Dakling]

I haven't tried to price them in Thailand but there is a full kit available for the 250 in the US for $375 (about 14,000 baht).

[mania]

I am seeing on some sites that guys are putting big bore kits on CBR250s that take them up to 305 cc. Some are also planning on trying to fit the crank from a CBR300 into the bored out 250 which would take displacement up to 350cc. All this could be done for a bit over $500 using kits and an OEM crank from a CBR300. Likely need to get a aftermarket ECU tuner to get everything working together properly but it would be an interesting project. If the crank replacement turns out to be problematic you would still have the bore kit taking you to 305cc vs the CBR300 true displacement of 286 cc.

Something sounds wrong with this ?

On the one hand I do like bore kits if done right & prefer

the extra displacement via bore rather than stroke as the bore/stroke ratio

remains high or higher than stock

Of course it will depend mainly on if the cylinder of the bore up is good quality whether you

want to consider it. Also what was the water jacket setup on the 250?

But to say you will use a bore up kit then also add a longer stroke crank I would think

will not work. Unless you have a taller 305 cylinder/ different head chamber what ever to go with it

Because that stroke needs to go somewhere

*That is of course if the longer stroke crank would even fit in the old 250 case

Also at some point valves/head porting etc & FI throttle bodies are going to come into play as you increase.

But I agree if well thought out projects can be fun

[dave_boo]

I am seeing on some sites that guys are putting big bore kits on CBR250s that take them up to 305 cc. Some are also planning on trying to fit the crank from a CBR300 into the bored out 250 which would take displacement up to 350cc. All this could be done for a bit over $500 using kits and an OEM crank from a CBR300. Likely need to get a aftermarket ECU tuner to get everything working together properly but it would be an interesting project. If the crank replacement turns out to be problematic you would still have the bore kit taking you to 305cc vs the CBR300 true displacement of 286 cc.

Something sounds wrong with this ?

On the one hand I do like bore kits if done right & prefer

the extra displacement via bore rather than stroke as the bore/stroke ratio

remains high or higher than stock

Of course it will depend mainly on if the cylinder of the bore up is good quality whether you

want to consider it. Also what was the water jacket setup on the 250?

But to say you will use a bore up kit then also add a longer stroke crank I would think

will not work. Unless you have a taller 305 cylinder/ different head chamber what ever to go with it

Because that stroke needs to go somewhere

*That is of course if the longer stroke crank would even fit in the old 250 case

Also at some point valves/head porting etc & FI throttle bodies are going to come into play as you increase.

But I agree if well thought out projects can be fun

What's wrong with using shorter connecting rods?

It is possible that one would run into issues with rod clearance...but if you have a large bore cylinder that may not even be a concern.

Sent from my GT-N7100 using Thaivisa Connect Thailand mobile app

[mania]

What's wrong with using shorter connecting rods?

It is possible that one would run into issues with rod clearance...but if you have a large bore cylinder that may not even be a concern.

Nothing wrong with short rods but if his point was to gain

additional displacement via stroke why would you then cancel it with shorter rods?

Point is he was saying

1- Big bore go from 250>305

2- then add stroke to go to 350

Ain't going to happen with the 250 bored to 305 cylinder alone

He needs 8mm more height or relief somewhere afaik

I know on a Kawasaki 250>300 they gained the cc boost by stroke increase of

7.2mm or say 5/16th" but it is a twin with 62mm pistons

On the Honda they increased stroke about the same as Kawasaki

but it is a single cylinder....But again they start on the 250 with a 76mm piston x 55 Stroke

They use the same 76mm pistons on their new 300 too

but their new stroke is now 63mm or 8mm more than the 250 on the new

300 or coincidentally again about 5/16th"

But that 300 is actually a 286 so Dakling would be better served with the

305cc short stroke IMHO

[ll2]

What's wrong with using shorter connecting rods?

It is possible that one would run into issues with rod clearance...but if you have a large bore cylinder that may not even be a concern.

Nothing wrong with short rods but if his point was to gain

additional displacement via stroke why would you then cancel it with shorter rods?

Point is he was saying

1- Big bore go from 250>305

2- then add stroke to go to 350

Ain't going to happen with the 250 bored to 305 cylinder alone

He needs 8mm more height or relief somewhere afaik

I know on a Kawasaki 250>300 they gained the cc boost by stroke increase of

7.2mm or say 5/16th" but it is a twin with 62mm pistons

On the Honda they increased stroke about the same as Kawasaki

but it is a single cylinder....But again they start on the 250 with a 76mm piston x 55 Stroke

They use the same 76mm pistons on their new 300 too

but their new stroke is now 63mm or 8mm more than the 250 on the new

300 or coincidentally again about 5/16th"

But that 300 is actually a 286 so Dakling would be better served with the

305cc short stroke IMHO

and with shorter stroke, bike will be revvier too.

[Dakling]

Con rod length has no impact on stroke. Stroke is dependent on the crank shaft. Changing con rod length only affects the distance between piston and crank. Crank dimensions alone dictate stroke.

Issue regarding cylinder sleeve length when adding stroke is legitimate though usually is not an issue. The real problem is will the stock 250 crank case accept a 300 crank without work. When you increase stroke the crank "throw" increased. Throw is normally not an issue in the direction of the cylinder but it can big a big issue it the crank comes too close to the bottom of the crank case when it is at bottom dead center.

Ok another re-edit because I am not yet sure if folks get the whole stroking thing. If you increase stroke (via the crank), you must have shorter con rods equal to 1/2 the stroke increase or "top dead center" will be too high and your piston will hit the valves or the head. The head will stay in the same place and the crank center of rotation will stay the same the only change is that the crank "throw" will be different. The shorter rod keeps the piston top dead center in the same spot but the bottom of the cycle will be where the added stroke comes in. Usually when you stroke out an engine the pistons still stay well within the cylinder and there is no issue about the cylinder length. You may need to use a piston with a shorter skirt but normally the cylinder is long enough that you don't need to. You definitely will need to re-hone the cylinder if you decide to stroke it since with the shorter stroke crank the lower section of the cylinder would have been below the rings and now it wont be. If you are trying to stroke beyond what the normal cylinders dimensions will allow, you will end up with lots of problems because going with longer cylinders increases the over all engine dimensions and now you might have clearance issues.

[mania]

Con rod length has no impact on stroke. Stroke is dependent on the crank shaft. Changing con rod length only affects the distance between piston and crank. Crank dimensions alone dictate stroke.

Sure it does especially in the context to which I was answering Daves Question/Reason

for using shorter rods

But that aside what you need to do is go get the parts manual for the Honda 250

you have & the new 300

That is the easiest way to see if they changed the cylinder height or not.

I can tell you the Kawasaki 250/300 is basically an exact same scenario as what your

describing. Meaning a manufacturer kept the bore the same & increased stroke

I have both parts manuals here for Kawasaki & have looked at what all changed out of curiosity

I can tell you Kawasaki uses two different cylinders for the 250 & the 300

What you said in your last post "can" be true but not by crank alone

They will get their extra cc's by taller cylinder or shorter pistons or shorter rods or a combination of those.

because all a stroked crank does is move the conecting rod journal further away from the main

journal.

All fine & well but not something that is a matter of just adding a crank

Dont mean to rain on your idea or anything & sounds like a fun project

But I think your 30k baht price might be only half to a third of what it will actually cost you.

I think you need to consider further than crank,bore kit & EFI controller

[dave_boo]

Con rod length has no impact on stroke. Stroke is dependent on the crank shaft. Changing con rod length only affects the distance between piston and crank. Crank dimensions alone dictate stroke.

Sure it does especially in the context to which I was answering Daves Question/Reason

for using shorter rods

But that aside what you need to do is go get the parts manual for the Honda 250

you have & the new 300

That is the easiest way to see if they changed the cylinder height or not.

I can tell you the Kawasaki 250/300 is basically an exact same scenario as what your

describing. Meaning a manufacturer kept the bore the same & increased stroke

I have both parts manuals here for Kawasaki & have looked at what all changed out of curiosity

I can tell you Kawasaki uses two different cylinders for the 250 & the 300

What you said in your last post "can" be true but not by crank alone

They will get their extra cc's by taller cylinder or shorter pistons or shorter rods or a combination of those.

because all a stroked crank does is move the conecting rod journal further away from the main

journal.

All fine & well but not something that is a matter of just adding a crank

Dont mean to rain on your idea or anything & sounds like a fun project

But I think your 30k baht price might be only half to a third of what it will actually cost you.

I think you need to consider further than crank,bore kit & EFI controller

Respectfully...the throw of the crank is the only thing that affects stroke on a reciprocating engine.

A thought experiment. You have a 53mm crank. That means your crank has from the "top" of the crankpin journals at TDC to the "bottom" (which end up on top) at BDC 53mm of travel. It doesn't matter if your conrod is 10cm or 100...it will only move a distance of 53mm. Going with a longer corod can increase compression.

[mania]

Respectfully...the throw of the crank is the only thing that affects stroke on a reciprocating engine.

A thought experiment. You have a 53mm crank. That means your crank has from the "top" of the crankpin journals at TDC to the "bottom" (which end up on top) at BDC 53mm of travel. It doesn't matter if your conrod is 10cm or 100...it will only move a distance of 53mm. Going with a longer corod can increase compression.

Sorry I think I am only confusing the issue

I was replying to your original Q..

What's wrong with using shorter connecting rods?

But it was in context at the time about what the OP would *possibly*

need to achieve a *displacement* with his 250 bored to 305

then stroked to gain another 50 (36 actually as the new 300 is 286cc)

Yes of course the crank affects the stroke & that is stroke is final & set

but it is not the only thing affecting the final *displacement*

Sorry for causing confusion in the thread the only point I had with my 1st reply was to caution

the OP to look at what else has possibly changed between the 250 & 300 Honda in achieving the

added cc's.

Kinda wish now I had not said anything

Good Luck OP

[dave_boo]

Respectfully...the throw of the crank is the only thing that affects stroke on a reciprocating engine.

A thought experiment. You have a 53mm crank. That means your crank has from the "top" of the crankpin journals at TDC to the "bottom" (which end up on top) at BDC 53mm of travel. It doesn't matter if your conrod is 10cm or 100...it will only move a distance of 53mm. Going with a longer corod can increase compression.

Sorry I think I am only confusing the issue

I was replying to your original Q..

What's wrong with using shorter connecting rods?

But it was in context at the time about what the OP would *possibly*

need to achieve a *displacement* with his 250 bored to 305

then stroked to gain another 50 (36 actually as the new 300 is 286cc)

Yes of course the crank affects the stroke & that is stroke is final & set

but it is not the only thing affecting the final *displacement*

Sorry for causing confusion in the thread the only point I had with my 1st reply was to caution

the OP to look at what else has possibly changed between the 250 & 300 Honda in achieving the

added cc's.

Kinda wish now I had not said anything

Good Luck OP

Yeah...don't worry...there's been plenty of times i've been ankle deep with my foot in mouth when posting.

[Ridercnx808]

There's some video of the CBR 300 top speed out now, theres also another video of the Ninja 300 top speed vs the CBR 300 top speed.

The rider on the CBR 300 is in full gear and sitting straight up, so it's possible that the top speed will be about 10kph higher in a full tuck and in street clothes. That's really not bad in comparison to the Ninja 300 with almost 25% more horsepower.

I've been waiting for some videos to come out, and I think it just made my mind up.

[roly]

I'm gonna go for the black. 137,000 in cha-am...

[JohnPark]

You could always get it lowered. Very quick and easy. I presume the rear suspension is adjustable the same as the 250. Would take the shop about 5 mins to lower both the front and rear.

Correct me if I'm wrong but I don't think you can lower it without buying lowering links, the adjustment on the suspension is just for preload adjustment. You may be able to touch the ground with less preload but don't think that's the right way.

[Shurup]

You could always get it lowered. Very quick and easy. I presume the rear suspension is adjustable the same as the 250. Would take the shop about 5 mins to lower both the front and rear.

Correct me if I'm wrong but I don't think you can lower it without buying lowering links, the adjustment on the suspension is just for preload adjustment. You may be able to touch the ground with less preload but don't think that's the right way.

You're right, changing the preload isn't the right way to lower the bike.

@332 Search for my thread "Lowering Ninja 300 for dummies". I did this on my (wife's) Ninja 300 and it was an easy project.

By the way, if you check the length of stock dog bones on CBR 300 and if they're shorted than the Ninja's dogbones (Which are 6 1/2" between the mount holes), then I may have some cheap dogbones for you to lower your bike Of course the mount holes need to be the same size as on CBR.

Here are some shots:

[properjob]

Does anyone know if the 'naked', unfaired CB300F version is going to be released in Thailand soon?

Perhaps it has already been released, but I've not visited a dealer in a while, and just found this thread. I'd be much more interested in the 300F riding position.

This American article says the 300F should be available in the States this coming fall/autumn.

pj

[andrewrooney]

Hey guys! I've had my CBR for about a month now, but I've been too busy to post anything! I see Charlie beat me to it

Anyway I've been really happy with the bike so far. Paid 133,000 for the black one from a Honda shop on Nawamin. Broke it in pretty easy for the first 500km. Since then I've put quite a few miles on it. Two weeks ago I took it up to Saraburi to go camping, and got a chance to open it up quite a bit. Then this last weekend I drove it to Sangklaburi and back to Bangkok. It's got enough power to handle the hills up in Kanchanaburi just fine with my fat a$$ plus my wife on the back. All in all very pleased with it, there's a few upgrades I want to make (definitely want to get an integrated taillight, the turn indicators on those long plastic stems are ugly) but so far it's been a great bike for the money.

[charlie42]

Hey guys! I've had my CBR for about a month now, but I've been too busy to post anything! I see Charlie beat me to it

Anyway I've been really happy with the bike so far. Paid 133,000 for the black one from a Honda shop on Nawamin. Broke it in pretty easy for the first 500km. Since then I've put quite a few miles on it. Two weeks ago I took it up to Saraburi to go camping, and got a chance to open it up quite a bit. Then this last weekend I drove it to Sangklaburi and back to Bangkok. It's got enough power to handle the hills up in Kanchanaburi just fine with my fat <deleted> plus my wife on the back. All in all very pleased with it, there's a few upgrades I want to make (definitely want to get an integrated taillight, the turn indicators on those long plastic stems are ugly) but so far it's been a great bike for the money.

Hi AR

When you say intergrated taillight , do you mean to do away with the ugly reg plate holder.

it takes the look off the bike,this is the next thing i want to do is take this off.

but i dont like the idea of drilling holes inthe plastic for the indicators.

reg plate can go in under like the thai lads.

can a costom part be bought ?

[andrewrooney]

Hey guys! I've had my CBR for about a month now, but I've been too busy to post anything! I see Charlie beat me to it

Anyway I've been really happy with the bike so far. Paid 133,000 for the black one from a Honda shop on Nawamin. Broke it in pretty easy for the first 500km. Since then I've put quite a few miles on it. Two weeks ago I took it up to Saraburi to go camping, and got a chance to open it up quite a bit. Then this last weekend I drove it to Sangklaburi and back to Bangkok. It's got enough power to handle the hills up in Kanchanaburi just fine with my fat <deleted> plus my wife on the back. All in all very pleased with it, there's a few upgrades I want to make (definitely want to get an integrated taillight, the turn indicators on those long plastic stems are ugly) but so far it's been a great bike for the money.

Hi AR

When you say intergrated taillight , do you mean to do away with the ugly reg plate holder.

it takes the look off the bike,this is the next thing i want to do is take this off.

but i dont like the idea of drilling holes inthe plastic for the indicators.

reg plate can go in under like the thai lads.

can a costom part be bought ?

Exactly, the plate holder and turn indicators are too ugly! Too big, and a really cheap plastic look. One of the few things I don't like about the bike. I want to get an integrated taillight that has the taillight and turn indicators all in one unit, so I can lose the rest. Something like this here:

That's a CBR250 in the picture. I need to find out if a light for the 250, or maybe the 500, will fit on the 300. Otherwise I'll need to wait until somebody makes one that's 300 specific.

Also I'd like to replace the front indicators with ones that are flush to the body. I think it would really clean up the look of the bike.

[charlie42]

Hey guys! I've had my CBR for about a month now, but I've been too busy to post anything! I see Charlie beat me to it

Anyway I've been really happy with the bike so far. Paid 133,000 for the black one from a Honda shop on Nawamin. Broke it in pretty easy for the first 500km. Since then I've put quite a few miles on it. Two weeks ago I took it up to Saraburi to go camping, and got a chance to open it up quite a bit. Then this last weekend I drove it to Sangklaburi and back to Bangkok. It's got enough power to handle the hills up in Kanchanaburi just fine with my fat <deleted> plus my wife on the back. All in all very pleased with it, there's a few upgrades I want to make (definitely want to get an integrated taillight, the turn indicators on those long plastic stems are ugly) but so far it's been a great bike for the money.

Hi AR

When you say intergrated taillight , do you mean to do away with the ugly reg plate holder.

it takes the look off the bike,this is the next thing i want to do is take this off.

but i dont like the idea of drilling holes inthe plastic for the indicators.

reg plate can go in under like the thai lads.

can a costom part be bought ?

Exactly, the plate holder and turn indicators are too ugly! Too big, and a really cheap plastic look. One of the few things I don't like about the bike. I want to get an integrated taillight that has the taillight and turn indicators all in one unit, so I can lose the rest. Something like this here:

fender1.jpg

That's a CBR250 in the picture. I need to find out if a light for the 250, or maybe the 500, will fit on the 300. Otherwise I'll need to wait until somebody makes one that's 300 specific.

Also I'd like to replace the front indicators with ones that are flush to the body. I think it would really clean up the look of the bike.

yes, it looks good, but would be even better with the reg plate under the wheel arch.

will give it a very sharp look, also read somewhere there's a 10 km top end difference

with this mod .

i agree the front indicators dont look so good, but are also very good at informing oncoming

traffic what your planning to do.

the flush one would look great, but thats no good when an oncoming driver

fails to notice you and well you can guess the rest.

i think i will stick with the stock fronts

[Rhys]

still in the wai roong stage..