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BBR 175 big bore kit

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What will i have to do to my cylinder head before installation of this kit??? How much will it cost??? Thanx in advance

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You won't need to do anything to your cylinder head. However, the stock cylinder will need to be bored to match the oversize piston. Your local motorcycle shop will probably charge you an hour worth of labor.

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Thanks a lot! Has anyone else tried this kit? how do you like it?

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You'll also need to put a sleeve in it (something BBR doesn't tell you) to make it a reliable motor. The walls would be too thin without a larger sleeve.

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You'll also need to put a sleeve in it (something BBR doesn't tell you) to make it a reliable motor. The walls would be too thin without a larger sleeve.

so i need to re-sleeve it and bore it? What would this cost?

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I have never heard of anyone needing to re-sleeve with the 175 kit? I would guess that if it was necessary a sleeve would be sold with the bore kit.

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I have never heard of anyone needing to re-sleeve with the 175 kit? I would guess that if it was necessary a sleeve would be sold with the bore kit.

I have heard from two people with the kits that they had to go with a sleeve because their mechanics said the walls are too thin if you want a motor that is reliable. Engines Only's 175 kit is the same size piston (67mm) as BBR's, and Frank at EO's says you need to: MUST RESLEEVE YOUR CYLINDER AT 67MM FOR A RELIABLE MOTOR.

Also, POWROLL says this about their 170 kit: This is the largest available bore-in kit which leaves a safe cylinder wall thickness.

Every Manufacture/builder that makes a 175+ kit comes with a Sleeve, I have no idea why BBR doesn't, and why they dont tell you need too?? :excuseme:

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I have never heard of anyone needing to re-sleeve with the 175 kit? I would guess that if it was necessary a sleeve would be sold with the bore kit.

I bought and installed the 175 kit in my wife's CRF this winter. Sent the cylinder out to get bored, but the shop told me I'd have about 0.045" wall thickness left (about the thickness of a dime). I had them sleeve it and bore it to fit the 67mm piston.

BBR sez they have not heard of a 175 kit failing and several others on the bb have the bore-only setup with no trouble so far. IMHO, if the BBK I put in my wife's bike failed because of the thin wall, she'd kick my ass. I feel much better knowing it's sleeved and most likely reliable as stock.

BTW, the BBK from BBR really wakes up the motor. I wish I could spring the bike heavier so could rip faster on it when I take it out - WFO from corner-to-corner in the woods is where it likes to play. :excuseme:

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If you are going to sleeve it you might as well get coeshows kit that makes it a full 188cc's... much nicer piston and more torque... it is a great kit at a great price... the only drawback if you see it as one is that you need to split the cases to bore for larger sleeve dia.

Good luck either way!

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If you are going to sleeve it you might as well get coeshows kit that makes it a full 188cc's... much nicer piston and more torque... it is a great kit at a great price... the only drawback if you see it as one is that you need to split the cases to bore for larger sleeve dia.

Good luck either way!

That's the main reason I didn't go with his kit; I really did not want to split the cases for the larger bore.

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oh come on guys... whats another few hours of work and a few bucks to bore... nothing in the big picture if you ask me...I understand if you have never layed a wrench on a motor... but if you can take the top end apart and reassemble then the bottom end is not that much more to do...

Just my 2 cents worth

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I've been running my BBR 175 kit w/out a sleeve for 2 years now and have not had any issues what so ever. I do probably above normal maint. and checks, but then again I RIDE it also. You should not have any issues by just having it bored.... maybe I've just been lucky? I doubt it. Many other friends of mine have done the same with positive results.

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Here's what happens on big bores. While the industry standard for minimum

cylinder wall thickness has been .040" for many years, a big bore is only as good as the tech boring your cylinder.

A stock CRF150's (and 230's) cylinder spigot is @69.2mm or 2.724" The BBR big bore piston at 67mm will leave adequate cylinder wall material IF the cylinder is bored STRAIGHT. I believe the BBR big-bore piston is made by Wiseco. I have remove a number of them when building engines up to 250cc.

The ones I have removed looked great except for one that was bored crooked. Even this crooked one was running well when torn down.

The BBR big bore is a top notch part, and if installed properly will provide excellent service.

I have seen so many crooked cylinders it's not funny. If your cylinder is bored crooked, even though the bore itself may be true, the remaining spigot material is thicker on one side and too thin on the other.

This is when failures can and do happen. .040" cylinder material (per side) should be plenty safe if the bore is true.

Also, the case does NOT support the cylinder in this area! The spigot receiver in the case is bored much larger than the cylinder spigot. This extra room is what makes a "bigger" bore kit like mine possible. My kit has a 69.5mm bore.

Good luck and ride safely.

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Gunner, I thought you had a 250X.

I do but i want my 150 to be my little play bike. Your crazy if you thought i was riding my 500 everywhere lol :ride: oh and i forgot to put it back in my sig. because i was trying to list my mods on my 500 but the list was too long so i had to deleted a few bikes and just left it out by mistake :ride:

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Here's what happens on big bores. While the industry standard for minimum

cylinder wall thickness has been .040" for many years, a big bore is only as good as the tech boring your cylinder.

A stock CRF150's (and 230's) cylinder spigot is @69.2mm or 2.724" The BBR big bore piston at 67mm will leave adequate cylinder wall material IF the cylinder is bored STRAIGHT. I believe the BBR big-bore piston is made by Wiseco. I have remove a number of them when building engines up to 250cc.

The ones I have removed looked great except for one that was bored crooked. Even this crooked one was running well when torn down.

The BBR big bore is a top notch part, and if installed properly will provide excellent service.

I have seen so many crooked cylinders it's not funny. If your cylinder is bored crooked, even though the bore itself may be true, the remaining spigot material is thicker on one side and too thin on the other.

This is when failures can and do happen. .040" cylinder material (per side) should be plenty safe if the bore is true.

Also, the case does NOT support the cylinder in this area! The spigot receiver in the case is bored much larger than the cylinder spigot. This extra room is what makes a "bigger" bore kit like mine possible. My kit has a 69.5mm bore.

Good luck and ride safely.

thank you very much

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