Mine went to 265cc 10.5:1 Wiseco w/ roller Mugen medium range cam, short valve guides for higher lift, ported, 34mm keihin carb, barnett clutch, white power shock, fork kit, Fabtech swing-arm. Awesome bike.. It was given away without me knowing about it.. End of story.
Not a bad idea to make sure all the head bolts can screw all the way to the bottom of the holes (prevent bottoming and false torque) and a touch of Coppaslip or oil on the threads will help with and even torquing down in two or three steps.
Personally I've never oiled or greased threads before torquing them, i was always taught this can give a false reading but that's just me, each to their own and as for gapping the rings, that was done pryor to making the video
Hi Steve, I have been pointed to a couple of companies in the USA that offer big bore kits and modified cams for xr250 & xl250 engines. Not having a great deal of joy with responses about compatibility with cb250rs mc02 engine. As you have experience of these engines, do you know if the xl250s engine up to 1979 is compatible for parts with the 1980 cb250rs? Basically, I am hoping to get a big bore kit from them and fit it in to the cb250rs. Cheers Jim
Hi Jim, yes they are pretty much the same engine, apart from a few minor details like cam timing and carburation. The lower crank cases have slightly different castings and the cam covers are slightly different but anything from the barrel up is interchangeable. The XL doesn't have a rev counter. hope this helps. Steve
Yes sorry about that, for those of you who follow my channel know I cant leave anything standard for very long and since this video I've removed the 305 engine and fitted an XL500 engine so will upload a video of that soon
Hi Swen, these big bore kits are rare these days so you'll just have to keep an eye out on ebay or some of the American sites like XRs only. most of them were made by Powroll but also Yoshimura and Henry Abe did them as well.
Yes they're fairly straight forward, yours will probably have an accelerator pump but the kits are pretty comprehensive, just take lots of photographs when you dismantle it and make a note of which groove the tiny circlip goes on the needle
A slack cam chain or balance weight chain will rattle rather than tap, if it's a top end tap then check your valve clearances or it could be wear in the head/rocker cover camshaft seating area, a good quality slightly thicker oil will help. Unfortunately the only way to check camshaft wear is to undo the rocker cover bolts, lift the cover and pop out the plastic plug then tighten the bolts back up and then see if you can move the camshaft up an down
@@malaika650 The 280cc kit is the largest overbore you can do on the original liner, the 305cc kit is a completely new liner but these are so rare now and were sold in the eighties by companies like Henry Abe, Yoshimura, and Powroll. You can make your own kits using a liner made for you and a piston from a Honda GX340 generator but there's a lot of machining to be done.
@@tevie54 GX340! Surprising diversion! ! Is the diameter of the piston pin the same? I thought it was ATC350. I think the GX piston is a low comp, but which of the Wiseco's 280cc high comp and power will be higher?
@@malaika650 It all depends on how much work you're prepared to do. The 280cc kit is easier, just a rebore and new piston. The 305 gives more power but is a lot more work if you're building your own kit. If you can find an original kit from Henry Abe, Powroll etc it's a case of pressing out your old liner, boring out the cylinder, pressing in the new liner, opening out the crank case mouth and reassembling the engine. If you're building your own kit you have to do all of the above but get a liner made for you, modify a GX350 piston by turning down the piston crown so it doesn't hit the head, then either bore out the small end of the con rod or make sleeves to fit the piston as the GX340 piston uses a 20mm pin instead of a 19mm. Like I say it's a lot of work but it does give a noticable power increase.
Good video thanks. I'd also like a few more HP - can I ask where you got the kit, and if you know what the revised power is, roughly? Oh, and carb mods required? Many thanks
Hi, my kit was in amongst a garage full of XL250 spares I bought a few years ago and was made by a company called Henry Abe Industries but there have been several companies that did them, Powroll being the most popular and I think Yoshimura did one as well. they're all very rare these days but do pop up on ebay now and then. Being a short stroke engine the power comes in at higher revs so initially it feels just like a standard XL250 but then it really flies. I run an RS 250 carb with the accelerator pump and if you're using a standard XL airbox just remove the foam filter but keep the gauze. Standard XLs put out about 20hp and RS's about 24hp but with the 305 and the bigger carb that gets pushed up to around the 27hp area with increased torque as well.
Hi Steve, thanks for the response. No wonder I've struggled to find a kit, having assumed it would be easy. Will keep looking as that little extra would make the bike more usable for the larger fellow like myself. Starting a general rebuild in a couple of months and may pick your brains if that's OK?
Absolutely, The reason I did it was because I ride to work two up so that extra power was really helpful when overtaking. There are other ways to increase the cc but that involves getting a liner made but I'm happy to help if that's what anyone wants.
As far as I'm aware 305cc (82mm bore) was the largest you could go on the S model because the new liner is very close to the oilway , I've heard of longer cranks to give more CCs but you're into raised barrels and machining the bottom crankcase to give more clearance then but if there is one then that would be great to see.
Yes that's correct, you have to press out the old liner, bore the barrel then press in the new liner, there are companys that will make liners to your spec but they are expensive. These kits are very rare these days but back in the 80's companys like Powroll, Henry Abe, and Yoshimura all made big bore kits for XL250's
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Mine went to 265cc 10.5:1 Wiseco w/ roller Mugen medium range cam, short valve guides for higher lift, ported, 34mm keihin carb, barnett clutch, white power shock, fork kit, Fabtech swing-arm. Awesome bike.. It was given away without me knowing about it.. End of story.
Stage 1 cam would of been nice addition hold those valves open bit longer up the main jet open air Box and pipe big gains nice and torquey
Wot no spacing of the ring gaps or oiling them before putting the bore on?
I really needed to see how you fit the rings on the piston without breaking them and how you slide the new barrel over the piston.
Not a bad idea to make sure all the head bolts can screw all the way to the bottom of the holes (prevent bottoming and false torque) and a touch of Coppaslip or oil on the threads will help with and even torquing down in two or three steps.
Personally I've never oiled or greased threads before torquing them, i was always taught this can give a false reading but that's just me, each to their own and as for gapping the rings, that was done pryor to making the video
There's one of these kits on ebay at the moment, there's no rings with it but you can use the rings from a Honda GX 340 generator engine
Piston and head gasket only, listing says Powroll High Performance Top End Big Bore
Great video thanks! I am planning a rebuild on my CB250RS motor, soon and this will help cheers
Mine needs a skim bore in order to stop it from smoking but it tight I could go maybe 275 or 300
Hi Steve,
I have been pointed to a couple of companies in the USA that offer big bore kits and modified cams for xr250 & xl250 engines. Not having a great deal of joy with responses about compatibility with cb250rs mc02 engine. As you have experience of these engines, do you know if the xl250s engine up to 1979 is compatible for parts with the 1980 cb250rs? Basically, I am hoping to get a big bore kit from them and fit it in to the cb250rs.
Cheers
Jim
Hi Jim,
yes they are pretty much the same engine, apart from a few minor details like cam timing and carburation. The lower crank cases have slightly different castings and the cam covers are slightly different but anything from the barrel up is interchangeable. The XL doesn't have a rev counter.
hope this helps.
Steve
My XL 1981 has a rev counter. If you used an RS head and carb, you should already have an extra 6hp over standard.
That is correct
No video of it running? your channel shows no XL 250 ?
Yes sorry about that, for those of you who follow my channel know I cant leave anything standard for very long and since this video I've removed the 305 engine and fitted an XL500 engine so will upload a video of that soon
Where can i buy parts og an xlx 250?
Is it possible to get a carbs for this?
where did you buy this kit?
how much are the big bore kits steve (UK ££) also does the BB kit make the engine more likely to wear quicker ?
They're not available any more unless you find one on ebay but the rest of the engine handles the extra power easily
Hi Steve. i got an CB 250 RS and also looking for a big bore kit. Can you tell me where to get it. Tahnks Swen
Hi Swen, these big bore kits are rare these days so you'll just have to keep an eye out on ebay or some of the American sites like XRs only. most of them were made by Powroll but also Yoshimura and Henry Abe did them as well.
Did you bore out the cylinder or is it a new cylinder?
You bore out the cylinder and fit a new liner
Thanks for the post buddy. I just bought a 2000 xr250r. My carb needs to be rebuilt. Have any experience rebuilding carbs?
Yes they're fairly straight forward, yours will probably have an accelerator pump but the kits are pretty comprehensive, just take lots of photographs when you dismantle it and make a note of which groove the tiny circlip goes on the needle
Any idea of good place to get carburetor kit for a P10a on 81 Honda xl250s thanks
@@gregkiehl64 I think the kits are made by Keyster ?? I just bought them from Ebay or you could try Dave Silver Spares
i have an xr250 it seems to tap intermittently then it goes away,happens when its hot or cold......any ideas?
A slack cam chain or balance weight chain will rattle rather than tap, if it's a top end tap then check your valve clearances or it could be wear in the head/rocker cover camshaft seating area, a good quality slightly thicker oil will help. Unfortunately the only way to check camshaft wear is to undo the rocker cover bolts, lift the cover and pop out the plastic plug then tighten the bolts back up and then see if you can move the camshaft up an down
Hi Steve,
Can you tell me your sleeve Outer Diameter?
Thanks
Sorry mate I can't remember, I made this video 4 years ago
Looking for a 305 big bore kit but having trouble finding one ? Does anyone have a link ?
For a 1980 250XL
Hello. Is this 82mm piston cylinder dedicated? Boring normal? Or did you replace the sleeve?
Yes it's a kit, new liner and boring out the cylinder to take the new liner
@@tevie54 Thank you！I know the kit that was released by Honda in the past, but do you still sell it? All I know is that I can do 280cc at Wiseco.
@@malaika650 The 280cc kit is the largest overbore you can do on the original liner, the 305cc kit is a completely new liner but these are so rare now and were sold in the eighties by companies like Henry Abe, Yoshimura, and Powroll.
You can make your own kits using a liner made for you and a piston from a Honda GX340 generator but there's a lot of machining to be done.
@@tevie54 GX340! Surprising diversion! ! Is the diameter of the piston pin the same? I thought it was ATC350. I think the GX piston is a low comp, but which of the Wiseco's 280cc high comp and power will be higher?
@@malaika650 It all depends on how much work you're prepared to do.
The 280cc kit is easier, just a rebore and new piston.
The 305 gives more power but is a lot more work if you're building your own kit.
If you can find an original kit from Henry Abe, Powroll etc it's a case of pressing out your old liner, boring out the cylinder, pressing in the new liner, opening out the crank case mouth and reassembling the engine.
If you're building your own kit you have to do all of the above but get a liner made for you, modify a GX350 piston by turning down the piston crown so it doesn't hit the head, then either bore out the small end of the con rod or make sleeves to fit the piston as the GX340 piston uses a 20mm pin instead of a 19mm.
Like I say it's a lot of work but it does give a noticable power increase.
Good video thanks. I'd also like a few more HP - can I ask where you got the kit, and if you know what the revised power is, roughly? Oh, and carb mods required? Many thanks
Hi, my kit was in amongst a garage full of XL250 spares I bought a few years ago and was made by a company called Henry Abe Industries but there have been several companies that did them, Powroll being the most popular and I think Yoshimura did one as well. they're all very rare these days but do pop up on ebay now and then. Being a short stroke engine the power comes in at higher revs so initially it feels just like a standard XL250 but then it really flies.
I run an RS 250 carb with the accelerator pump and if you're using a standard XL airbox just remove the foam filter but keep the gauze.
Standard XLs put out about 20hp and RS's about 24hp but with the 305 and the bigger carb that gets pushed up to around the 27hp area with increased torque as well.
Hi Steve, thanks for the response. No wonder I've struggled to find a kit, having assumed it would be easy. Will keep looking as that little extra would make the bike more usable for the larger fellow like myself. Starting a general rebuild in a couple of months and may pick your brains if that's OK?
Absolutely,
The reason I did it was because I ride to work two up so that extra power was really helpful when overtaking. There are other ways to increase the cc but that involves getting a liner made but I'm happy to help if that's what anyone wants.
do you have a link to this bore kit for online purchase?
No the kit is very rare now and you can only find it if you are lucky enough to find one on ebay, read some of the previous answers
I'm doing a 412cc 86mm piston on mine soon.. so can you convert a 250 to a 350?
As far as I'm aware 305cc (82mm bore) was the largest you could go on the S model because the new liner is very close to the oilway , I've heard of longer cranks to give more CCs but you're into raised barrels and machining the bottom crankcase to give more clearance then but if there is one then that would be great to see.
Necesitó en motor para la moto honda 250 proling XL modelo 83 o deseo saber donde puedo llevar el chasis para restaurarla en colombia
Hello, where can I get that piston kit?
It's no longer available so you'll just have to keep an eye on ebay
great job,where abouts are you in the uk?
I'm in Bedfordshire
Would love to know where this kit could be purchased from. Is it a standard barrel but with a new liner installed?
Yes that's correct, you have to press out the old liner, bore the barrel then press in the new liner, there are companys that will make liners to your spec but they are expensive.
These kits are very rare these days but back in the 80's companys like Powroll, Henry Abe, and Yoshimura all made big bore kits for XL250's
Nice work
Quien me podría ayudar con un cabezote de honda 250 año 1990 4 valvula acadenilla
Deu certo??
yes it works very well, I use it every day
Hey sir, can i buy an engine, xlx250
I heard that..O fk use it myself sometimes . lol
Ai esta um motor que eu sei de cor kkk monto e desmonto o da minha direto
Carlos boa tarde verifique o cabeçote isso é caro nelas jogue agua na vela com a moto ligada se sair bolhas está rachado e é caro
Klik..kk..
This is USELESS. He shows nothing