CB250RS Handlebars

[xwhatsit]

Oh, and another thing: handlebars. Mine are... less than ruler-straight haha. They don't actually bother me overly, as the right side is lower than the left, rather than being closer to me than the left. Is it important to somehow obtain CB250RS handlebars, or are handlebars some kind of common aftermarket items (like wingmirrors seem to be) that I can pick up, universal for any bikes? I wouldn't mind getting some straight bars, rather than the ones I've got that do an S-bend upwards, but I'm easy really so long as they're not ape-hangers.

I take it I can just transfer all my switch gear/accelerator crap off the old ones onto the new ones? The more I think about it the more complicated it seems. Anybody know anything?

Thanks...

[Kickaha]

Any of the bike or accessory shops should have a selection of bars that you could look at, and yes you can just swap all your stuff over onto the new bars

[CB250RS-Old_Rider]

I have just this moment bought home a Honda CB250RS (Blue) which I bought through Trademe.co.nz

The info I am looking for is this: The Decompression Lever cable is broken which leaves the decompression lever on the top of the engine is always down facing forward…..The bikes starts alright , with the choke out and once it heats up idles not too bad for an old bike….But I am wondering if the decompression lever is open all the time as I only seem to get about 80 - 90Kms.ph at reasonable revs ….Now I know the bike is old-ish 1986 89thou on the speedo and Secondhand but I still would have thought it would do better than this….Unless of course it needs rings , or worse, but it doesn’t smoke. It just feels like it should do better….Any thoughts about the decompression lever thingy ?????

Your input would be of great value to me ….

Cheers

Mike

[Ixion]

Oh dear. Here we go again. Get a compression tester on it and see what it shows.It is most unlikely to be the (really totally unnecessary) compression release (it's a 250 FFS).

But do bear in mind that 'reasonable revs' by the standards of Briddish 650s is lugging by CB250RS standards.

[Rosie]

I take it I can just transfer all my switch gear/accelerator crap off the old ones onto the new ones? The more I think about it the more complicated it seems. Anybody know anything?

Thanks...

I switched over the bars on the sherpa, it's a bit fiddly to transplant all the switch gear etc, but not terribly complicated (unless you get it all out of order on the new bars). If you can loosen everything off, and slide them off the end of the old bars (bars may need to be loosened or removed so you have enough slack in the cables/wires), it makes life easier than dismantling things fully.

If the new bars are going to be a significantly different shape/width to the old bars, make sure your cables and wires are going to be long enough.

Does the CB have one-piece bars? Would dirtbike bars be an option? They are a very common aftermarket item, and you can get a big range of shapes/widths etc.

[Ixion]

I think the Persian gentleman has long since sorted his bars. And much else also.

[Rosie]

I think the Persian gentleman has long since sorted his bars. And much else also.

Doh! Thanks. This is what happens when I work late

[Bonez]

As you alluded to the depression lever could be being forced down onto the RH exhaust rocker arm by the spring, most probably reducing the valve clearance to nil gap I should imagine (well nill at the adjuster end any way). You could put it in a vertical, nuetral, position using some lockwire. Taking the front rocker cover off should reveal whether this is occuring or not.

xerxesdaphat could probably post a pic of its correct position.

I'd throw in a new spark plug and set the gap as well. Got access to a workshop manual?

These engines love to rev with a red line at around 9200rpm. The one I owned had a sweet spot from around 5000rpm thru to 85000rpm. Don't be afraid to use it.

Also these motors are prone to cracking heads. Good wee bikes all the same.

[xwhatsit]

Hey man, give me an hour or two and I'll be able to scan the appropriate page of the Haynes manual. And take a photo of my bike with the decompression lever in `normal' riding position.

I've disconnected the cable before, and the lever just sits there and does nothing. I think you have to put some pressure on it to make it do anything -- I certainly didn't note any power loss.

They really howl for a single, rev the snot out of it, it won't hurt it. With standard gearing mine will do 140kph, supposed to be able to get 150kph but by that stage I think you'll be into the red zone of the rev counter. Mine's geared way tall now as an experiment, cuts down the top speed as it doesn't have the grunt to get up there. That `sweet spot' is certainly noted -- there's a moment around 5,500rpm where the intake noise changes and it feels like it's coming `on cam' and howls up to the redline. Great fun around narrow Parnell backstreets in second and third.

[xwhatsit]

Here we go. Manual doesn't say much about the decompressor. I'm still not quite sure how it works, I've examined the manual and my collection of engine bits on numerous occasions and it still escapes me.

Basically you're just supposed to set it so there's a bit of free play in the end of the cable at TDC. You can move it back and it will stop against something; the cable is holding it a little bit forward of that point. When you kick it, the cable lets it go forward the way the spring is pulling it.

Here's some photos of my filthy engine (can't make it stop weeping oil from the valve cover, especially bad in hot weather or with winter muck on it). In the blow-up diagram the decompressor lever is #47.

Like I said, I've disconnected the cable before and it didn't seem to make a difference. I think it does its work sort of halfway in-between fully-out (disconnected position) and normal position. It is unnecessary, it's quite easy to kick over without it, but it is nice to have in a freezing cold winters day when your boots and the kickstarter are slippery -- reduces the likelihood of banging your shin -- and also is nicer on the kickstart lever itself (which, like the head, is prone to cracking).

[TygerTung]

I have a CB250RS which I race and it usually lives in the 8000-11000 rpm range and has been doing so for a few years now with no ill effects. These motors seem pretty unburstable so don't worry about a few revs.