XBR500 info needed...again...

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XBR500 info needed...again...

Yes, yes, yes. I know I've asked this 100,000 times, but things are looking up in terms of my potential XBR500 ownership.

In the garage we/I have an F-reg, 40,000 mile XBR500. Before it was out firmly at the back of the garage, it was said that it felt a little breathless. Difficult starting (both electric and kick) combined with the aforemetioned poor running suggested that compression was low. I know the Honda XL OHC singles are know for eating heads/valvetrains, so I'm guessing that this is what's happened here. So engine strip time it is.
But like I'd leave it standard
Now, the XBR500 shares it's engine with the XL600, albeit in sleeved down form. Am I right in thinking that an XL600/XR600 liner/piston would fit straight in, and so therefore XL600/XR600 tuning goodies? Would Honda have left the crank/bottom end alone for a simple sleeve down job?

You asked this before.Have you checked the stroke specification. Is the 650 stroked and well as bored???Is the piston the same weight, if not is the balance shafts the same or is the crank balance different.Adding a bigger bore to an engine that is allready more than the ideal cyl size is unlikely to give you more power (just the same power lower down, you rev limit wil be reduced, fine on a trail bike) without additional work (ie an increase in the breating ability, carbs, gas flowing, pipe).compare part numbers.Kev

I would very much doubt it.Honda have always been buggers for changing things for the sake of it.Nige

The stroke and bore of the Dominator and the SLR (644cc) is 82mm x 100mm respectivley.While the same piston fits in the XR as the SLR the barrel of the SLR/Domi is 2mm taller.The heads of most honda singles of that cc are interchangable I think but I have no experience of the XBR's specifically so I would check your figures.To be honest I would just replace the whole engine with a dominator etc lump and be done.If you do that all HRC parts from the XR600 (cam etc) will fit.

*edited 'cos the origianl post read like it was typed by an idiot...*I'll have a look in the workshop manual tonight - it covered both the XL 600 and the XBR600, so there's a fair chance that they'll share more than a few parts...Hopefully it'll have a load of specs in there, then I'll be able to see just how work could be involved.I'd like to keep the XBR500 cases, simply because of the oil pipe that runs along the outside of them - adds to the "retro" look

Hmmm, I've just been reading a bit about the 500/650 engine swap. It's not just a straight in and out job...Interesting read though...Find it under the "Technical" section at www.bikerworld.co.ukStill tempted

Why are you keen to upgrade it thr XBR is a nice little bike and th engine is very smooth and sweet ( a bit bland for my taste) but there nice in a Honda sorta way.I would be happy just to rebuild what you have.Whats the damage to the lump? Kev

KFZ wrote

Why are you keen to upgrade it thr XBR is a nice little bike and th engine is very smooth and sweet ( a bit bland for my taste) but there nice in a Honda sorta way.I would be happy just to rebuild what you have.Whats the damage to the lump? Kev

Haven't looked, but from what I've read and from what my dad described there's something up with the head. Also, there's quite a substantial oil coming from where the exhaust downpipe leaves the head...It's 41,000 miles old and from what I've seen, it's due some work in that area. If it's a rebuild, XR600/NX650 engines and their required bits are more plentiful and threfore cheaper...

maybe??Well the first thing id do is get a reasonable idea of the damage.wip the head offf and see.At least run a compression test.Kev

A head rebuild, rebore and new piston is going to be a lot cheaper and easier than an engine swap with an engine of unconfirmed condition.As KFZ said , whip the head off and have a look, you cant make a educated decsion until then

My XBR had 60,000 on the clock when I sold it. I believe it finally died at 110,000. Not bad huh?I would love to get another one...and give it the cafe racer look

To be honest mate I have looked at the bikerworld report and you do have everything you need other than specialist tools.Are you mechanic enough to do this?I am no spannermonkey but I would attempt this taking advice from a mechanic about the electrics as this is my weak point.But as maddog says - why not rebiuld the one you have?

As conversions go, that looks very straightforward, at least you have something to refer to!

AFAIK the wrist pin on the 600 and 650 is thicker than on the 400 and 500 so you have have your con rod machined out. Other than that it sounds very doable

my xbr500 engine is running a xl600r head. the stroke is the same. this give you the chance to run a high compression piston. i change my con rod to a aftermarket xl600r for strength which was a full rebuild job but you could do without and just do top end. you will have to change the relevant gaskets to xl600r and set the valve clearance to xl600r. kiss your electric start good bye kickstart only. looking at a slr650 starter but not tried yet. it is a lot of strain on the top end. im 14k since re-build and im looking at a top end off job. this was my fault down to exhaust. but you keep on top of it then you will get a nice power increase and torque to tow a car. 

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