Thumper Club Forum

Technical => Bike Problems/Questions => Topic started by: richardeblack on October 13, 2020, 02:46:53 PM

Title: XBR500 pistons and liners
Post by: richardeblack on October 13, 2020, 02:46:53 PM
Hello All,
Started sorting out the engine of an XBR I am rebuilding and found that out of the 7 cylinders I have checked, only one is really good.  One is cracked, most are scored some are badly worn (all to be expected really as they come from high milage bikes). 
I think I can find bits good enough to build this engine but could do with being able to get oversize pistons or standard pistons and new liners to build up at least two  other engines.
Does anyone know where pistons are available from?  Will I have to go for overboring to 100mm and use XR600R pistons?  Will the standard liner go out to 100mm?
All really annoying as none of my engines smoked so I suspect I can get away with using the cylinders I have but would like to build up a really nice one when I can.
Any suggestions welcome.
Thank you,
Title: Re: XBR500 pistons and liners
Post by: themoudie on October 13, 2020, 05:37:55 PM
Aye Richard,

Link for piston: Honda-xbr500-1986-g-germany_model (

Link for barrel: Barrel (  Eye watering!  :(

This is just a starter. It appears that the barrel doesn't use a liner, which would have been a logical way to go, in my head!

Regards, Bill
Title: Re: XBR500 pistons and liners
Post by: Moto63 on October 13, 2020, 07:41:14 PM
Wowsers that barrel ain’t chirpy, chirpy cheap, cheap is it 😲
Title: Re: XBR500 pistons and liners
Post by: mthee on October 13, 2020, 08:02:21 PM
Secondhand off fleabay?

Title: Re: XBR500 pistons and liners
Post by: richardeblack on October 18, 2020, 01:24:20 PM
All so expensive!  Thanks for looking folks.  Managed to find a useable barrel (a bit scored but not too bad) had it cleaned up and was just starting to put it back together and, wonder of wonders, find that the little end has been siezed and picked up on both the piston and little end!  Found another piston and gudgeon pin in my pile of spares but just don't know what to do about the little end. Unfortunately they don't have bushes in the XBR and run direct in the steel con rod.  No idea what to do now! Looks like I will have to strip the whole thing down  and try and find enough bits to do a complete engine rebuild.  Really beginning to doubt if it is worth bothering with it!  I will have to get it re registered anyway (not a problem and only £25 as I have the number plate for it) but what a mess!  Truly fed up with it all.
Ah well, back out into the garage to see if I have any decent bits to build an engine from ground up. 
Can't believe the little ends aren't even bushed.
Thanks again for the suggestions.
ps. the cylinders do have liners, haven't tried to knock one out yet so will work with the tattiest ones first.
Title: Re: XBR500 pistons and liners
Post by: themoudie on October 18, 2020, 04:31:20 PM
Aye Richard,

Commisserations!  :(  Been there with other engines and it appears that with engines of this era a complete engine rebuild for under £500 is cheap. Unless you have the engineering facilities and experience to do the machining. Most places these days are at least £40 an hour for labour even one man bands, unless they are retired and doing for it a 'hobby'. ;)

I am pretty sure it would be possible to bush the little end, but not having the engineering training, I am not sure of the practicalities of specific materials and it all depends how much 'meat' is around the little end eye. But, clean up the little end of the rod, bush it with a phosphor bronze bush, drill the oil holes and then ream to give a tight but smooth fit, as per Honda spec sheet for the motor.

Alternatively, a new rod and a crank rebuild as the big end may have suffered when the little end nipped up. All speculation, unless evrything is closely examined. I use a watch makers loupe x 10 magnification, after washing down with brake cleaner.

You can see in the two attached images some of what I faced with the XT600E engine for the SRX400 Mono rebuild and it was still running!  ::)  There was getting on for 3mm play between the inner and outer races of the nearside main bearing and rust build up on the offside crank journal. The fifth gear pinion had pitted teeth and the resulting swarf, along with silicone gasket and fluff from rags had half filled the oil pump strainer and there was still plenty of metal sitting in the bottom of the crank cases. All in, the spares, a crank rebuild and barrel hone cost nearly £1,100, my time was for nowt and this was three and half years ago.

All the best, Bill
Title: Re: XBR500 pistons and liners
Post by: richardeblack on October 19, 2020, 10:35:16 AM
Thanks Bill,
All a bit depressing.  Looking like time to give up on the poor old XBRs.  I will just gather together the best bits and hope I have enough to see me out.  I don't do many miles since I retired so I should be ok.  I had been hoping to build up 2 or 3 including a stripped out minimal one but I don't think I have enough good spares. 
At least with my British stuff spares are readily available and fairly cheap and most of the components are repairable (bushes etc).
Thanks again.
Title: Re: XBR500 pistons and liners
Post by: themoudie on October 19, 2020, 03:35:35 PM
Aye Richard,

The intention was not to sow the seeds of doom and despondency. But just make you aware of some of the drawbacks I have found restoring '80's Japanese singles. I am fairly sure that 'Ian' of Telford, inspite of having a series of trials and tribulations with new machines, would express similar views on spares availability and prices for SRX and XBR machines of the '80's era.

I agree that keeping your 'good' spares to keep the running XBR machine in good fettle is probably the best bet and the British machines spares prices are often cheaper and more readily available.

Whether the impression I have is true or not, I don't know, but lots of British bikes are still being used regularly, whilst Japanese bikes are restored, often to a standard of finish brighter than when they left the factory and then consigned to a wall/den/living room as a focal piece and not used. :(  The number of machines that my local MoT station owner sees annually, with less than 200 miles in the previous year, is quite amazing.

Increasingly, I am inclined to reduce the accummulation of bits and whole machines, regardless of market whims, so that I can enjoy my favourite bikes out and about, whilst I can. A workshop full of 'spares' and machines, whilst you are unable to use them just screws your head, in my experience.

Good health, Bill
Title: Re: XBR500 pistons and liners
Post by: richardeblack on October 21, 2020, 08:12:51 AM
Thanks again Bill
Sound advice.  I have decided to follow it and, once the XBR I'm working on is done and (Probably) sold I will work my way through my mountain of spares and dispose of surpluses. Sadly I think my stock of useable bits will end up quite small. On the bright side I have found suppliers of not too expensive parts like con rods (unfortunately the other side of the Atlantic) as some of the parts are interchangeable with XR600R and 650 which were popular over there and had a longer production run.
Thanks again for all your help and wise thoughts.
Title: Re: XBR500 pistons and liners
Post by: themoudie on October 21, 2020, 09:06:56 PM
Thank you Richard, no bother.

Good health, Bill
Title: Re: XBR500 pistons and liners
Post by: Ian on October 21, 2020, 11:18:19 PM
Hi Richard, my knowledge of XBRs is somewhat limited, but have you thought about fitting a Mash or one of the similar Shineray engines? I don't know if engine mountings are compatible but at least you should be able to find a lower mileage example.
Just a thought
Ian 👍
Title: Re: XBR500 pistons and liners
Post by: richardeblack on October 22, 2020, 10:49:33 AM
Thanks Ian,
Had a look at specs in the thought that they might be just a straight copy so possibly able to use parts in the XBR but unfortunately a different bore and stroke. Also the engines are much lower power than the XBR.  I will have a closer look just in case there are possibilities there though.  I will also try and measure up the exhaust to see if that can be made to fit as XBR exhausts are very difficult to find at a sensible price.
Thanks very much for the suggestion.
Title: Re: XBR500 pistons and liners
Post by: Rossco500 on October 22, 2020, 08:33:06 PM
Hi Richard - I wouldn't give up hope just yet. Parts do crop up now and again. Germany seems to be a good source for some stuff but I'm not sure how Brexit will affect prices. Its nearly got to the stage where its cheaper to buy a decently running bike than to rebuild the engine.
I recently bought a decent one at reasonable money as the tank had rotted out at the sides - surprising as the rest of the bike shows signs of having seen very little use in the wet and only 11.5k miles. Has the original shocks, exhausts and seat cover. I originally bought it as a parts bike but on closer examination it appears to be a very early red one on a "B" Reg.
I'll keep my eyes open for you in case I come across anything that might help you out


Title: Re: XBR500 pistons and liners
Post by: richardeblack on October 24, 2020, 10:38:08 AM
Thanks for the reassuring words Tony.  I have also found that some of the parts of the xl600r (con rods and maybe crank ) as well as some of the other trail versions so that give a bit more to choose from.
I have actually found another engine bottom end with a just about acceptable small end so will strip it out and maybe use that one on the bike I am building.
So generally I am not feeling so fed up about it at the moment.  Looks like I have enough parts to keep me going for a while.
Does anyone know if I can fit the xl600 cylinder to the xbr500 engine?  could I use the 500 head or would I have to machine it out a bit to keep the compression ratio down?
Thanks again all who have helped me.
Title: Re: XBR500 pistons and liners
Post by: Rossco500 on October 24, 2020, 10:43:53 PM
Hi Richard - a few years back Classic Bike included an article on buying an XBR. It included the following advice from Martin Sweet of Slipstream Tuning -
"You can get a bit more power by swapping the XBR head and barrel for an XL600 top end, but you have to make sure it's from a single carb XL or you'll run into problems. Or you can still get big bore kits from JE ( They list oversize pistons up to 102.4mm bore size - though you have to fit a new liner and open up the crankcase mouth if you want to go that big. That's when it starts to get expensive. You can go up to 2mm oversize on the stock liner. The bottom end of the XBR engine is strong enough to take the extra power. Even for racing, we will re-use the stock con-rod - after shot peening and polishing - when rebuilding a crank"

Their number was 01732 743248 a few years back - might be worth speaking to him for advice

I think the topic may also be covered in the ADV Rider GB500 site although you'd have to wade through it. Some other useful info in it anyway though

I have a crank from an engine that seized with 20k miles on it - the owner forgot to tighten the sump plug after an oil change! Even broke the camshaft in half. I doubt I'll ever use it and if you want it you can have it for the cost of the postage. Not sure its any use but sure you can have a think about it. Oh, and in response to your other post, you can polish the casings - I'll post a few photos

Hope this is useful


Title: Re: XBR500 pistons and liners
Post by: themoudie on October 25, 2020, 12:21:30 AM
Aye Richard and Tony,

Martin rebuilt my XT600E crank for me and supplied the correct parts, also advised on oil pump replacement. Quality work.

He also supplied parts and rebuilt the crank for my older SRX 600 motor that has now done over 54,000 miles before the top end started to blow oil! Bottom end still appears sound.

Best to telephone and after 10:00am as Martin was semi-retired when I last spoke, but his workshop know what they are doing. Not sure about the email or website addresses these days.

Contact Slipstream Tuning

Phone:  01732 743248

Fax:  01732 743385



Address: Unit 1 Block 5, Vestry Industrial Estate, Otford Rd, Sevenoaks TN14 5EL

Good health, Bill
Title: Re: XBR500 pistons and liners
Post by: richardeblack on November 27, 2020, 10:32:10 PM
Thanks again for the helpful suggestions.
On checking all my barrels again I was very excited to find one that is .25mm oversize although the liner has some odd marks on it.  Luckily I have some scored standard barrels that will clean up at .25mm os so will get them bored.  I am dead chuffed as that will mean I have two really good sets of barrels and pistons on the shelf ready for the next XBR to be done.
Thanks again.