Rebuilding an XBR engine in mind - Going to do it!

[guest1130]

So, I got my XBR running for the remainder of the summer, but I'm totally not done with the bike yet. Since I'm starting my (hopefully) final year in the uni this autumn and this might be the last winter for a long time to get my hands on an equal machinery that my school has to offer, I'm thinking about doing a complete rebuild on the XBR engine.

The engine has 68 000 km's in it, and I'm not sure if it has ever been opened, so it might be a good time to do it, right?

My plan is this:
- Tear the engine to bits
- Wetblast all the alloy parts thoroughly with soda as the media (my friend has the equipment to do it)
- Replace all the gasgets with new ones
- Check for any wear on the parts/bearings and replace if necessary
- Put the engine back together with new bolts

...sounds simple enough...

Anyways, since I know there are ppl here who have rebuilt engines, any advice and tips are welcome before starting the job.

For starters - how much special tools are needed and can I acquire them as universal tools or do they need to be honda specific?
What else should I buy in advance? Gaskets and a stainless bolt-set can be found from the e-market, but are there any bearings that must be replaced when opening the engine (bottom end as well)?
I'm going to keep the original bore on the barrel if possible, so are new piston rings a must-have too?

I know some of you here have experience with vapor blasting (if I'm correct, that is water+glass beads), do you know if wetblasting with soda will make a ready surface for the alloy or does it need to be coated with something afterwards? Also, does it damage any of the sealing faces or bearing walls?

And mainly, am I going to be WAY over my head with this project or is it doable with a good set of tools, little knowledge and steady hands?

[JOOLZ]

Hi XBR engines are simple to work on there are a few special tools you will need, a Honda flywheel puller easily obtainable from ebay or dealers, a bearing puller to remove the bearing from the crankshaft and a camchain tensioner tool, get yourself a haynes manual for the honda xl and xr600 range as it has all the info you will need to rebuild your engine except the bore diameter specs which are obviously different. I wouldnt use a soda mixture on aluminum as I get a feeling it my react with the metal. 68,000  for an XBR engine is not a huge amount if it doesn't rattle or smoke I would leave it alone

[Steve H]

68,000  for an XBR engine is not a huge amount if it doesn't rattle or smoke I would leave it alone

Agreed, If it aint bust dont fix it. If you are still unconvinced I would suggest getting prices for all of the genuine Honda gaskets, if they are anything like Yamaha prices it should be enough to put you off.

[guest295]

I agree too: ripping apart a perfectly good engine for the hell of it doesn't make sense. What goes wrong with these engines is the cam bearings (ha!) and cams. I've heard of line-boring the head for proper bearings or bushings, and plasma-spraying and regrinding the cams.

[guest1155]

just a suggestion but why not get hold of a broken or suspect xr600 lumpand rebuild that. if memory serves me correctly they are kickstart only which is what i believe you were looking for with the xbr project,it will give you more cubes and if the motor is poorly to begin with then it a) won't cost a lot to buy in the first pace so b) you won't feel so intimidated about messing around with it and of course c) if you do manage to make a mess of it you won't have lost the engine that runs your bike or lost a great deal of cash either.

[guest1130]

just a suggestion but why not get hold of a broken or suspect xr600 lumpand rebuild that. if memory serves me correctly they are kickstart only which is what i believe you were looking for with the xbr project,it will give you more cubes and if the motor is poorly to begin with then it a) won't cost a lot to buy in the first pace so b) you won't feel so intimidated about messing around with it and of course c) if you do manage to make a mess of it you won't have lost the engine that runs your bike or lost a great deal of cash either.

This has crossed my mind, yes. If I can find a suitable engine for the right price, this is well worth concidering. How similar are the engines? They have the same crankcases and external dimensions? What about the transmission, do I need to swap the internals from an XBR lump to the donor?

[SteveC#222]

The Honda NX650 dominator engine fits in and if you swap the clutch basket and primary gears the gearing is right too. If you really wanted to you can tune it with a smoothbore carb, flowed head, HRC cam and ceramic slipper piston like this guy!

http://lovik.tripod.com/Clubman6-schottmeier.html

[guest1130]

Well, I've decided to rebuild the lump next winter. The clutch is starting to slip pretty bad, it's eating oil and making a rattling noise every now and then.

The plan is to take it apart, send all the parts to be vapor blasted and painted, replace all the seals, gaskets, bearings and worn parts, and change the generator cover and clutch assembly to that of an XL 600 (to get rid of the starter motor housing).

I haven't rebuild an engine before, but feel confident that I can pull it off. I'm starting to pre-order some of the obvious components soon, and I'd appreciate some tips if you have experienced that some brands or types of components are good/bad. My shopping list for now is:

• XL 600 generator cover (used)
• XL 600 clutch arm assembly (used)
• New clutch plates
• Complete set of gaskets
• Complete set of stainless engine bolts

I'm gonna get the bearings, seals and worn parts as I go.

[guest1670]

I haven't rebuilt one of these engines, but I have rebuilt several engines. In my experience, it pays to research all the parts you might possibly need, price up accordingly, and double it. 'If it ain't broke don't fix it' is very sound advice indeed, IMHO.

As I say, I'm not au fait with this particular engine, but surely the clutch can be sorted without major overhaul? Clutch slip could be down to poor adjustment, dirty oil, worn plates or a combination. A new set of plates could cost the thick end of £100 alone. Take them out and measure to see if they are within spec before you shell out.

If you tear the engine apart, you WILL find wear. You do not know the condition of the bore until you have the barrel off. You may get away with rings, you may need rings, piston, rebore, etc etc.

The trouble with this sort of thing is, you tend (quite sensibly) to adopt the mentality once you've started that as you have it apart, now is the time to renew everything that has wear. You will need a good manual, preferably a genuine one (Haynes is ok but it lies at critical moments!), and deep pockets.

Pattern gasket sets are often of dubious quality, and seldom contain everything you need, even if they say they do. Using pattern head and base gaskets in particular can be a risky business and if Honda prices are comparable to Yamaha, a single head gasket can cost as much as a complete pattern gasket kit!

Not trying to put you off, but there are lots of bikes consigned to boxes that would otherwise still be running, due to enthusiastic owners going in with rose-tinted glasses. If you do take the plunge, there will be lots of help and advice available on here I am sure, but everything else will need paying for!

[guest1130]

Thanks for the input, Martin!

I know these projects tend to become costly, but right now I feel that its time for it. The bike has more than 70'000 km's on the clock, and I have no idea about the engines service history. I'm one of those guys who just don't rely on things they haven't checked for themselves - and I fear the engine needs a lot of care. Hopefully I'll get away with nothing major like an overbore with a new piston. I do own a scanned copy of the XBR service manual, which has all the info I need.

Of course I could just replace stuff as it breaks, but given the mileage and age of the lump, a lot of stuff is bound to give in or need serious adjusting in the following year or two and I hate taking the bike apart mid-season.

[guest1326]

If when riding the bike the gearbox and clutch are OK then I'd suggest leaving the bottom end alone. What tends to wear on XBR and related engines is the valve gear, namely the camshaft and rockers. If the engine has had regular low mileage oil changes then it might well be OK, but the top end oiling is marginal at best and you may well have to do some repairs. I don't think new cams are available but the rockers may well be still available from David Silver's. A better option if needed would be to get the cams and rockers re-tipped and ground by someone like Phil Joy Cams. These will probably out last genuine Honda replacements anyway and cost less to boot. The valve gear can be checked by taking off the cover on top of the engine and and wear will be very easy to see. If you do need to replace any parts it would also be good to replace the cam chain and possibly the guide and tensioner as well.