Cylinder head repair XBR500

[xbruby]

Just bought a spare engine for my XBR from flea bay.

The engine was sold with top end removed and with the ususal crack between exhaust port and spark plug entry port.

I came accross a chap a couple of years ago who told me this was easy to repair and in fact recomended machining a new spark plug port to the centre of the valve arrangment.

Anybody either repaired or modified an XBR cylinder head before? Any suggestions as to where I can take it for repair work?

Thanks in advance,

Andy

[002]

Dont bother with repairing the crack !
All the RFVC motors do it.
I've rebuilt quite a few with a crack or two and they have been fine for thousands of miles after.

Just sort out the valves as you would normally and forget sbout the cracks.
Never heard of anyone moving the spark plug !
Cant think of anywhere else for it to go !

Jethro

[xbruby]

Thanks for the info.

I would like to repair the crack however and then perhaps polish the intake and exhaust ports. I would quite like to investigate any other top end improvements such as HC piston fitment?

Any advice?

Andy

[SteveC#222]

Have you seen this?

GB500 hop up

while the top end is off,it wouldn't be that much more trouble to go the whole hog.

Also some interesting bits on GB500 FAQ

GB500 FAQ

Oh yes, there is a supertrap silencer for the XBR on Ebay

PPS If you do all of the above......I want a go on the finished article!!!   

[xbruby]

Article very interesting, as this is a spare engine I would like to improve performance. Don't know if I will go the whole hog however!

Looking at the top end components, particularly the rocker arm contact faces, they look quite worn and may need replacement. Does any one know if these are readilly available? Cam shaft looks OK, head and piston crown surprisingly clean, the only noteable problem appears to be the crack in the cylinder head.

Andy

[002]

Article very interesting, as this is a spare engine I would like to improve performance. Don't know if I will go the whole hog however!

Looking at the top end components, particularly the rocker arm contact faces, they look quite worn and may need replacement. Does any one know if these are readilly available? Cam shaft looks OK, head and piston crown surprisingly clean, the only noteable problem appears to be the crack in the cylinder head.

Andy

Yes parts easily available,and dont worry about the crack !

Jethro

[#88]

hi XBRudy
 I raced an XBR a few years ago and built my own motors,I had a crack in the head and got the thing welded up but it was a big job as the valve seat had to come out then welded up then machined and the valve seat put back in and the seat recut.Raced a tigcraft with a dominator motor
same thing crack in the head didnot bother went fine.I had a couple of rockers needing repaired so I got David Newman Camshafts to repair them quality job and not to expensive,he also done a camshaft regrind for me.David Silver also does rocker arms for them.
    cheers the noo Brian #88

[OMEGAMAN]

hi XBRudy
 I raced an XBR a few years ago and built my own motors,I had a crack in the head and got the thing welded up but it was a big job as the valve seat had to come out then welded up then machined and the valve seat put back in and the seat recut.Raced a tigcraft with a dominator motor
same thing crack in the head didnot bother went fine.I had a couple of rockers needing repaired so I got David Newman Camshafts to repair them quality job and not to expensive,he also done a camshaft regrind for me.David Silver also does rocker arms for them.
    cheers the noo Brian #88
[/quote    Are you the guy from Nr. Edinborough who sold the Blue Tigcraft/xbr a couple of years ago?]

[xbruby]

Thank you #88, so I can buy replacment rockers at David Silver? That is good news.
Listening to the advice offered I have now adopted the view 'crack, what crack'?

After hearing what you went through to get a repair done it would cost more than I paid for the engine! I will treat it to new rockers however, will call David silver for prices today, best make sure I am sat down at the time?

Thanks,

Andy

[Hondapartsman]

SEP maybe, or the cylinder head shop which is in Ireland but does mail order etc. My Rs has a cracked head, as did the heads on the two spare engines I got. Runs okay with the crack (I had no money to fix so decided to try it anyway) for all I know my other runner has a cracked head as well although eventually I did track down a good one which will go on one of the spare engines one day when I can afford/get around to having the barrel for that rebored.