Help for a mate

[Kenny]

Friend rides a R45 with a 865cc Siebenrock kit fitted. Loves the bike and has spent quite a bit of time and money on it.
Unfortunately ( and, yes, he is kicking himself for not doing the valves over winter) on a ride out yesterday the bike dropped an exhaust valve
and it looks now that he will need a new head ( in fact a pair of heads as exhaust thread on other side is also worn ) and a
Siebenrock piston and barrel.
Mate is in 'pissed off' mood at the moment.
Any ideas on best way to get the bike back on the road? He could try and source new heads and have them reworked etc
and buy a Siebenrock 'half' kit or maybe go the R65 ( short stroke/heavy flywheel ) route and simply fit the whole R65 engine, if he can find one.
Any input for him would be appreciated.

 

[Bubb]

That’s a bugger….feel sorry for the poor lad.

Hope he gets it back on the road and it doesn’t cost him too much money.
Worth seeing if motorworks etc have a pair of heads….. get mikeyboy to fit brand new valves etc….
Do siebenrock sell one cylinder?…

 

[Gelandestrasse]

Try Cray Engineering for the parts, too.

 

[squibb34]

You can get pistons separately, so may be worth a conversation.......... https://www.siebenrock.com/en/engine-parts/power-kit-860cc/?p=1

Maybe the head will clean up - talk to @mikeyboy. I got away with re-cutting the seats & new valves/guides when something similar happened with SWMBO's bike.

What seems strange here is that the bike appears to be running rich, or maybe a little oily - this usually occurs when they run lean, unless your buddy has been ignoring the valve clearances for many years.

 

[mikeyboy]

I’ve got a pair of 65 barrels and heads,I can take a look next week to evaluate the condition.
IMHO an 860 kit with 45 heads/carbs etc is. A bit of a waste as the valves and carbs are not big enough,
This may well be the reason it’s dropped a valve if it’s been running on standard carbs/jetting.
If he’s prepared to spend the dosh on a replacement 860 barrel/piston he would be better off trying to source some post 81 65 heads and 32mm carbs.
Failing that,fit an 80/100 motor with new header pipes.

 

[Kenny]

I’ve got a pair of 65 barrels and heads,I can take a look next week to evaluate the condition.
IMHO an 860 kit with 45 heads/carbs etc is. A bit of a waste as the valves and carbs are not big enough,
This may well be the reason it’s dropped a valve if it’s been running on standard carbs/jetting.
If he’s prepared to spend the dosh on a replacement 860 barrel/piston he would be better off trying to source some post 81 65 heads and 32mm carbs.
Failing that,fit an 80/100 motor with new header pipes.

Thanks guys...I've let him know results/advice etc. Mikey, he is sitting on his hands at the moment, so if okay, I'll contact you should he go the 650 route

 

[Stirlingmoz]

I’ve got a pair of original BMW, new old stock R65 cylinders. Still in the BMW boxes if it helps.

 

[Nin]

R80 barrels, heads (the later ones) and pistons sitting in the loft if they’ll fit?


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