Head overhaul

[PW Cymru]

Having returned from my Scotland trip I decided to have a look at the tick-over as it became unstable after about 1000 miles during the trip.

Bike ran fine at high speed but cut-out at idle.

So starts to set the valve clearances before having a go at the tick-over only to find no clearance. Would back the inlet adj and eventually achieved a clearance but the exhaust doesn't have sufficient adjustment to set the clearance.

I think its probably reasonable to assume I've got a bit of a valve regression issue.

So any recommendations on where to send them for overhaul/unleaded conversion.

 

[Rob Farmer]

Steve Scriminger. He's doing heads this week so if your quick you should get a quick turnaround

£15 postage for a pair of heads recorded delivery. He's doing a pair for me this week.

 

[ebbo]

fading out and dying at tickover... Drove me nuts a few years back. It was caused by worn O ring seals on the carbs butterfly spindles sucking air in. I bought service kits as part of the process to try and fix the problem and found on one side the O ring was really worn out. Once replaced all was well.

I’m sure I read if you spray some WD40 around the carbs on the cable sides you might hear the engine note change as it gets sucked through it to the engine but I can’t confirm it as I didn’t try.

 

[PW Cymru]

Steve Scriminger. He's doing heads this week so if your quick you should get a quick turnaround

£15 postage for a pair of heads recorded delivery. He's doing a pair for me this week.

Thanks Rob,

I'll take the other one off later and get them packed.

How much did SS quote?

 

[Rob Farmer]

he hasn't Paul. It's for the head where the valve seat dropped so price will depend on if any machining is required.

The last pair of heads I had done came to around £250 with seats, valve guides and valves.

 

[Deleted account 111026]

Glad to hear he's doing heads this week, he's got 4 of mine at the moment, two for unleaded conversion plus new valves, guides, etc, plus two for my project bike which are having the 46mm inlet valves fitted.
Steve is definately the man if you're looking for a BMW airhead specialist.

 

[PW Cymru]

he hasn't Paul. It's for the head where the valve seat dropped so price will depend on if any machining is required.

The last pair of heads I had done came to around £250 with seats, valve guides and valves.

Thanks Rob,

Both heads off now so I'll pack them tomorrow and give him a call on Tuesday before posting. £250's not too bad, I'll (or should I say the kids) will just have to eat beans for a while.

Barrels are coming off too to replace the pushrod tubes and seals when I can get my hands on a circlip plyers to take the gudgeon pins out.

 

[Kenny]

Leave the pistons in place and just pull the barrels off !!

 

[PW Cymru]

Leave the pistons in place and just pull the barrels off !!

Thanks Kenny, Pistons left in place just need to get a good circlip plyers to remove the pin.

Q, RealOEM shows the O-ring at the base of the barrel (1981 R100RS) but I've got the full gasket fitted, should I revert back to the O-ring's or am I missing something.

I would asume that with the full ali base gasket fitted I'd lower the compression, haven't measured the thickness yet but will when the barrel's off.

 

[Rob Farmer]

Bin the ally base gasket and fit the standard O ring. I've no idea why people fit the gaskets to later engines. 9.5:1 isn't a particularly high compression ratio so there doesn't seem much point in lowering it

 

[PW Cymru]

Thanks, off to Halfords to get the pliers.

 

[PW Cymru]

Barrels off, both base gasket and base o'ring fitted by a previous owner but only one stud o'ring eash side

Seems to have been a cautious person with a bad memory