Unleaded fuel

[oblertone]

Could someone explain what will happen if I keep running my 80/7 on unleaded fuel ?

As far as I am aware it has never been converted for unleaded but LRP appears to be like rocking horse shite !

Maybe this should have gone in the Airheads section !

 

[cookie]

the theory:

the exhaust valve seats will get so hot that minute bits of the seat will stick to the valve when it opens causing the the valve to recede into the head. valve clearance will reduce with the possibility that the valve will then be incapapble of sealing totally. valve will then burn.

depending on actual vehicle & use (high speed is bad) this may or may not actually happen. check the valve clearances often. if they close up too quickly, it's an indication that recession is occurring.

worst case scenario is that you will have to replace the exhaust valve seats & probably valves too, which is what you would do as a preventative measure anyway.

 

[Steptoe]

how many miles had the engine done on leaded, the lead is absorbed by the valves and seats so it offers protection for a while after stopping use of leaded fuel, depending on the mileage leaded was used for.

 

[oblertone]

Zero speedo

Can't say about the milage but suspect it's been to the moon and back as it's an ex MetPol bike.

Do any of the available additives work ? or are they all 'snake oil'.

The cost of getting the heads done professionally is probably more than the bike is worth, is this a DiY job ?



ps - welcome back Steptoe !

 

[wessie]

Re: Zero speedo

Do any of the available additives work ? or are they all 'snake oil'.

I've heard good reports about this one from Morris Lubes

 

[cookie]

Re: Zero speedo

The cost of getting the heads done professionally is probably more than the bike is worth, is this a DiY job ?

3 to 4 hours work to remove & refit heads. pretty basic, but you'll need a torque wrench.
always seems to cost £200 to 350 to do the work on the heads, depending on whether new valves are fitted, how shagged the guides are (exhausts always need doing IMO). don't forget top end gasket set.

at least you can fix the inevitable oil leaks from cylinder base/pushrod tubes at the same time

look in motobins book or site for exact costs.

 

[oblertone]

Thanks cookie !

I don't mind doing basic, and i've got a torque wrench. Just as long as the new bits don't have to be pressed in or require specialist tools.

Leaking pushrod tubes, yes i've got them too !

 

[cookie]

send the heads to somewhere that knows what they are doing for the engineering & do the fitting yourself.

i've had BMW heads done at the cylinder head shop (the best, but don't hold your breath on turnaround ) & motobins (cheaper, much quicker & OK)

local bodgers round here (south coast) are shite IMO & best avoided. a dropped seat makes a lot of mess

 

[(RIP) Kaister]

there is also the theory that the surfaces of the valves and seat inserts have considerably work hardened over the many miles - effectively 'forging' the surfaces to compress the crystalline metal structure to give a much harder surface.

depending on your riding style, i'd guess it wouldn't be flat-out, wide open throttle stuff - then i'd ride it around as it is being sure to check the clearances more often, as cookie says.

put the mileage and gap sizes into excel and make a graph of the line - if it noticeably changes from a straight line graph, you'll see the imminent wear increase about to start and be able to catch it.

Not that any damage will be done, anyway - just clearances.

You're more likely to drop a n exhaust valve head at high mileage,though - if you cane them