93 oct fuel (gas)

Restoration forum Bmwbike.com
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Pablo Prato

93 oct fuel (gas)

Post by Pablo Prato »

I have problems with R67/2 and R60 (low pressure motors) they put the sparks plugs out few minutes running, they loks black, dark and can't be cleaned.
I use Liqui Moly lead sustitute.
What coud I do?
(R69S haven't the problem)
Allan Atherton

Re: 93 oct fuel (gas)

Post by Allan Atherton »

In all three bikes, drain the tank and the carbs, put in fresh gas without the lead substitute, and put in new plugs.

If you have any problems after that, you will know the LiquidMolly is not the cause.

Lead substitutes cause problems. They do not burn as cleanly as lead used to burn, and people also add too much, which makes the problems worse.

My R27, R60/2 and R69S all run well on plain 92 octane gas, and have had no valve problems in 7000 miles on each bike since rebuild.
Pablo Prato

Re: 93 oct fuel (gas)

Post by Pablo Prato »

Thaks a lot.
I will do it.
Best regards
Prosper Keating

Re: 93 oct fuel (gas)

Post by Prosper Keating »

I had problems with 95 octane unleaded. My R60/2 - with high compression pistons - runs OK on Super (Lead substitute) but is better on 98 Unleaded.

However, I also had the same problems as you (with Bosch 240 plugs). I tried everything. It ran well on some old AC Delta plugs until some vandal kicked the tops off them outside a bar here in Paris. I caught him as he was finishing the second one...

I am now running the bike on 3-point Lodge HNs from the 1950s - still available and probably remanufactured today - and have had no problems since fitting them. You will not have problems with your valve seats. I have never had problems with any of my old bikes running on unleaded, except that the motors run a bit hotter.

PK
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