RC rebuild

[MichaelS]

I hope to have this completed for the new season and be able to take it to the North West 200. It has been off the road for 16 years so one more should be on the road again. However, while the engine is being re-built I wanted to check what the fuel position is given it runs on leaded. I was watching a recent car renovation programme and they had the valves re-worked so the engine could run on unleaded. Is this necessary or worth it?

Many Thanks

Michael

[Anonymous]

Hi Mike. No need for any fancy valves or seats. The R,s despite misguided media reporting to the contrary when new, are fine running unleaded fuels.

[Anonymous]

Hi Michael

That is good news you are getting it running again, yes they are fine on unleaded fuel

Most old cars have cast iron cylinder heads and the seats are cut straight into the soft iron,That is why old classic cars need to have hardened seats and new valves fitted, Aluminum Heads have seats in which are hardened from the factory

Was reading an interesting article in the latest VJMC mag on modern fuel, most fuel company’s in the UK now ad 5% ethanol to their regular unleaded petrol now,whereas most super unleaded has no ethanol in,with the exception of Shell V power which has 0.1% ethanol added

When i went to Spa this year on my CB1100F with a few of the R owners i filled up with 93 octane and managed to run out of petrol after 129 miles,i worked it out to 29mpg, it was hot and we we going fairly fast

Down there i filled up with 98 super and was getting around 40 mpg on the way back,was a bit cooler on the way back but bike ran better on 98, have been using Super unleaded in all my bikes since

Remember i am just down the road if you need any help

Keith

[MichaelS]

Thanks Andy and Keith that is very helpful to know.

Keith I appreciate your offer and I will keep in touch. As a matter of interest while the engine is out, the crank is being re ground and new shells put in are there any items that might be worth addressing before re- assembly?

regards

Michael

[Anonymous]

Hi Michael

I have always understood the Honda cranks cannot be reground as Honda never made any bearing shells for reground cranks

I know there are company’s who grind down worn crank bearing journals , weld and regrind to std size, would not be my first choice in a R engine

You can use a 900f crank in a 1100 engines as long as you use a CB900F primary chain and primary shaft sprocket, all 3 of my CB1100F’s have 900 cranks in and many people who race 1100s use 900 cranks

Other things to check are the condition of the Cam chain tensioners and Cam chains,Probabley best to replace the Chains if in doubt, strip the head and lap the valves in, fit a set of Viton valve seals, these are a modern material and far better to use, most valve seals supplied with gaskets sets do not last long

Check the cylinder bores and pistons for wear, if they are badly worn you can fit a 2mm oversize Wiseco piston kit which makes it 1123cc

Also check the condition of primary shaft rubber dampers,primary chain and tensioner

Keith

[MichaelS]

Hi Keith,

thanks for for this I will speak to the mechanic about each of these points.

regards

Michael

[Author]

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