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M79 TAB


slowdude

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@MV8 you were absolutely right. I just took it for a 30 minute drive, the valve tappets have quieted down substantially (to where I hear other rattles/noises), but they don't sound worrisome.

 

Thank you so much- I owe you a beer in September if you're going to be at the 7's trackday!

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What was the oil pressure when it started going? Change the oil and add the "marvel" for another try before tear down to clean/replace the lifters. Marvel is red but it is not just atf.

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12 minutes ago, MV8 said:

What was the oil pressure when it started going? Change the oil and add the "marvel" for another try before tear down to clean/replace the lifters. Marvel is red but it is not just atf.

Pressure is thankfully good, but it definitely sounds like one cylinder isn't firing. I'll get it home today and change the oil + filter again. Worst case I put new lifters in for peace of mind. I have to keep reminding myself that this car was significantly cheap for a reason.

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Exactly. Very similar to miata HLA lifters and similar issue. A good cleaning and it will probably be fine. I'm wondering if 5w40 would be better for the lifters yet adequate for the bottom end hot at high revs. 

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46 minutes ago, IamScotticus said:

Enough oil changes!

Get it to an engine man.

There's nothing there that's special, its 30 yo technology already. 

This is the plan. The only "rover k series" guy I could find is booked until August. I'm out of country from june/July, so I'll throw it on a tender and slowly accumulate parts. Time to focus on the CB750.

 

Thanks all for your guidance / assistance!

 

@JohnCh apologies for derailing the other thread.

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No apologies necessary!  This has been a great conversation. Keeping it all in one place will simply improve discoverability for anyone having a similar issue in the future.

 

-John

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18 hours ago, slowdude said:

Time to focus on the CB750.

What year CB750? I had a Nighthawk 750 among others. Long ago, I spent time as a motorcycle mech for Harley and a dealer working on the usual imports. I like the old goldwings.

goldiebilder1.jpg

1981GoldwingCustomRear580.jpg

naked_honda_gold_wing.jpg

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16 minutes ago, IamScotticus said:

Crossflow!

This is the backup plan if the Cortina is too far gone rust wise, why I haven't gotten rid of it yet.

I'm not sure if the harness would need to be replaced etc. I know caterham sells some rover k series to duratec conversions. I will say the brief moment I had the car out a few days ago and got the right exhaust note at 4k rpm, it sounded Fantastic. Will dig in and see what needs to be done and decide there.

 

Spoke to Dave Andrew's and he's getting together a list of what he could get put together. Engines are still fairly affordable.

 

 

@MV8, 77, so the last few years of the SOHC 750. I got the bike in pieces for free and did brakes / suspension / valves / basic electronics. Im colorblind so the wiring is taking a lot longer when they all look the same shade of grey/brown. I hope to get it done this month, and then I will at least have 2 completed motorcycles.

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Update, replaced plugs, ran liquimoly engine flush+ new filter. Put new oil in +marvel and the engine is a bit quieter. Quieter to notice the the rear a arm bushings need to be replaced.

 

On a side note, I'm burning oil a little bit under heavy acceleration (4k and above). Cheap $20 amazon boroscope is showing some gnarly carbon build up.

 

Send photos to engine builder, he said pistons look good, so reccomended valve stem seals.

 

He's sending me an emerald K6 with some tunes as well, as I am stumbling at idle with the rover MEMS, then I can run diagnostics.

 

This weekends plan is a leak down test to confirm suspicions.

 

Then it's just new tappets, head gasket, valve stems and getting the car to the mechanic. I'm hoping I can get the car buttoned up while I am overseas, so it's ready when I am back in August.

 

 

Screenshot_20230507-161252_USB endoscope camera for Samsung, Redmi, Sony, Huawei.jpg

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  • 5 months later...

Car is finally back together and I have about 100 miles on the new Engine. I didn't realize how poorly it was performing before.

 

K series is straight linear power from 2k.

 

I had the following done:

Piston rings (omega)

Mahle Crank Bearings

New Valves

Valve stems cut to spec

Valves lapped

Lifters replaced

Water pump / tensioner / pulleys / timing belt

Piper vernier for the cams

Radtec heavy duty radiator installed

 

Have 100 miles on it in 2 days of good weather. 60 was a round trip to work, alternating between 3k and 4.5k every 5 or so with occasional slow pulls up to 5k. As I start to get more mileage in, I'll get a bit more bold as the engine is incredible.

 

Next up at some point this winter (after getting a good amount of mileage in on the engine), install the new de dion + powerflex bushings and install my emerald ECU.

 

Next spring will be considering what to do with the lifters.

 

It's back and even better than before, what a car.

 

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1 hour ago, CBuff said:

Congrats @slowdude  while longer and likely more expensive than anticipated. Sounds like the payoff was better than expected. Keep it running till spring when (I hope) to meet up for a blat. 

Absolutely, need some time at palmer or Thompson together!

 

Price was not too bad. Machine shop which did majority of work listed above was 1100, labor plus installation of radiator + timing + reassembly was another 1800 and has a warranty on labor and parts.

 

Not cheap by any means, but better to spend the money to do it right, vs kicking it down the road as the past 6 (out of 9) owners have done!

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