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The Engine Is Back!


Guest Larson250

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Guest Larson250

I have just got my engine back, and speaking to the guy who rebuilt it he thought that it was well put together before the big end started to fail on the rolling road.

 

The cause of the problem in his opinion was "massive over fuelling with the timing being slightly out".

 

He tried to re-grind the crank and having took 1/16th of an inch off one side of one of the mains it was still scored on the other side. He said he would have had to remove 1/8th to get rid of all the marks.

 

Needless to say that was scrapped.

 

Check out the photo's of the main and big end bearings, that is after about 20 mins running after the original rebuild.

 

Strangely enough i'm going to be a little more cautious this time. I need to sort out the bike carbs before I put them on.

 

The saga continues!!!!

 

Dean

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I'd have thought possbly crank oil ways not thourghly cleared of swarf if it has been reground or even a dodgy oil pump, all assuming you had enough good oil in there to start with.

 

It would have had to certainly been massive over fuelling bordering on hydraulicking if that was the case in my opinion.

 

I have rebuild many engines over the years both bike and car engines and i've never had any problems what so ever like you have experienced.

 

Mike

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Good to hear things are on the up Dean!

Over fueling could not possibly have caused it, that will do a few things like oil dilution, or kill a spark plug but in twenty five years in a workshop I've never seen excess fuel do that!

Anyway what's important is the build is coming on!

 

Regards,

 

Tony

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Guest qwerty_100

actually i read this and thought no dont go there... I need a rebuild anyone reccomend engine reconditioners down south, sussex

 

cheers john

[

I agree with Tony Looks more like oil starvation as over fueling would normally cause bore wash first, just an observation glad its all on the mend Regards Kev.

/

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Guest mower man

Hi 1.

overfueling? was the sump full of fuel ?

2 timing SLIGHTLY out ?

3was the oil pump drive correctly fitted?

4I don't like to say it but I think someone is looking for a way of explaining aC--p build

5 the only time in 40+years I've seen brgs destroyed like that is NO oil + lots of crap

these are my opinions and I could be very wrong but Iwould not let who ever build ME another one !

regards mower man

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Guest mower man
I don't understand, how can overfuelling cause big end failure? Just by replacing the oil with petrol from down the bores? Could that happen in 20 minutes?

Hi answer to the above YES it could happen in 20 seconds mowerman

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Guest Ian & Carole

I keep looking at those shells and they really got very hot, which says that they lacked oil.

 

No way was that damage caused by "over fueling"

 

For what it's worth, lack of oil............IMHO caused this............. not petrol.

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Guest qwerty_100
I keep looking at those shells and they really got very hot, which says that they lacked oil.

 

No way was that damage caused by "over fueling"

 

For what it's worth, lack of oil............IMHO caused this............. not petrol.

Hi Dean Ihave some carb balancing gauges from my bike racing days if you need them I am often at one of the Leicester hospitals working you are welcome to use them. regards Kev

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Guest Larson250

Hi Guys,

 

Thanks for all the replies, some interesting comments. All I can go on is what the guy said, he seemed to think that the floats are not cutting th efuel off and maybe overflowing into the cylinder. There was petrol in the oil but he could not say how much as it obviously evaporates when the engine is dismantled.

 

Tony, it is coming on and to be fair I had lost the will to live at one stage, however i'm in a more positive mood again and looking forward to getting it finally finished. I'm confident that if I can sort the fueling it would be ready for the IVA.

 

I can assure you that the engine has ran no longer than 20 mins, as you can imagine I was gutted to find the damage caused in such a short period of time.

 

Kev (qwerty) I would love to take you up on the offer on the use of your vacuum guages if possible please, I'm sure we could arrange a meet at some stage if thats ok.

 

Thanks again all,

 

Dean

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Very strange as the engine looked and felt great when it was built up, no tight spots, good clearnaces etc.

I agree I'd be amazed if that was excess fuel, must be oil starvation. Given that this is the second time its happened, I'd want to know exactly what's going on with that engine before I go any further - what was the oil pressure like when it was running? Blocked gallery, failing pump, I don't know but somethings amiss.

I'll pop over at some point today anyway. There's a guy round the corner here might have some vacuum gauges, so I'll ask him later.

Might be better to see if you can get a loan DGAV or DGAS carb to get everything running and settled. More variables = more hassle and less easy to trace faults.

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Guest mower man

Hi it's me again, been mulling this one over again I once had problems with a Ford cross flow that would loose oil pressure dramaticly ,it was ok on idle or beeing run up whilst stationary but once on the road oil press would fail, after a lot of head scratching etc we pulled it down and found that the block was cracked under the engine mount,it took ages to find we changed the block andhad no more probs!! hope this helps . Thanks forb the quick response to my pm ,Dean all offers still stand regards mowerman

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Popped over today and was amazed to see the oil pump was absolutely knackered with scoring as well. The bearings were the worst I had ever seen. Mystery really.

Oh well, at least its back in and rebuilt.

Good luck in finishing Dean, its looks a great build all round and fantastic in orange.

 

Cheers

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