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Compression findings


Sheep

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I don't what it is recently but if its not one thing it another....

Now i have my correct set of carbs on my EFE she starts up on the button but since the first time i had the thing running back in late November i have always been concerned with the fumes it gives off when running.I decided not to think about it too much until i got the fuelling sorted.Now i have good fuelling,all bar a road set up,and good ignition but the thing still puffs when twisting the throttle.Today i took her out of the shed and ran it to get her hot and although the fumes died down a little it still puffed when revving up.(the revs hang a bit but i have yet to fine tune the carbs).

So i carried out a compression test and got these results-

Dry test

1=100

2=100

3=120

4=100

Wet test

1-120

2=120

3=150

4=120

So when the seller advertised it as a 'non runner due to dirty carbs but the engine is good,i will stand by this'...makes me think he is telling me porkys.....bast@rd...looks like i am needing new hone and rings :(

 

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Italian tune - I like it.

If it doesnt work out then I personally wouldnt bother with the hone & rings unless you intend to sell it on. Bores dont wear round & a lot of the oil control is due to the piston to bore clearance. If its worn to the extent its using oil then a rebore & pistons is the only fix. More money!!

Nick

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Usually valve stem seals result in puffs of smoke on over run. If you take the  exhaust off and shine a torch into the exhaust outlets you can usually see some oil tracks through the soot coming from  the valve stems if the seals have let go. 

What colour is the smoke? If it's over fueling then that can cause black smoke. It can also wash oil off of the bores.

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I have more smoke/fumes when revving up,less on over run.The smoke colour is grey/blue and is tough on the eyeballs lol....in the confines of the shed anyway!!.Its not a massive amount but i cannot comment how much when actually riding it as i haven't had it on the road yet.I bought it,stripped it,tarted it and put it back together.I never touched the engine internally as i took it on good authority (the sellers) that the engine was good.

It was very smoky after the test when it burnt off the test oil ;)

Wouldn't the compression figures be enough to say the bores are worn?

I could use this as a good excuse for a bigger cc or oversize kit but funds are tight at the mo...for the bike anyway..

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Running it in the shed (also not good for your health) without any load on it will not give a good diagnosis especially if its not been run for a while. Rings could be gummed up, carboned up valve seats etc. all could give low compression readings - its going to need some abuse first before making terminal judgement

Edited by Gixer1460
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if its been stood then theres a chance the rings may be stuck, or the valve seats need lapping. as has been said, an italian tune (i like that term) may well shake it from its torpor. get it nice and hot with some fresh oil in it and the compression may well improve. aside from that valve seals being fooked wont affect compression, and i assume youve checked the valve clearances. have you checked the engine breather to see if its blowing fumes out.

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So let me get this straight....you are actually advising me to get it on Her Majesty's highway,wring the bikes neck like a loon,which in turn would probably mean breaking a law or two???

and to think i thought this site was aimed at sensible God fearing,high viz wearing goody goodies lol

I have not done the valve clearances johnr but it is now on the list.No smoke from the breather either....(that rhymes) it does have fresh oil and filter tho ;)

 

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I have my own private drag strip near me , it even has two lanes marked out with white lines ,cats eyes and a roundabout for a return run . Sometimes I see slow cars using it , but they always tend to move over when I'm there . I think they all must have clubbed together in secret last year , and had it resurfaced - no doubt out of respect for my generosity  with the use . 

 

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  • 2 weeks later...

My bike was sat for years. I never bothered with valve clearances, except checking them. It's now had an Italian tune( I love that termxD) and only now after a thousand + miles she needs shims oil and filter, sump off and oil pick up check. then it's time to see what it can do :) oh and new pads all round. Well that's how I've allways done it where shims are involved cos of the expence of the shims and the time it takes.

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