Cu poor performance

Post by **TimL** » 20 Mar 2006, 22:28

I have just purchased a 1980 airooled 2 litre with cu twin carbs ( stock)
after some dizzy problems i have now got sluggish performance.which i believe could be carb related?
the timing is set at 5 deg after tdc using vac / retard unit
it advances to around 38 deg. ticks over fine and sounds great BUT when you try to drive it it lacks power. when cold it really struggles it feels if its holding back wants to go but cant. manging only a few miles perhour once warm it will have a top speed of fifty MPH with slow acceleration. but ticks over fine does nt stall.
the plugs are new , leads are new. plugs were black dry in colour ( too much petrol?)
i have adjusted the mixture screw on left carb top no change.
tried adjust each mixture screw on each carb by screwing in fully then out 2 1/2 turns slight change in plug colour. poor performance though

I notice that previous owners have plugged the venturi set screw with bolts? not good what does this venturi do? has anyone got parts to help rebuild or used carbs going cheap suggestions welcome

Post by **germman** » 20 Mar 2006, 23:29

i am not going to guess what the problem is ,but i gave up fiddling about with them and sent em off for a rebuild and a modification to the throttle spindals to stop em leaking air , by steve @ gasure
http://www.gasure.co.uk/solex.htm

quality job and much cheeper than trying to find new or good 2nd hand

#200-250 for good 2nd hand ones or 300-500 fer new, last time i looked

Post by **TimL** » 21 Mar 2006, 18:02

thats a worth while link and one i will bare in mind thanks you

Post by **alden1957** » 21 Mar 2006, 21:12

Hi Tim
Check for air leaks around rubber "t" pieces pipes inlet manifold, and of course check yr throttle spindles on both carbs for movement. will effect performance if any leaks present.....
Another avenue..brakes binding?...accelerator cable not opening throttle fully?....
Just some thoughts..
Al

Post by **ermie571** » 21 Mar 2006, 21:25

can vouch for the throttle cable bit....mine now has a couple of nuts to increase the travel of the cable - looks a bit of a bodge, but works.

Hubby discovered that when foot was flat to floor, throttle had much more travel in engine compartment. The nuts have released a few more mph, and a tad more acceleration

the air cooled ain't going to be fast though. Scoobs gets a good 25mph up a steep hill, and I live in a valley at the bottom of two. Scoobs is LPG, so slught decrease in power. On the motorway, can get 60-65, but happy at 60

Emma

Post by **TimL** » 21 Mar 2006, 22:49

what is the actual top speed of one of these, my 2 litre bay will happily accelerate up to 70 mph fairly quickly ( idont drive it at this)
Just wondering if im too expectant of this T25 as im guessing they are heavier than a bay.
however the throttle is worth furthet investigation as the van feels like it could possibly go faster but just cant

Post by **germman** » 21 Mar 2006, 23:52

I have read lots over the years about AC engines and performance, and although mine has been beefed up and balanced ,i can cruise (if i dont care about economy !!

) at 85-95 mph , and can push it to just over the ton ,107mph if you belive a 20 odd year old speedo !

but in standard form tuned spot on i could only ever get 75mph out of my old ac van ,most important thing to remember about AC engines is they benifit from being revved ,the last thing you wanto do is "lugg " the engine , so when u r chugging up that hill remember your not doing the engine any favors better to screem up !

Post by **Spannerrack** » 22 Mar 2006, 00:22

I have a very good set of carbs if you need them give me a call on 07909518515

george

Post by **ermie571** » 22 Mar 2006, 08:47

I have had a set of spannerack's carbs - they are running loverrrrrly!!!

wanto do is "lugg " the engine , so when u r chugging up that hill remember your not doing the engine any favors better to screem up !

Now that I didn't know... why is this??

Emma

Post by **cumbriankeith** » 22 Mar 2006, 13:17

To lug(g?) an engine is American-speak for what we would call to "labour" it - that is to leave it in too high a gear for the load on it - from a hill etc.

The reason this is particularly important for our air-cooled engines is that higher revs in a lower gear provides loads more cooling-air over all the hot bits (heads+barrels+oil cooler). So don't be frightened or shy of giving it lots of revs under load - these motors thrive on it. Some say after a hill when the engine is hot you should leave it in a lower gear even under less load to keep the volume of cooling air high and cool the thing down better. Instruments like rev counter/oil temp and even cylinder head temp are useful and (paranoid) gazing at them helps pass the time whizzing down those autoroutes in the heat of the summer.

Post by **TimL** » 22 Mar 2006, 19:32

Spannerrack i may be calling you by the weekend, i think swopping the carbs should atleast rule that out as a potential problem.

Now i havent checked the tappets. Is this done in the same way as none hyrdolic type4 lumps and whats an ideal gap?
How are these bled and how will i know if they need bleeding

Post by **TimL** » 26 Mar 2006, 18:30

well i had a look at the carbs not only do i have two bolts in the venturi but also a broken butterfly in the right hand carb so no wonder im experiencing problems

spannerack to the rescue

Post by **Flibbertigibbet** » 26 Mar 2006, 18:51

[quote="TimL"]what is the actual top speed of one of these quote]

most I have got out of mine was 86 mph...generally will sit between 60-70 is a 2 litre Aircooled just about to go round the clock for third time (if lucky) on same engine as for hills............veeeeeeeerrrrrrrrrryyyyy slow

Post by **ermie571** » 26 Mar 2006, 18:52

Tim,
just had a frellin good drive in scoobs.

Bear in mind that I have a new (recon) engine with only 4,000 on the clock.

Drove upto Northants from Kent a2, M11 a14. Up - steady 60-65, odd touches of 55. She never likes coming back - the hills seem hillier, and there is a couple of places where she dropped to third and 45, but still going forwards!

Seems happy on the level at 65 - no screaming, and a tiny bit left underfoot in the right conditions. We even did that overtaking thing!!!

Very enjoyable drive. The 2.1 watercooled don't care about gradient much..... that is the main difference. Get the a/c cruising (may take a while to get there), then she is truly loverrrrrly.

Emma

Post by **TimL** » 31 Mar 2006, 20:14

i think i must have a dam good engine in my bay as it will accelerate and blow the pants of my 2litre t25. my 2 litre bay will reach 70 mph far faster, which im suprised about. both are fully kitted westys

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Cu poor performance

Cu poor performance

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Don't lug the engine