Club 80-90 Forums

i have fitted a recon ct1600 Aircooled into my t25,it ticks over and revs fine,but when i try to drive it it cuts out,and can hear it back firing.the timing has been set up properly.i have to get revs high to pull off.any help would be appreciated.

Backfiring and loss of power normally indicate an air leak somewhere in the system. Check all connections between the carbs and the heads including the rubber tubing.
Could also be caused by a weak spark. Check polarity of cables to coil and the condition/security of the HT leads from coil to dizzy and from dizzy to spark plugs. Most power related problems related to driving under load but not when idling can be caused by a weak ignition system. This includes the coil as well so make sure you have the correct one fitted!

have now found that there is a spark on no 1 cylinder but nowt else ,removed the lead and engine sounded the same.

Eh??

Spark on no1 and not on anything else but sounds the same.. you mean you have a perpetual motion engine where it runs on no cylinders

Please explain

Think what you mean is that no 1 has no effect on the sound of the engine...

Does the lead have a spark? remove the spark plug to see if thats working.. if ok. might be worth removing the rocker cover and checking the valves/adjusters havent stuck/adjusted incorrectly..

thats it engine sounds same when no 1 lead is disconnected.there is a spark.will have a look under rocker cover see if theres a prob.cheers

Check spark plug too, often overlooked! They can break down inside and you dont notice by just looking at it. Try swapping two around and see if the problem moves to that cylinder.
Does the engine wobble at all when on tickover and if you hold wour hand close to the exhaust pipe end, does the pulse of exhause coming out seem constant or erratic?

done compression test 1=130 2=130 3=135 4=125......engine seems to be running on all 4 cylinders,but is erratic at times and engine does rock then its smooth.when driving it seems as tho its holding back

Back to my first post then!
How was the timing set up by the way?

well only thing it can be is an air leak,so where do i look.all plugs ,leads etc are new.

dont know how timing was set up cuz chap who did it is on hols,so waiting for him to come back.how should it be set,its fitted with a 009 dizzy.cheers kev

Oh dear... A 009 dizzy is not a good dizzy to have on these motors. The timing curve is all wrong for the engine. Most people find this out afterwards thogh so it's not your fault!
I have noticed the timing on these varies from one engine to the next even though you are setting it up to the timing marks.
Here's my advice...
Slightly loosen bolt holding dizzy bracket in place at base of distributor so you can just turn the body of the distributer by hand. Start engine and turn distributor by hand one way or the other until maximum revs are obtained and then turn distributor slightly cloclwise until you hear the revs just drop a little. Tighten the bolt back up and take her for a spin. Should be a great improvement hopefully.
Try to mark the distributor somehow before moving though so you can put it back to the original position in case this doesn't help but I think it should!