Lacking power uner load - at around 5000rpm

[Guest Greaser]

Hey there

could do with some help.i have an 850 t3 1976 cafe racer.Was going beautifully, blasing up to 120mph, then it started lacking power, felt like the engine was flooding, happened whenever i put it under load - like when trying to accelerate, seemed to be aroun the 5000rpm range, i could still gradually build the speeed up slow by working throuugh the gears and slowly acelerating but when trying to give it a blast it would lack the power.

I have changed the spark plugs, one looked a bit oily or black, have sprayed cleaner stuff through the carbs, have checked all the fuel tabs and lines. and no change - its got electronic timing ignition so is sposed to be fine on the timing............

suggestions have been - valves, and loads of others. my gut feeling is that one of the jets is blocked...

any ideas appreciated.

[Guest Nogbad]

Sounds like fuelling. However, before you tear the carbs down, get a compression gauge and test your compression on both cylinders. This will eliminate valves and rings. I see you are in London, you are welcome to borrow my compression tester if you want.

 

If the compressions are ok, take the carbs off and strip them thoroughly for cleaning, and put everything back with clean filters (if fitted). Then balance the carbs accurately.

 

If a plug is visibly oily, you may have a cylinder problem on that side, so a compression test should be the first step.

 

Another thing could be coil / ht lead breakdown. This would give a bad / no spark on one side at high speed. Swap leads and coils in turn and see if the problem of black plug swaps sides.

[Mal]

Greaser

 

while there may be folk here who can help you may get more answers to this problem at the site below, its a good place to get info on all Guzzis (as opposed to mainly V11s).

 

http://morini.com.au/phpBB2/index.php

 

good luck

 

Mal

[jrt]

I have changed the spark plugs, one looked a bit oily or black,

 

one of the jets is blocked

 

60376[/snapback]

 

 

Sounds more like you're flooding it. If a jet is blocked, it would run lean and the plugs would be whitish.

Worst case is you have a burnt valve. I had similar behavior on mine. Do a compression test on the cylinders and eliminate that possibility.

More likely is the enrichening (choke) circuit. Check your choke seating- you could really be flooding the motor. The chokes on those old Del Orto's sometimes dont seat real good particularly if the cables bind up.