Hi All, a bit of advice please if you would be so kind - first the good news, the Black 'n Gold Darmah engine started fairly easily this evening after nine years standing idle, with no nasty noises thus far. It would not idle reliably, even with both idle speed screws fully home, and the idle mixtures 3 turns out - but I understand that this is not un-common. The carbs ( 40mm ) have a full set of new pilot and main jets, needles, emulsion tubes and slides. The thing that worries me is the temperature of the silencers. The Vert Cylinder silencer temperature seems fairly normal after 10 mins running in the garage, ( never above 3k rpm) but the Horizontal silencer was almost too hot to touch even at the very end. Is this a sign of running too lean ? The new pilot jets are size 60. Both plugs look a bit oily and black. They had a 0.4mm gap, now opened out to 0.6. Any guidance most gratefully received, best regards dp Just thought, maybe there is leak on the inlet stub, and it's pulling in air ??
It's good that you got straight on the plugs as this is far more important than silencer temperature although a factor not to be ignored of course. I don't know what your exhaust set-up is like - is there a link pipe between horizontal and vertical pipes for starters?. If you try (very briefly!) touching each exhaust outlet with a non-plastic garden glove on etc, does the temperature still feel vastly different? If you are happy that horizontal plug is not much different to vertical one/no signs of serious overheating then you would learn more from a 'plug-cut' which you can do when you come to ride the bike.
I used to set up my 750 bevel one cylinder at a time. Then connect both plug leads and then balance it. Are the pumpers both working ok on the carbs?? My Delortos hated being left for long periods, often needing several strips and cleans till all was good. Have you tried swapping the plugs around to see if the reverse happens. Gunsons carbtune kit, i used to also find usefull on occassions.
Hi Guys, thanks for your replies. I do have a link pipe, and I have just ordered a couple of carb stub inlet rubbers from Mdina. The old one isnt too bad, looks like its been nipped up ok - but might as well replace it while the carb is off. I will check the carbs again, and keep you posted ! They both originally had size 70 pilot jets in, now have 60's as per The Book. I wonder if there was a good reason for that ??
the jet size increase could have been to compensate some engine tuning mods or even just an exhaust system change.
you can illuminate an air leak by spraying wd around throttle bodies/carburetors-insulators. a wee bit messy but effective. if the tick over increases you have an air leak.
do you have the bosch ignition or the old motoplat unit?on the bosch unit you can adjust the sensors,check this!!! the older motoplat unit is ofthe fried and doesn't work well. also check the thick rubber between the head and the intake manifolds.you must tighten the bolts wich hold the manifold VERY gently,I use a hose clamp around the rubber and THEN tighten the bolts or it may happen that the rubbers get disorted and you get a leak...ask me how i know
Cheers, I have the Bosch units, but I understand that a setting gauge is needed to check the alignment of the pick-ups ?? I have ordered a new set of intake stub rubbers - and will tighten them very carefully !! Thanks for your help all you guys
It could be that the cylinder you think is too hot is the correct one and the cooler one is not firing/fuelling at all and just leaching heat via the link pipe. What happens if you pull the plug leads one at a time? Although i would not want to do it for any length of time a good healthy pot will run as a "single"
Pulling each plug lead off at tickover is the way the Guzzi factory and Owners Handbook instructed how to set up the Le Mans I & II.....they had virtually the same (if not the same) carbs........they reckone the single cylinder should run on for 'six beats'. ....mine would idle at 850 rpm with both plugs in place and drop to around 450 when one plug was pulled off......and keep running.
Its getting worse ( or is it ?) !! I replaced the inlet stub rubber and started the bike. It does not idle yet, as I haven't had time to set things up as yet. After three or four minutes at 2000 to 2500 rpm I noticed that both zorst headers were glowing cherry red !! Jezz - switched off immediately. Both plugs look OK. Now that I have thought about this I guess that this is not surprising, running a stationary bike in a dark-ish garage at medium revs - any comments guys ??
I was going to suggest doing that deliberatly, get both pipes glowing to make sure both pots are firing equally. Or as close to equal as this method allows. I do not think its a very satisfactory solution and potentially harmful but it may have given you enough of a clue as to which direction to go in to be worthwhile. At least each of the cylinders is indeed firing. For the same reason, i was also reluctant to suggest the "pull a plug lead" trick as it puts a strain on the bearings. More importantly though, very slow running means the oil pump is very slow also. On balance a couple of seconds is worth the risk to diagnose a problem and get the bike back on the road.
Don't carbs usually have various drillings or bypass systems specifically for idling? If the bike has been sitting for some time and the carbs were never drained, these, if present, are likely to have become gummed up.
Cheers Guys, you have given me plenty to think about and great advice to try out ! Hi Steve, I have two Delorto Manuals, one with a black cover "The Carb Manual" and "A Guide 1.1" with a white cover - is yours a different manual ?? If so I will gladly zap you a few sovs for a copy as these two are all the importer seem to have. The carbs are spotless, and I hope to get a couple of laps of the village in soon, to get it properly warmed through - will keep you posted, Best Wishes to All, regards dp
I assume you have been to this site.......?? Bevel Heaven - Vintage Ducati Bevel Drive Motorcycle Extravaganza. These extracts from a Guzzi owners handbook might also help...... On my Guzzi I used the same method, but with a Gunsons Sparkplug thingy as well........I think that's why I could get it idle at such low revs........I would use the same on my SS if someone hadn't nicked the Gunsons sparky thing.
Many thanks _ I am awaiting delivery of the sparky doings - cant wait !! I often have a look at B Heaven - some great stuff on there !
Hi, sorry if its already been mentioned but is it running on both pots? When you start the engine from cold put your hands on the headers near to the heads and see if both pipes get hot. This should happen within seconds of starting.
