Ok people, so done the deal, bought the bike (LM 2)…test ride revealed poor idle, and lack of accellerator pump “kick” on opening throttle in a “spirited” way…
So bit the bullet, ordered rebuild kits inc new accellerator pump diaphragms, just need to know if there’s any wrinkles or issues I need to be aware of before the spanners come out?
I’ve got a 3l utrasonic cleaner…again, anything I need to know?
As ever, your sage advice much appreciated. Thanks.
It sounds like you have all the kit! Maybe some fine piano wire for clearing jets?
Have a look here
Bet of luck!
I reckon it’s the right start. But be ready for it not to work. I tried this on PHM40s and I couldn’t work out why it didn’t seem to fix it.
These are 45 year old carbs, intended to ( and probably for most of their life ) run without filters, just flame arrestor mesh. I eventually bought new carbs ( Eurocarb, you’ve just got to love 'em ) and it all came right. The old slides/bores were so worn there was masses of air leaking around the slides.
My LM1 is still on the original PHF36s but I think they’re leaking air around the slides too. I’m just holding on until they become too much of a problem. Yours might just be there…
You can see if the accel pumps are working with by looking at the jet in the 7 o’clock position carb inlet (aft looking forward) with the aid of mirror and flashlight, and by opening the throttle you can see the squirt of fuel from the jet if they are working.
I’d agree with Andy that when run without filters the slides wear, but that would depend on running time and environmental conditions, you see the level of wear after cleaning.
I recently got an old Le Mans 11 running again after decades in storage, fortunately no wear in the carbs as it was low mileage. Carbs were stripped, ultrasonically cleaned with passages blown through with compressed air, and then rebuilt with new seals and pump diaphragms, but despite this, still struggled to get both accel pumps working reliably. In the end both accel pump non return valves (pick up in float bowl and at accel pump ‘reservoir’ chamber) were replaced with new and all OK since.
Also checked jets fitted were original sizes for a UK bike.
Despite several trips through the ultrasonic cleaner, carb cleaning spray and compressed air, the original non return valves wouldn’t reliably seal, allowing the fuel in the accel pump reservoir to leak back into the float bowl.
The only other issue I had was getting it to idle correctly, which I suspect was due to the float height setting, as there is difference between the values quoted in the Guzzi manuals and the figure quoted by Dellorto, and this issue has been debated on this forum as I read through it several times, although don’t think it delivered a definitive answer.
IIRC with the Guzzi setting the float sits lower in the bowl so there’s a reduced head of fuel, so I needed to have the mixture screws several turns out to get it to idle, with the Dellorto settings, a higher head of fuel in the carbs and much more realistic setting of the mixture screw, and much easier to balance the carbs.
That’s my experience anyway, hope it helps.
Out of interest, how many miles has the bike done?
Hi Crusty…an indicated 8160, so expecting little wear, we shall see what’s what when they come off.