MV Agusta 175 CST

[DomC]

Hello all, I'm new here so please bear with me if I do anything wrong!
I'm looking for guidance with a problem with a 1955 MV 175 CST which I bought some months back, it was sold to me by an elderly gent's son, the old boy had sadly passed away. The chap had started fitting a VAPE CZ 12volt kit to the bike and I completed it however I'm not now able to start the bike. (It was running before the conversion).
I've set and re-set the timing, TDC on the compression stroke, there's excellent compression and I've got a nice blue spark at the plug. Fuel is fresh stuff and is getting into the cylinder as the spark plug stinks of it when I took it out to check.
The little Dellorto carb primes ok. I've tried all combinations of choke and throttle settings, with the choke fully on and the throttle 3/4's on it spits a little flame out of the exhaust (I realise choke and throttle on isn't a normal way to start a cold engine but I was trying everything).  This backfire / small flame confirms to me that compression, spark and fuel are present but that something isn't quite right.
I'm a locomotive engineer rather than a bike engineer but I'd really appreciate your thoughts, tips, guidance. No problem if you can't help, I'll just have to persevere.
Photo of bike attached.


Thanks, DC
Apologies, this bike isn't a Guzzi (I've just sold my Imola).

[Oca Grassa]

I know absolutely zero about MV models much less a vintage MV. However an engine runs on 3 things. Air, fuel and spark at the correct time. A backfire as you describe (after fire) could come from compression as well as spark but my gut feeling is something in your valve timing is off. Possibly too much advance. Just my thought. Like I wrote, I know beans about vintage MVs….and was a diesel engineer by trade.

[QuattroValvole]

Timing 180 degrees off?

[guzzisteve]

A simple search, if you haven't-----------------------------------------------------

https://www.mvagusta.net/threads/mv-agusta-175-ab-1957-america-manual.250245/

file:///C:/Users/iguzz/Downloads/175CSTA_HB-1.pdf

Looks like static timing is 18* just looking but not translating

Parts----------------------------

file:///C:/Users/iguzz/Downloads/175CSTA%20(AB)_PB.pdf

Sure looks like your bike.

[MattP]

spark plug   i had them spark out but not under compreshen drove me nuts,

[Stretch]

Methinks, like some others, that the timing is out.

Maybe a big, fat, spark on the exhaust stroke instead of the compression stroke?

It looks like a fun little bike!   

                                    -Stretch

[guzzisteve]

It would be nice if OP comes back to let us know how it goes.

[pehayes]

We have several of those MVs that participate in the annual Giro d'California in October.  I consider those owners as experts.  One of them is even an importer of the VAPE system.  I would suggest  you browse over and join that discussion forum to ask detailed questions.  Find the group at:

MotoGiroDiCaliforni a@groups.io

Patrick Hayes
Fremont CA