guzziriders.org - moto guzzi forum Homepage
Forum Home Forum Home > Technical > Small Blocks
  New Posts New Posts RSS Feed - 750T Motoplat ignition timing
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

750T Motoplat ignition timing

 Post Reply Post Reply Page  <123
Author
Message
iceni View Drop Down
Senior Member
Senior Member
Avatar

Joined: 16 Sep 2014
Location: Colchester
Status: Offline
Points: 2480
Post Options Post Options   Thanks (0) Thanks(0)   Quote iceni Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jun 2016 at 15:49
This probably has nothing to do with it, but I had it on the side stand when it started on one cylinder. As soon as it cut out, I put it on the centre stand and left it while I worked on another bike. Later, I went for a ride, and it ran ok, but before I put it down to "one of those things" I think I need to go for a longer ride and see if the problem returns when the engine is hot
Will post again re progress (or not)!.
Back to Top
Brian UK View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: 13 May 2014
Location: Surrey
Status: Offline
Points: 17641
Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jun 2016 at 21:42
Sorry if I'm stating the obvious, but have you checked the choke plungers are seating correctly? Also the neoprene washer in the bottom of the plungers can become badly worn. Both would cause rich running.
Brian.

Better 5 minutes late in this world than years early in the next.
Back to Top
GuzziLancs View Drop Down
Senior Member
Senior Member
Avatar

Joined: 29 May 2016
Location: Appleton
Status: Offline
Points: 155
Post Options Post Options   Thanks (0) Thanks(0)   Quote GuzziLancs Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 2016 at 07:23
Hi Brian, thanks for the message.
 
Nothing wrong with stating the obvious sometimes. I've stripped and cleaned out the carbs a couple of times so I hope its not a problem but won't do any harm to recheck the choke.
I'm replacing the main jet and atomiser as I think they are not to spec but not sure if this would cause the bike to run excessively rich and one cylinder to cut out.
Also do you think the compression readings are high (175/180 psi) and what would cause this?
Other thoughts are an intermittent fault in ignition circuit when warmed up giving poor spark?
 
Regards
Keep calm and carry on fettlin'
Back to Top
Brian UK View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: 13 May 2014
Location: Surrey
Status: Offline
Points: 17641
Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 2016 at 09:18
If jets are the same both sides, it couldn't cause a problem on one side only. But the choke (enrichener) on that side would if fuel can leak past. Main jet size in any case, only affects the mixture over 3/4 throttle.
 
Compression, that looks good, not overly high.
 
On the Motoplat system, is there a large capacitor in the circuit? I seem to remember there was. If so then they do break down over time, so maybe that might give a problem with the spark. Just guessing though.
Brian.

Better 5 minutes late in this world than years early in the next.
Back to Top
GuzziLancs View Drop Down
Senior Member
Senior Member
Avatar

Joined: 29 May 2016
Location: Appleton
Status: Offline
Points: 155
Post Options Post Options   Thanks (0) Thanks(0)   Quote GuzziLancs Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 2016 at 19:00
Thanks Brian, both sides are running rich but only the right cuts out when warm.

The condenser you mention is no longer available but not sure of the technical details so difficult to replace with like for like.

Corresponding with a guy who sells that stuff says it should run without it but I'd rather replace it and see if it makes a difference.

I know what you mean about the main jets but I just thought I'd try and get it back to spec and then see before I think about replacing the more expensive bits.

Regards
Keep calm and carry on fettlin'
Back to Top
Mike H View Drop Down
Senior Member
Senior Member
Avatar

Joined: 21 May 2014
Location: East Anglia
Status: Offline
Points: 8733
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 2016 at 22:20
I agree about getting the jets back to standard, and start from there.

"Chicken nuggets don't dance on a Tuesday."
Back to Top
Thetar View Drop Down
Falcone
Falcone
Avatar

Joined: 10 Aug 2018
Location: Ireland
Status: Offline
Points: 42
Post Options Post Options   Thanks (0) Thanks(0)   Quote Thetar Quote  Post ReplyReply Direct Link To This Post Posted: 28 Dec 2018 at 16:53
Did you ever get to the bottom of this?
Back to Top
Simon B View Drop Down
Guzzino
Guzzino


Joined: 30 Aug 2019
Location: cheltenham
Status: Offline
Points: 1
Post Options Post Options   Thanks (0) Thanks(0)   Quote Simon B Quote  Post ReplyReply Direct Link To This Post Posted: 30 Aug 2019 at 09:21
Hi, I have recently come across the same problem with my 91 750t... Did you manage to find the cause for this? The bike pops and bangs but doesn't start!  

Thanks
Back to Top
GuzziLancs View Drop Down
Senior Member
Senior Member
Avatar

Joined: 29 May 2016
Location: Appleton
Status: Offline
Points: 155
Post Options Post Options   Thanks (0) Thanks(0)   Quote GuzziLancs Quote  Post ReplyReply Direct Link To This Post Posted: 31 Aug 2019 at 17:07
Hi, sorry for delay but I’m on holiday at the moment.
I no longer have the 750T, it was more of a project that I sold about 2 years ago so the details are a little hazy.
From what I recall I ended up replacing the ignition system including the coils and I also ended up with bigger jets after trying various  sizes, although it still ran a bit rich but it did run better. 
Good luck and I hopE this is useful.
Keep calm and carry on fettlin'
Back to Top
 Post Reply Post Reply Page  <123
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.063 seconds.