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by Gui.dorey
Tue Sep 01, 2020 10:36 am
Forum: Four stroke
Topic: Mk1 Sq 4
Replies: 6
Views: 191

Re: Mk1 Sq 4

Maybe loosen ALL the studs and then tighten them up again to the recommended torque. But I’ll let the more experienced members chime in, because I’m really not sure.
by Gui.dorey
Tue Sep 01, 2020 9:11 am
Forum: Four stroke
Topic: Mk1 Sq 4
Replies: 6
Views: 191

Re: Mk1 Sq 4

Hello T.J., I am going through the exact same thing as you, although I am already a bit further than you. I posted my last results on your previous thread just a few days ago. Perhaps you have read it and can we can compare notes. Anyway, I used this sheet for the torques (see 2nd page). I am not su...
by Gui.dorey
Sun Aug 30, 2020 9:10 pm
Forum: Four stroke
Topic: Mk1 Sq 4 BLOWING HEAD GASKET
Replies: 23
Views: 1088

Re: Mk1 Sq 4 BLOWING HEAD GASKET

Hello chaps, here's an update on my head gasket. After my last blown gasket (copper), I redid the whole thing with a set of newly arrived Otto's. I followed all the instructions on assembly scrupulously - This time a thin bead o cooper sealant only around the pushrod tunnels on both sides of the gas...
by Gui.dorey
Mon Aug 24, 2020 1:55 pm
Forum: Four stroke
Topic: Tuning SQ4 by ear
Replies: 2
Views: 187

Re: Tuning SQ4 by ear

Adrian, I just went through that, so here’s how I did it. I have no claim on being perfectly correct, it’s just how I went about it. After the initial timing, I marked the distributor with a sharpie to have a reference - see picture, you’ll see my markings in blue. Btw, that bolt you see is the one ...
by Gui.dorey
Wed Aug 12, 2020 5:01 pm
Forum: Four stroke
Topic: Mk1 Sq 4 BLOWING HEAD GASKET
Replies: 23
Views: 1088

Re: Mk1 Sq 4 BLOWING HEAD GASKET

Well, mine just blew again. Grrrr... and lots of unrepeatable words. Same place as always - 9:00 on both the rear cylinders. This time with a copper gasket. I will try once more with new Ottos that I managed to get, but if it doesn’t work, I believe there is really a problem with the mating surface....
by Gui.dorey
Wed Aug 05, 2020 5:05 pm
Forum: Four stroke
Topic: MkI Square Four fine tuning and performance troubles
Replies: 10
Views: 477

Re: MkI Square Four fine tuning and performance troubles

Slacken the lock nut on the distributor so that you can just move the distributor by hand. Take the bike for a run and as you are going along move the distributor round to see if there is an improvement. This was what I used to do on my C15 back in the 70s. Paul, that sounds like a quick way to cra...
by Gui.dorey
Tue Aug 04, 2020 4:35 pm
Forum: Four stroke
Topic: MkI Square Four fine tuning and performance troubles
Replies: 10
Views: 477

Re: MkI Square Four fine tuning and performance troubles

Another thought is of course ignition timing. Could it be that the advance mechanism on the distributor is not working properly and not advancing as it should? How does one check for this? Without the engine running it all seems all right to me, but how does one really know? I’ve really no idea how ...
by Gui.dorey
Tue Aug 04, 2020 4:30 pm
Forum: Four stroke
Topic: MkI Square Four fine tuning and performance troubles
Replies: 10
Views: 477

Re: MkI Square Four fine tuning and performance troubles

The cam followers are new, but the camshaft is not. When I set up the valve timing, I did find that the total lift was slightly less than the 0.3125” by about 0.0027”, and when plotting the graphs my line going through the mid points was slightly leaning to the right. It didn’t seem like a sign of e...
by Gui.dorey
Mon Aug 03, 2020 4:22 pm
Forum: Four stroke
Topic: MkI Square Four fine tuning and performance troubles
Replies: 10
Views: 477

Re: MkI Square Four fine tuning and performance troubles

Hello Klaus, It’s definitely the engine. Happens in all gears above a certain rpm. I can’t remember exactly which sprocket combination I have, but I do believe it’s the solo gearing. Stupidly enough I never wrote it down. I remember I checked the front springs during the rebuild and they are the sol...
by Gui.dorey
Mon Aug 03, 2020 7:54 am
Forum: Four stroke
Topic: MkI Square Four fine tuning and performance troubles
Replies: 10
Views: 477

Re: MkI Square Four fine tuning and performance troubles

Hullo Simes, that could be. She does run happily all day on country lanes between 70-80 kph and doesn’t get excessively hot or anything. That’s a good sign and I probably should not worry too much at this stage. We’ll see.

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