G80CS... and the saga continues
Posted: Sat Sep 15, 2018 11:09 pm
Hi all,
Well my issues continue with my '55 G80CS. I've ridden the last 2 weekends at rallies, and both, were in hilly areas.
First things first. My oil burn continues on overrun, and, consumption is still out of control - 70ml per 70miles. I can only assume this is a combination of intake valve guide and blow by the rings.
So, that out of the way - my last rebore and new piston resulted in a +40, and my Amal 389 is set with a 30 pilot, 420 main and usual 106.
Now, Timing is set using the stick in the hole, but, I take the time to get it just right to 1/2" BTDC. The bike is usually a little hard to start, as it floods easily with the 420 main, but I was advised to use that main, by a guy who's worked with Matchy's for many years and has actual information from the factory with carb settings with compression ratio and cam combinations.
So, generally, the bike performs 'well', although I don't have a baseline of how it 'should' perform. Since going to the big main, I can cruise at 50mph ok, and 55 if I want to. That said, it still doesn't pull up hills unless you drop a gear and keep the motor spinning.
I've had the bike up to 70mph along the flat, and it didn't seem like it'd explode or whatever... but certainly took it's time to get to that speed. I still think it struggles to hold 50mph over ant hills - ie, rolling rises in country areas.
So to the last 2 rallies. I've always had issues with hills. Last weekend, was up and over a small mountain range a number of times. When going up one of the long drags uphill , running in 3rd, then second, it wasn't labouring, but I could feel it getting hot on my right leg. I decided to drop speed, and engage 1st, and let it spin up the hill.
It got hotter, and spark broke down a number of times, Missing and banging. I thought that must have been pre-ignition. No pinging though. That said, I backed off let it regroup, then it I made it to the top of the hill in one bit, and it started to cool down as I rode along the top. This happened on both saturday and sunday runs, on different roads.
To this weekend.
Rode yesterday, and it was up over 2 mountain ranges. - Why the rally staff use these mountain roads for old bike rallies is beyond me... The first part of the run was up a long drag, which would be an 7-8mile run to the top, with a few downhills and flat sections inbetween obviously.
Ignition broke down twice, and it began to get VERY hot, and I could feel it getting tight. The last steep pinch, I had to engage first gear and pray I go up. I did, and despite the hill, sort of felt ok and 'normal' after that and on the way down the hill.
THen we went along another 20 miles along the flat and it went ok.
Till the next hill. Which is very steep and winding but only a few miles to the top. 1st gear was engaged early due to the incline, and the bike got really hot, smoked a lot from around the engine etc. I got passed by a M21 like I was standing still, little 2strokes, A B31 plunger and 2 350 matchy's like, I was standing still. It should be said, I also cannot go up hills generally any better than my father in laws 350 compy which is just flogged out like you wouldn't believe.
Quite demoralizing.
I got to the top, but I was so close to fully nipping it up. I had to will it to the top in a cloud of smoke and oil coming from everywhere.
So, WHAT THE HELL?!
I just had an idea... Is it the plug? Could it be that simple? I use NGK B7ES. Are they reliable at high temp and load? (I've swapped out plugs regularly with new B7ES's and don't seem to have any different results)
see photo below. (just pulled plug) I've just ordered some new Bosch plugs - W5CC and W7CC's to try.
As soon as it gets under a decent amount of load, it starts to break down and heat up. I'm feeling like sending the Mag back to the guy and getting him to check it, but he's already had it twice... It should be mint.
Long and the short is, I think i've blown the head gasket or, at least the head has loosened off due to the over heating, as I couldn't start it after the beer stop yesterday, without bump starting it, (very low compression) and had very little power on the return trip to camp. Luckily it was all down hill. When accellerating though, I could hear it choofing - which I'd say is a head gasket.
ANY IDEAS GUYS?? Going to throw this compy in the ocean before much longer! I wanted to ride this and my '56 at the november JAMPOT Rally, and its looking like it won't make the distance!!!
Well my issues continue with my '55 G80CS. I've ridden the last 2 weekends at rallies, and both, were in hilly areas.
First things first. My oil burn continues on overrun, and, consumption is still out of control - 70ml per 70miles. I can only assume this is a combination of intake valve guide and blow by the rings.
So, that out of the way - my last rebore and new piston resulted in a +40, and my Amal 389 is set with a 30 pilot, 420 main and usual 106.
Now, Timing is set using the stick in the hole, but, I take the time to get it just right to 1/2" BTDC. The bike is usually a little hard to start, as it floods easily with the 420 main, but I was advised to use that main, by a guy who's worked with Matchy's for many years and has actual information from the factory with carb settings with compression ratio and cam combinations.
So, generally, the bike performs 'well', although I don't have a baseline of how it 'should' perform. Since going to the big main, I can cruise at 50mph ok, and 55 if I want to. That said, it still doesn't pull up hills unless you drop a gear and keep the motor spinning.
I've had the bike up to 70mph along the flat, and it didn't seem like it'd explode or whatever... but certainly took it's time to get to that speed. I still think it struggles to hold 50mph over ant hills - ie, rolling rises in country areas.
So to the last 2 rallies. I've always had issues with hills. Last weekend, was up and over a small mountain range a number of times. When going up one of the long drags uphill , running in 3rd, then second, it wasn't labouring, but I could feel it getting hot on my right leg. I decided to drop speed, and engage 1st, and let it spin up the hill.
It got hotter, and spark broke down a number of times, Missing and banging. I thought that must have been pre-ignition. No pinging though. That said, I backed off let it regroup, then it I made it to the top of the hill in one bit, and it started to cool down as I rode along the top. This happened on both saturday and sunday runs, on different roads.
To this weekend.
Rode yesterday, and it was up over 2 mountain ranges. - Why the rally staff use these mountain roads for old bike rallies is beyond me... The first part of the run was up a long drag, which would be an 7-8mile run to the top, with a few downhills and flat sections inbetween obviously.
Ignition broke down twice, and it began to get VERY hot, and I could feel it getting tight. The last steep pinch, I had to engage first gear and pray I go up. I did, and despite the hill, sort of felt ok and 'normal' after that and on the way down the hill.
THen we went along another 20 miles along the flat and it went ok.
Till the next hill. Which is very steep and winding but only a few miles to the top. 1st gear was engaged early due to the incline, and the bike got really hot, smoked a lot from around the engine etc. I got passed by a M21 like I was standing still, little 2strokes, A B31 plunger and 2 350 matchy's like, I was standing still. It should be said, I also cannot go up hills generally any better than my father in laws 350 compy which is just flogged out like you wouldn't believe.
Quite demoralizing.
I got to the top, but I was so close to fully nipping it up. I had to will it to the top in a cloud of smoke and oil coming from everywhere.
So, WHAT THE HELL?!
I just had an idea... Is it the plug? Could it be that simple? I use NGK B7ES. Are they reliable at high temp and load? (I've swapped out plugs regularly with new B7ES's and don't seem to have any different results)
see photo below. (just pulled plug) I've just ordered some new Bosch plugs - W5CC and W7CC's to try.
As soon as it gets under a decent amount of load, it starts to break down and heat up. I'm feeling like sending the Mag back to the guy and getting him to check it, but he's already had it twice... It should be mint.
Long and the short is, I think i've blown the head gasket or, at least the head has loosened off due to the over heating, as I couldn't start it after the beer stop yesterday, without bump starting it, (very low compression) and had very little power on the return trip to camp. Luckily it was all down hill. When accellerating though, I could hear it choofing - which I'd say is a head gasket.
ANY IDEAS GUYS?? Going to throw this compy in the ocean before much longer! I wanted to ride this and my '56 at the november JAMPOT Rally, and its looking like it won't make the distance!!!