Thanks David I will be checking both the gen and the mag just to be sure...Even so the noise is coming from the front right hand side...so we will see what is when I dig in again..
Cheers and thanks,
Eric
MK1 carb tuning and BTH noise?
- Thread starter Ducdude
- Start date
Thanks David I will be checking both the gen and the mag just to be sure...Even so the noise is coming from the front right hand side...so we will see what is when I dig in again..
Cheers and thanks,
Eric
The common areas for pipe discolouration are the union of the pipes and the front section of the silencer. A friend used to say (vis a vis pipes) blue is bad and gold is good. Trouble is that too much of either is bad. I had a whine from the generator drive on my C Comet that turned out to be a top hat bush slowly losing its grip on reality. One would have thought that it would just "let go" but no, it seized and slowed the bike down VERY quickly. So, any similar bushes in your timing chest?
Hi Eric
Blueing exhausts could also mean retarded. What ignition timing are you running? I'm at 40 BTDC now, at the 34 that seems to be reccomended nowadays, mine ran hot and strangled (9:1 comp).
Needle position shouldn't affect top speed, I'm up to 240 main jets on 932 Mk 1 without air filters.
H
Blueing exhausts could also mean retarded. What ignition timing are you running? I'm at 40 BTDC now, at the 34 that seems to be reccomended nowadays, mine ran hot and strangled (9:1 comp).
Needle position shouldn't affect top speed, I'm up to 240 main jets on 932 Mk 1 without air filters.
H
Wow, that is unusual. I am running 8 and a bit:1, standard 276 carbs with 190 main jets and 34º advance on a modern BT-H on my Rap. My post war Comet is running similar comp. with coil ignition on 36º and 930 concentric with 220 main. What sort of adv/ret mechanism are you using Howard and have you checked the range? One has to be careful comparing jet sizes on different types of carburetters as they are not equivalent (equijet?). The silencer also plays a big part in obtaining the correct jetting on our bikes.
Hi Eric,
I had a whining sound from the front end of my Shadow engine a month ago. I also suspected the BTH and/or the dynamo. The sound got worse, and the engine was seizing up.
The culprit turned out to be a worn-out bushing in the front cam, slowly approaching end-of-life. The engine is now being rebuilt from the bottom up. No more patching!
Cheers
Carl
I had a whining sound from the front end of my Shadow engine a month ago. I also suspected the BTH and/or the dynamo. The sound got worse, and the engine was seizing up.
The culprit turned out to be a worn-out bushing in the front cam, slowly approaching end-of-life. The engine is now being rebuilt from the bottom up. No more patching!
Cheers
Carl
I'm using Pazon. I have to say I'm suspicious of the timing mark, but based on how Pazon recommend setting the timing, it's now on 40 degrees.......... and I intend to try 42 when I can. Every time I advance the timing it seems to improve and 34 (if that's what it was) was very wrong. Peter Appleton is running 40, and that's what prompted me to go that high, but I've had no sign of pinging yet, and the old addage is when it pings, turn it back a degree.
Your carbs are probably in line with what I'm running. I worked out that 932s were about 25% more choke area than standard Shadow carbs so I started with a jet 25% bigger - 230, that seemed a bit weak so I'm on 240, and that seems near enough. I'd have tried 250, but I haven't got any, and the 260s I've got would probably be a bit high. Plug chops don't give much of a clue anymore, so it's down to easing the throttle down when pulling hard etc.
H
ps it runs nicely all through the range, docile and torquey at low revs and fairly rapid when the taps are opened.
Last edited:
Well I have to go into the case any way to check things out so I will re-go-over all the bushings and make sure they spin feely...they all did 400 miles ago but who knows what I will find. While in the timing case I will clean a few things up with the compression release and put in a new comp release port to try an keep the oil at bay.. Thanks,
Eric
Last edited:
Hi Howard,
I am running my BTH at 35 degrees BTDC with the original 60 year old heads and pistons on the shadow. Compression is at about 150psi in each cylinder and leak by is 7 and 8%. So the heads/cylinders seem to be doing their job.
The needle position was raised for the around town performance which was less then impressive. Better now all the way up. I am still working on the 932 MK1s and I am convinced that the 210's are to small and I am currently planning on trying the 230's to see how that feels.
Time will tell...
Many thanks,
Eric
Thanks ! I was thinking a delrin gear would also work as a replacement for the PFA one. Have we any experence with the delrin gears? I do have the original fibre gear, do you know if that will fit on a BTH?
Thanks,
Eric