Post by: paulbaker1954 on October 01, 2019, 08:08:29 PM
Ht leads checked
Plugs checked
Plug caps checked
carbs as clean as a bloody operating theatre
float levels ok
no fuel starvation
Head completely overhauled by machine shop (valves checked, lapped in and head skimmed)
Boyer system tested at Boyer and no issues
All wiring to Boyer system checked and all connectors replaced
Have run with Boyer system connected direct to battery and with spare leads from stator plate (ie all loom connections taken out of the equation)
Still getting this afterfire on 1 and 2 and quite frankly I am running out of ideas
It is intermittent, seems to get worse as engine warms and often in initial start get a really loud afterfire
I am sure this is something stupid and obvious but I cannot trace this damn fault
All ideas (however crazy) welcome
Post by: Erny on October 01, 2019, 08:16:35 PM
Hope you'll find root cause soon
Post by: paulbaker1954 on October 01, 2019, 08:21:15 PM
Paul said to hear this... fully understand your frustration!
Hope you'll find root cause soon
Me 2
Further thought are there any members near me that would be willing to come and have a listen/spare a couple of hours !!!!
Post by: K2-K6 on October 01, 2019, 08:46:21 PM
I'm unfamiliar with what you've got to indicate that with Boyer system.
Post by: Nurse Julie on October 01, 2019, 09:02:13 PM
Post by: Laverda Dave on October 01, 2019, 09:05:04 PM
Good luck and hope you solve it.
Post by: Erny on October 01, 2019, 09:13:30 PM
Post by: philward on October 01, 2019, 09:38:09 PM
Post by: Seabeowner on October 01, 2019, 09:41:00 PM
Post your video clip again to remind us. It sure sounded like a misfire caused by spark at wrong time. Still like to see it tested with points.
Does it disappear when the bike is revved?
You could try the exhaust system that came with the bike or has that gone in the bin. And was it you who had a failed exhaust on your pattern replacements?
Post by: Rob62 on October 01, 2019, 10:57:39 PM
Post by: K2-K6 on October 02, 2019, 10:11:28 AM
This thread makes me wonder if the timing marks are compliant with what you now have spec wise.
There can be a notable timing difference from the different iteration of mech.
Post by: paulbaker1954 on October 02, 2019, 11:20:39 PM
Reasoning being was wondering if I was getting some stray AC out of the rectifier interfering with the Boyer box. That said I did check the rectifier diodes a week or so ago and all were ok. Result no change.
Then swapped plugs from 1 and 2 with 3 and 4 (already did this as part of initial checks) but this time seemed to sort the problem. Go figure.......... That said only had chance to run the bike for 5 mins but sounded smoother and no backfiring.
Here is where I confess to possible stupidity in that I may have not been pushing the plug caps fully home on the plugs on 1 and 2 all the time. I am guessing that if the caps are not fully home on the plugs this would for sure cause intermittent firing resulting in unburnt fuel in the exhausts
That said I did take bike to professional mechanic who claimed he had adjusted plug gaps so he clearly didn’t put em back properly either!!!
Doesn’t make much sense as I had done all this before but don’t care if the issue is sorted.
If this turns out to be the cause I will feel REALLY STUPID as I know that in my early days of cars with no other knowledge first thing ever was to wiggle the plug caps!!!!! Maybe sometimes knowledge is dangerous as you sometimes simply forget the basics!!!!!!!
Will be doing some more testing over next week or so and may still not be out of the woods but feeling more optimistic that I have finally tracked this issue.
Good news is out of all this......
I have a fully overhauled head (skimmed to fix the original oil leak from around the timing chain area), with reground valves, fully reconditioned carbs, new inlet rubbers and when running now is ticking over smooth as anything.
I have learnt a lot through this frustrating process that will stand me in good stead so I am ok with all the stuff I have done
Post by: K2-K6 on October 03, 2019, 09:09:58 AM
As you say, to get experience like this is invaluable however it's acquired really. It all serves to help running them longer term and been quite a walk through of all the various functions and testing that may help others too.
Post by: Laverda Dave on October 03, 2019, 11:35:11 AM
The first thing I always do now with a missfire is change the plugs, cheap and easy fix.
Now go and thrash it before the weather gets bad 👍.
Post by: philward on October 03, 2019, 03:54:50 PM
PS - Ref my previous suggestion - misread your post prior to my suggestion as if misfire was on 1 - 4 (hence same ignition circuit) - yet another senior moment! (becoming ever more frequent!
Post by: Bryanj on October 03, 2019, 11:59:50 PM
Post by: paulbaker1954 on October 04, 2019, 11:10:41 PM
New plugs fitted today, synced carbs, sorted malfitting plug caps
PURRING LIKE A KITTEN NOW
This has been a frustrating but valuable learning curve but with fully reconditioned head, new plugs, new inlet rubbers with decent clips and nicely balanced carbs this bike is running smoother than it ever has. Ticks over lovely at 1k
Yet to get out on the road but all now looking really good
Many thanks to all who have added advice and wisdom over the last few weeks, that’s why this forum is so great and the advice and ideas have been so much more useful than the so called pro mechanic I used. I am not dishing him just that intimate knowledge of these bikes is so valuable which he did not have.
Post by: Trigger on October 05, 2019, 08:31:46 AM
Had a twin in last year for a new cam chain, easier to drop the engine to do this job. New chain fitted, engine back in but, no spark. Instead of the mind thinking, no electrics have been disconnected apart from the alternator, i started by changing the plugs, then the coils and caps, then the CDI unit, then the pick up. Lucky i had the same bike sitting in the workshop so just swapping parts and scratching my head. Right i thought, it must be the ignition switch and as i lowered the ramp, i noticed the kill switch was off ::)
Post by: philward on October 05, 2019, 08:11:17 PM
Post by: Erny on October 05, 2019, 08:19:49 PM
Post by: paulbaker1954 on October 05, 2019, 11:02:44 PM
Some times it is obvious that it is unbelievable :o
Had a twin in last year for a new cam chain, easier to drop the engine to do this job. New chain fitted, engine back in but, no spark. Instead of the mind thinking, no electrics have been disconnected apart from the alternator, i started by changing the plugs, then the coils and caps, then the CDI unit, then the pick up. Lucky i had the same bike sitting in the workshop so just swapping parts and scratching my head. Right i thought, it must be the ignition switch and as i lowered the ramp, i noticed the kill switch was off ::)
Pleased to hear it’s just not me that misses the obvious sometimes. Spent 5 minutes in Ireland this summer pressing the starter on my Yam Tracer and engine not turning over, eventually realising it was in gear and there is an inhibitor switch that stops you starting it in gear!!!
Post by: paulbaker1954 on October 12, 2019, 11:34:31 PM
The new rubbers and decent clips have resulted in a smoother tick over than it has ever had and the head skim has finally resolved the oil leak where this tale began ( oil was seeping out around the timing chain area of the head)
Many thanks to all who have helped with advice and put up with my frustration over the last weeks, this forum is just a great resource
Post by: Erny on October 15, 2019, 06:54:13 AM
Keep riding and enjoy your bike
Post by: JamesH on October 15, 2019, 06:16:20 PM