Hi
From a great running bike to not so good now. The only thing I did was change all the bulbs to Led. a bit of history, the C15 was completely rebuilt with all new bearings etc. I converted it to 12v and installed a Boyer electronic ignition, new battery, coil and new OKO carb.
The bike didn't miss a beat (175 miles) until after I did the bulb change but I suppose this could just be a coincidence. the bike starts great and after about two minutes when warm the tickover deteriorates and runs very uneven. If I then leave it to cool down it runs good again and then after 2 mins runs rubbish and so on. Ive changed the coil for a new one and it does the same so I intend to take the carb to bits and clean it today. Any other ideas if the carb clean doesn't work, could it be a faulty electronic ignition?
Did you try changing all the bulbs back again to how it was and then run the bike?
I believe led lights are polarity sensitive - are they all wired in correctly? I would certainly put the bike back to a condition you knew it ran well with.
Put all the bulbs back and still running rough, I just cleaned the carb and still rough :-[. I'll keep looking.
Did you put the points ignition back?
do you have an insulating gasket between the carb and head or is it big enough?
sounds like when warming up the fuel is evaporating, otherwise could be the coil breaking down when getting warm, I had a customer with a modern Triumph that had hoses rigged from the front to over the coils as they were getting too warm and the cooler air flow kept them coler.
Test the battery and voltage whilst running, Boyer like plenty of volts.
"Did you put the points ignition back?"
I guess this would be the the acid test to see if the Boyer is breaking down or swap it for another EI. Do these breakdown easily? most people say install and forget.
"do you have an insulating gasket between the carb and head or is it big enough?"
There is a 1" ally flange and then rubber hose that the carb sits in so all is cool and airtight (WD spray test done) also I did ride the bike when the weather was very hot without any issue.
"otherwise could be the coil breaking down when getting warm"
I did swapped it yesterday with new coil and had the same bad running.
"Test the battery and voltage whilst running, Boyer like plenty of volts."
Did this and voltage was 12.5v when riding and then stopped after the run went to 12.9v.
Tonight I swapped the spark plug, plug cap HT lead and checked the valve clearances, the bike ran good when opened up but with an erratic tickover. So almost there. Is there a quick test that would eliminate the boyer first before revert back to putting points back in? Also could it be possible when I installed the led bulbs it inadvertently messed up the Boyer and I have to buy a new one.
You don't mention what you're using for your 12V rectification and regulation - is it a modern combined unit?
If the bike ran OK with the lights off before the swap to LED then I can't see what difference that would make and how it could upset your EI unit.
Cheers,
Bernie
Could be the OKO carb settings are not right. With a non standard setup it can take experimentation to get the correct settings.
Hi Berie - It's a MKIV EI and single phase power box alternator regulator.
Hi Julian - When the carb arrived I installed it straight from the box and it started after a couple of kicks. I could tell straight away that it was running great just from the tickover and blipping the throttle so took it for a ride, and 20 mile later it never missed a beat, and now after 175 miles without messing with anything apart from the bulbs.
I'm going to check all the wiring today to make sure there's nothing come loose before going back to points. Looking at all other forums with Boyer issues most of them find a cracked solder joint or loose spade end and one person said they had to change the spark plug cap to a resistor type cap. Well if it improves when I put the points back I'll stick with them.
Please give us feed back if you do find what is causing the problem, could be of use to some of us in the future!
My C15 has a mk4 Boyer B. EI kit waiting to be fitted, by me, but I will give it a miss until I am a bit more certain of its reliability.
Many people seem to just "fit and forget" according to what I have read, but I fitted an EI system to a Suzuki GT 250 in 1976 and it failed about 3 miles down the road on its first run...what a slog that was pushing it home!
Things must have improved since then, hopefully.
Hope you are successful in finding your fault.
I just come back from a 5 mile run still on Boyer and the bike ran very well ??? and didn't breakdown apart from that erratic tickover. The throttle response in all ranges were good so I'm now thinking I just have a pilot issue (probably just dislodge something when I cleaned it). I've ordered another OKO carb so I'll wait till it comes and just do a straight swap and see if it instantly makes it better before I swap the EI back to points. On another note is it usual to have a small amount of smoke coming from the exhaust after a rebuild i.e. new piston and rings etc. Does this go away when the rings have bedded in?
With having the lights on tonight, when I got back home the battery was down to 12.4v from 12.9v so I'm guessing the alternator isn't putting enough back into the battery. I'll try the led bulbs again tomorrow and see what happens. Is there a better (upgrade) alternator I can just install? The one on at the moment is a three wire converted to a two wire (6v to 12v conversion).
Hope you don't mind all the questions but it's driving me bonkers.
Rings do take time to bed in if the cylinder was rebored, and if not rebored it should have been deglazed to give the new rings a chance to bed in properly. A worn inlet valve guide, or missing valve stem oil seal , if C15s have them, can cause a bit of smoking too.
Perhaps the alternator rotor has lost some of its magnetism over the years and needs to be replaced?
Thanks for the replies so far.
My C15 is positive earth, so does it matter if the bracket around the coil is bolted to the frame.
No
Great stuff, thanks Adrian
Re-reading your posts,B, it seems that your engine runs fine at speed , and the tickover is OK when cold but becomes erratic when the engine warms up.
That does sound like a carb. fault or an air leak when things expand with the heat...a coil breakdown would have been a possibility but you have eliminated that.
A bad electrical connection, made worse by temperature could be a culprit, maybe caused while fiddling with the leds.
Or the Boyer...but hopefully not!
Just an update - the new carb arrived today and installed it in 10 minutes. It still had a slight erratic tickover but not as bad as before and it keeps on running on tickover without stopping which is a big bonus. I took it through the lanes and it was really nice through the speed range. So I think it must be the Boyer. I also have another distributor that turned up today so I'll change it to points when I get chance. But to be honest the bike ran really well at speed (40mph) so I might just keep it as it is, at least it keeps running without conking out.
just a thought...head gasket? torqued down evenly or play in distributor or points shaft allowing it to float around therefore upsetting the Boyer?
Everything seems ok in that department Chaz.
Earlier I had one of those light bulb thoughts and might have solved it, I just need to put my thoughts into action if I'm correct.
I'm guessing that you all think that I have already tried what I'm about to say but haven't asked, probably my fault really for not saying.
I'm sat there thinking the only thing that I have wrong with the bike is the uneven tickover when it gets warm, all other ranges on the throttle are good.....so it has to be the Pilot (Johnan said probably carb fault). When I installed the new carb on saturday I had to unscrew the air mix screw approx another two times to get a jittery tickover (light bulb come on) I need to put a smaller pilot jet in to see what that does.
Is anybody with me on this or am I talking rubbish.
The pilot jet is the part which supplies most of the fuel at low throttle openings. It has a small hole in it which restricts fuel flow though it. Both the pilot air screw and pilot jet affects carburation from idle to around 1/4 throttle.
that said , I would have thought it would affect at both cold and warm, BUT, you say you have a new carb (Brand New?) , Im suspicious that if its still got the same problem then chances are its not that.
let me tell you a story. we went with our eldest to Gloucester to get him a Suzuki Bandit, his first 600. I rode it back home 50 miles, as far as the J17 M4 junction. He got on the bike and rode the 5 miles home. rode it into the garage and parked it. it stayed there for 3 months. It wouldnt start. we bought another loom, coils, cdi, plugs and kill switches but still no start. I had traced wires , nothing. Finally, I took it to a big dealer , after a week we called them, they had just sent it out on a test ride.
They had also traced the wiring.... we wouldnt have found the fault...there was a break in the wire near the ignition switch, when off the ends touched, when ignition turned on the broken ends repelled like a magnets. the ironic thing was, the second loom we bough (from a breakers) had exactly the same fault, presumably why the bike was broken.
It could be possible that the new carb has the same fault, machining swarf blocking a hole or jet.... maybe a time to go back to the start again.
One thing nobodies mentioned is your tappet clearance, not enough clearance would mean the valves staying slightly open when the engine warms up. wont cost you anything to check 10thou for Ex and 8thou for inlet.
Well I sorted my running issue out. I installed a smaller pilot jet to 32 (was 35) and and larger main jet to 130 (was 100). It now starts very easy, ticks over without stopping and pulls through all the gears very good.
Glad you sorted it out!
Well done. only just seen and read through this post. Pilot jet or bit of dislodged swarf was my first thought.