Hard to Cold Start (2011)

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BPR7EIX

Darn it Cash, you made me go out in the middle of the night and check :wink:

I fully agree with the comments about the Mikuni failing to dump a good amount of fuel into the pots as opposed to the Amal flood triggers- it's obvious as they were specifically designed to do that for starting purposes. It is a drawback alright. I thought persisting with it in the hope of better gas milage due to the pathetic size of the fuel tank might make it worth it. The carb I have is brand new, as in not blocked or anything and has a new inline prefilter to it. I will check out the jetting as I have a few different ones kicking around...

I think a starting point (definatley NO pun intended) is to get a degree wheel onto the timing and make sure it is correct. Also I have some standard NGK plugs, I just put the iridium ones in because I thought more spark = better starting but Cash's comment about the double supression makes me wonder now.

Also I will check the crankcase breather and timing chain tension- I did have a look at it and it is brand new but I will check it properly, might as well cover as much as possible while I am resting up the leg, did I also mention I have a titanium rod through my right femur and gang plates around the pelvis? Yeah so I really need this bit*h to be easier to start :|
 
Dodgy,


Well there it is BP-R-7EIX the wee beggar. I couldn't tell how I know this. :roll: There can't be too much wrong with the bike as it runs fine hot.

The carb's cold start mechanism is a separate circuit and when off has no influence on normal running. You're only left with poor spark, over rich or weak cold start, and or a weak leg. Try starting the bike on its main stand and hold the throttle in varying positions from zero to quarter after that the cold start has little effect. Oh! and try the first kick or two with the enricher off. Does the motor run OK and 8 stroke at times when cold with the enricher on ?

Best of luck,

Cash
 
Shoot some starter fluid in there. If it still don't fire then you know its not a fuel issue. My combat will get stuck in a compression where I can stand on the kicker and not budge the motor. When this happens I pop it in gear and bump it forward or backwards. This usually frees things up a bit.
 
yeah Get some of this, and what you don't use you can squirt in the carb. :roll:
An Australian made product that they didn't nick from us poor Kiwis like Split Enz, Phar Lap and Pavlova ( they can keep Russell Crowe)... :wink:
Hard to Cold Start (2011)
 
Luck of the draw on who's manhood gets challenged by a Commando. I would not bother with a degree wheel, if ya can get it started and warmed up, to then advance till back fires then retard till it just don't backfire on kick offs. Then and only then is it worth while to index and mark actual TDC and best timing setting you settle on. I re-broke a fresh R knee joint fracturing, after ok to start and run by the trial-error method then thought I'd dial in in proper with time light and it back fired me up on locked knee to topple me down a slope, took 10 min to stop white knuckled pain and gimp off.

My guess is you are too advanced on initial timing and need to check needle in place in carb and float level. Miki carb should start as well as Amals hot or cold.
I've had carb bolts get loose to give crappy low speed operation but flew fine on throttle, which sucked the carb up tighter to gasket. Went round and till saw gasket hanging down. Don't know if double resistance is an issue on Trispark, so should ask them, as well as try only one item with resister rating.
 
Dodgy,

Further to Cash's point about the damped plugs, you should check the caps as well (if you're using the good-looking NGK caps with white lettering, they are very likely resistive caps). Caps AND wires can each be of the suppressor persuasion, that is, each providing 5 kilohms of series resistance. A total resistance of 5k is all that the spark plug string (wires, cap, and plug) can tolerate and still reliably sustain the spark through combustion. Just ring out the combination wire+cap. If you're using iridiums, than the wire-cap string must be less than 1 kilohm.

Rick
 
I feel for you. My right leg / back etc is bad & getting weaker fast with age. Last night I used the bike for a series of short around town stops & dinner. On the way home I made one last stop & when I tried to leave it started right up & died right down when I flipped on the headlight. Would not start!!! Kicked kicked kicked... Checked fuse (good) gas is good, new petcocks etc. Realized the switch for the headlight was on sucking battery juice when kicking so I turned it off & shazzam! First kick start. I'm having charging issues & all the start stop short low rev trips with headlight on drained the battery down to sub 10 volts. Boyer not happy. If you haven't allready, turn your headlight off when starting. Won't help w / commpression but if if fires at least your leg getts a break. I think I need a new stator/rotor, cuz a good system would have kept the batt charged. I'm thinking Sparx 200watt plus solid state reg/rectifier unit.
 
If you are standing on the left peg, like I do, make sure you don't have the rear brake light on too. Everything helps.

Dave
69S
 
Thanks for all the assistance folks 8)

Tried putting in normal NGK BP7ES plugs, also upped the main jet from the 260 it came with to a 280 and now it starts a lot easier and running above 4,500rpm is a lot better, it does need a bit more playing with the timing. I put the degree wheel on her and it was 2 degrees out. Set the timing with a strobe to nearly right and will get a friend to help later in the week to get it spot on. Other than a few oil leaks that I am attending to with some new gaskets I have made for the rocker covers (I took them on and off quite a few times in search for TDC :roll: ) and a few new copper washers here and there it is going pretty nicely.
Even got to enjoy a great ride through some very winding roads with Mr 72Combat and he posted the run up on here.
So a little play with the timing should clear up the higher rpm niggles, as for the starting from cold- if I can get it to turn over with a decent kick, it starts quite well but it is the kicking part that is hard. It is not catching as it kicks over easily with the plugs out, put them back in and a cold engine and it needs a mighty good kick. Looking at the heads and the gap between the lower head fin and the upper barrel fin it seems that someone has planed the crap out of the head. Maybe a bit later on I can stick a .40 head gasket in there...?

Anyways, out there riding it, great day and made the workshop time I have spent on it worthwhile :wink:
These are great bikes, so I bought a bit of a lemon, ah well, getting on top of it now 8)
 
Just remember when you kick it, be committed and if the bike senses fear, it will bite you.

swoosh "kickmaster" dave
 
With electronic ignition and Iridiums, it should start first kick. On Saturday morning, Mairnecommando was having a moment with his - also mikuni. When he put the enricher on it fired up and ran fine. Personally, I would try and set the enricher circuit to be a little bit richer for starting.
 
Madnorton said:
With electronic ignition and Iridiums, it should start first kick. On Saturday morning, Mairnecommando was having a moment with his - also mikuni. When he put the enricher on it fired up and ran fine. Personally, I would try and set the enricher circuit to be a little bit richer for starting.
Click to expand...

At least he's got a fancy new seat to sit on if it doesn't! How'd that work out for him?
 
Thanks again for all the help on this. The cold starting is a lot better after the plug change but the running issue is still there and I am stumped.

A new clue has emerged when I replaced the ammeter because the old one had no needle.

So the problem is at 4000rpm and above and only when the bike is good and warm. It does not happen for the first 30 or so miles and it can rev out nicely to 5 or 6,000.
But when it is warmed up and in any gear, when it gets to 3,900-4000rpm it pops out of the exhaust pipes and at the same time the ammeter needle shoots to the far right of the scale when it pops out of the mufflers. It is not a loud banging, just a pop pop and you cannot rev it out any further.
Just to recap, here is what it is running and what I have done;
850cc reconditioned motor, good compression
Tappets set.
Positive earth cleaned and tightened, all wires checked and any suspect connectors replaced
6V coils (new)
Leads (new)
NGK resistor plug ends (new)
Tri-spark ign (new)
NGK BP7ES plugs (new)
Mikuni VM34 carb (new)
This could only be on the main jet circuit of the carb and I have tried from 240/260/280/300 and no change.
Idles fine, starts fine-ish, pulls fine up to 3,900 then it all goes to hell. Played with the timing, advancing and retarding in increments and then road testing. Does not seem to make much (if any)of a difference. What the heck is going on? Why does the ammeter needle fly off to the right (+) when it pops out the mufflers? :(
 
Try lowering the needle (raise the clip). The range you speak of seems to be the upper range of the needle/needlejet function. Why lower it? It worked for me.
 
Dodgy

You mentioned the motor was reconditioned, suggest you check the camshaft timing. Heavy kickstart could be a related to miss timed camshaft.

Is there a story to the rod in the femur?
 
norsa1 said:
Dodgy

You mentioned the motor was reconditioned, suggest you check the camshaft timing. Heavy kickstart could be a related to miss timed camshaft.

Is there a story to the rod in the femur?
Click to expand...

Good point there Dodgy as I would have thought it should be easier to kick over than my Combat.....the 850 being the touring model... :roll:
I had to pull it over to a kerb to get a straight leg kick. ( at the time no centre stand)
 
This poor running at higher revs sounds electrical to me. Are you running the ignition feed wire through the kill switch as per the standard wiring set up? The Norton kill switch works by running the feed through the switch which simply breaks and interrupts the flow of current when the button is pushed, they become corroded internally and pass much less than the 9 volts generally required to fire an electronic ignition. I use these kill switches when fitted to simply trigger a relay that I connect directly from battery power to the ignition. Since the problem is worse as the machine heats up perhaps there is high resistance in these or other feed wires and it gets higher as the heat builds up in various connectors or joins. As an experiment connect power directly from the battery to the ignition and see if the problem persists - you will have no kill switch so all of the usual caveats about 'not trying this at home' apply.
 
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