I'm new to the forum but have already found a lot of usefull information by searching through old threads.
Unfortunately I have a problem that's starting to drive me crazy... Please forgive me for what I feel could turn out to be a very long 1st post!
I bought a MC16 in Portsmouth last year. As I live in Denmark I had a rather long journey home...
I'm sure some of you know the bike already, it's an hybrid:
MC18 rear swingarm, MC21 front end, magtek rear wheel and what seems to be an MC16 FIII exhaust. And in a custom blue/silver paint job that I personaly find more seldom than good looking
At first it started just fine, tick over was somewhat rough... seemed a bit rich on the mix and would stop when put into gear if not reved some (and yes I'm familiar with reving 2-strokes during take off - but this was with the clutch fully engaged).
After 100 miles or so the bike started running rough (partly on one cylinder and won't rev up).
Got to my first destination and after turning the bike off it was really hard to start again. Surely only ran on one cylinder by now.
As I have earlier had an TZR with YPVS, and the feel was a bit like when the YPVS was stuck closed I checked the RC servo, cables and allignment, all looked good.
Got the spark plugs out and had no spark on one of them and it looked fouled (can't remember which though)
Replaced spark plug and it got me all the way home (approx. 500 miles). Though at the end it started to make the same rough running...
I then left it over winter and pretty much forgot about it.
Was convinced it was all down to a way to rich mixture so started last week by cleaning the carbs and checked all settings.
All jets are standard, MJ 110, SJ 35, float heigh 13mm, needles standard.
Air screw was 2 turns from fully in. Set this to 1½ turn as per specifications (though I understand this would give an even richer mixture).
Must admit I didn't have a new gasket set, so had to do with the old, but they don't seem to be leaking anyway.
Air filter was very oily so gave it a good clean. Airbox had been modified by drilling 4 holes in the top cover (pretty standard mod from what I understand).
Checked the wires for the coils, cleaned them and made sure the "plugs" was nice and tight.
Measured the resistance to 9.65-9.85 kOhm with the plug caps on (spot on from what I understand).
One thing that surprised me was the tiny ground wire on the bike, is this really standard? I cleaned the ground to frame connection (at the bracket for the upper cylinder coil). Measured resistance to approx. 0.3 Ohm from the battery.
Gave the battery an overnight charge and replaced the spark plugs (didn't look to good).
After this small "service" I haven't been able to start the bike up, so I'm now looking for any help that will point me towards my problem(s)?
I have spark when holding either plug to the cylinder head (though not sure how strong the spark should be), and one or both cylinder(s) it does fire very shortly.. But only when holding the throttle partly open.
Pulling the plugs shows that it's getting petrol okay, maybe it's even being flooded!
I will check compression tomorrow, must admit that I didn't think of this at first as the seller had a receipt for a top end rebuild from Stan Stephens less than 1000 miles ago. I don't have the paperwork with me at the moment, but if I remember correctly it also had new crankshaft seals.
Before I gave up tonight I cleaned the flywheel and pick-up coils but haven't tried to start it up since... Thought I would leave it overnight to let any excess fuel vapurise.
As I have spend quite a few hours trying to figure this out I have the following questions that I hope some of you could help answer:
1.
I get about 13.5 volt on the battery, dropping slowly when ignition is on. When trying to start around 12.8 volt. Is this okay or should I try to connect a backup battery?
2.
Bike was fitted with BR9ECM plugs (not specified for the MC16).
I know that BR is the resistor type spark plug, but will these put more strain on the ignition system?
I have now installed BR9ES plugs (B9ES was not availible of shelf at the local dealers).
3.
Plug caps are 5 kOhm resistor type, are these correct for the MC16?
4.
Should I try to install new float valves? Float height looked good, but the mixture sure seems to be very rich.
Next on my list is:
Compression test
Installing a battery that I know holds current
Better ground wire (negative battery connection)
Cleaning the exhaust
Cleaning the RC valves
New float valves
Checking all cables to/from the CDI
I'm still of the impression the mixture is to rich, but I'm not sure if it's possible that it's so bad it won't start at all?
I'm aware I adjusted the air screw by half a turn, could this be the reason it won't start?
Also what could cause the mixture to be that rich? Float valves that doesn't seal?
By the way I find the foam air filter to be very restrictive, and air gun can hardly blow air through, even now that I've cleaned it, is this normal?
Any thoughts are welcome, and thank you for a great forum with loads of great information...
