FCR-MX 39 starting problem

threedigits · Sep 11, 2016

Bike is FS 450E 2005 model with an FCR-MX 39 carburettor.

I had driven the bike working perfectly normal the day before, and it started like a charm and has done so for 3 years regardless of the weather or temperature (above 0 Celcius). It has always started at the first crank with e-starter and choke enabled. I only drove for an hour on a paved road with no problems at all.

Nothing had been done or changed to the bike but..
The problem is, suddenly the next day the engine won't crank over and does not start with the choke ENABLED when starting the bike with th e-starter. It really has trouble turning the engine over like it's too strong opponent for the starter, and also makes a loud bang in the pipe after a while of super slow and hard cranking.

But it does crank with the e-starter very well and strongly immediately with the choke disabled, starts with low rpm ofcourse as the engine is still cold, and works well when I enable the choke AFTER the engine is already running. Then the bike works just like always with no problems.

I have charged the battery full and it should be fine. Also changed the spark plug to a brand new one but it made no difference.

Any ideas? Did not find a helpful thread so far.

Taffy · Sep 11, 2016

possibly your PJ is blocked. tight valves.

look into the carb.

Taffy

threedigits · Sep 11, 2016

Taffy said:
possibly your PJ is blocked. tight valves.

look into the carb.

Taffy

Edit: obviously you mean the Pilot Jet ? Howy can it prevent the engine from being able to crank?

Thanks Taffy !

Taffy · Sep 12, 2016

you may also find tight tappets. try and get the staple on the ignition flywheel to 9 o clock on the compression stroke and then check your valve clearances. you need what is called "a sixth of a turn". you may find even some damage there, as if something mechanical has broken etc.

to do the PJ on a 450 is a sod. the carb can't really be dragged out of the frame but we do it and have a look at everything while we are there.

regards

Taffy

threedigits · Sep 12, 2016

Taffy said:
you may also find tight tappets. try and get the staple on the ignition flywheel to 9 o clock on the compression stroke and then check your valve clearances. you need what is called "a sixth of a turn". you may find even some damage there, as if something mechanical has broken etc.

to do the PJ on a 450 is a sod. the carb can't really be dragged out of the frame but we do it and have a look at everything while we are there.

regards

Taffy

So today I checked my valves. I did the good old 1/6 turnee and after putting it all back together, the bike fired up like a match.

I repeated the ingnition 4-5 times with the e-starter, choke enabled and it fired up right away every time. I'll try again tomorrow, if it still works I believe I owe you a thank you, Taffy.

Edit: I did not touch my carb and the PJ yet at all. I also bombed around the block with the bike and it worked normally (=kicked ***)

threedigits · Sep 12, 2016

Taffy said:
you may also find tight tappets. try and get the staple on the ignition flywheel to 9 o clock on the compression stroke and then check your valve clearances. you need what is called "a sixth of a turn". you may find even some damage there, as if something mechanical has broken etc.

to do the PJ on a 450 is a sod. the carb can't really be dragged out of the frame but we do it and have a look at everything while we are there.

regards

Taffy

I did not get the ignition cover off the engine because it felt so tight from the left down part. Wonder why?

I did the straw in the spark hole -TDC check instead.

threedigits · Nov 28, 2016

EDIT: altered battery details

So far I have checked my valves, pulled out the carb and given it a good cleaning and replaced my battery ( the old had died while trying to start countless times).

The electric starter just won't work. Kickstarting works like a charm everytime, and the bike runs just like it should. The starter does try but still can't crank the engine over.

I replaced the old battery with a YTZ7S with a more powerful 5,5Ah. The Old YTX5L 4,2Ah worked 3 years with no problems before. No difference - no juice to crank over.

zaga · Nov 29, 2016

Hi

No juice ?

Check battery cables, replace cables with stronger ones

Check auto decomp spring

Replace starter with Taffy beefy starter

ZAGA

ned37 · Nov 29, 2016

Replace starter with Taffy beefy starter

i believe the "beefy" starter was meant for the '01-'02 models

threedigits · Nov 29, 2016

zaga said:
Hi

No juice ?

Check battery cables, replace cables with stronger ones

Check auto decomp spring

Replace starter with Taffy beefy starter

ZAGA

To check the auto decomp, can I open the valve cover (the whole cover, not the valve clearance check lids) in my 2005 model without any huge problems? Is it just a matter of taking it off, or does for example the camshaft come loose or something?

zaga · Nov 29, 2016

Yes you can take the cover without any problems
Nothing will come out of place

Enviado do meu iPhone usando o Tapatalk

Taffy · Nov 29, 2016

ned37 said:
i believe the "beefy" starter was meant for the '01-'02 models

well the thing is Ned, I don't want to take peoples's money under false pratences so I thought that that was being straight.

I sold a beefy to a 2007 owner this week. his had burnt out so.. why not?

but as our advert says: it makes diddly squat later on so don't bother. so saying blah blah "pre 1901" does me out of business because people take anything literally. the idea is to say what it fits but also (in the detail) mainly, "what it benefits". I have to leave a window see.....

Taffy

canolman · Nov 30, 2016

ned37 said:
i believe the "beefy" starter was meant for the '01-'02 models

Will the R6/CBR600 mod not work on the 450 Ned? Saying that if the decomp is at fault?

threedigits · Nov 30, 2016

I checked the voltage from the starter while actuating it, and it gave me 10,6V even tho the battery was almost full. I belive it should show more.

I also took off everything:

Cleaned connections, took off and disassembled the starter. Cleaned and checked it from inside and put back together. The coals were good but the thing had a lot of black dust inside, could this tell a tale about it being in it's end? Or could my starter solenoid relay be faulty, has anyone had problems with them?

I also took off the valve cover, and the auto decomp looked fine visually and the spring worked. I can not say if the spring resistant is too loose, so maybe it slips off too soon ? How could I tell...

In the end no change. Does not crank over the compression with E-starter

ned37 · Nov 30, 2016

Will the R6/CBR600 mod not work on the 450 Ned?

iirc, when i was doing my '02 650, i compared the starter to my '04 450 and it was different in length, but comparing some pics i took, they look the same. judge for yourself. it was a while ago. the pic on the left is the 450.

ned37 · Nov 30, 2016

the starter bodies on the sm-14 are all the same, but the mount portion varies in length.

threedigits · Nov 30, 2016

I have now tried it with a very strong battery, but it still has no power to crank over the compression stroke. It did make it tho once or twice with a lot of continuos actuating with no choke enabled.

It is almost as if the auto decomp works only once in a while, even it seemed okay when I popped the valve cover.

Is there a danger of valves hitting the piston in actuating the manual decompressor when E-starting? Does it open the valves enough for that to happen?

Palle · Dec 1, 2016

threedigits said:
I checked the voltage from the starter while actuating it, and it gave me 10,6V even tho the battery was almost full. I belive it should show more.

I also took off everything:

Cleaned connections, took off and disassembled the starter. Cleaned and checked it from inside and put back together. The coals were good but the thing had a lot of black dust inside, could this tell a tale about it being in it's end? Or could my starter solenoid relay be faulty, has anyone had problems with them?

I also took off the valve cover, and the auto decomp looked fine visually and the spring worked. I can not say if the spring resistant is too loose, so maybe it slips off too soon ? How could I tell...

In the end no change. Does not crank over the compression with E-starter

What have you changed since last time it did work? Cam chain and so on!

threedigits · Dec 1, 2016

Nothing, absolutely nothing was changed between working and not working. It worked very well the day before the problem started one morning. And the bike works really well when kickstarted and starts with ease, but not with the E-starter.

Now I have changed the sparkplug and battery, and done all the things listed in previous posts

nsman · Dec 1, 2016

In a situation like this when all logic defies the end result most times its because you are looking in the wrong place.When you eventually find the problem it all seems so logical that you wonder why you did not see it at the beginning.
In this case I think you should look at what could be causing the engine to require more power to electic start it than to kick start it.
Possibly a crank or balancer bearing on its way out?

FCR-MX 39 starting problem

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