Solved: Help with non start after rebuild EC400FSE (decompressor)
 

Hello, three years ago I took my 2003 400 Fse off the road for repair as the engine was sounding very unhealthy. After a complete strip down of everything including of course the engine it was quite evident that the cam lobes on the exhaust camshaft and the buckets were in a terrible state.

So I traced some good camshafts and caps/carriers from a DRZ. However there was a fault with the auto decompressor on the exhaust camshaft, the seller refused to take a return and after some searching and advice I see on a couple of forums I removed the decompressor from the camshaft.

So three years later (and with a lot of spare time) I have rebuilt the bike and put the engine (that's been sitting built since last year) in the bike. Should mention I replaced the rings, shimmed up to spec and all new gaskets etc.

So from yesterday after trying to start the bike its's evident there is a big problem trying to start it. Even with a big car battery connected via jump leads the bike will turn over very very slowly. It kind of turns for about 2 revolutions stops then just about gets turning again

I have successfully started the bike a few times over the two days by operating the starter and then assisting it by using the kick start pedal to fire it into life. When running the engine and performance is perfect.

Turn it off and same issue, very slow turn over and no start. It is impossible to kick start the bike manually.

I am guessing that removing the auto compressor has caused this!!!!!!!
Could anyone possibly confirm this for me, I don't mind sourcing another camshaft in the knowledge that this should cure the fault. I've owned the bike from new and really want to keep it but don't want to spend unnecessary money on it,

You 100% need the auto de compressor on those 4t motors. They were a absolute pig of a starting system when they were brand new, age will not have made them better. If anything I would be modifying the decomp system to open the valve a little earlier if possible.
Good luck.

Thank you, yes I suspect it has to be the removal of the decompressor that has caused this problem, so will try and source another camshaft and fit this.

If it works I may also think about updating the starting system that I have seen documented also.

Hotcams
 

Hi, I fitted a Hotcams DRZ400 stage 2 exhaust cam Pt No 2252-2E to my 02 400FSE. Got it on Ebay from USA. Was about ?110. No machining of the head as it doesn't have the vernier sprocket like the one in the other post. Profile is virtually identical to GG original. Been running since 2015 with no issues.

Did they make a noticeable difference to torque/top end

update: I now have another good DRZ exhaust cam, will fit this tomorrow and update results if the starting issue is resolved

Update:

Replaced yesterday exhaust camshaft (with working decompressor part) and attempted to start but still unable to start the engine :confused:

Removed the starter motor and gave it to a friend who use rebuild stuff like this. He stripped it down, gave it a good clean up and refresh and fitted it this afternoon.

It's turning much better now (still lazy but that seems to be normal for these bikes). But after the fourth attempt over a couple of minutes it started. When the engine is warmed up and I turn it off it restarts every time on first or second attempt. I have left it a few hours and it started on the third attempt.

What I have also done is put back on the camshaft without the decompressor part fitted and tried this as a comparison. It still starts ok as well, though admittedly a little bit harder, you can tell the battery and starter struggles just that little bit more but it does start.

Hope this information helps someone.

If it struggles to start when cold it can be that your valves need adjusting.

Is it timed correctly?
Check that the timing chain is not stretched beyond spec?

I didn't notice much difference with the new cam. As I said it was identical to the original gasgas item although the clutch tends to slip now if you give it a handful in 5th or 6th.
I did also buy, at the time, used DRZ standard cams but decided to sell them on but can't remember exactly why. I do remember that they had a much milder profile and the timing was different.
I always jump start the bike for the first start of the day because it still struggles when not been used for a couple of weeks. It's usually okay off its own battery after that.
I've run leads from the battery out to an Anderson connector under the side panel by the air filter and just plug a car battery in and it starts really easily. I think it doesn't help that the oil drains into the engine from the frame when unused for a few days.
I also rebuilt the starter motor. Because of its mounting position, it get water inside which rusts the brush plate causing the brushes to stick.

With the recent engine build I done I rechecked the valve clearances, I would say they are in spec but on the tighter side so think these should be ok, I reckon a few miles on them they will settle in nicely.

Timing marks are all good.

Interesting about the timing chain as I did not replace this.

I'll now ride the bike until about November and perhaps do some more to the engine over the winter