Help with non start after rebuild EC400FSE (decompressor)

[jason r]

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,

[Gasser Nate]

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.

[jason r]

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.

[Gordonian]

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.

[jason r]

Originally Posted by Gordonian

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

[jason r]

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