400 none starter

[59viperman]

hi folks, got a problem with my 77 400. I bought the bike back in January and parked it up in the workshop, I have spent all that time trying to locate a yellow tank for it and I was lucky enough to score one this week. anyway I fitted new plugs air and oil filters and put fresh fuel in, I gapped the plugs to 0.8mm as per the manual and she just refuses start. I have had one or two half hearted puffs and that's it. she fired straight up when I got it by the way so I do know she runs, one thing though, she is fitted with one of those plastic oblong clear fuel filters and there is a air bubble about an inch above it in the fuel pipe, the filter has very little fuel in it and by that I mean tiny, thing is the plugs are damp to wet to look at but not soaking as you would expect with the amount of spinning it has done. I have waited at least half an hour between  tries so I haven't just plugged away at it . any ideas? I have been as detailed as I can.

[PatM]

If you suspect theres no fuel getting to the carbs, then just remove and re-hose it without a filter. They do fail! as well as leak...
Whipping a plug out will tell if shes fueling

[Bitsa (Ralph Wright - RIP)]

Viperman,
I assume there is nothing blocking the air intake under the seat.
2 all plugs spark?
3 After fitting new tank is the cap seal not blocked?
4 Remove the fuel filter and after no problem re fit
5 Carbs might need a clean if standing for a while
6 I take it the choke flaps are opening?
Something to go on wish you luck
Cheers
Bitsa

[59viperman]

thanks chaps , I will try all of above, I have just come back in from the workshop because after another try the ns pipe is warm, all others stone cold. is removing the carbs a big job ? I would love to give the a good blow out.

[Bitsa (Ralph Wright - RIP)]

Hi
Not the easiest set to get off but with all the fours its a knack.Because I have worked on them before I did not find them to be a big problem but other members may disagree.The Last one I rebuilt I had the carbs off more times than the old ladys drawers and have to say the honda was easier.Just take your time and all will be fine.
Cheers
Bitsa

[Clem2112]

The battery's state of charge makes a big difference on my 400/4..... it has Dynatek ignition which I suspect can make matters worse if the charge is low. I iused to blame the carbs or stale fuel but only use non-ethanol BP 97 now and the carb internals are spotless.
Also have an inline filter, with a removable porous core which I took out !, but this bubble trap has no effect on fuel flow here.

On Sunday, having just rebuilt the top end on mine, it was a sod to start as usual.
I think the battery voltage was a bit low and the electric starter made things worse.
It started after a few attempts but took a while to run cleanly so the carbs could be balanced.
I think that running at low revs for half an hour while getting the carbs sorted drained the battery some more.
The bike was then left for 4 days wating for weather to improve, without the Optimate charger connected (forgot ) and when I tried to start it again it took a few minutes to get all four cylinders running and then the idle was lumpy with the usual racket even though the carbs were synched.
Quick check on the battery showed 12v with no load, 11.8v with ignition on....seems low to me.
For the first few miles it hesitated at low revs but improved by the the time I returned home after some steady running above 4000 revs.
Left the bike to cool for an hour, as I wanted to check the plug colours.
 After doing the plug check it started up first time with no choke and held a fairly steady idle well under 1000 revs. Battery voltage was 12.5V with ignition off this time.

[59viperman]

hmm, lots of food for thought there boys, couple of afternoons in workshop me thinks starting tomorrow. will report back.

[Lynx]

You have got the points and coild leads the rigjht way round haven't you  ?

[59viperman]

like I say lynx, when I got it she fired up no problem. problem is a house move and renovation got in the way and she just stood, always kept in dry workshop though, got a big list of things to go through now and you have just mentioned points, give them a good looking at too. cheers.

[Clem2112]

Assuming battery is tip top,  electrics are Ok or have been checked out so good sparks.

Try draining each float bowl (I use a piece of sculpted hosepipe under the screw) then allow fresh fue to flow in. What's in teh bowls could be water laden cos of teh ethanol). I have found this helps after a long lay up.

[59viperman]

 :)well I went through all suggestions today, finally plucked up the gander to take the carbs off. good job I did, I have never seen so much shite in float bowls in my life. I had every jet out cleaned and blown with the airline, refitted them and first prod of the tit she went, smooth as silk no nocks rattles or anything . tickover is a different story though, 3000rpm ? something not right there me thinks, any suggestions ? thanks for all the help by the way , without it I would still be scratching my head. oh one more thing, I think a good ultrasonic clean would be a good idea. I don't suppose anyone on here is in the business ?

[Clem2112]

40 quid u/sonic bath from Maplins worked for me. Other brands are available.
Plus a bottle of sea clean fluid but de-ionised water would do.

[Bitsa (Ralph Wright - RIP)]

Viperman
Can you not slow here down with the usual method the main screw?
If not could have an air leak somewhere,orings on manifoldes etc
Cheers
Bitsa

[59viperman]

yep, slowed it down with the main screw. I now know why the previous owner had it speeded up, cam chain knocking like a bag of spanners. adjuster bolt very rusty looking.

[Clem2112]

Just a thought..
Knocking you say.... That sounds like imbalanced carbs rather than camchain .
If the camchain is loose the sound is normally a higher pitched tinkling sound which quietens as the revs rise.