Bike over heating after 40 mile ride

[Ken4004]

https://youtube.com/shorts/fo1BwZChoxk?si=zYPBbhgGbNOJM228


Bike carbs sync these don’t look bad to me they were well out but not surprising as I had the carbs apart

[Ken4004]

Everything set up again today so just to recap :-

The fuel cap breather is working correctly

The oil filter and oil strainer are clean

The spark plugs look gaps are correct

The timing has been reset and checked with a timing light

The advance mechanism is moving freely and advancing the timing when revel up.

Carbs have been balanced with pro tune

The fuel is flowing freely from tank, removed fuel Tap a cleaned filter just a few bits on the filter.

Bike starts straight away and idles nicely at 1200 rpm

Bike revs up to 6000 freely ( haven’t gone past that as still running in) when not in gear



Wife has been very patient with me so need to get reading for our holiday so that’s it till I get back in a couple of weeks.

Jobs to do

Remove spark plugs and clean with a blow torch to clean up then go out for a run and see how she feels, thanks everyone for your input.

One last thing I think I need some new leads for my coils they are too short on number two cylinder and the spark plugs caps need changing, there is a possibility that I might  be getting an occasional misfire on number two cylinder because of the ht leads I think.

Can anyone recommend a new set of coils for my 400 4 that are decent , original coils are ok but leads are moulded  in so cannot be changed so ideally I would like some coils that I can change the leads on when they get ropy.

[Ken4004]

Alternatively if someone has a set of coils they are not using I could fit them to my bike and modify the originals in slow time

[TrickyMicky]

No disrespect, but even when running in, if you do not go above 6000RPM, then you are not doing it any favours, they don't even start breathing properly till about 7000 or 7500, so if you were going uphill in top gear at 6000 or less then, yes, you could overheat as you are virtually labouring it. You mentioned your other bike which is no comparison whatsoever with the 400, which has very small pistons, very oversquare dimensions allied to no flywheel. They do need to be kept spinning at a reasonable rate.

[Ken4004]

Hi Tricky that’s a very good point , I didn’t really think about this particular road being an issue but from what I have read on this forum this bike needs to be reved hard so really I wasn’t giving it a chance.

I haven’t wasted my time re running through the set up because things had changed and needed to be tweaked while the bike settled down after the rebuild.

Had a lot of issues fitting the exhaust the first time because it was from another bike but once fitted and heated up it was relatively east to remove and refit.

Next time I go out for a ride I’ll give it some more revs just being over cautious I suppose.

[McCabe-Thiele (Ted)]

Everything set up again today so just to recap.

Can anyone recommend a new set of coils for my 400 4 that are decent , original coils are ok but leads are moulded  in so cannot be changed so ideally I would like some coils that I can change the leads on when they get ropy.

I fitted Dyna S coils as part of their electronic ignition kits,  I adapted the existing coil brackets to make the Dyna coils fit.

[TrickyMicky]

We've all been there Ken, but if it's any consolation, I've just dug out my original owners handbook, and it advises for the first 600 miles, do not exceed 8000RPM, and that's with everything being brand new.  Enjoy it!!!

[Ken4004]

Thanks For the info I’ll open her up a bit more, I must say I am very impressed with the handling around the bends it really inspires confidence.

[McCabe-Thiele (Ted)]

This is an interesting looking bit of kit - not cheap, with Boyer-Bransden name.
www.ebay.co.uk/itm/364680555365

[Ken4004]

I noticed yesterday that no 2 exhaust pipe warmed up a little slower than the test although it seemed to start OK so I believe the cable / plug on no 2 is occasionally breaking down.
The leads on all plugs are a bit short like they have been shorted a number of times so time for new hardware .

[K2-K6]

I noticed yesterday that no 2 exhaust pipe warmed up a little slower than the test although it seemed to start OK so I believe the cable / plug on no 2 is occasionally breaking down.
The leads on all plugs are a bit short like they have been shorted a number of times so time for new hardware .

That rings alarm bells for a poor running cylinder. Given that your other investigations have not given anything confirmed as probable cause, that partially missing cylinder needs investigating for both ignition and idle circuit fuel supply.

If you have a borescope it would be worthwhile looking in there to see if there's anything untoward.  The cheap type for phone, with front & side facing camera are really good value to get decent inspection.

Hope you have a good holiday, anywhere interesting  ?

[Ken4004]

I noticed yesterday that no 2 exhaust pipe warmed up a little slower than the test although it seemed to start OK so I believe the cable / plug on no 2 is occasionally breaking down.
The leads on all plugs are a bit short like they have been shorted a number of times so time for new hardware .

That rings alarm bells for a poor running cylinder. Given that your other investigations have not given anything confirmed as probable cause, that partially missing cylinder needs investigating for both ignition and idle circuit fuel supply.

Off to Kefalonia in Greece for three weeks , going around the whole Island staying one or two nights in several places so should see the whole island,

I was looking at horoscopes a couple of months ago and thought it might be useful bit of kit and it appears that I was right , I did a very detailed and meticulous clean of the carbs when I had them off the bike but as I said before I am not ruling anything out.
I was going to change the coils anyway in the future because of the dodgy looking leads so this is a good a time as any to get it done and cross another possibility off the list.

Thanks for the advice regards Ken

If you have a borescope it would be worthwhile looking in there to see if there's anything untoward.  The cheap type for phone, with front & side facing camera are really good value to get decent inspection.

Hope you have a good holiday, anywhere interesting  ?