Hi Guys,

another newbie question.

I noticed a strange pulsing when at constant speed on the last ride that kind of felt like the bike was almost pulling back (kind of like catching a regular large headwind). this would happen at any constant rev and any speed as long as it was constant. My first thought was to check / clean carbs and balance but then I jacked the bike up on centre stand and noticed this strange clunking that was regular enough to be a probable cause. You will notice in both videos its regular but does not happen the same time every revolution and become worse the higher the speed.

first gear

second gear

watch the second clip and you will see the bike visibly jump towards the end.

this could of course be just because the bike is on a centre stand and the swing arm has no pressure.

the sprockets front and back are good as is the chain (not a single stiff link). Chain tension is fine as is the Cush drive and bearings.

The new clutch was just installed along with oil change (by mechanic not me).

Any ideas / suggestions welcomed or if anyone is able to pop their bike on the centre stand and let me know if its the same it would really help cancel it out.

thanks guys !!

 

Ok, I have pulled the sump and clutch basket of, been through each gear and watched as a friend turned the bike over using a wrench attached to the ignition pulse generator nut and everything looked fine.

There was quite a bit of aluminium in the filter and it looked like it had been peeled of rather than chunks. Having had a clutch plate fall to pieces on me a couple of days after buying the bike I have put it down to that.

When putting the bike back together I have realigned the wheel again and the clunk doesnt look as bad so I am going to replace the sprockets and chain any way to see if that resolves the problem.

 

I showed the videos to my guy and he said it could be worn dogs on the gears or other worn gearbox components, causing some slippage and jerking. Hopefully it's just the clutch, keep us all informed.
Good luck!

 

my f4i and 650r makes the same exact sound on rearstands, i've dismissed it as the chain clunking.
mine clunks more because the chain is looser on a rear stand while your swingarm is stretched out on center. i dunno if we're talking about the same sound.
to me it seems like your clutch is slipping for whatever reason.

 

Yeah that's just your chain hitting the swing arm, it'll do that on the stand. Your chain looks pretty rusty in the vid though.


But your probably right about the carbs/air filter needing a clean.

 

thanks guys that was really comforting to know.

I have just had to replace the headers so I took the opportunity to pull the sump off and inspect every cog and gear change with a friend cranking the engine over so I am fairly confident that the gears are ok.

I paid to have the fibre plates replaced on the clutch a couple of days after buying the bike but im still not convinced its right.

I have had the clutch apart again myself and checked each plate including the steels, all of which were flat and not coloured. It all went together nicely but I can feel the pulsing still at constant revs and it certainly has a loss of power now. I'm putting this down to carbs as the exhaust is practically straight through now.

 

If you've put aftermarket headers on then you will need to rejet the carbs to suit, and that should solve the surging issues.

 

Thanks,

Initially I was worried about re-jetting but I have learnt so much over the last month and the guides are so good on here I'm not too worried about it.

I have noticed that after 7k revs it pulls much better and below 3k its not bad so that means needle jet rather than main jet (correct?). Do the standard carbs have adjustable needles or is it just the aftermarket kit. Is this something I could smooth out by first trying the fuel mixture screw ?.